WO2024233799A2 - Stents and stent-grafts having high density support scaffolds - Google Patents

Abstract

An intravascular prosthesis includes a scaffold having a plurality of radially expandable circumferential rings arranged along a longitudinal axis with circumferential gaps therebetween. At least some of the expandable rings comprise cells including struts joined by crowns, and midpoints in the struts of at some or of the cells have a radius R measured from a longitudinal axis of the scaffold, and midpoints in the gaps between circumferentially adjacent cells have a radius r measured from a longitudinal axis of the scaffold. The outer surface of the scaffold maintains a circularity of at least 97% measured as r/R x 100 after the scaffold is radially expanded by up to 200% from the delivery radius, and the scaffold is configured to be radially expanded from a delivery configuration to a deployed configuration in situ in a target blood vessel.

Description

STENTS AND STENT-GRAFTS HAVING HIGH DENSITY SUPPORT SCAFFOLDS

CROSS-REFERENCE TO RELATED APPLICATIONS

[001] This PCT application claims the benefit of U.S. Provisional Nos. 63/586,268 (Attorney Docket No. 32016-733.102), filed September 28, 2023, and U.S. Provisional No. 63/501,454 (Attorney Docket No. 32016-733.101), filed May 11, 2023, the entire contents of which are incorporated herein by reference the entire content of which is incorporated herein by reference. [002] This PCT application will also be a continuation-in-part of U.S. Patent Application No. 18/482,711, (Attorney Docket No. 32016-730.301), filed October 6, 2023, which claimed priority from of PCT/US2023/16449, filed on March 27,2023, which claimed the benefit of U.S. Provisional Nos. 63/324540, (Attorney Docket No. 32016-730.101), filed March 28, 2022, 63/327,326, (Attorney Docket No. 32016-730.102), filed April 4, 2022, and 63/487,773, (Attorney Docket No. 32016-730.103), filed March 1, 2023, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[003] 1. Field of the Invention. The present invention is related generally to medical apparatus and methods, and more particularly, to stents and stent-grafts having scaffold patterns configured for deployment over aneurysms in a patient’s cerebral, cardiac, and peripheral vasculature.

[004] Every year millions of people worldwide suffer strokes. There are two general classes of strokes. Ischemic strokes are caused by a clot or other blockage cutting off the blood supply to the brain. This is the most common type of stroke. Hemorrhagic strokes are caused by bleeding in or around the brain resulting from a ruptured cerebral artery, commonly referred to as a “cerebral aneurysm.” The present invention is particularly concerned with the treatment of cerebral aneurysms but could find use in the treatment of aortic and other vascular aneurysms as well as other vascular conditions that benefit from stent and/or stent-graft placement.

[005] Cerebral aneurysms may be treated by both surgical and less-invasive, catheter-based techniques. Surgical techniques require opening the patient’s skull to form a craniotomy through which the surgeon can insert instruments to operate directly on the patient's brain. In some instances, the brain must be retracted to expose the defective blood vessel. After access is established, the aneurysm may be treated in a variety of ways. For example, the aneurysm may be closed by placing a clip across an opening typically referred to as the “neck” to block arterial blood from entering the aneurysm from the parent vessel. While very effective, such surgical interventions are traumatic and elderly patients and patients with comorbidities are often excluded. [006] Less-invasive procedures have been developed and typically rely on the delivery of stents, stent-grafts, and/or embolic and other vaso-occlusive devices or materials into a target aneurysm. Stents and stent-grafts are intended to bypass or divert flow from entering the aneurysm while vaso-occlusive devices or materials may be used to promote hemostasis or fill an aneurysm cavity entirely. Frequently, coils or other vaso-occlusive devices may be delivered through the wall of a previously placed stent or graft, particularly when treating wide-neck aneurysms.

[007] Cerebral stents and stent-grafts usually comprise self-expanding or balloon expandable scaffolds to hold the device open after implantation. Such scaffolds may be covered with a sleeve of a polymeric or other material to form a stent-graft. Stents and stent-grafts are typically delivered to a target aneurysm through a delivery “microcatheter” delivery catheter.

[008] In order for these stents and stent-grafts to be small enough to pass through microcatheters configured to access remote cerebral blood vessels, the stent’s metal “density” is usually reduced to decrease size and increase flexibility. When reduced density stents are expanded, however, the stent structure bridging the aneurysm neck can become open and a very porous, often failing to provide sufficient isolation to “clot off’ the aneurysm, i.e., the blood in the aneurysm will not clot. In such cases, the stents often must be used in combination with vasoocclusive devices, such as the coils discussed above, to occlude the aneurysm.

[009] For these reasons, it would be desirable to provide stents and stent-grafts having structures with enhanced flexibility while retaining sufficient density when expanded in the cerebral or other vasculature to effectively treat an aneurysm. The stents and stent-grafts should be available in very small diameters and be suitable for both balloon expansion and selfexpansion. It would be further desirable to provide catheters and systems for delivering such stents and stent-grafts to remote regions of the cerebral and other vasculature. At least some of these objectives will be met by different aspects of the present invention.

[0010] 2. Listing of Background Art. Flow-diverting stents and similar devices having a variety of scaffold patterns are described in WO2019/059949; US2010/0204779; US8915954;

US7942920; US7918884; US2013/0123901; US2011/0034991; US10959865; US8764814; US8323760; US8206428; US7625401; US7291165; and US7247166.

SUMMARY OF THE INVENTION

[0011] The present invention provides improved intravascular prostheses having supporting scaffolds which optimize flexibility during delivery and wall coverage after deployment. The scaffolds have specific patterns which are highly flexible when radially constricted in their delivery configurations and which maintain a high wall density after radial expansion to their delivery configurations. While usually combined with covering membranes to form stent-grafts, the scaffolds of the present invention may also have “open” configuration when used, i.e., be free of membranes or other covers when deployed. The intravascular prostheses of the present invent will most often also be configured for balloon expansion but in other instances will be configured for self-expansion.

[0012] In a first aspect of the present invention, the intravascular prostheses will comprise a radially expandable scaffold including a plurality of radially expandable circumferential rings arranged along a longitudinal axis with circumferential gaps therebetween. At least some of the expandable rings comprise cells including struts joined by crowns, and a membrane is optionally secured to the expandable scaffold (typically being molded or laminated with the scaffold). Alternatively, the scaffolds may be free from membranes or any other covers, for example being configured as flow-diverting stents for treating cerebral aneurysms.

[0013] The scaffolds cells of the present invention will typically have a radius R measured from a longitudinal axis of the scaffold to midpoints of the struts on an outer surface of the cell, while midpoints of the gaps between circumferentially adjacent cells will have a radius r measured from the longitudinal axis of the scaffold, where R > r. The outer surface of the scaffold, either the membrane or the bare metal scaffold, maintains a circularity of at least 97% measured as r/R x 100 after the scaffold is radially expanded by up to 200% from the delivery radius, usually being at least 97% measured as r/R x 100 after the expandable supporting structure is radially expanded by up to 100% from the delivery radius, more usually being at least 97% measured as r/R x 100 after the expandable supporting structure is radially expanded by up to 50% from the delivery radius, often being at least 98% measured as r/R x 100 after the expandable supporting structure is radially expanded from the delivery radius, and preferably being at least 98.5% measured as r/R x 100 after the expandable scaffold is radially expanded from the delivery radius.

[0014] In a second aspect of the present invention, the scaffold of the intravascular prosthesis comprises an expandable coil including successive helical turns disposed along a longitudinal axis. The turns of the expandable coil have gaps therebetween and comprise undulating bends and struts which allow the turns to radially expand. Successive turns are inclined at an acute pitch angle in a range from 85° to 89.9°, preferably from 86° to 89° degrees, and more from 86° to 88° relative to the longitudinal axis relative to the longitudinal axis. A membrane is optionally secured to the expandable coil (typically being molded or laminated with the coil), and the expandable coil is configured to be radially expanded from a delivery configuration to a deployed configuration having an axial blood flow passage therethrough. The rotatable impeller is configured to be disposed in the axial blood flow passage therethrough. [0015] In a third aspect of the present invention, the intravascular prosthesis, comprises a scaffold including a plurality of radially expandable circumferential rings arranged along a longitudinal axis with circumferential gaps therebetween, wherein at least some of the radially expandable circumferential rings comprise serpentine or zig-zag structures including struts joined by crowns. A multiplicity of supporting elements each have a base end and a free end, wherein the base ends of the supporting elements are attached to an inner side of the crowns and the free ends are disposed between adjacent struts attached to the crown.

[0016] In preferred instances, the free ends of the supporting elements are recessed within or flush with the circumferential rings and do not protrude into the circumferential gaps prior to radial expansion of the distal tip. Alternatively, at least some of the free ends of the supporting elements may protrude into the circumferential gaps after expansion of the distal tip, and in both cases the supporting elements are usually configured to lie within a cylindrical envelope defined by the scaffold.

[0017] In a fourth aspect, the present invention provides an intravascular prosthesis delivery system comprising an elongate catheter body having a distal end, a proximal end, and an inflatable balloon at the distal end. A balloon expandable intravascular prosthesis having any of the designs described herein, may be mounted over the inflatable balloon.

[0018] In a fifth aspect, the present invention provides an intravascular prosthesis delivery system comprising an elongate sheath having a distal end and a proximal end. A self-expanding intravascular prosthesis having any of the designs described herein, may be is constricted within a lumen at the distal end of the elongate sheath.

[0019] In a sixth aspect, the present invention provides methods for delivering intravascular prostheses into a patient’s vasculature. An intravascular prosthesis as in any one of the proceeding claims may be coupled in its radially constricted configuration to a distal end of a delivery device. The distal end of the delivery device is positioned at a target aneurysm within a patient’s vasculature, and the intravascular prosthesis is deployed to span the target aneurysm. In some instances, the intravascular prosthesis is deployed with an inflatable balloon. In other instances, the intravascular prosthesis is released from radial constraint within a delivery sheath to self-expand at the target aneurysm.

[0020] In particular instances, the intravascular prostheses and methods of the present invention may comprise a membrane which is non-porous.

[0021] In particular instances, the intravascular prostheses and methods of the present invention may comprise a membrane which is porous.

[0022] In particular instances, the intravascular prostheses and methods of the present invention may comprise a membrane which is perforated. [0023] In particular instances, the intravascular prostheses and methods of the present invention may comprise a membrane which extends fully over the scaffold or coil.

[0024] In particular instances, the intravascular prostheses and methods of the present invention may comprise a membrane which extends over only a central portion of the scaffold or coil leaving terminal end regions uncovered.

[0025] In particular instances, the intravascular prostheses and methods of the present invention may comprise a membrane which carries a pharmaceutically active agent.

[0026] In particular instances, the pharmaceutically active agents may comprise one or more anti-platelet agent, anti-fibrotic agents, anti-inflammatory agents, anti-proliferative agents, antiglaucoma agents, immune suppressive agents, anti-diabetic agents, anti-viral agents, anti- angiogenic agents, anti-VEGF agents, serine protease, complement activation inhibitor, antihistamine agents, or combinations thereof.

[0027] In particular instances, the pharmaceutically active agents may comprise a factor Xa inhibitor, a factor Ila inhibitor, or a combination of a factor Xa inhibitor and a factor Ila inhibitor, optionally combined with one or more additional pharmaceutical agents, for example as listed above.

[0028] In a first aspect, the present invention provides an aspiration catheter, such as but not limited to a cerebral aspiration catheter, a coronary aspiration catheter, an arterial aspiration catheter, or a venous aspiration catheter, which comprises a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending therebetween. The aspiration catheter has an expandable distal tip with a central passage (or a passage) contiguous with the aspiration lumen of the tubular catheter body. An expandable supporting structure is attached to, embedded within, or otherwise coupled to the expandable distal tip of the tubular catheter body. In some instances, the expandable supporting structure may be attached to an outer or inner surface of an expandable membrane, but more often will be embedded or laminated within an expandable membrane, such as a polymeric membrane comprising one, two, three or more layers and being composed of one, two, three or more polymeric materials or other materials.

[0029] The phrase “distal tip” as used herein and in the claims refers to a length or region at the distal end of the aspiration catheter. The distal tip will typically be constructed differently than a proximal region or shaft of the aspiration catheter. In particular, the distal tip will typically be configured to expand from a small diameter or from low-profile configuration or from as delivered configuration or from a delivery configuration to a large diameter or to a larger configuration or to an expanded configuration or to a deployed configuration, or to an enhanced extraction configuration, which has a larger clot aspiration force or clot extraction force when a vacuum is applied at a proximal end of the aspiration catheter and the distal tip is engaging a clot, wherein the expanded (or deployed) configuration of the distal tip remains substantially the same (or remains substantially expanded or deployed) when the vacuum is applied, thereby resisting collapse, typically being balloon expandable but sometimes being self-expanding. In contrast, the proximal region or shaft will typically have a fixed diameter along its length. The fixed diameter of the proximal region or shaft may be constant or may vary along its length. The distal tip in the as delivered configuration maybe a first clot extraction configuration while the expanded configuration maybe a second clot extraction configuration wherein the second clot extraction configuration has a larger extraction force than the first clot extraction configuration. In other examples, the expanded configuration maybe the clot extraction configuration or maybe the preferred clot extraction configuration as it typically has enhanced clot extraction force. The distal tip typically terminates at the distal end of the aspiration catheter.

[0030] The supporting structure is typically in the form of a scaffold and is configured to permit radial expansion of the expandable membrane, typically by the application of a radially outward expansion placed within the supporting structure using a balloon or other expandable member, and is configured to enhance collapse resistance of the expandable membrane, particularly when the distal tip is engaging a clot (or blocked or plugged with clot) and a vacuum is being applied through the aspiration lumen, i.e., resist or prevent collapse of the expandable membrane or prevent a decrease in the lumen configuration of the expandable membrane, after expansion of the expandable supporting scaffold to the expanded configuration, or the supporting scaffold substantially maintain the expanded lumen configuration of the expandable membrane, when a vacuum is applied at a proximal end of the aspiration lumen while engaging a clot). [0031] The supporting structure typically comprises a plurality of radially expandable rings arranged along a longitudinal axis with gaps therebetween (forming circumferential gaps between adjacent rings). The radially expandable rings will typically comprise circular, square, rectangular, oval, helical or other looped ring elements, where the looped ring elements are configured to non-elastically elongate (along their curved lengths) to permit circumferential expansion of the distal tip. Exemplary ring elements can be formed as serpentine, zig-zag ring, box (square or rectangular), diamond, or other patterns comprising bends that non-elastically open in response to a radially outward force supplied by a balloon or other expandable deployment member or structure. Exemplary rings maybe open cell design, closed cell design, combination of open and closed cell designs, or other. Exemplary ring designs maybe formed from a tubular body, a bent wire, a patterned sheet rolled up into a tube, or printed, or other. [0032] Exemplary open cell supporting structures may comprise serpentine and zig-zag ring patterns comprising struts joined by crowns, where the crowns comprise the “bends” which non- elastically open to allow radial and circumferential ring expansion. While every circular or circumferential ring may have an even or odd number of crowns and struts, each side or face of the ring may have even or odd number of crowns. Each ring (including terminal ring(s)) preferably has at least 14,17, 12, 26, 30, 32, 34, 38, 40, 42, 60, 80, 100, 120, 140, 161, 160, 180, 200, or more crowns as counted on both side/face of the ring. For example, when a ring is referred to as having 14 crowns, the total number of crown when counting both sides or faces of the ring is 14. Higher crown numbers of 60, 80, 100, 120, 1400, 1600, 180, 200, and 400, and above are preferred when the supporting structure does not include additional supporting elements or when the supporting structure cells within a ring, or cells within a plurality of rings, or cells within each ring include a few supporting elements or include at least some but not all supporting elements, as described below. Fewer crown numbers, such as 14, 22, 26, 30, 32, 34, 38, 40, 42, 48, 60, and 80, are usually sufficient when the supporting structure includes at least some, or substantial number of supporting elements per ring, per at least some adjacent rigs, or per each ring of the expandable tip. The number of crowns per ring, or per at least some adjacent rings, or per the rings along the length of the expandable supporting structure is configured to allow the expandable supporting structure to expand to the expanded configuration.

[0033] It has been found that both (1) a higher number of crowns or other bends in the absence of supporting elements and (2) a lower number of crowns in combination with supporting elements will enhance circularity of the rings in the distal tip in both the as delivered configuration and the as expanded configurations, maximizing available aspiration lumen area. The phrase “number of crowns or bends per ring” refers to the total number of crowns or bends as counted in a single 360° turn about each ring. While the number “number of crowns or bends per ring” will usually be constant for each ring in an open cell supporting structure, in some instances the number may vary from ring to ring. Enhanced circularity of the distal tip (expandable supporting structure and expandable membrane) in the expanded configuration can increase the aspiration lumen area, increase the vacuum force, resist lumen collapse and deformation when a vacuum is applied at a proximal end of the aspiration lumen and the distal tip is engaging a clot (or when the distal tip is blocked or plugged with clot or other substances). Furthermore, enhanced circularity resist deformation and/or kinking of the expandable distal tip in the as delivered configuration when the catheter is advanced into the vasculature. Maximizing circularity of a ring maybe further enhanced by having a small cell period and/or small cell amplitude. In a preferred example, the expandable supporting structure comprises a plurality of rings wherein at least some rings, preferably substantially all rings are configuration to have a large number of crowns, a small cell period, and a small cell amplitude., to have an enhanced circumferential circularity. [0034] In a preferred ring pattern, such as a serpentine patterns for example, comprising struts joined by crowns, the ratio of (1) the number of bends, e.g. crowns, crowns per ring to (2) the circumference (perimeter) of the ring measured in millimeters (mm) is typically at least 3 crowns or bends per mm of circumferential length, frequently being at least 4 crowns or bends per mm of circumferential length, usually in a range from 3 to 18 crowns or bends per mm of circumferential length, typically from 4 to 15 crowns or bends per mm of circumferential length, and most preferably ranges from 4 to 12 crowns or bends per mm of circumferential length. An increased number of crowns or bends or a high ratio of crown or bends per circumference length in each ring (or in some instances in most rings or in other instances in a plurality of rings) improves circularity of the distal tip (including the expandable supporting structure and the expandable membrane) in the expanded configuration, increases aspiration lumen area or maximizes lumen area, enhances vacuum force, and resist collapse of the distal tip when a vacuum is applied to the proximal end of the aspiration lumen and the distal tip is engaging a clot. In addition, the higher number of crowns or crowns to circumference length ratio increases the resistance to collapse of the distal tip comprising the expandable membrane and expandable supporting structure when a vacuum is applied at a proximal end of the aspiration lumen and the distal tip is engaging a clot (or blocked with clot or other substances). Furthermore, having a small cell period, enhances circularity further. In addition, having a small cell amplitude may further enhance circularity.

[0035] For example, in embodiments comprising supporting structure comprising supporting elements, 40 crowns per ring in the as delivered 2 mm outer diameter expandable tip will typically be sufficient to maintain circularity after expansion while 60, 80, 100, or more crowns per ring may be needed to provide equivalent support with supporting structures which do not include supporting elements. Thus, the number crowns per ring in as delivered supporting structures having a 2mm outer diameter for example including supporting elements will typically range from 30 to 75, preferably from 40 to 75, and more preferably from 50 to 60. The range for rings not having supporting structures will be from 60 to 150, preferably from 70 to 120, more preferably from 100 to 120. The ratio of number of crowns to circumference in mm for embodiments including supporting elements will range from 3 to 10, preferably from 4 to 9, more preferably from 4.5 to 8, and most preferably from 5 to 7, while the ratio of crown number to circumference (measured in mm) for embodiments without supporting elements will range from 5 to 18, preferably from 6 to 12, more preferably from 8 to 12, and most preferably from 10 to 12.

[0036] Exemplary closed cell supporting structures may comprise “box” structures joined end- to-end by links in circular, helical or other patterns. Typically, the boxes will be joined by circumferential links to form circular rings which are in turned joined by axial links to form the supporting scaffold or other supporting structure. Alternatively, the circumferential links may be arranged in a helical or spiral pattern to form a continuous series of rings, preferably without additional axial links or attachment points.

[0037] While the boxes will typically be square, diamond, or rectangular, boxes may have any closed polygonal structure which includes a plurality of straight (or sometimes curved) sides joined by bends. In some instances, circular and oval closed shapes could also be considered boxes within the scope of the present invention. Such box structures will be configured to circumferentially elongate (expand) when a radial opening force is applied inside of the supporting structure in the distal tip of an aspiration catheter.

[0038] In a preferred example, the expandable distal tip comprising the expandable supporting structure has an outer diameter in the as delivered configuration of about 1 mm, 2 mm, 3 mm, 4 mm, or of about 5 mm, or the expandable distal tip comprising the expandable supporting structure has an outer diameter in the as delivered configuration ranging from 1mm to 5mm. In other examples, the distal tip comprising the expandable supporting structure has an outer diameter in the as delivered configuration of about 7 mm, 8 mm, 9 mm, or of about 10 mm. Typically, the distal tip has a cylindrical shape in the as delivered configuration. In some other examples, the distal tip may have other shapes such as funnel, cone, an oblong, oval, or other shapes, in the as delivered configuration. In yet another example, the distal tip comprising the expandable supporting structure wherein the distal tip has cylindrical shape, oblong shape, oval shape, cone shape, funnel shape, or other shapes, in the expanded configuration, wherein the distal tip outer diameter in the expanded configuration ranges from 2 mm to 1 0mm, preferably ranges from 3 mm to 8 mm, and more preferably ranges from 3 mm to 7 mm. The outer diameter of the distal tip may vary along the length or about the circumference of the distal tip or may be fixed or constant along the length or about the circumference of the distal tip.

[0039] In some instances, the scaffold or other supporting structure will also include supporting elements, which will help support spaces which open in in the support structure as the support structure is being expanded. For example, in a support structure including serpentine rings comprising crowns and struts, as the rings expands, the struts will spread apart and leave unsupported spaces or gaps therebetween. The gaps between adjacent rings will also be unsupported spaces, both before and after the supporting structure is radially expanded. The membrane will lack support in those gaps, and the circularity and/or crush strength (crush resistance) of the expanded distal tip will both decrease. Additionally, such unsupported regions of the membrane will be at increased risk of invagination (collapse or partial collapse of the membrane and/or expandable supporting structure) when a negative pressure is applied to the aspiration lumen of the catheter when a clot is engaged, particularly when the open distal tip is partially or totally occluded with clot, or when the expandable tip is delivered to the vasculature in the as delivered configuration.

[0040] The supporting elements of the present invention will be configured to fill as many of the open space within a ring. In contrast, the spaces or gaps between axially adjacent rings will preferably be free from supporting elements (although axial links and other portions of the supporting structure will usually be present in some examples while in other examples the spaces or gaps between axially adjacent rings maybe free from any supporting elements or attachment points and free from any portions of the supporting structures). The spaces between adjacent rings should have minimum number of supporting structure, if any, in order to enhance flexibility, particularly in the unexpanded delivery configuration.

[0041] In certain examples, in the unexpanded, delivery configuration, the supporting elements of the present invention will cover or fill from 50% to 98% of the unsupported area within each ring, preferably from 65% to 95%, more preferably from 75% to 95%, and most preferably from 80% to 95%. In contrast, in the expanded configuration (i.e., after deployment in a blood vessel), the supporting elements of the present invention will cover or fill from 10% to 85% of the unsupported area within each ring, preferably from 15% to 85%, more preferably from 20% to 85%, and more preferably from 40% to 85%.

[0042] Preferred supporting elements will be “cantilevered” from the ring and be configured to fill or to support the openings or gaps within an “axial width” of a ring, usually remaining outside of the gaps and spaces between adjacent rings in order to support the distal tip after it has been radially expanded, without significantly reducing flexibility of the distal tip as it is being advanced into the vasculature, or without reducing flexibility of the distal tip as it is being advanced into the vasculature, or while maintaining the flexibility of the distal tip as it is being advanced into the vasculature. Exemplary supporting element having a base (proximal) end and a free (distal) end. The base end is usually attached to one of the radially expandable rings (e.g., to a ring structural element, such as a crown or a strut) and the free end is often oriented toward the gap between adjacent rings, usually not extending into the gap between adjacent rings in the as delivered configuration. In a preferred example, the expandable supporting structure comprises a plurality of supporting elements within each ring each having a width, a length, and thickness, sufficiently to support unsupported spaces (or region) within said ring, to prevent collapse or invagination (partial collapse) of the unsupported region, when a vacuum is applied to extract an engaged clot at the distal end of the aspiration catheter. In another example, the expandable supporting structure comprises a plurality of circumferential rings wherein at least some rings comprise a plurality of supporting elements configured to resist collapse or resist invagination of the unsupported region when a vacuum is applied at a proximal end and a clot is engaging the distal end of the aspiration catheter. In yet another example, the expandable supporting structure comprises a plurality of circumferential rings wherein at least some rings comprise at least some supporting elements configured to resist collapse or resist invagination of the unsupported region when a vacuum is applied at a proximal end and a clot is engaging the distal end of the aspiration catheter.

[0043] In some cases, the supporting elements may extend into an adjacent gap between adjacent rings even prior to radial expansion of the distal tip, but preferably most or all of the supporting elements are configured to be recessed (or confined) within an axial width of the ring (or within an amplitude of a ring cell) prior to ring expansion and will extend further, protrude further, or emerge towards the adjacent gaps between adjacent rings or into the adjacent gaps between adjacent rings as the distal tip is radially expanded (or only after radial expansion of the distal tip, or during the radial expansion of the distal tip). It has been found that presence of the supporting structures in the gap between adjacent rings prior to distal tip expansion will reduce tip flexibility during advancement in the vasculature prior to distal tip deployment. Such loss of flexibility is undesirable.

[0044] The use of such “cantilevered” supporting elements as “supporting of unsupported regions or gaps located within rings axial width” which are deployed to enhance support of the expandable membrane after deployment of the distal tip without increasing stiffness of the distal tip during delivery (introduction and advancement) of the aspiration catheter into and through the patient’s vasculature. Use of the supporting elements also allows increased expansion of the distal tip (thus increasing the available aspiration lumen diameter) while resisting collapse when a vacuum is applied at a proximal end of the aspiration lumen. In another example, the supporting elements deploy (or protrude, or extend further) towards a gap between two adjacent rings, or deploy into a gap between two adjacent rings, as the distal tip is expanded (or after the distal tip expansion) to enhance support of the expandable membrane after deployment of the distal tip without increasing stiffness of the distal tip during delivery (introduction and advancement) of the aspiration catheter into and through the patient’s vasculature.

[0045] The supporting elements may have various shapes and configurations such as I, T, U, M, Z, curved shaped, straight shaped, or other shapes and configuration to support or to enhance support of the unsupported segments of the expandable membrane, preferably without increasing stiffness of the distal tip. The free end may have a flat shape, rounded shape, spherical shape, or other shapes. The width of the supporting elements maybe the same along the length of the supporting elements or different. The supporting elements may be tapered, either increasing or decreasing in width in a direction from the attached base end to the free distal end.

-l i[0046] In a preferred instance, the dimensions of the supporting elements will preferably be selected to fill or occupy as much of the unfilled spaces or gaps within any given ring (but usually not between adjacent rings) in the supporting structure which may exist prior to expansion. For example, gaps between struts joined by crowns on a ring may be filled with supporting elements cantilevered from the inside curve of the crown, as illustrated in many embodiments herein. The cantilevered supporting elements can be patterned fill virtually the entire space between the struts, leaving only cuts or very small separating lines therebetween. By maximizes the area of the supporting element prior to expansion, coverage of the gap which is created after expansion is also maximized between the struts after the ring is expanded. In a preferred example, the width of the supporting elements at the attached base end is approximately equal to or larger than the width of the structural element (e.g., strut, crown, or link) to the location at which the supporting element is attached.

[0047] While the supporting elements and the expandable supporting structure are typically formed from the same material, in some instances they be formed from different materials or types of materials, e.g., (1) one may be formed from a metal and the other from a polymer or (2) one may be formed from a metal or a polymer and the other from a different metal or a different polymer.

[0048] In another preferred example, the supporting elements are recessed in space between structural elements of the rings, e.g. in space between struts joined by crowns, so that the distal ends of said supporting elements do not extend substantially beyond peaks of adjacent crowns or other structural element into the gaps between adjacent rings in the as delivered configuration. [0049] In specific examples, the supporting elements may have one base end and one free end, two free distal ends, three free distal ends, or more.

[0050] In another example, the supporting elements may have two or more base ends attached each to one or more structural element on one ring (the same ring). Such supporting elements may have one, two, three, or more distal free ends.

[0051] In another example, the supporting elements may be bisected to have at least two base ends, each base end being attached to a different structural element on a single ring. The base ends of the supporting element may be attached to an axially inner or to an axially outer surface of a ring or of a ring’s structural elements comprising a crown, a strut, or a link.

[0052] In specific examples, the radially expandable rings are arranged within a cylindrical “envelope” prior to expansion. The cylindrical envelope is a virtual space having an inner generally cylindrical surface and an outer generally cylindrical surface and an annular volume therebetween, where the radially expandable rings will be dimensioned and arranged to lie within this space prior to expansion. Usually, the supporting elements are also configured to lie within this virtual cylindrical envelope prior to expansion of the rings. The cylindrical envelope may have a diameter greater than, equal to, or smaller than that of the tubular catheter body prior to expansion.

[0053] In specific examples, the distal tip of the expandable supporting structure may be configured to expand into a cylinder, a cone, or a combination thereof after expansion to an expanded configuration. In a preferred example the distal tip of the expandable supporting structure maybe configured to expand from a cylindrical configuration to an expanded cylindrical configuration, to an expanded cone shaped configuration, or to an expanded cone shaped distal tip configuration to maximize or to enhance the suction force when a vacuum is applied at a proximal end of the aspiration lumen. In another example, the distal tip of the expandable supporting structure maybe configured to expand from a cylindrical configuration in the delivery configuration to a substantially cylindrical shaped configuration after the expandable supporting structure is expanded to an expandable configuration, wherein the expanded configuration is larger than the delivery configuration, or wherein the expanded configuration is larger than the as delivered configuration by a range from 1.1 to 4 times larger, preferable 1.3 to 3 times larger. In yet another example, the distal tip of the expandable supporting structure is configured to expand from a cylindrical configuration to an expanded cone shaped configuration, at a proximal segment of the distal tip, and is continuously connected to an expanded cylindrical shaped configuration distal to the expanded cone shaped configuration. In still other configurations, the expanded configuration may be a combination of a long conical proximal base (there will usually be at least a short conical portion at the proximal end) attached to the proximal end of the shaft and a distal cylindrical portion. A number of specific configurations are illustrated in the figures. [0054] In specific examples, the expandable supporting structure is configured to expand in response to expansion of a balloon catheter within the expandable supporting structure. The balloon catheter maybe configured to be delivered together with the aspiration catheter comprising the expandable supporting structure at the distal end, typically said balloon catheter being delivered together along with the aspiration catheter, within the aspiration lumen of the aspiration catheter, wherein after the distal end of the distal tip of the aspiration catheter is positioned adjacent to a clot, the balloon catheter is expanded to expand the expandable supporting structure to an expanded configuration, and is then deflated and withdrawn out of the aspiration catheter prior to applying a vacuum at a proximal end of the aspiration catheter to extract the clot. In another example, the balloon catheter is delivered to the distal end of the aspiration catheter after the aspiration catheter is delivered to and positioned adjacent to a clot, wherein the balloon catheter is advanced through the aspiration catheter until the balloon reaches the expandable distal tip segment or reaches the expandable distal tip, then it is expanded to expand a distal tip segment of the aspiration catheter and is then deflated and removed from the aspiration catheter and a vacuum is applied at a proximal end of the aspiration catheter to remove (extract) the clot. In another example, an expansion catheter having an expandable member at a distal end of said catheter, said expandable member is expanded, to expand an expandable distal tip comprising an expandable supporting structure (scaffold) and an expandable membrane, wherein the distal tip is incorporated into or coupled to the distal end of an aspiration catheter wherein the expandable member comprises a balloon, a scaffold, a cage, or other structure capable of expanding to expand the expandable supporting structure from an as delivered configuration to an expanded configuration. The expandable member maybe polymeric, metallic, or other material wherein said member being expandable from an as delivered configuration, a crimped configuration, or a deflated configuration to an expanded configuration. While the distal tip may be fully expanded along its entire length, often only a portion of the length of the distal tip may be expanded by the balloon or other expandable member depending on the patient anatomy or other circumstances. The portion of the distal tip that is expanded can be controlled by adjusting the length of the balloon present in the distal tip during expansion and/or selecting an expansion balloon having a different length.

[0055] In a preferred example, the expandable supporting structure of the distal tip of the aspiration catheter is formed from a deformable material, preferable plastically deformable material. In a preferred example, the expandable supporting structure is formed from a plastically deformable metal or metal alloy. In a specific example, the expandable supporting structure is formed from a metallic material comprising stainless steel alloy, cobalt chrome alloy, platinum chromium alloy, or other metal or metal alloy.

[0056] The expanded shape of the supporting structure will usually be determined by the shape of the balloon or other expanding structure, i.e., expansion of a cylindrical balloon within the plastically deformable supporting structure will impart a cylindrical shape to the distal tip while expansion of a conical balloon will impart a conical shape to the distal tip.

[0057] In some less preferred examples, the expandable supporting structure may be configured to self-expand when released from radial constraint. The radial constraint may be positioned over the expandable supporting structure. In other example, the radial constraint may be positioned within the expandable supporting structure (inner lumen) and is configured to release the expandable supporting structure in-vivo, to allow expansion of the expandable supporting structure. The expandable supporting structure in one example is formed from a shape memory material such as NiTi / nitinol or other shape memory material.

[0058] The supporting elements may have any one or more of a variety of shapes and attachment locations on the expandable structure. For example, the supporting elements may extend, in an axial direction to the radially expandable rings, towards the gap between adjacent rings, or extend into the gap between adjacent rings. In other examples, the supporting elements may extend in a circumferential direction to the radially expandable rings, typically attached to the outwardly curved surfaces of the crowns (peaks), extending circumferentially into an adjacent gap. In other examples, the supporting elements may extend in an axial direction to the radially expandable rings into the gap contained within or bounded by a ring’s axial width or is contained within or bounded by the space between structural elements of each ring or of said ring, typically attached to the curved surfaces of the crowns. In still other examples, at least some of the supporting elements may comprise any one or more of linear and/or non-linear segments, may have expanded tips (forming contact pads as discussed hereinafter) at the free end. In some examples, the supporting elements may branch into two or more segments in a direction toward the free end. The supporting elements may have the same or different lengths or widths. In some specific examples, the supporting elements may have a length equal to or less than a length of an adjacent strut length in the as delivered configuration. In other examples, the supporting elements may have a length equal to or less than the ring cell amplitude in the as delivered configuration, or less than 1 time the ring cell amplitude in the as delivered configuration. In yet another example, the supporting elements may have a length equal to or less than the length of the ring period in the as delivered configuration. In other examples, the supporting elements may have a length greater than the ring cell amplitude only in the expanded configuration.

[0059] In some examples, the supporting elements are attached to one or more of axial inner crown regions, axial outer crown regions, struts, mid strut, or attached to axial or circumferential links.

[0060] In some preferred examples, at least some of the radially expandable rings comprise a serpentine, zigzag, box, diamond, or other pattern including struts joined by crowns, and at least some of the adjacent rings are joined in one or more locations by axial links or attachment points using soldering, bonding, or fusing crown on adjacent rings for example, or as patterned. Alternatively, at least some of the adjacent rings maybe joined end-to-end in a helical arrangement free from axial links or attachment points, and wherein preferably the amplitude on the at least some rings are fixed within each ring. In a preferred example, at least two adjacent rings, or at least some adjacent rings, of the expandable supporting structure distal tip have no more than two links or two attachment points joining said at least two adjacent rings (or joining said at least some adjacent rings). In another example, the comprises a plurality of circumferentially expandable rings including struts joined by crowns, wherein one or more adjacent rings being axially separated by gaps and being unconnected, typically the one or more unconnected adjacent rings are located at the distal end of the distal tip of the aspiration catheter, and are held together by an expandable membrane attached to the one or more adjacent unconnected rings providing the distal tip enhanced flexibility in the as delivered configuration and allowing the one or more rings to expand from an as delivered configuration to an expanded configuration. In a preferred example, an expandable supporting structure comprising a plurality of adjacent expandable rings wherein along a length of said expandable structure, adjacent rings have two or less connections or attachment points joining said adjacent rings, preferably adjacent rings have one connection or attachment point joining said adjacent rings, wherein the length is the entire length of the expandable structure, or a segment along the axial length of the expandable structure, wherein the segment comprises two or more rings. In yet a preferred example, the expandable supporting structure comprising a plurality of adjacent rings joined end to end in a helical arrangement to enhance flexibility of the aspiration catheter to navigate tortuous anatomy in the as delivered configuration. The adjacent rings in this example are not joined by links or attachment points on the adjacent rings, and the at least some adjacent rings each has fixed (or constant or same) ring cell amplitude, preferably all the at least some rings have the fixed (or constant or same) ring cell amplitude. In this example, at least some rings maybe patterned into an open cell pattern, a closed cell pattern, or a combination of open and closed cell pattern along a length of the expandable scaffold.

[0061] Alternatively, in another example, at least some of the adjacent rings in the expandable supporting structure may be joined end-to-end in a helical arrangement. Such helical arrangements will typically comprise a “smooth” helix free from additional curves or bends, i.e. a curve formed over on a conical or cylindrical surface that would become a straight line if the surface were unrolled into a plane. In other instances, one, two, three or more additional bends, curves or other secondary non-linearities can be superimposed over the helical rings to enhance bendability of the expandable structures, particularly in their crimped or reduced diameter configurations during delivery. Such one, two, three or more additional bends, curves or other secondary non-linearities may be formed from an expandable supporting structure or a nonexpandable structure. In a specific preferred example, the expandable supporting structure forms a helical coil.

[0062] In other preferred examples the expandable membrane may comprise an elastic membrane, or an in-elastic membrane (stretchable membrane). The elastic and/or in-elastic membrane may comprise one or more elastomers, polymeric material, or other material. In a preferred example, the expandable membrane is selected from a group consisting of NeuSoft UR862A, NeuSoft UR852A. NeuSoft UR842A, NeuSoft NEU 455-50A, NeuSoft™ 596-50A, NeuSoft NEU 455-55A, NeuSoft NEU 455-60A NeuSoft NEU 455-65A, Tecothane AR-62A, Tecoflex EG 80A, Tecoflex EG 85A, Tecoflex EG-93A, Tecoflex TT-1074A, Tecoflex TT- 1085 A Tecoflex TT- 18095 A, Elastollan S 50 A 15SPF Elastollan S 60 A 10W Elastollan S 60 A 10WH, Pellethane 2103 -70 A, Pellethane 70 A, Pellethane 2363 -80 A, Estane 2103 -70 A, ReZithane Rx50A, Texin RXT 70A, Chronoflex C 80A-Q, Chronoflex AL 75A-Q, Chronoflex C 80A-Q, Polyblend 1100-75A, ResMart Ultra TPU 60A , ResMart Ultra TPU 70A, ResMart Ultra TPU 85A, ResMart Ultra TPU 90A, ResMart Ultra TPU 95A, Ecoflex 00-30, Ecoflex 00-20, Ecoflex 5A, Dragon Skin 20, Pebax 2533, Pebax 3033, chronoprene, chronothane, chronosil, polyethylene, such as LDPE, HDPE, Ultra HMWPE, or the like, Pebax such as Pebax 2533, Pebax 3533, Pebax 4033, Pebax 4533, Pebax 5533, Pebax 7233 or the like, Nylon such as Nylon 12, Nylon 6/6 or Nylon 6, Polyurethanes such as Pellethane 2363-55D, Pellethane 2363-65D, ResMart Ultra TPU 64D, ResMart Ultra TPU 72D, Fluoropolymers such as PTFE, Poly(vinylidene fluoride-co-hexafluoropropylene), Poly(vinylidene fluoride-co- hexafluoropropylene), Fluorinated ethylene propylene, Polychlorotrifluoroethylene, or the like, or combination thereof, or other elastomers, polymers, or other material.

[0063] In one example, the expandable membrane is comprised of a polymeric elastic membrane which may have isotropic properties, but in other instances may have anisotropic properties, for example the elastic membrane may have a higher elasticity in a circumferential or radial direction than in an axial direction.

[0064] In some instances, the expandable membrane may be formed by heat shrinking over or onto the expandable supporting structure such as a scaffold. In other instances, the expandable membrane may be formed by laminating the expandable supporting structure such as a supporting scaffold between two or more layers of the polymeric material such as elastomer(s) material, elastomer(s) on an outer surface and an inelastic/ stretchable polymeric material on an inner surface of the expandable structure, stretchable/inelastic material on both outer and inner surface of the expandable structure, or a stretchable material on the outer surface and an elastic material on the inner surface of the expandable structure. For example, the two layers of elastomer(s), two layers one elastic and one stretchable, or two layers both stretchable may be bonded to each other over (sandwiching) the expandable supporting structure such as a supporting scaffold so that there is a seal between or bonding of the two layers as well as said two layers are sandwiching, bonding to, and/or adhering to the scaffold or other expandable structure. In another example, the expandable membrane comprising a polymeric or other material configured to stretch and/or expand from an as delivered configuration to an expanded configuration, wherein the material is configured to expand from said as delivered configuration to a larger configuration ranging from 1.1 to 5 times larger than the as delivered configuration. The expandable membrane is configured to have axial, radial, and/or circumferential stiffness to allow radial flexibility while maintaining axial push transmission. The expandable membrane is configured to allow radial expansion of the expandable supporting structure and/or allow axial movement of the expandable supporting structure rings as the rings are being expanded from the as delivered configuration to an expanded configuration.

[0065] In a preferred example, an aspiration catheter, which comprises a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending therebetween. The aspiration catheter has an expandable distal tip with a central passage contiguous with the aspiration lumen of the tubular catheter body, said expandable segment comprising an expandable supporting structure is attached to or embedded within an expandable membrane. In one preferred example, the expandable supporting structure is patterned from a tube, a bent wire, or rolled up patterned sheet. The tube, rolled up sheet, or bent wire in the preferred example are patterned into said expandable supporting structure being expandable from as delivered configuration to an expanded configuration. In some other preferred examples, an aspiration catheter, which comprises a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending therebetween. The aspiration catheter has an expandable distal tip with a central passage contiguous with the aspiration lumen of the tubular catheter body. An expandable supporting structure is attached to or embedded within the expandable distal tip of the tubular catheter body, the tubular catheter body may be reinforced with a reinforcement structure over at least a portion of its length, proximal to the expandable tip, by one or more of a coil, a scaffold, a scaffold with supporting features, or other means. In some instances, at least a portion of the catheter body reinforcement structure comprising one or more of a coil, scaffold, or braid that may be formed continuously with the expandable supporting scaffold or other expandable supporting structure of the expandable tip. In a preferred example, the reinforcement structure and the expandable scaffold or other expandable supporting structure are formed from a patterned tube. In other example the reinforcement structure and the expandable scaffold or other expandable supporting structure are formed from a bent wire. In other instances, the reinforcement structure in the catheter body may be separately formed from the supporting scaffold of the expandable distal tip and are then coupled or joined together by one or more of solder, fusing, bonding, or weaving the structures together, overlapping them over a length segment at their interface.

[0066] In another example, an aspiration catheter, which comprises a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending therebetween. The aspiration catheter has an expandable distal end, with a central passage contiguous with the aspiration lumen of the tubular catheter body, said expandable distal end comprising an expandable supporting structure attached to or embedded within an expandable membrane. In one specific example, the expandable distal end comprising the expandable supporting structure has a length ranging from 0.5mm to 50cm, preferably ranging from 1cm to 25cm, and more preferably ranging from 2cm to 10cm. In yet another example, the expandable distal end may have a length spanning substantially the length of the aspiration catheter. In specific examples, the expandable distal end may have a length ranging from 50cm to 150cm. In a preferred example, the expandable distal end comprises an expandable distal tip wherein the distal tip comprises a segment of the expandable supporting structure attached to or embedded within an expandable membrane. In some specific examples, the expandable distal tip segment includes the expandable distal end segment. In some other instances, the expandable distal tip is the same as the expandable distal end.

[0067] In other preferred examples, at least some of the multiplicity of supporting elements may have their base ends each attached to a strut. In other preferred embodiments, at least some of the multiplicity of supporting elements may have their base ends each attached to either the inner curved surface or the outer curved surface of a crown. The supporting elements may be extending or oriented axially, circumferentially, or at other angles or directions relative to the supporting scaffold or other expandable supporting structure, supporting scaffold rings, or structural elements of the scaffold rings.

[0068] In a second aspect, the present invention provides an aspiration catheter having an alternative expandable supporting structure design. The alternative aspiration catheter comprises a tubular catheter body having a proximal end, a distal end, and a lumen extending therebetween. The expandable supporting structure is attached at or is incorporated into the distal end or to the distal tip of the tubular catheter body and has a central passage contiguous with the lumen of the tubular catheter body, and the expandable supporting structure includes an expandable membrane and an expandable scaffold or other expandable supporting structure configured to radially expand the expandable membrane. The expandable membrane is typically elastically expandable, and the expandable scaffold or other expandable supporting structure is typically inelastically expandable, i.e., the scaffold plastically deforms to and maintains an expanded shape and size in response to radial expansion by a balloon or other radial expansion tool. In this way, the expanded supporting structure “supports” the membrane in an expanded configuration.

[0069] In other instances, the membrane could be plastically or otherwise inelastically expandable while the supporting structure is elastic or inelastic, but such embodiments are generally not preferred.

[0070] The expandable supporting structure may comprise a plurality of radially expandable rings arranged along a longitudinal axis, wherein at least some of the radially expandable rings comprise “expandable cells” having bends which can plastically deform to allow radial opening of the ring. The cells may have an “open” configuration, such as U-shaped cells in serpentine rings and a V-shaped in zig-zag rings; squares, rectangular, or other regular or irregular polygons with one or more missing sides; and O-shaped cells. Alternatively, cells may have a “closed” configuration, such as diamond shaped, or box-shaped cells in boxed rings, wherein the box shape can be rectangular, square or other or other regular or irregular polygonal shapes.

[0071] Supporting elements may be positioned inside or outside of an open cell. For example, the base of a cantilevered supporting element may be attached to the inside bent surface of a crown and positioned between adjacent struts in a U-shaped, V-shaped, or O-shaped open cell. Alternatively, the base of a cantilevered supporting element may be attached to an outside bent surface of a crown and extend away from struts into a gap adjacent a U-shaped, V-shaped, or O- shaped open cell.

[0072] Supporting elements may also be positioned inside or outside of a box or other closed cell. For example, the base of a cantilevered supporting element may be attached to an inside surface of the box and project into an interior space of the box. Alternatively, the base of a cantilevered supporting element may be attached to an outside of the box or onto circumferential links which attaches the boxes or other closed cells together to form a ring.

[0073] Typically, at least one end of a supporting elements is attached to at least one location on a strut or crown or the ring of the radially expandable rings. In some instances, however, at least some of the supporting elements may be unattached to the supporting scaffold or other expandable supporting structure and are attached or coupled only to the expandable membrane so that they will reinforce the V-shaped, O-shaped, U-shaped, or square/box shaped spaces between struts to enhance resistance of the expandable membrane to collapse under vacuum/negative pressure when the distal tip is blocked or plugged with clot or other substances. [0074] In some instances, at least some of the supporting elements may extend in a circumferential direction from the radially expandable rings into the cell space (V-shaped, O- shaped, U-shaped, or square/box shaped space). In a preferred example, at least some supporting elements extend circumferentially from an outer crown region to an adjacent outer crown region, in one direction or in two opposite directions. In another preferred example, at least some supporting elements extend circumferentially from a strut to an adjacent strut, in one direction or in two opposite directions. In other instances, at least some of the supporting elements extend in an axial direction from the radially expandable rings into and/or beyond the cell space (V-shaped, O-shaped, U-shaped, or square/box-shaped space). In a preferred example, the supporting features are configured to shorten when the expandable supporting structure is expanded to an expanded configuration such that said supporting features length is equal to or less than the amplitude of the expandable ring cell, or the supporting features do not extend axially beyond the peak of an adjacent crown. In another preferred example, the supporting features are configured to deploy or project further when the expandable supporting structure is expanded to an expanded configuration providing enhanced support to the expandable membrane and providing the expandable membrane enhanced resistance to collapse when a vacuum is applied at a proximal end of the aspiration lumen.

[0075] In a preferred example, the present invention provides an aspiration catheter having an expandable supporting structure design. The aspiration catheter comprises a tubular catheter body having a proximal end, a distal end, and a lumen extending therebetween. The expandable supporting structure is attached at or incorporated within the distal end (or distal tip) of the tubular catheter body and has a central passage contiguous with the lumen of the tubular catheter body, and the expandable supporting structure includes an expandable membrane and a supporting scaffold or other expandable supporting structure configured to radially expand the expandable membrane. The expandable supporting scaffold or other expandable supporting structure comprises a plurality of radially expandable rings arranged along a longitudinal axis, wherein at least some of the radially expandable rings comprise a serpentine or zigzag or open other open pattern including struts joined by crowns forming a V-shaped, O-shaped, U-shaped, or open square/box shaped space therebetween. A multiplicity of supporting elements are positioned in the V-shaped, O-shaped , U- shaped, or square shaped space to support the membrane in said V-shaped, O-shaped , U-shaped, or open square/box shaped space in the as delivered configuration and/or in the expanded configuration, and wherein the supporting scaffold or other expandable supporting structure resist collapse of the membrane in said space in the expanded membrane and scaffold or other expandable supporting structure configuration when a vacuum is applied at a proximal end of the aspiration lumen and the distal tip is blocked or plugged with clot or other substances, and wherein the supporting scaffold or other expandable supporting structure being capable to contract from the expanded configuration to a smaller configuration when the aspiration catheter is withdrawn into a guiding catheter having an inner lumen configuration smaller than the expanded configuration of the supporting scaffold or other expandable supporting structure.

[0076] In a preferred example, the present invention provides an aspiration catheter having an expandable supporting structure design. The aspiration catheter comprises a tubular catheter body having a proximal end, a distal end, and a lumen extending therebetween. The expandable supporting structure is attached at the distal end (or distal tip) of the tubular catheter body and has a central passage contiguous with the lumen of the tubular catheter body, and the expandable supporting structure includes an expandable membrane and a supporting scaffold configured to radially expand the expandable membrane. The expandable supporting scaffold comprises a plurality of radially expandable rings arranged along a longitudinal axis, wherein at least some of the radially expandable rings comprise a serpentine or zigzag or open pattern including struts joined by crowns forming a cell space there between. A multiplicity of supporting elements are positioned in the cell space to support the membrane in said cell space in the as delivered configuration and/or in the expanded configuration, and wherein the supporting elements resist collapse of the membrane in said space in the expanded membrane configuration when a vacuum is applied at a proximal end of the aspiration lumen and the distal tip is blocked or plugged with clot or other substances, and wherein the supporting elements allow contraction the expanded supporting structure from an expanded configuration to a smaller configuration when the aspiration catheter is withdrawn into a guiding catheter having an inner lumen configuration smaller than the expanded configuration of the supporting structure.

[0077] In a third aspect, the present invention provides a method for aspirating clot from a patient’s vasculature. The method comprises positioning a distal end of the expandable supporting structure of any of the aspiration catheters, as described, in the patient’s vasculature at or near a region of clot. The expandable supporting structure is expanded, typically by balloon expansion (but alternatively by self-expansion), to engage a clot or to engage a vascular wall adjacent the region of clot. A negative pressure (vacuum) is applied to a proximal end of the aspiration lumen in the catheter body to aspirate the clot into the aspiration central passage of the expanded expandable structure.

[0078] In a preferred example, the present invention provides a method for aspirating clot from a patient’s vasculature. The method comprises positioning a distal tip of the expandable supporting structure of any of the aspiration catheters, as described, in the patient’s vasculature at or near a clot. The expandable supporting structure is expanded to an expanded configuration, typically by balloon expansion but alternatively by self-expansion, to engage a clot or to engage a vascular wall adjacent to a clot. A vacuum is applied to a proximal end of the lumen in the catheter body to aspirate the clot into the central passage of the expanded expandable structure, at least a portion of the expandable supporting structure is optionally contracted from the expanded configuration to a smaller configuration, prior to removal from the vasculature.

[0079] In a fourth aspect, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and a lumen extending along a longitudinal axis. A distal tip has a proximal end incorporated into or is attached to the distal end of the tubular catheter body and a central passage (aspiration lumen) longitudinally contiguous with the lumen of the tubular catheter body. The distal tip is adapted to expand from an as delivered configuration to a radially expanded configuration or from a radially contracted configuration to a radially expanded configuration in response to a radially outward expansion force applied within the distal tip segment, and the distal tip comprises an expandable membrane and an expandable supporting structure such as a scaffold where the expandable scaffold or other expandable supporting structure comprises a plurality of rings spaced-apart along the longitudinal axis with gaps therebetween. At least some of the rings comprise a malleable metal or metal alloy configured to plastically deform to circumferentially expand the scaffold or other expandable supporting structure in response to the radially outward expansion force applied from within the distal tip.

[0080] In some instances, the expandable membrane is attached to an inner and/or outer surface of the expandable scaffold or other expandable supporting structure. In other instances, the expandable scaffold or other expandable supporting structure is embedded in or within the expandable membrane, wherein the expandable membrane comprises at least two membrane one is attached to an outer surface of the expandable scaffold or other expandable supporting structure while the other is attached to an inner surface of the expandable scaffold or other expandable supporting structure. In other instances, an aspiration catheter comprising an expandable tip, wherein the expandable tip comprises an expandable membrane and an expandable supporting structure such as a scaffold where the expandable scaffold or other expandable supporting structure comprises a plurality of rings spaced-apart along the longitudinal axis with gaps there between and within each of the rings, wherein the rings comprise structural elements comprising struts and crowns. The expandable scaffold or other expandable supporting structure is embedded in or within the expandable membrane, wherein the expandable membrane comprises at least one membrane wherein the at least one membrane is softened and/or melted over an outer surface of the expandable scaffold or other expandable supporting structure and/or over an inner surface of the expandable scaffold or other expandable supporting structure, allowing the expandable membrane to protrude or flow into the gaps present within the ring structural elements and gaps present between adjacent rings, adhering to said rings and rings structural elements, providing a unified (an integrally) expandable scaffold/membrane(s) system, expandable from contracted or as delivered configuration to an expanded larger configuration. The expandable membrane, in a preferred aspect, covers an outer and/or an inner surface of the expandable structure, and also covers wherein covers comprises one or more of fills, flows into, or protrude into at least some gaps present within each ring of the expandable scaffold or other expandable supporting structure and gaps present between adjacent rings of the expandable scaffold or other expandable supporting structure, wherein the flowing membrane adheres sufficiently to the scaffold or other expandable supporting structure rings structural elements to provide a unified system (integrated system) being capable to expand from an as delivered configuration to an expanded configuration as an integrated system. The expandable membrane in a preferred aspect flows into gaps present between each of the rings, within each of the rings structural elements comprising struts joined by crowns, wherein the one or more expandable membranes in a preferred aspect covers an outer surface and/or inner surface of the expandable scaffold or other expandable supporting structure, covers at least some side surfaces of the expandable scaffold structural elements, preferably covers substantially all side surfaces of the expandable scaffold structural elements, and covers substantially all gaps between adjacent rings of the expandable scaffold or other expandable supporting structure. The expandable scaffold or other expandable supporting structure in a preferred aspect comprises an outer surface, an inner surface, and two side surfaces. In other aspect, an expandable scaffold or other expandable supporting structure is formed from a bent wire comprising an outer surface and an inner surface.

[0081] In some instances, the scaffold or other expandable supporting structure has an as delivered configuration or a radially contracted (e.g. crimped) delivery configuration and an expanded deployed configuration. Typically, the radially contracted configuration has a maximum outer diameter in a range from 0.5 mm to 30 mm, usually from 1.0 mm to 5 mm, and more usually from 2mm to 5mm, and the radially expanded configuration has a maximum outer diameter in a range from 1 mm to 60 mm, preferably from 1.5 mm to 45 mm, more preferably from 3 mm to 45 mm.

[0082] In some instances, the distal tip may be configured to expand from an initial cylindrical shape to an enlarged cylindrical configuration in response to the radially outward expansion force applied within at least a portion of the distal tip. In other instances, the distal tip is configured to expand from an initial cylindrical shape to an enlarged conical configuration in response to the radially outward expansion force applied within at least a portion of the distal tip. In a preferred example, the enlarged conical configuration ends at the distal end of the distal tip, providing the largest area (cross sectional area) for clot extraction.

[0083] In some instances, the tubular catheter body may have a working length from the proximal end to the distal end in a range from 50 cm to 200 cm, an outer diameter in a range from 0.5 mm to 30 mm, and an inner lumen diameter from 0.25 mm to 25 mm.

[0084] In some instances, the distal tip may have a bending resistance below 1 N, preferably below 0.5 N, more preferably below 0.3 N, and most preferably below 0.2 N in its initial radially contracted configuration or in the as delivered configuration as measured by a three-point flexure test (described in more detail below). The distal tip may also have a collapse pressure (vacuum) at or above 0.5 atm, preferably at or above 0.75 atm, and more preferably at about 1 atm, in its radially expanded configuration, and most preferably above 1 atm in its radially expanded configuration when a vacuum is attached to a proximal end and a clot (or plug) is engages and blocks the open distal end of the distal tip. In other examples, the distal tip may have a bending resistance range from 0.1N to 2N, preferably range from 0.1N to 0.5N, more preferably range from 0.1N to 0.35N, and most preferably range from 0.1N to 0.2N, in its initial radially contracted configuration or in the as delivered configuration.

[0085] The bending resistance is a measure of the distal tip flexibility to navigate tortuous anatomy. A lower the bending resistance indicates a higher flexibility and a better ability of the distal tip to navigate tortuous anatomy. The bending resistance of the distal tip (or any other portion of the aspiration catheter) may be measured by a three-point flexure test, such as ASTM F2606 Standard Guide for Three-Point Bending of Balloon Expandable Vascular Stents and Stent Systems or equivalent. A section of the catheter rests perpendicularly on two lower static supports with a wedge centered between them. The spacing of the two supports is 13 mm. The middle of the supported catheter section is displaced by lowering the wedge which is held in an upper grip of an Instron Tensile Tester (Instron, Norwood, MA, USA) at a deflection rate 5.0 mm/min while measuring the resistance force. The test is ended when the displacement reaches 2 mm (approximately 15% of Span Length). The three-point bending resistance for that catheter section is equal to the maximum deflection force measure during the test.

[0086] The collapse pressure is the vacuum or negative pressure which, when applied at the proximal end of the catheter body lumen, will cause the distal tip to at least partially collapse when distal tip is fully occluded. By “at least partially collapse,” it is meant that an irreversible contraction (contraction that is not resolved after applied vacuum is stopped) of more than 5%, of more than 10% or of more than 15% of the distal tip inner lumen diameter or configuration. In a preferred example, the distal tip inner lumen diameter or configuration comprising a plurality of expandable rings under applied vacuum in the expanded (deployed) configuration is configured to have the expandable rings in the expanded configuration resist collapse when a vacuum is applied at a proximal end of the aspiration catheter and the distal tip is blocked or plugged with clot or other substances; or is configured to resist collapse by contracting no more than 5%, no more than 10%, or no more than 15% of any of the distal tip rings configurations when the rings are under applied vacuum in the expanded configuration of the rings and the tip engaging a clot (or a plug), or preferably by contracting no more than 10%, of the expanded configuration under vacuum, or most preferably by contracting no more than 5% of the expanded configuration under vacuum. In another example, the distal tip inner lumen diameter or configuration comprising a plurality of expandable rings under vacuum of about latm, in the expanded deployed configuration, resist collapse by radially contracting by no more than 5% of any of the expandable rings, wherein the said radial contraction of no more than 5% is substantially reversible to the expanded configuration when the vacuum or negative pressure applied at a proximal end of the catheter body lumen with the central passage of distal tip is removed or stopped (i.e., the distal tip inner lumen diameter or configuration expands to the larger expanded configuration.

[0087] In another example, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and a lumen extending along a longitudinal axis. A distal tip has a proximal end attached to the distal end of the tubular catheter body and a central passage longitudinally contiguous with the lumen of the tubular catheter body (aspiration lumen). The distal tip is adapted to expand from an as delivered configuration to a radially expanded configuration or from a radially contracted configuration to a radially expanded configuration in response to a radially outward expansion force applied within the distal tip, and the distal tip comprises an expandable membrane and an expandable supporting structure such as a scaffold where the expandable scaffold or other expandable supporting structure comprises a plurality of rings spaced-apart along the longitudinal axis with gaps therebetween. At least some of the rings comprise a malleable metal or metal alloy configured to plastically deform to circumferentially expand the scaffold or other expandable supporting structure in response to the radially outward expansion force applied from within the distal tip. In a preferred example, the expandable tip comprising an expandable membrane and expandable scaffold or other expandable supporting structure are configured to radially contract by no more than 15%, preferably by no more than 10%, and more preferably by no more than 5% of any of the expandable rings, when a vacuum is applied to a proximal end of the aspiration lumen and the distal tip is engaging a clot (or plug), and to passively expand (without outward expansion force applied within the distal tip by an expandable member), wherein said expanded configuration is larger than the contracted configuration when the applied vacuum is stopped (or removed), preferable wherein the expanded configuration is larger than the contracted configuration and is substantially the same as the expanded configuration prior to applying any vacuum. In another example, the distal tip inner lumen diameter or configuration under vacuum of about latm, in the expanded deployed configuration, radially contracts by no more than 15%, preferably by no more than 10%, and more preferably by no more than 5% resisting collapse, wherein the said radial contraction is substantially reversible when the vacuum or negative pressure applied at a proximal end of the catheter body lumen with the central passage of distal tip is removed or stopped (i.e., the distal tip inner lumen diameter or configuration expands to a larger configuration, larger than the contracted configuration under vacuum).

[0088] In another example, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending along a longitudinal axis. A distal tip has a proximal end attached to the distal end of the tubular catheter body and a central passage longitudinally contiguous with the aspiration lumen of the tubular catheter body. The distal tip is adapted to expand from an as delivered configuration (or from a first extraction configuration) to a first radially expanded configuration in response to a radially outward expansion force applied within the distal tip, wherein the first radially expanded configuration (second extraction configuration or extraction configuration) ranges from 1.1 to 2 times the as delivered configuration, and wherein the distal tip comprises one or more expandable membranes and an expandable scaffold where the expandable scaffold comprises a plurality of expandable rings spaced-apart along the longitudinal axis with gaps therebetween, and wherein the expandable rings comprise structural elements including struts joined by crowns. At least some of the rings comprise a malleable metal or metal alloy configured to plastically deform to circumferentially expand the scaffold or other expandable supporting structure in response to the radially outward expansion force applied from within the distal tip. The expandable tip comprising the one or more expandable membranes and expandable scaffold comprising a plurality of expandable rings are configured to radially contract to a first contracted configuration wherein the first contracted configuration is smaller than the first expanded configuration but larger than the as delivered configuration, preferably wherein the first contracted configuration is smaller than the first expanded configuration by no more than 15%, preferably by no more than 10%, and more preferably by no more than 5% smaller than the first expanded configuration when a vacuum is applied to a proximal end of the aspiration lumen wherein the applied vacuum, or when the applied vacuum ranges from 0.75 atm to 1 about atm, and wherein the expandable tip is configured to passively expand, to a second expanded configuration wherein the second expanded configuration is larger than the first contracted configuration and equal to or smaller than the first expanded configuration, when the applied vacuum is removed or stopped, wherein the expandable tip passively expand without outward expansion force applied within the distal tip by the one or more expandable membranes, and wherein the expandable tip is configured to contract to a second contracted configuration, wherein the second contracted configuration is smaller than the first contracted configuration and equal to or larger than the as delivered configuration, when the distal tip is withdrawn into a guiding catheter positioned proximally to the distal tip in the patient anatomy. In one example, the expandable distal tip has a length ranging from 0.5 mm to 500 mm, preferably having a length ranging from 1 cm to 50 cm, and more preferably ranging from 1 cm to 25 cm. The one or more expandable membranes of the expandable distal tip in one example extends proximally beyond the proximal end of the distal tip of the aspiration catheter. In another example, the one or more expandable membranes of the expandable distal tip has about the same length as the expandable scaffold and are both incorporated within or attached at their proximal end to the distal end of the aspiration catheter. In yet another example, the one or more expandable membranes extend from the distal end of the distal tip to a proximal end of the aspiration catheter.

[0089] In some instances, the distal tip comprising an expandable scaffold or other expandable supporting structure has a minimum bending radius without deformation and/or kinking of 5 mm, preferably 3 mm, and more preferably 2 mm in its as delivered configuration or the radially contracted configuration, and preferably, a minimum bending radius without deformation and/or kinking of 10 mm, preferably 6 mm, and more preferably 2mm in its radially expanded configuration. Minimum bending radius may be determined by bending the distal tip about a cylinder of a known radius and observing if the distal tip deforms and/or kinks.

[0090] In some instances, the rings of the expandable scaffold or other expandable supporting structure span a length in a range from 0.25 mm to 500 mm or more measured in a longitudinal direction, preferably a range from 1 mm to 100 mm, more preferably a range from 10 mm to 70 mm, and most preferably range from 20 mm to 50 mm.

[0091] In another example, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending along a longitudinal axis. A distal tip has a proximal end incorporated into the distal end of the tubular catheter body and a central passage longitudinally contiguous with the aspiration lumen of the tubular catheter body. The distal tip is adapted to expand from an as delivered configuration to a first radially expanded configuration in response to a radially outward expansion force applied to the distal tip, wherein the first radially expanded configuration ranges from 1.1 to 2 times the as delivered configuration, and wherein the distal tip comprises one or more expandable membranes and an expandable scaffold where the expandable scaffold comprises one or more expandable rings spaced-apart along the longitudinal axis with gaps therebetween, and wherein the expandable rings comprise structural elements including struts joined by crowns. The one or more rings are composed of a malleable metal or metal alloy (or alternatively are formed from shape memory metallic alloy) configured to plastically deform to circumferentially expand the scaffold or other expandable supporting structure in response to the radially outward expansion force applied from inside the distal end or distal tip. In a specific example, the expandable scaffold consists of one, two, or three expandable rings. In another specific example, the expandable scaffold consists of one expandable ring.

[0092] In some instances, the distal tip comprising an expandable scaffold or other expandable supporting structure has a minimum bending radius without deformation and/or kinking of 5 mm, preferably 3 mm, and more preferably 2 mm in its as delivered configuration or the radially contracted configuration, and preferably, a minimum bending radius without deformation and/or kinking of 10 mm, preferably 6 mm, and more preferably 2mm in its radially expanded configuration. Minimum bending radius may be determined by bending the distal tip about a cylinder of a known radius and observing if the distal tip deforms and/or kinks.

[0093] In some instances, the rings of the expandable scaffold or other expandable supporting structure span a length in a range from 0.25 mm to 500 mm or more measured in a longitudinal direction, preferably a range from 1 mm to 100 mm, more preferably a range from 10mm to 70mm, and most preferably a range from 10 mm to 40 mm.

[0094] In some instances, the expandable scaffold or other expandable supporting structure consists of from 1 ring to 800 rings or more, preferably consist of 25 rings to 650 rings or more, more preferably consist of 50 rings to 500 rings or more, spanning one or more expandable axial segments lengths ranging from 0.2 mm to 50 cm, preferably ranging from 10 mm to 40 cm, more preferably ranging from 15 mm to 25 cm said rings arranged in a longitudinal direction from the distal end of the distal tip to a distal end or to a proximal end, of the aspiration catheter. In a preferred example, the expandable scaffold or other expandable supporting structure comprises or consists of a plurality of rings per mm of axial (longitudinal) scaffold or other expandable supporting structure length, ranging from 2 rings/mm to 5 rings/mm of length, preferably consists of from 2.5 rings/mm to 4 rings/mm of length, and more preferably consists of from 3 rings/mm to 4 rings/mm of length, of axial (longitudinal) scaffold length.

[0095] In some instances or examples, the expandable supporting structure comprises a plurality of adjacent rings having a gap between the adjacent rings. In some examples, the gap between adjacent rings has length in a range from 0.0125 mm to 0.25 mm measured in a longitudinal/axial direction, preferably from 0.025 mm to 0.2 mm, and more preferably range from 0.05 mm to 0.17 mm.

[0096] In some instances, the axial length of gap (i.e., gap length measured is an axial direction) between adjacent rings may be constant. In other instances, the axial length of gap between adjacent rings may be variable. For example, the length (or axial length) of gaps between at least some adjacent rings range from 0.05mm to 0.2mm. In another preferred example, a plurality of adjacent rings spanning at least 3mm segment along a length of the expandable structure, more preferably spanning at least 7mm segment along a length of the expandable scaffold, more preferably spanning at least 20mm segment along a length of the expandable scaffold wherein the adjacent rings having gap lengths adjacent the adjacent rings ranging from 0.05mm to 0.2mm.

[0097] In some instances, the distal tip has at least 2 ring per mm of axial length, preferably at least 3 rings per mm of length, typically from 1.5 to 5 rings per mm of length, and more typically from 2 to 5 rings per mm of length, or more typically from 3 to 4 rings per mm of length. [0098] In some preferred instances, at least some of the adjacent rings are joined continuously, end-to-end in a helical arrangement. In other instances, at least some of the adjacent rings are planar, arranged in parallel, and joined by axial links or other means such as attachment points and are not joined end-to-end. The parallel planes may be normal or inclined relative to a longitudinal axis of the distal tip in its as delivered configuration. The adjacent rings may be joined preferably by a single axial link or attachment point, or by no more than two axial links or two attachment points. In some preferred instances, at least some adjacent rings of the expandable scaffold are joined continuously, end-to-end in a helical pattern or arrangement. In other instances, at least some adjacent rings of the expandable scaffold are planar, arranged in parallel, and joined by axial links or attachment points joining or connecting structural elements on adjacent rings. In this other instance, the scaffold adjacent rings are not joined continuously end-to-end in a helical arrangement. The parallel planes may be normal or inclined relative to a longitudinal axis of the distal tip in its as delivered configuration. The adjacent rings may be joined preferably by a single axial link or attachment point, or by no more than two axial links or attachment points.

[0099] In other instances, at least some adjacent rings of the expandable scaffold are planar, arranged in parallel, and are unconnected to each other. (Unconnected by links, attachment points, or joined end to end in a helical arrangement). The parallel planes may be normal or inclined relative to a longitudinal axis of the distal tip in its as delivered configuration The at least some adjacent rings in this instance are covered by one or more membrane adhering to the unconnected adjacent rings, holding them together, and allowing the at least some adjacent ring to expand from an as delivered configuration to an expanded configuration. This allows for enhanced deliverability of the distal tip to navigate vascular anatomy in the as delivered configuration and allows the at least some rings to expand from an as delivered configuration to an expanded configuration and resist collapse of the distal tip from the expanded configuration when a vacuum is applied at a proximal end of the aspiration lumen and a clot is engaging (or a plug is blocking) the distal end of the distal tip.

[00100] In some instances, at least some of the adjacent rings in the helical and/or planar arrangement may comprise non-linearities.

[00101] In some instances, all the adjacent rings in the helical and/or planar arrangement are free from non-linearities.

[00102] In some instances, at least some of the adjacent rings have thickness ranging from 0.03 mm to 0.3 mm, preferably ranging from 0.05 mm to 0.25 mm, more preferably ranging from 0.05 mm to 0.2 mm. [00103] In some instances, the malleable metal comprises a metal or metal alloy selected from the group consisting of Cobalt Chrome such as L-605, MP35N, Stellite 6B, ASTM F1537/F799 Alloy 1, ASTM F1537/F799 Alloy 2, Stainless Steel such as 316, 316L, 316LS, 316LVM, 304, 304V, 304L, 304LV, 304LVM, 410, 410L, 410S, 420, 420L, and 420S, Tantalum, Niobium, Tungsten, Molybdenum, Molybdenum, Molybdenum alloys such as Molybdenum-Rhenium where total of the two adds up to 90% to 100% and may include one or more metals such as Boron, Calcium, Chromium, Cobalt, Copper, Gold, Iron, Lead, Magnesium, Manganese, Mercury, Nickel, Niobium, Platinum, Rare Earth metals, Silicon, Silver, Sulfur, Tantalum, Tin, Titanium, Tungsten, Yttrium, Zinc, and Zirconium, Platinum, Platinum alloys such as Platinumiridium, Platinum-Chromium, Platinum-Cobalt-Chromium, Magnesium, Magnesium alloy such as Mg-3Al-lZ , Mg-Zn-Se and Mg-Zn-Cu, Zinc, or the like, or other.

[00104] In some instances, the scaffold or other expandable supporting structure comprises metal or metal alloy selected from the group consisting of Nitinol, Superelastic Nitinol, or the like, or other. In such instances, the expandable supporting structure is constrained in the as delivered configuration and is released from the constraint to expand the scaffold to the expanded configuration.

[00105] In some instances, the expandable membrane comprises one or more of an elastic membrane, and/or inelastic but stretchable membrane, and/or one or more plastically deformable membrane where the membrane may comprise one or more membranes comprising polymers, elastomers, or other as listed previously.

[00106] In some instances, the elastic membrane may have isotropic properties. In other instances, the elastic membrane may have anisotropic properties. For example, the membrane may have a higher elasticity in a circumferential direction than in an axial direction.

[00107] In some instances, the expandable membrane may comprise an elastic membrane, an inelastic but stretchable membrane, or other type expandable material. Suitable material examples as listed previously.

[00108] In some instances, the inelastic membrane may be configured to stretch, or plastically deform as the scaffold or other expandable supporting structure expands. In other instances, an inelastic membrane may be configured to unfold as the as the scaffold or other expandable supporting structure expands.

[00109] In some instances, the distal tip may be formed by heat shrinking the tubular membrane on the expandable scaffold or other expandable supporting structure. In other instances, distal tip may be formed by laminating the expandable scaffold or other expandable supporting structure between layers of the tubular membrane. For example, the layers may be bonded to each other so that there is a seal between the layers. In a preferred example, the one or more expandable membranes flow and cover at least some side surfaces of the expandable supporting structure structural elements, adhere to said structural elements sufficiently to provide a unified system (an integrated system) in the as delivered configuration and when expanded to an expanded configuration. In yet another example, the polymeric layers on an outer surface of the scaffold and on the inner surface of the scaffold may be bonded to each other and/or adhere to the scaffold structural elements so that there is a seal between the layers and/or adherence to the structural elements providing a unified integrated system expandable from an as delivered configuration to an expanded configuration. In a preferred example, the structural elements of the scaffold are not free to move or expand without moving or expanding the expandable membrane adjacent to said structural elements. In yet another example, the layers on an outer scaffold surface and inner scaffold surface may be bonded to each other so that there is a seal between the layers. In yet another example, the layers on an outer scaffold surface and on an inner scaffold surface maybe coupled, attached, and/or adhered to each other substantially eliminating the gaps between the structural elements (or filling the gaps) of the scaffold, and providing a unified expandable scaffold being expandable from an as delivered configuration to an expanded configuration. In yet another example, the one or more layers on an outer surface of the scaffold or the one or more layers on an inner surface of the scaffold are melted or laminated onto the structural elements of the scaffold, eliminating at least in part the gaps between said structural elements and adhering to said structural elements providing the scaffold the ability to expand from an as delivered configuration to an expanded configuration as a unified system.

[00110] In some instances, the tubular membrane may consist of at least two membrane segments, where the at least two membrane segments may comprise a single type of material, at least two types of material, or three or more different material types.

[00111] In some instances, the at least two membrane segments may cover at least an outer surface of the expandable scaffold or other expandable supporting structure. In some instances, the at least two membrane segments may cover at least an inner surface of the expandable scaffold or other expandable supporting structure. In some instances, the at least two membrane segments cover both an inner surface and an outer surface of the expandable scaffold or other expandable supporting structure, wherein at least one membrane segment of said at least two membrane segments covers an outer surface of the scaffold while at the least the second membrane segment covers an inner surface of the expandable scaffold.

[00112] In some instances, the tubular catheter body may be reinforced over at least a portion of its length by a catheter scaffold or other supporting structure, typically a flexible but nonexpandable supporting structure. In specific examples, the catheter scaffold or other supporting structure may be formed continuously with the expandable scaffold or other expandable supporting structure. For example, the catheter and supporting scaffold may be patterned from the same tube or bent wire. In other instances, the catheter scaffold and the expandable scaffold may be formed from one or more bent wires which each span at least portions of the typically non-expandable catheter scaffold and the expandable distal tip scaffold.

[00113] In some instances, the expandable scaffolds may further comprise a multiplicity of cantilevered or other supporting elements, each supporting element having a base end and a free end, wherein the base end is attached to one of the radially expandable rings and the free end extends toward or into an adjacent axial and/or circumferential gap.

[00114] In some instances, at least some of the plurality of rings may comprise struts joined by bends (crowns) and at least some of the multiplicity of supporting elements have their base ends attached to a strut and at least some of the multiplicity of supporting elements have their base ends attached to a bend (crowns).

[00115] In some instances, at least some of the multiplicity of supporting elements may have their base ends attached to an inside surface of the ring, i.e., the inside bend of a crown.

[00116] In some instances, at least some of the multiplicity of supporting elements may have their base ends attached to an outside surface of the ring, i.e., an outside surface of a crown, or to the apex of the outside surface of a crown.

[00117] In some instances, at least some of the multiplicity of supporting element have a constant width over their distal portions. In some instances, at least some of the multiplicity of supporting element have a constant width over their entire length.

[00118] In some instances, at least some of the multiplicity of supporting element have a variable width over their distal portions.

[00119] In some instances, at least some of the multiplicity of supporting element have distal tips which extend into an adjacent circumferential, axial or other gap.

[00120] In some instances, at least some of the multiplicity of supporting element have distal tips which terminate flush with the bends that struts join the struts.

[00121] In some instances, at least some of the multiplicity of supporting element have distal tips which are recessed between adjacent bends that join the struts.

[00122] In a fifth aspect, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and a lumen extending along a longitudinal axis. The distal end comprises an expandable distal tip and a central passage where the central passage is typically longitudinally contiguous with the lumen of the tubular catheter body. The distal tip is adapted to expand from a radially contracted or as delivered configuration to a radially expanded configuration in response to a radially outward expansion force applied inside the distal tip, and the distal tip includes a tubular membrane covering (e.g., adhered to, attached to, bonded to, or laminated with) an expandable scaffold or an expandable supporting scaffold. The expandable scaffold or the expandable supporting scaffold comprises a plurality of rings spaced-apart along the longitudinal axis with gaps therebetween (extending between rings) and at least some of the rings comprise circumferentially adjacent cells having bends (such as crowns) configured to unbend (such as to expand) in response to a radially outward expansion force applied inside the distal tip to allow the ring to expand from the radially contracted or as delivered configuration to the radially expanded configuration, wherein the radially expanded configuration is larger than the contracted configuration. In some preferred instances, at least some adjacent rings of the expandable scaffold or expandable supporting scaffold are joined continuously, end-to-end in a helical arrangement, typically free from axial links or attachments points. In a preferred instance, the at least some adjacent rings of the expandable scaffold or expandable supporting scaffold have a fixed cell amplitude within each ring. In other instances, the at least some adjacent rings of the expandable scaffold or expandable supporting scaffold have a fixed cell amplitude within the at least some rings. In rare instances, the at least some adjacent rings of the expandable scaffold or expandable supporting scaffold may have a variable cell amplitude within each ring or within the at least some rings. The at least some adjacent rings in this instance have a pitch angle in a range from 70° to 89.9°, or from 75° to 89.9°, usually from 80° to 89.9°, more usually from 84° to 89.75°, and frequently from 85° to 88.5° degrees as patterned, or as delivered, relative to the longitudinal axis of the scaffold or distal tip. As used herein and as illustrated in the drawings, the “pitch angle” will be the acute angle (between 0° and 90°) not the obtuse angel (between 90° and 180°) formed by the ring relative to the longitudinal axis of the distal tip of the aspiration catheter. In some other instances, at least some adjacent rings of the expandable scaffold or the expandable supporting scaffold are planar, arranged in parallel, and are joined by one axial link or attachment point joining structural elements on adjacent rings. In rare cases, the at least some adjacent rings are joined by no more than two axial links, by no more than two attachment points joining structural elements on adjacent rings, or by no more than one link and no more than one attachment point. The parallel planes may be normal or inclined relative to a longitudinal axis of the distal tip in its as delivered configuration.

[00123] In some instances, the cells may be arranged in any one or more of a box pattern, diamond pattern, a sinusoidal pattern, serpentine pattern, an omega-wave pattern, a zig-zag pattern, a square wave pattern, a rectangular wave pattern, an undulating pattern, a slotted pattern, open cell pattern, closed cell pattern, a combination of open and closed cell patterns, a combination of patterns, or other, and the like. [00124] In some instances, adjacent and/or non-adjacent rings have crowns that are in-phase or out-of-phase.

[00125] In some instances, the cells may comprise struts joined by bends.

[00126] In some instances, at least some expandable cells on one or more rings of the expandable scaffold, or at least some expandable cells on at least some rings of the expandable scaffold, or at least some expandable cells on each ring of the expandable scaffold, or the at least some circumferentially adjacent cells of at least some rings of the expandable scaffold, or at least some circumferentially adjacent cells on at least some adjacent rings of the expandable scaffold may, or substantially all cells on the expandable scaffold, or all cells along a length of a scaffold wherein the length is less than the length of the scaffold, or all cells along the length of a scaffold, have a cell period (distance between like points on circumferentially adjacent cells measured in the contracted configuration) in a range from 0.03 mm to 1.3 mm, preferably from 0.04 mm to 0.8 mm, more preferably from 0.05 mm to 0.5 mm, and most preferably from 0.05 mm to 0.15 mm, in the as delivered configuration, or in the as patterned configuration. Having a small cell period enhances circularity of a ring, or circularity of the plurality of rings, or circularity of the expandable scaffold, thereby enhances navigation of the expandable scaffold into the vasculature without deformation or kinking in the as delivered configuration, and said enhanced circularity resist collapse of the expandable distal tip when expanded to the expanded configuration and a vacuum is applied at a proximal end of the aspiration catheter while the distal tip is engaging a clot (or is plugged). Furthermore, having small cell period increases (or enhances) the aspiration area within the ring, within the plurality of rings, or within the expandable scaffold or expandable distal tip.

[00127] In some instances, the circumferentially adjacent cells on at least one ring or on at least some rings (or at least some circumferentially adjacent cells on the same ring, or at least some circumferentially adjacent cells on at least some adjacent rings) of the expandable scaffold, or at least one ring, or at least some rings, or all the rings of the expandable scaffold, may have a peak-to-peak amplitude (ring width in the longitudinal/axial direction (the axial width of a ring)) in a range from 0.05 mm to 1.2 mm, preferably from 0.05 mm to 0.8 mm, more preferably from 0.15 mm to 0.5 mm, and most preferably from 0.15 mm to 0.35 mm, in the as delivered configuration or in the as patterned configuration. In a preferred example, the cell amplitudes of each cell on the same ring have the same length (is fixed or is constant) in the as delivered configuration or as patterned configuration. In another preferred example, at least some adjacent rings have cell or ring amplitude being the same length on said at least some rings. Having small amplitude enhances flexibility of the expandable scaffold thereby enhances the navigation of the expandable scaffold (or expandable distal tip) when the aspiration catheter is advanced into the vasculature. Furthermore, having small amplitude further strengthen the expandable scaffold in the expanded configuration and resist collapse of the scaffold or the expandable membrane coupled to the scaffold when a vacuum is applied at a proximal end of the aspiration catheter and the distal tip is engaging a clot.

[00128] In some instances, the circumferentially adjacent cells (or at least some circumferentially adjacent cells, or at least some circumferentially adjacent cells on at least some adjacent rings, or all cells on the expandable scaffold, or at least some cells within a ring, or all cells within at least some rings, or all cells within rings of the expandable scaffold) may have a cell period to a (peak to peak axial width of a ring) amplitude range as follows: In one example, a cell period to a (peak to peak axial width of a ring) amplitude range from 0.3 : 1 to 1.6: 1. In other example, a cell period to a (peak to peak axial width of a ring) amplitude range from 0.4: 1 to 1.5:1. In yet other example, a cell period to a (peak to peak axial width of a ring) amplitude range from 0.5: 1 to 1.3:1. In yet other example, a cell period to a (peak to peak axial width of a ring) amplitude range from 0.6: 1 to 1.2: 1. In yet other instances, a cell period to a (peak to peak axial width of a ring) amplitude range from 1 : 1 to 1.6: 1. In yet other instances, a cell period to a (peak to peak axial width of a ring) amplitude range from 0.3: 1 to 1.2: 1, measured in the as delivered configuration or in the as patterned configuration for all the examples. In some other examples, the circumferentially adjacent cells (or at least some cells on a ring or on a plurality of rings or on at least some rings, or all cells on at least one ring or on at least some rings, or at least some rings of the expandable scaffold) may have a cell period and a (peak to peak axial width of a ring) amplitude each having a length of 0.25mm ± 0.2mm, preferably each having a length of 0.25mm ± 0.15mm, and more preferably each having a length of 0.25mm ± 0.1mm, measured in the as delivered configuration (or measured in the as patterned configuration). Having the length of at least some cell periods and amplitudes within a ring or within a plurality of rings or within at least some rings being within ± 0.2mm of each other enhances symmetry and/or compactness of the rings of the expandable scaffold resisting deformation and/or kinking when the expandable scaffold navigates into the vasculature in the as delivered configuration.

[00129] In some instances, each ring (or at least some rings) may include from 2 cells to 15 cells per mm of circumference, preferably each ring (or at least some rings) may include from 3 cells to 10 cells per mm of circumference, and most preferably each ring (or at least some rings) may include from 4 cells to 9 cells per mm of circumference.

[00130] In some instances, at least some rings in the scaffold or other expandable supporting structure may have a ratio of (1) number of bends to (2) circumference, where the ratio is typically in a range from 0.8 per mm to 15 per mm, preferably from 1 per mm to 15 per mm, more preferably from 2 per mm to 15 per mm, more preferably from 3 per mm to 15 per mm and most preferably from 4 per mm to 12 per mm. Supporting structures having cantilevered or other supporting elements will typically have fewer bends per unit length of the ring circumference.. [00131] The ratio of (1) number of bends to (2) circumference may be constant or variable over at least some rings, over all or a portion of the scaffold or other expandable supporting structure. [00132] In some instances, the rings may span a segment of the distal tip having a length in the distal tip in a range from 0.5 mm to 500 mm or more, usually from 10mm to 100 mm, and more usually from 10 mm to 40 mm, measured in a longitudinal direction.

[00133] In some instances, the rings may span a segment of the distal tip having a length in the distal tip in a range from 0.5 mm to 500 mm or more, usually from 10mm to 100 mm, and more usually from 10 mm to 40 mm, measured in a longitudinal direction. In some instances, the scaffold is composed of one expandable ring spanning a length in the distal tip in a range from 0.1mm to 0.5 mm, usually from 0.15 mm to 0.35 mm, and more usually from 0.15 mm to 0.3 mm, measured in a longitudinal direction.

[00134] In some instances, the distal tip may have from 1 to 10 rings per mm of length of the distal tip, usually from 2 to 8 rings per mm of length of the distal tip, more usually from 3 to 5 rings per mm of length of the distal tip.

[00135] In a preferred example, the rings of the expandable supporting structure comprise bends, e.g., crowns, and struts, where the bends have a length measure along their arc and the struts have an axial length, wherein a ratio of the arc length of the bend or crown to the axial length of the strut ranges from 0.2: 1 to 2: 1, preferably from 0.5: 1 to 1.5: 1, and more preferably from 0.75: 1 to 1.25:1. In specific preferred examples, the arc lengths of crowns and axial lengths of the struts connected to the crowns are each in a range from 0.05 mm to 0.25 mm, preferably from 0.075 mm to 0.225 mm, and more preferably from 0.1 mm to 0.2 mm, preferably being about 0.15 mm, or preferably being 0.15 ± 0.05mm, , for example being 0.15 ± 0.05mm. [00136] In some instances, at least some of the adjacent rings in the expandable distal tip may be formed from a tube or a bent wire and joined continuously in an end-to-end in a helical arrangement. For example, the at least some adjacent rings may be joined at an absolute pitch angle in a range from 70° to 89.9°, or from 75° to 89.9°, usually from 80° to 89.9°, more usually from 84° to 89.75°, and frequently from 85° to 88.5° as patterned or as delivered, relative to the longitudinal axis. The absolute pitch angle may be constant or variable along at least some rings, or along the length of the expandable scaffold (or a long a length of the expandable scaffold wherein the length is shorter than the length of the scaffold or along other expandable supporting structure) or other expandable supporting structure. The absolute pitch angle of at least some adjacent rings maybe constant or variable along the length of the expandable scaffold or other expandable supporting structure. The pitch angles are typically measured in the as patterned configuration. Alternatively, the pitch angles above maybe measured in the as delivered configuration. In a preferred instance, the at least some adjacent rings are free from links or attachments points between the adjacent rings. In other preferred instances, the at least some adjacent rings have fixed cell amplitude within each ring or within the at least adjacent rings. In rare instances, at least some adjacent rings may have attachment point or links connecting adjacent rings. In other rare instances, at least some adjacent rings may have a variable cell amplitude or a variable ring amplitude within each ring or within the adjacent rings.

[00137] In other instances, at least some of the adjacent rings may be arranged as separate parallel planes and joined by axial links or joined by other means such as crowns on adjacent rings which are fused/soldered or otherwise joined together (attachment points). The separate parallel planes may be oriented perpendicularly or at an angle relative to a longitudinal axis of the scaffold or other expandable supporting structure when straightened. In some instances, the separate adjacent rings are not joined together by links or by other means but are held together by one or more expandable membrane containing, covering, and/or embedding the separate rings. [00138] In some instances, at least some of the cells may comprise a malleable metal or metal alloy configured to plastically deform. The malleable metal may comprise a metal or metal alloy as identified previously in this application.

[00139] In some instances, the radially contracted configuration of the scaffold or other expandable supporting structure and/or the distal tip may have a maximum diameter in a range from 0.5 mm to 30 mm, usually from 1.3 mm to 5.5 mm, and the radially expanded configuration may have a minimum diameter in a range from 1 mm to 40 mm, usually from 2 mm to 5.5mm. [00140] In some instances, the distal tip may be configured to expand from an initial cylindrical shape to an enlarged cylindrical configuration in response to the radially outward expansion force applied within the distal tip.

[00141] In some instances, distal tip may be configured to expand from an initial cylindrical shape to an enlarged conical configuration in response to the radially outward expansion force applied within (or applied from inside) the distal tip.

[00142] In some instances, circumferentially adjacent cells in at least some of rings in the distal tip may have round, oval, oblong, flat or substantially flat outer and/or inner surfaces which define “facets” in a polygonal structure. In those instances, the ring may have a first radius from an axial center line of the ring to the circumferential center of each facet and a second radius from an axial center line of the ring to the a circumferential edge of each facet where the length of the first radius is from 97% to 99.9% of the length of the second radius, preferably being from 98% to 99.7%, more preferably being from 98.5% to 99.5%, and most preferably being from 99% to 99.5%, in the expanded configuration. This provides the expandable distal tip with one or more of the following: enlarged inner lumen configuration (or maximum inner lumen configuration), enhanced aspiration lumen area, maximize the aspiration lumen area in the expanded configuration, resist collapse in the expanded configuration under vacuum when the distal tip is engaging a clot (or blocked or plugged with clot or other substances, enhance deliverability of the aspiration catheter distal tip, and enhance deformation resistance or kink resistance of the expandable distal tip in the as delivered configuration when navigating the vasculature. In a preferred instance, the expandable tip in the expanded configuration has a “circularity” (as defined below with respect to FIG. 16) ranging from 97% to 99.9%, preferably ranging from 98% to 99.5%, and more preferably ranging from 98.5% to 99.5%. In another preferred instance, the circularity of the expandable tip in the expanded configuration is greater than 97%, preferably greater than 98%, more preferably greater than 98.5%, and most preferably greater than 90%. The circularity of the expandable distal tip refers to the inner lumen configuration. Alternatively, the circularity of the expandable distal tip measuring the outer circumference of the distal tip.

[00143] In some instances, the tubular catheter body may have a length from the proximal end to the distal end in a range from 50 cm to 200 cm, an outer diameter in a range from 0.5 mm to 30 mm, and an inner lumen diameter from 0.25 mm to 25 mm. In one example, the expandable distal tip length ranges from 0.5 mm to 50cm. In another example, the expandable distal tip length is the same as the distal end length. In other examples, the expandable distal tip comprises substantially the entire length of the catheter tubular body. In yet another example, the expandable distal tip is composed of an expandable scaffold (or expandable supporting scaffold) covered with or embedded within one or more polymeric material, wherein the expandable scaffold comprises one circumferential ring, said one ring comprises a plurality of struts joined by crowns, and wherein the ring is expandable from an as delivered configuration to an expanded configuration, said ring resist collapse when a vacuum is applied at a proximal end of the aspiration lumen and the distal end of the distal tip is opposed to a clot or plugged. In some other instances, the expandable scaffold comprises 2, 3, 4, or 5 circumferential rings.

[00144] In some instances, the expandable distal tips may further comprise a multiplicity of supporting elements, where each supporting element may have a base end and a free end and where the base end is attached to one of the radially expandable rings and the free end extends towards or extends into an adjacent gap in an axial and/or circumferential direction to the distal tip. For example, at least some of the plurality of rings may comprise struts joined by bends and at least some of the multiplicity of supporting elements may have their base ends attached to a strut and/or at least some of the multiplicity of supporting elements may have their base ends attached to a bend. [00145] In other instances, at least some of the multiplicity of supporting elements may have their base ends attached to an inside surface of the ring (or the rings ring’s structural elements) and/or attached to an outside surface of the ring (or the ring’s structural elements).

[00146] In some instances, at least some of the multiplicity of supporting elements may have a constant width over their distal portions or along their entire length. In other instances, at least some of the multiplicity of supporting element may have a variable width over their distal portions or along their length. In other instances, at least some of the multiplicity of supporting elements may have a larger width at their base and a constant width along the remaining length of the supporting elements. In a preferred example, the width of the supporting elements is larger than the width of an adjacent struts, crown, or ring segment. Having larger supporting elements width that adjacent structural elements allow contraction of the expandable scaffold or other expandable supporting structure after expansion of the scaffold to an expanded configuration when the scaffold is withdrawn into a guiding catheter having an inner lumen smaller than the expanded configuration of the expandable scaffold.

[00147] In some instances, at least some of the multiplicity of supporting elements may have distal tips which extend toward and/or into the adjacent circumferential and/or axial gap.

[00148] In some instances, at least some of the multiplicity of supporting elements may have distal tips which terminate flush with adjacent bend or crowns that join the struts.

[00149] In some instances, at least some of the multiplicity of supporting elements have distal tips which are recessed between adjacent bends that join the struts in the as delivered configuration and wherein the supporting elements project further towards or further into an adjacent gap.

[00150] In still other aspects, the present invention provides methods for aspirating clot from a patient’s vasculature comprising positioning a distal tip of any one of the aspiration catheters described herein in the patient’s vasculature at a region of clot. The distal tip is expanded to its radially expanded configuration, or to a radially expanded configuration from an as delivered configuration, to engage a vascular wall adjacent the region of clot, or to engage a clot, and a negative pressure is applied to a proximal end of the lumen in the catheter body to aspirate the clot into the central passage of the expanded expandable supporting structure (the aspiration lumen). The expanded configuration has a suction force larger than the as delivered configuration under the same applied vacuum. The suction force in the expanded configuration is larger by a range from 1.1 to 10 times, preferably larger by a range from 1.5 to 6 times, more preferably larger by a range from 1.8 to 6 times the suction force of the as delivered configuration.

[00151] In some instances, at least a portion of the expandable scaffold or other expandable supporting structure remains at least partially unexpanded after expansion of another portion of the expandable scaffold. The at least partially unexpended portion may have a variety of shapes such as cone shape, oval shape, oblong shape, flat shape, or other shapes. In some other instances, at least one segment of the expandable scaffold or other expandable supporting structure comprises remains unexpanded after expansion of another adjacent segment of the expandable scaffold or other expandable supporting structure to the expanded configuration. [00152] In still other aspects, the present invention provides a method for aspirating clot from a patient’s vasculature comprising positioning a distal tip of any one of the aspiration catheters described herein in the patient’s vasculature at a region of clot. At least a segment of the distal tip is expanded to its radially expanded configuration from an as delivered configuration (contracted configuration) to engage a vascular wall adjacent to the region of clot, or to engage a clot, and a negative pressure is applied to a proximal end of the lumen in the catheter body to aspirate the clot into the central passage of the expanded expandable structure. In other examples, the clot is aspirated in the contracted (as delivered) configuration without expanding the distal tip to the expanded configuration.

[00153] In some instances, a segment or other portion of the expandable scaffold or other expandable supporting structure remains at least partially unexpanded after expansion of another portion of the expandable scaffold.

[00154] In still other aspects, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and a lumen extending along a longitudinal axis. An expandable coil comprising successive helical turns is disposed along a longitudinal axis, where the expandable coil comprises undulating bends and struts and said successive turns having a gap therebetween, wherein the successive turns are inclined at an acute pitch angle relative to the longitudinal axis. A jacket is disposed about the expandable coil. In a preferred example, the acute pitch angle ranges from 70° to 89.9°, usually from 80° to 89.75°, and more usually from 82° to 89.75° degrees, relative to the longitudinal axis, in the as patterned or as delivered configurations. In a preferred instance, at least some successive turns are free from links or attachment points joining said adjacent turns. In yet another preferred instances, at least some adjacent turns have fixed cell amplitudes within each turn or within the at least some adjacent turns.

[00155] In some instances, the expandable scaffold or other expandable supporting structure is composed of an expandable coil wherein the expandable coil comprises a plurality of adjacent expandable rings joined continuously, end-to-end in a helical arrangement, wherein each ring comprises structural elements comprising struts joined by crowns, and wherein the expandable coils have an acute pitch angle ranging from 70° to 89.9°, preferably ranging from 80° to 89° degrees, relative to the longitudinal axis as patterned or as delivered. The expandable coil is expanded from an as delivered configuration or a contracted configuration to an expanded configuration by an expandable supporting structure radially expanded in an interior of the expandable coil such as a balloon catheter, wherein said expandable coil is said to be balloon expandable.

[00156] In some instances, the expandable coil may be configured to be expanded by an expandable supporting structure radially expanded in an interior of the expandable coil. For example, the expandable coil may be balloon expandable.

[00157] In some instances, the coil may be formed at least in part from a malleable metal or metal alloy. In some other examples, the coil may be formed from a malleable metal or metal alloy.

[00158] In some other instances, the coil maybe formed from a shape memory metal or shape memory alloy, wherein the expandable distal tip is constraint in the as delivered configuration and is released to expand to the larger expanded configuration. Examples of shape memory alloys include nickel titanium alloy, or other.

[00159] In some instances, at least a proximal portion of the tubular catheter body may be nonexpandable.

[00160] In some instances, at least a proximal portion of the tubular catheter body may be radially expandable.

[00161] In some instances, the expandable coil may be attached to a reinforcement member in a proximal segment of the catheter body.

[00162] In some instances, the expandable coil and the reinforcement member may be formed from a continuous wire or tube.

[00163] In some instances, the adjacent rings may be joined at an acute pitch angle in a range from 70° to 89.9°, preferably range from 80° to 89.9°, more preferably range from 85° to 89° degrees, and most preferably range from 86° to 89° relative to the longitudinal axis in the as patterned configuration or in the as delivered configuration.

[00164] In some instances, the expandable coil may be attached to distal end of the tubular catheter body, incorporated within the distal end of the tubular catheter body, or coupled to the distal end of the tubular catheter body. In some other instances, the expandable coil may extend from the distal end of the tubular catheter body to a proximal end, or to the proximal end of the tubular catheter body. The expandable coil in some instances maybe attached to a proximal end of the tubular catheter body.

[00165] In some instances, expandable coil is embedded or laminated in the expandable membrane or embedded or laminated in the tubular catheter body. [00166] In some instances, the expandable coil may have a crimped delivery configuration and an expanded deployed configuration.

[00167] In some instances, the crimped delivery configuration of the expandable coil has a maximum outer diameter in a range from 0.5 mm to 30 mm and the expanded deployed configuration has a maximum outer diameter in a range from 1.5 mm to 40 mm.

[00168] It should be appreciated that all features and aspects of the apparatus and methods of the present invention described herein may be arranged in different combinations and are covered by the claims even if no specific embodiments or examples of the particular combinations have been provided. The features which are described in whole or in part in all paragraphs, examples, embodiments, drawings and other aspects as set forth herein may be combined in ways not specifically described and may be part of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[00169] FIGS. 1 A to ID illustrate an exemplary scaffold of the intravascular prostheses of the present invention having supporting elements and shown in the form of a bare metal stent (FIG. 1A), a fully covered stent-graft (FIG. IB), a partially covered stent-graft (FIG. 1C), and in a radially expanded, deployed configuration (FIG. ID).

[00170] FIG. 2 is a detailed view of one end of the scaffold of FIGS. 1 A to ID.

[00171] FIG. 3 is an enlarged, detailed of the scaffold of FIGS. 1A to ID.

[00172] FIGS. 4 A and 4B illustrate an alternative scaffold embodiment suitable for the intravascular prostheses of the present invention in the form of a bare metal stent having helically arranged circumferential supporting rings free from supporting shown in a delivery (unexpanded) and deployed (expanded) configurations.

[00173] FIGS. 5 A and 5B illustrate recessed and protruding supporting elements of the type found in the scaffold embodiments of FIGS. 1 A to ID shown in a delivery (unexpanded) configuration.

[00174] FIG. 6A is a detailed view of the scaffold of FIG. 4B.

[00175] FIG. 6B is a detailed view of adjacent circumferential supporting rings of the expandable scaffold of FIG. 4B.

[00176] FIGS. 7 A and 7B illustrate measurement of a “pitch angle” between adjacent turns of a helical expandable scaffold of the type illustrated in FIGS. 4 A and 4B.

[00177] FIGS. 8 A to 8C illustrate membrane-supporting scaffolds having varying pitch angles and varying gap lengths between adjacent rings.

[00178] FIG. 9 is a cross-sectional view of a support scaffold of the present invention embedded in a membrane in the form of a stent-graft illustrating how cells of the supporting scaffold create flat “facets” in the outer surface of the radially expandable scaffold. Circularity is defined as a ratio of a radius (r) of the facet in the membrane intermediate the cells to a radius of the cells (R) x 100, expressed as a percentage.

[00179] FIG. 10 defines various characteristics that can be used to define the rings of a scaffold or structure of a helical, radially expandable scaffold of the present invention.

[00180] FIGS. 11 A to 11C are side, perspective, and “rolled-out” views of an expandable scaffold comprising a plurality of transversely oriented, axially linked (or joined) expandable rings.

[00181] FIG. 12 identifies various characteristics that can be used to define the structure of an expandable scaffold comprising a plurality of transversely oriented, axially linked (or joined) expandable rings, such as those shown in FIGS. 11 A to 11C.

[00182] FIGS. 13A and 13B are side and perspective views of a scaffold of the present invention having radially expandable rings arranged helically as connected omega-shaped cells. [00183] FIGS. 14A to 14C are detailed exemplary views illustrating different bending patterns that can be utilized in individual radially expandable scaffold rings of the present invention.

[00184] FIGS. 15A and 15B are “rolled-out” views of a closed-cell box ring pattern shown in its non-expanded and expanded configurations, respectively.

[00185] FIGS. 16A and 16B are “rolled-out” views of a closed-cell box ring pattern shown in its non-expanded and expanded configurations, respectively, further comprising “cantilevered” supporting elements recessed between circumferentially adjacent box elements in the nonexpanded configuration.

[00186] FIGS. 17A and 17B are “rolled-out” views of a section of an alternative, closed-cell box ring pattern shown in its non-expanded and expanded configurations, respectively.

[00187] FIG. 18 is a “rolled-out” view of a section of an alternative closed-cell box ring pattern, similar to that shown in FIGS. 17A and 17B, shown in its non-expanded and expanded configurations, respectively.

[00188] FIG. 19 is a “rolled-out” views of a section of an alternative closed-cell box ring pattern shown in its non-expanded configurations.

[00189] FIGS. 20 A and 20B are detailed views of a single cell of a closed-cell box ring taken along line 20-20 in FIG.19, shown in non-expanded and expanded configurations, respectively. [00190] FIGS. 21 A to 21C illustrate an exemplary method for embedding a radially expandable supporting scaffold in a polymer membrane to form a vascular prosthesis in accordance with the principles of the present invention.

[00191] FIG. 22 is a cross-sectional view of a region of a wall of a vascular prosthesis fabricated by the method of FIGS. 21A to 21C, shown in a radially expanded configuration. [00192] FIG. 23 A is a “rolled out” view example of a supporting scaffold or other expandable supporting structure having helically arranged circumferential supporting rings constructed in accordance with the principles of the present invention.

[00193] FIG. 23B is a detailed view of adjacent circumferential supporting rings of the expandable distal tip of the supporting scaffold of FIG. 23 A.

[00194] FIG. 23 C is an image of the supporting cell space of FIG. 23 A incorporated into polymeric tubular envelope (one or more membranes) in an unexpanded configuration (as delivered configuration).

[00195] FIG. 23D is an image of the supporting scaffold and polymeric tubular envelope (one or more membranes) of FIG. 23C shown after the integrated membranes/expandable scaffold were radially expanded by a balloon from an as delivered configuration to an expanded configuration.

[00196] FIG. 24A is a “rolled out” view of another example of a supporting scaffold having helically arranged circumferential supporting rings constructed in accordance with the principles of the present invention.

[00197] FIG. 24B is a detailed view of adjacent circumferential supporting rings of the expandable distal tip of the supporting scaffold of FIG. 24A.

[00198] FIG. 25A is a “rolled out” view of a further example of a supporting scaffold having helically arranged circumferential supporting rings constructed in accordance with the principles of the present invention.

[00199] FIG. 25B is a detailed view adjacent circumferential supporting rings of the expandable distal tip of the supporting scaffold of FIG. 25 A.

[00200] FIGS. 26 A to 26AP illustrate a variety of alternative examples of geometries, scaffold designs, and connection locations and shapes for the supporting elements of the present invention.

[00201] FIG. 27 is a “rolled out” view of a further example of a supporting scaffold having adjacently linked circumferential supporting rings with differing frequency of number of crowns, gap widths, cells periods, cells amplitudes and differently configured examples of supporting elements constructed in accordance with the principles of the present invention.

[00202] FIG. 28 is a “rolled out” view of an alternative example of a supporting scaffold having helically arranged circumferential supporting rings free from supporting elements constructed in accordance with the principles of the present invention.

[00203] FIG. 29 is a detailed view of adjacent circumferential supporting rings of the expandable distal tip of the supporting scaffold of FIG. 28. [00204] FIG. 30 illustrates an alternative example of the supporting scaffold of the present invention having discrete supporting pads (or islands) located between struts of a serpentine supporting ring.

[00205] FIGS. 31A and 3 IB illustrate exemplary helical supporting structures comprising two and three nested continuous helical rings, respectively.

[00206] FIGS. 32 and 33 illustrate how the “pitch angle” as referred to herein can be determined as an acute angle.

[00207] FIGS. 34A and 34B are side and “rolled-out” views of an expandable scaffold comprising a plurality of parallel, axially linked (or joined) expandable rings which are inclined relative to a longitudinal axis of the scaffold.

[00208] FIG. 35 is a “rolled-out” view of an expandable scaffold having segment with cells aligned in phase and out-of-phase.

[00209] FIG. 36 is a “rolled-out” view of an expandable scaffold comprising a plurality of rings with gaps therebetween having varying lengths.

[00210] FIG. 37A is a “rolled-out” view of an expandable scaffold comprising a plurality of rings with gaps therebetween arranged in a helical pattern.

[00211] FIG. 37B is a detailed exemplary view of the rings of FIG. 37A showing that each ring has a serpentine pattern.

[00212] FIGS. 37C to 37E are rotated side views of the expandable scaffold of FIG. 37A.

[00213] FIG. 38A is a “rolled-out” view of an expandable scaffold comprising a plurality of rings with gaps therebetween arranged in a helical pattern where individual rings have a first curved shape in the rolled-out pattern.

[00214] FIG. 38B is a detailed view of the rings of FIG. 38A showing that each ring has a serpentine pattern.

[00215] FIGS. 38C to 38E are rotated side views of the expandable scaffold of FIG. 38A.

[00216] FIG. 39A is a “rolled-out” view of an expandable scaffold comprising a plurality of rings with gaps therebetween arranged in a helical pattern where individual rings have a second curved shape in the rolled-out pattern.

[00217] FIG. 39B is a detailed exemplary view of the rings of FIG. 39A showing that each ring has a serpentine pattern.

[00218] FIGS. 39C to 39E are rotated side views of the expandable scaffold of FIG. 39A.

[00219] FIG. 40 is “rolled-out” view of a ring pattern comprising S-shaped expandable elements joined by non-extendable circumferential links shown prior to expansion.

[00220] FIG. 41 is “rolled-out” view of a ring pattern comprising a bent wire having integrated cantilevered supporting elements. [00221] FIGS. 42A to 42C illustrate delivery of a balloon expandable vascular prosthesis in accordance with the principles of the present invention.

[00222] FIGS. 43A to 43C illustrate delivery of a self-expanding vascular prosthesis in accordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[00223] Referring now to FIGS. 1 A to ID, a first exemplary stent-like vascular prosthesis 10 constructed in accordance with the principles of the present invention comprises or consists of a supporting scaffold 12 including a plurality of radially expandable circumferential supporting rings 14. The rings 14 comprise U-shaped bend structures or cells structures including struts 16 joined by crowns 18 having supporting elements 20 between the struts, as seen in FIGS. 2 and 3, where adjacent rings 14 are connected in an end-to-end in a helical pattern, The scaffold is typically a metal scaffold configured for balloon expansion, e.g., a malleable metal as described elsewhere herein. As shown in FIG. 1A, the scaffold 12 has 15 crowns on each side of each ring (helical turn) but that number can vary.

[00224] In a second exemplary embodiment, as shown in FIG. IB, a vascular prosthesis 30 comprises the scaffold 12 of FIG. 1 A embedded in or covered by a membrane 32 to form a stentgraft. In some embodiments, the membrane 32 may be non-porous and configured to prevent blood flow therethrough. Such non-porous membranes would be useful, for example, in the peripheral vasculature where total isolation of an aneurysm is desired or where the stent-graft is deployed for bypass or similar purposes.

[00225] When used in the cerebral vasculature, in contrast, it will often be preferred that the membrane be configured to allow a controlled blood flow into the aneurysm to promote clotting to close the aneurysmal sac. In such cases, the membrane may be porous, foraminous, slotted, mesh-like, or otherwise configured to provide a controlled blood flow thereacross.

[00226] In a third exemplary embodiment, as shown in FIG. 1C, a vascular prosthesis 40 comprises the scaffold 12 of FIG. 1 A embedded in or covered by a membrane 42 to form a stentgraft. Unlike membrane 32 which covers the entire length of the supporting scaffold 12 of stentgraft 30, membrane 42 covers only a center portion 44 of the scaffold 12, leaving the terminal ends 46 uncovered. In this way, the covered center portion 44 can be positioned to cover the neck of a target aneurysm while the uncovered terminal ends 46 can be expanded and firmly anchored into the blood vessel wall away from the aneurysmal neck.

[00227] FIG. ID shows the scaffold 12 of vascular prosthesis 10 in its radially expanded configuration intended for implantation. Typically, but not necessarily, the supporting scaffolds 12 will be laser cut from metal tubes, for example, in the “rolled out” pattern shown in FIG. 1 A to ID. [00228] As best seen in FIG. 2, the terminal end 46 of the scaffold 20 includes a terminal ring 26 has a bifurcation 28 which provides a transition from the helical orientation of the rings 20 and a “squared” distal face of the terminal ring 26. This “squared" construction eliminates having a free distal end of a ring exposed to the vascular lumen as the vascular prosthesis is advanced through the vasculature.

[00229] As best seen in FIG. 3, supporting elements 20 of scaffold 12 are located between adjacent pairs of struts 16 and have a base end 22 attached to an inner radius of the crown 218. Unattached ends 24 of each supporting element 22 are recessed in the space between adjacent struts 16 but otherwise occupy most or all of the space between adjacent struts prior to ring expansion.

[00230] FIGS. 4A and 4B illustrate an alternative embodiment vascular prosthesis 50 comprising or consisting of a supporting scaffold 52 including a plurality of radially expandable circumferential supporting rings 54. The rings 44 comprise U-shaped bend structures or cells structures including struts joined by crowns but lacking supporting elements of the type previously described, where adjacent rings 54 are connected in an end-to-end in a helical pattern and the scaffold is typically a metal scaffold configured for balloon expansion, e.g., a malleable metal as described elsewhere herein. The scaffold 52 is shown in its radially constricted, delivery configuration in FIG. 4 A and in its radially expanded, deployed configuration in FIG. 4B.

[00231] As shown in FIG. 5 A, distal tips 86 of most or all of cantilevered supporting elements 84 will remain recessed within an axial width of a ring 72 (as indicated by lines 88) until the scaffold 70 is radially expanded. While it is usually preferred that the supporting elements 84 remain recessed, in some instances, distal tips 86’ of cantilevered supporting elements 84’ may protrude into the gap regions outside of lines 88, as shown in FIG. 5B. In all instances, the supporting elements 84 and 84’ enhance both circularity and crush resistance of the scaffolds 72 and 72’ after radial expansion without significantly increasing their bending stiffnesses when being introduced through tortuous anatomy prior to expansion.

[00232] As shown in FIGS. 6 A and 6B, an alternative supporting scaffold 90 suitable for use in the vascular prostheses of the present invention comprises a plurality of radially expandable, helically arranged supporting rings 92 comprising struts 94 joined crowns 96 in a serpentine pattern without supporting elements. These are like the scaffold pattern shown in FIGS. 4A and 4B. In order to enhance circularity and crush resistance, the supporting rings 92 have a pattern which inherently provides enhanced support to an attached expandable membrane when used in an expandable stent graft. More specifically, the supporting rings comprise serpentine or zig-zag rings having a width W in a range from 0.1 mm to 1 mm, preferably from 0.3 mm to 0.4 mm; a gap G between adjacent rings in a range from 0 mm to 1 mm, preferably from 0.05 mm to 0.4 mm; crowns arranged along axial lines separated by a spacing CS in a range from 0.1 mm to 1 mm, preferably from 0. mm to 0.4 mm; and struts diverging from the crowns at an angle a in a range from 0° to 90°, preferably from 20⁰ to 40 °, prior to expansion.

[00233] Pitch angle is an important characteristic of the helically arranged scaffold rings of the present invention. FIGS. 7 A and 7B illustrate how the “pitch angle” of a helical scaffold, such as that shown in FIGS. 6A and 6B, can be measured. FIG. 7A illustrates a “rolled-out” pattern of an exemplary helical scaffold 100 in its crimped or pre-expanded configuration, while FIG. 7B illustrates a “rolled-out” pattern of the same helical scaffold 100’ in its radially expanded configuration. The pitch angle of the pre-expanded scaffold 100 is measured between a line LI along the longitudinal axis of the scaffold and a line L2 drawn parallel to the rings 102 in the scaffold. The pitch angle al of the scaffold 100 in the pre-expanded or in the as delivered configuration is typically from 70° to 89.9° or more typically from 80° to 89.9, preferably from 84° to 89.9°, and more preferably from 85° to 89° degrees, and most preferably from 86° to 88°. The pitch angle a2 will greater than the pitch angle al for any given scaffold since the pitch angle increases as the scaffold radially expands, approaching 90° as the scaffold fully expands. [00234] FIGS. 8 A to 8C illustrate helically arranged supporting scaffolds having serpentine rings with different pitch angles. Supporting scaffold 110 shown in its pre-expanded configuration in FIG. 8 A has a pitch angle of 87°. Supporting scaffold 112 in FIG.8B shown in its pre-expanded configuration has a pitch angle of 86. Supporting scaffold 114 in FIG. 8C shown in its pre-expanded configuration has a pitch angle of 85°.

[00235] FIG. 9 illustrates the how a faceted outer surface of the radially expandable vascular prosthesis comprising a membrane supported by an expandable scaffold of the present invention approaches a circular perimeter (achieves enhanced “circularity”). Cross-sectional views of an exemplary radially expandable distal tip region 120 are shown in a pre-expanded configuration (120) and a radially expanded configuration (120’). A circumferentially expanding ring 122 is embedded in a polymer membrane 124, so that the outer surface of the radially expandable outer surface forms a number of relatively flat facets 126 between struts 348 of the scaffold 342. [00236] In its pre-expanded configuration 120 (FIG. 9), the radially expandable vascular prosthesis has a first radius r2 from an axial center line C of the ring to the circumferential center of each facet 126 and a second radius R2 from the axial center line C of the ring to the a circumferential edge of each facet 126, and wherein the length of the first radius r2 is from 80% to 99.9% of the length of the second radius R2, preferably being from 95% to 99.5%, more preferably being from 97.5% to 98.5%, and most preferably being from 98.5% to 99.5.

[00237] Still referring to FIG. 9, in its expanded configuration 120’ (e.g. a radial expansion of 50% or less, usually of 100% or less, and sometimes of 200% or less), the radially expandable vascular prosthesis has a first radius R1 from the axial center line C of the ring to the circumferential center of each strut 128 and a second radius rl from the axial center line C of the ring to a circumferential edge of each facet 126, and wherein the length of the first radius is from 75% to 99% of the length of the second radius, preferably being from 97% to 99%, often being from 98% to 99%, more typically being 98.5%. A circularity in the expanded configuration greater than 97% is preferred, greater than 98% is more preferred, and greater than 98.5% is most preferred,

[00238] FIG. 10 identifies various characteristics that can be used to define the structure of a radially expandable helical rings of the present invention, with values as shown in Table 1 below.

TABLE 1 : Characteristics of a Helical Ring Pattern

[00239] While the scaffold rings illustrated thus far have been helically arranged, in other instances, the scaffold rings of the present invention can be arranged in parallel to each other, typically being arranged orthogonally relative to a longitudinal axis of the scaffold in an unstressed condition and being longitudinally attached by axial links. FIGS. 11 A to 1C are side, perspective, and “rolled-out” views of such an expandable scaffold 130 comprising a plurality of such transversely oriented, expandable rings 132 joined by axial links 134.

[00240] FIG. 12 identifies various characteristics that can be used to configure the structure of an expandable scaffold comprising a plurality of transversely oriented, axially linked expandable rings, such as that shown in FIGS. 11 A to 11C, with values as shown in Table 2 below.

TABLE 2: Characteristics of an Axially Linked Ring Pattern

[00241] FIGS. 13A and 13B are side and perspective views of a scaffold 140 having helically arranged radially expandable rings 1422 with a repeating omega-shaped cell pattern.

[00242] FIGS. 14A to 14C are detailed views illustrating different bending patterns that can be utilized in the radially expandable distal tip rings of the present invention. Supporting rings 150 having serpentine bending patterns are shown in FIG. 14A. Supporting rings 152 having zigzag bending patterns are shown in FIG. 14B. Supporting rings 154 having box box-shaped (squareshaped) bending patterns are shown in FIG. 14C.

[00243] FIGS. 15A and 15B are “rolled-out” views of a ring pattern comprising closed-cell box rings 160 shown in its non-expanded and expanded configurations, respectively. Boxes 162 in each ring circumferentially elongate from a rectangular, non-expanded shape as shown in FIG. 15A to a generally hexagonal, elongated shape, as shown in FIG. 15B. Such elongation allows each ring to radially expand in response to an opening force provided by a balloon or other deployment tool.

[00244] FIGS. 16A and 16B are “rolled-out” views of a rings 170 comprising closed-cell boxes 172, shown in its non-expanded and expanded configurations, respectively. The rings 170 are similar to the rings 160 illustrated in FIGS. 15A and 15B. rings 170, except that they further comprise cantilevered supporting elements 174 recessed between attached to circumferential links 176 circumferentially adjacent box elements 172 in the non-expanded configuration (FIG. 16A). The cantilevered supporting elements 174 remain in spaces between adjacent expanded boxes to provide further support for the surrounding membrane (not shown) after the rings are radially expanded, as shown in FIG. 16B.

[00245] FIGS. 17A and 17B are “rolled-out” views of rings 180 comprising alternative closedcell boxes formed from side members 182 and cross members 184. The side members 182 are initially formed in a U-shape when the rings are in a non-expanded configuration, as shown in FIG. 17 A. The U-shape elongates as the rings are radially expanded, as shown in FIG. 17B.

[00246] Closed cell boxesl90 may also be formed as shown in FIG. 18 with U-shaped structures penetrating only partially into the space between cross members 182.

[00247] Referring now to FIGS. 19, 20A, and 20B, a particular serpentine ring arrangement comprises U-shaped cells 200 with U-shaped supporting elements 202 extending across openings 204 between adjacent crowns 206. The U-shaped supporting elements 202 are configured to expand from a crimped configuration, as shown in FIG. 20A to an expanded configuration as shown in FIG. 20B as the ring is radially expanded.

[00248] FIGS. 21 A to 21C illustrate an exemplary method for embedding a radially expandable supporting scaffold 210 into a polymer membrane 212 (FIG. 21C) which may include one or more of the same or different membrane materials. Individual rings 214 of supporting scaffold 210 will have a serpentine pattern with struts 216 having gaps 218 therebetween, as shown in FIG. 21 A. The supporting scaffold 210 may be embedded in the polymer membrane 212 by first placing sheets 226 and 228 of the desired polymer or polymers over exterior and interior surfaces of the rings 214, as shown in FIG. 21B. By applying heat and pressure to the polymer sheets, the polymer will flow into the gaps 218, forming a continuous polymer membrane matrix 230 having exterior and interior surfaces 232 and 234, respectively, as shown in FIG. 21C.

[00249] A section of a vascular prosthesis comprising the scaffold 210 and the polymer membrane matrix 212 is shown in its radially expanded configuration in FIG. 22. The polymer matrix 212 is elastic, allowing it to stretch and thin as the distal tip is expanded. While the polymer membrane will usually exert a radially closing force, the expanded supporting scaffold 210 will have sufficient hoop strength (crush resistance) to hold the distal tip open against both the elastic force of the polymer membrane and any other forces that might be applied during deployment and use.

[00250] Referring now to FIGS. 23 A to 23D, a supporting scaffold 360 pattern includes supporting elements 368 attached to the outer curved walls of crowns 366 which join adjacent struts 364. In contrast to the pattern of FIGS. 2A-2C, the supporting elements 368 do not extend between adjacent struts 364 but rather extend into a gap or open space between adjacent radially expanding circumferential support rings 362. A second difference is that the support rings 362 are joined continuously, end-to-end to form a helical pattern. FIG. 4C is an image showing an expandable region of an aspiration catheter with the scaffold pattern of FIGS. 4 A and 4B in a radially constricted configuration (or as delivered configuration) suitable for delivery. FIG. 4D is an image of the same structure shown in FIG. 4C after it has been balloon-expanded to an expanded configuration, preferably to its maximally enlarged configuration suitable for aspiration. The distal end ring is configured to have a flush end with an approximately 90° pitch angle relative to the longitudinal axis in the as patterned or as delivered configuration (as shown). The end and immediately adjacent rings may be configured in various ways. The ring adjacent the end ring is this example was truncated along the circumferential path of said ring and connected to the end ring as shown in FIG. 4 A. The end ring and ring adjacent the end ring may have different acute (or 90°) pitch angles (as shown). Alternatively, the ring before end and end ring may also have same or different cells amplitude, cells periods, structural elements widths, and/or number of crowns. The expandable scaffold 360 pattern has a pitch angle of about 86°. The pitch angle in other examples may range from 70° to 89.9°, preferably may range from 80° to 89° relative to the longitudinal axis in the as patterned or as delivered configuration. It is important to note that even though the supporting elements extend into gap regions (or other spaces) between adjacent rings, usually these supporting elements do not extend into adjacent ring regions, thereby maintaining enhanced deliverability of the expandable scaffold segment into the vascular anatomy.

[00251] Referring now to FIGS. 24A and 24B, a supporting scaffold 370 having a helical pattern similar to that of scaffold 360 comprises a plurality of radially expandable circumferential support rings 372 including struts 374 and crowns 376. Support elements 378 differ from support elements 68 in that they have bifurcated end support discs. The supporting elements form a circumferential envelop about the scaffold circumference along a scaffold length or along the entire length of the scaffold. The circumferential envelop typically has a fixed axial length, width, shape, and/or geometry (as shown), and provides support to the one or more expandable membranes to resist collapse of the one or more expandable membranes after expansion from an as delivered configuration to an expanded configuration and a vacuum is applied at a proximal end of the aspiration catheter with the distal tip is blocked or plugged with clot or other substances. In this example, the supporting elements base is at crowns peaks regions. The supporting elements extend axially beyond each ring amplitude or beyond at least some rings amplitude wherein the amplitude is the axial distance between two adjacent peaks on the same ring. In some instances, the supporting elements may have varying lengths, widths, shapes, or geometry within a ring or along at least some rings, wherein the different widths, lengths, shapes, or geometries continue to provide support to the expandable one or more membrane to prevent collapse under vacuum in the expanded configuration of the at least one or more membranes. The proximal end ring of the expandable scaffold is composed of an expandable segment (shown) and a non-expandable segment (truncated), defining the transition between the expandable scaffold and the reinforcing coil. The first non-expandable reinforcement coil segment may be attached to one or more locations on the adjacent expandable ring and/or on the adjacent reinforcement coil turn, or remain free from being joined, other than being joined in a helical pattern to adjacent turns.

[00252] Referring now to FIGS. 25 A and 25B, a supporting scaffold 380 has a helical pattern similar to that of scaffolds 360 and 370 and comprises a plurality of radially expandable circumferential support rings 382 including struts 384 joined by crowns 386. Support elements 388 differ from support elements 368 and 378 in that they extend primarily in a circumferential direction allowing adjacent support rings 382 to be positioned very closely together in an axial direction prior to expansion. In this example, the supporting elements extend substantially into the entire gap between rings, leaving a small gap in between adjacent ring. This type of supporting elements configuration provides the one or more membranes enhanced resistance to collapse when the membranes are expanded from an as delivered configuration to an expanded configuration and a vacuum is applied at a proximal end of the aspiration catheter. On the other hand, such design configuration where the gap is small is more suitable for anatomy that is not tortuous. In this example and other example, it is important to note the symmetry of the supporting elements within each ring, preferably within at least some rings, and more preferably along substantially the entire length of the scaffold. Such symmetry provides resistance to deformation and/or kinking when navigating the vasculature. It also provides a more enhanced resistance to collapse of the expandable membrane. In some instances, one or more supporting elements may be missing within one or more rings providing a non-symmetrical supporting element pattern yet maintaining the resistance to collapse of the expandable membranes.

[00253] As shown thus far, the support elements have generally comprised a straight structure having a base end attached to a radially expandable circumferential support ring and a free end located in a space between adjacent struts, between adjacent struts joined by crowns, or a gap between adjacent support rings. As shown in FIGS. 26A-26N, however, the geometries and attachment locations of the support elements may vary widely. Support element 404a shown in FIG. 26A has a base end attached to an inner radius or wall of crown 402 and a free end terminating in an oval contact pad 405a in a V-shaped, O-shaped space between adjacent struts 400. The oval contact pad 405a has a major axis aligned an axial direction. As shown in FIG. 26B, a support element 404b terminates in an oval contact pad 405b having a major axis aligned in a circumferential direction.

[00254] Support element 404c in FIG. 26C is similar to the previously described support elements except that it terminates in a triangular contact pad 405c with a pointed tip directed away from the attached crown. Support element 404d in FIG. 26D is similar to all of the previously described support elements except that it terminates in a triangular contact pad 405d with an expanded base directed away from the attached crown. Supporting element 404g shown in FIG. 26G has a base attached to a center of an inside wall of crown 402 and a circular contact pad 405g having a hole in its center circumferentially aligned with the attachment point.

[00255] Support elements having curved shafts are shown in FIGS. 26E, 26F, 26H, and 261. Support element 404e shown in FIG. 26E has an S-shaped shaft with a base end attached on one side of an outer curve of crown 402 and a circular contact pad 405e circumferentially aligned with the outermost point of the crown. Supporting element 404f shown in FIG. 26F has a base attached to the outermost point on crown 402 and a circular contact pad 405f circumferentially aligned with said outermost point. Supporting element 404h shown in FIG. 26H has a base attached to the outermost point of the crown 402, a shaft with a simple 90° bend, and a circular contact pad 405h axially offset from said outermost point. Supporting elements 404i shown in FIG. 261 have their base ends attached along the length of struts 400 and circular contact pads 405i attached to their free ends. The shaft has an approximately 120° bend.

[00256] Supporting element 404j shown in FIG. 26J is similar to those shown in FIGS. 2A-2C having a circular contact pad 405j at the free end of a linear shaft but includes a short split 406j formed in crown 402j to permit an increased radial expansion.

[00257] In other examples, supporting elements may have bends, bifurcations, multiple contact pads, and their structural features to enhance their ability to support the expandable membranes in regions between adjacent struts and/or adjacent support rings. As shown in FIG 26K, supporting element 404k is bifurcated into a Y-shape and has a pair of contact pads 405k. Supporting element 4040 shown in FIG. 26L also has a bifurcation with a pair of contact pads 405 £ and third contact pad 4060 located at the point of bifurcation.

[00258] In still other examples, supporting elements may be formed as linked, linear segments optionally having contact pads at some or all junctions between the links. For example, as shown in FIGS. 26M and 26N, supporting elements 404m and 404n, respectively, each comprise a pair of linear segments with a contact pad 405m and 405n, respectively, at a terminal free end and an inner contact pad 406m and 406n, respectively, at the junction between the segments. The linear segments in supporting element 404m are attached at an approximately 120° angle while the linear segments in supporting element 404n are attached at a right (90°) angle. [00259] Referring now to FIGS. 260 to 26R, a variety of T-shaped supporting elements having base ends attached to an inner surface of a U-shaped crown are illustrated. The T-ends may extend into a gap between adjacent rings and may be flush with either ring as shown in FIGS. 260 and 26P. Alternatively, the T-ends may be flush with the ring to which they are attached (FIG. 26Q) or may extend into the intermediate gap without contacting either ring (FIG. 26R). In some examples, supporting elements within each ring extend in the same direction as shown in FIF. 260. Alternatively, supporting elements within each ring may extend in opposite directions as shown in FIG. 26P.

[00260] Referring now to FIG. 26 S, supporting elements having base ends attached to an inner surface of a U-shaped crown may have unattached ends having different terminal geometries extending into a gap between adjacent rings. For example, some of the terminal ends may be provided with a bumper or stop element configured to engage an adjacent ring to maintain a desired gap region therebetween.

[00261] Referring now to FIG. 26T, supporting elements having base ends attached to an inner surface of a Box-shaped, or U-shaped crown may have recessed unattached ends (free ends) which fill essentially all space between adjacent struts on each ring (or which fills or covers substantially all the space between adjacent struts on each ring in the as patterned or as delivered configuration). This is a preferred ring geometry as shown in more detail in FIGS. 11 A to 1 ID discussed in detail below.

[00262] Referring now to FIGS. 26U to 26 Y and 26P, a variety of supporting elements having base ends attached to an outer surface of a U-shaped crown are illustrated. The unattached ends (free ends) of the supporting elements may have T-shaped, L-shaped, deflected, or a variety of other geometries, and will fully or partially extend into a gap between adjacent ring elements, the terminal ends may be flush with an adjacent ring, as shown in FIGS. 260, 26U, 26W, 26X, and 26Y, or may leave an intermediate gap without contacting adjacent ring (FIG. 26V).

[00263] Referring now to FIGS. 26Z to 26AD, a variety of supporting elements may be attached to a side of a crown and extend circumferentially toward and adjacent crown. Single lateral supporting elements are shown in FIGS. 26Z, 26AB, and 26AC, while a pairs of sliding lateral elements are shown in FIG. 26AA and 26AD. The lateral elements may optionally extend over the outer surface of an adjacent crown, as shown in FIG. 26 AC.

[00264] As shown in FIGS. 26 AE to 26AP, the supporting elements may be formed as “lock and key” structures comprising a straight or male element which is slightingly received in a slotted or “clevis” member. Such supporting elements can accommodate circumferential movement and/or axial movement of adjacent ring elements as the scaffold is radially expanded, such expandable or accommodating supporting elements may extend across and opening of a U-shaped cell (including a pair of struts joined by a crown), as shown in FIGS. 26 AD and 26 AE, or may extend from one ring to an adjacent ring as shown in FIGS. 26AF to 26AP. The base end of the male element and/or clevis element may be attached to an inner or outer surface of a crown, to an inner surface of a strut, and may extend in a circumferential direction or may be inclined at an angle relative to the circumference. Either or both of the male elements and slash or the clevis element may have one or more bends. Various geometries and combinations are shown in FIGS. 26AE to 26AP, but it should be appreciated that many other specific geometries could be utilized.

[00265] FIG. 27 is a “rolled out” view of a further example of a supporting scaffold 410 having adjacently linked radially expandable circumferential supporting rings 412 having differing widths and differently configured supporting elements 414 constructed in accordance with the principles of the present invention. As with previous examples, the supporting rings 412 are constructed with pairs of struts 415 joined by crowns 416. Supporting elements 414a are linear beams similar to supporting elements 52 described with reference to FIGS. 2A-2D. Supporting elements 414b have a single bend and are similar to supporting elements 404m shown in FIG. 26M but lacking a middle contact pad between adjacent linear segments and attached to a strut 415 rather than a crown 416. Supporting elements 414c are short, straight beams having a distal contact pad. Supporting elements 414d have a single bend are similar to supporting elements 404h in FIG. 26H. The scaffold rings as shown can have differing number of crowns on adjacent rings, differing cells periods on adjacent rings, supporting elements having differing shapes, number, and frequency on adjacent rings, differing gaps between rings, and/or differing rings amplitudes.

[00266] As shown in FIGS. 28 and 29, a supporting scaffold 420 comprises a plurality of radially expandable circumferential supporting rings 422 comprising struts 424 and crowns 426. Unlike previous examples, there are no supporting elements attached to the supporting rings 422. Instead, the supporting rings 422 have a pattern which inherently provides enhanced support to an attached expandable membrane when used in an expandable distal tip of an aspiration catheter. More specifically, the supporting rings comprise serpentine or zig-zag rings having a width W in a range from 0.1 mm to 1 mm, preferably from 0.3 mm to 0.4 mm; a gap G between adjacent rings in a range from 0 mm to 1 mm, preferably from 0.05 mm to 0.4 mm; crowns arranged along axial lines separated by a spacing CS in a range from 0.1 mm to 1 mm, preferably from 0.25 mm to 0.4 mm; and struts diverging from the crowns at an angle a in a range from 0° to 90°, preferably from 20° to 40°, prior to expansion.

[00267] FIG. 30 illustrates a further alternative embodiment of the supporting scaffold 440 of the present invention having discrete supporting pads 450 located between struts 444 of a serpentine radially expandable supporting ring 442. The struts 444 are joined by crowns 446 in a conventional manner, and adjacent supporting rings 442 are joined by links 447. The supporting pads 450 are attached to the supporting the membrane 452 in V-shaped regions between adjacent struts 444 but are otherwise not attached to the remaining components of the expandable supporting structure 440. Preferably though not necessarily the supporting pads 450 may have a triangular shape corresponding to the V-shaped region in which they are attached. They may also have other shapes such as circular, oval, or other rounded shapes.

[00268] As illustrated thus far in this application, the exemplary helical supporting structures have usually consisted of a single helically wound serpentine, zigzag or other ribbon having bends that allow for elongation upon radial expansion of the associated ring. In other instances, as illustrated in FIGS. 31 A and 3 IB, supporting structures 500 and 502 may have two, three, four, or more helically nested helical rings. As shown specifically in FIG. 31 A, the supporting structure 500 includes first and second helically nested rings 510 and 512, respectively. As shown specifically in FIG. 3 IB, the supporting structure 502 includes first, second, and third helically nested rings 520, 522, and 524, respectively.

[00269] FIGS. 32 and 33 illustrate how the “pitch angle” of a helical scaffold can be measured. FIG. 32 illustrates a “rolled-out” pattern of an exemplary helical scaffold 600 in its crimped or pre-expanded configuration, while FIG. 14B illustrates a “rolled-out” pattern of the same helical scaffold 600’ in its radially expanded configuration. The pitch angle of the pre-expanded scaffold 600 is measured between a line LI along the longitudinal axis of the scaffold and a line L2 drawn parallel to the rings 602 in the scaffold. The pitch angle ai of the scaffold 600 in the preexpanded or in the as delivered configuration is typically from 70° to 89.9° or more typically from 80° to 89.9, preferably from 84° to 89.9°, and more preferably from 85° to 89° degrees, and most preferably from 86° to 88°. The pitch angle a? will greater than the pitch angle ai for any given scaffold since the pitch angle increases as the scaffold radially expands, approaching 90° as the scaffold fully expands.

[00270] FIGS. 34A and 34B are side and “rolled-out” views of an expandable scaffold 680 comprising a plurality of parallel, axially linked expandable rings 682 which are joined by axially links 684 inclined relative to a longitudinal axis of the scaffold at an acute pitch angle as.

[00271] FIG. 35 is a “rolled-out” view of an expandable scaffold 690 having segments 692 and 694 with cells aligned in-phase and out-of-phase, respectively.

[00272] FIG. 36 is a “rolled-out” view of an expandable scaffold 700 comprising a plurality of rings 702 with gaps 704 therebetween having varying lengths.

[00273] FIG. 37A is a “rolled-out” view of an expandable scaffold 800 comprising a plurality of rings 802 with gaps 804 therebetween arranged in a helical pattern. The rings 802 are “smooth,” i.e., linear and free from bends and curves in the rolled-out pattern. As shown in detailed view FIG. 37B, rings 802 will each have a serpentine pattern. Although a simple serpentine pattern comprising struts 806 joined by crowns 808 is illustrated in FIG. 37B, the rings 802 may comprise any cell patterns described herein or otherwise known in the art.

[00274] FIGS. 37C to 37E are rotated side views of the expandable scaffold 800 of FIG. 37A. The view of the scaffold 800 as shown in FIG. 37D is rotated 90° in a first rotational direction relative to the view in FIG. 37C while view shown in FIG. 37E is rotated 90° in the opposite rotational direction. As the rings 802 of scaffold 800 are “smooth,” i.e., free from bends, the side view does not vary as the scaffold is rotated about is longitudinal axis.

[00275] FIG. 38A is a “rolled-out” view of an expandable scaffold 820 comprising a plurality of rings 522 with gaps 524 therebetween arranged in a helical pattern where individual rings have a first curved shape in the rolled-out pattern. The individual rings 522 are non-linear, including two curved or bent regions 532, one of which spans the joined ends, e.g., 534a and 534b when the scaffold is rolled. As shown in detailed view FIG. 38B, the rings 522 will each a serpentine pattern. Although a simple serpentine pattern comprising struts 526 joined by crowns 528 is illustrated in FIG. 38B, the rings 522 may comprise any cell patterns described herein or otherwise known in the art.

[00276] FIGS. 38C to 38E are rotated side views of the expandable scaffold 520 of FIG. 38A. The view of the scaffold 520 as shown in FIG. 38D is rotated 90° in a first rotational direction relative to the view in FIG. 38C while view shown in FIG. 38E is rotated 90° in the opposite rotational direction. The curves 532 in rings 522 of scaffold 520 cause the observed inclination of each ring 522 to shift from a rightward tilt, as shown in FIG. 38D, to a leftward tilt, as shown in FIG. 38E.

[00277] FIG. 39A is a “rolled-out” view of an expandable scaffold 840 comprising a plurality of rings 842 with gaps 844 therebetween arranged in a helical pattern where individual rings have a second curved shape in the rolled-out pattern. The individual rings 842 are non-linear, including three curved or bent regions 852 (one of which spans the joined ends 854a and 854b when the scaffold is rolled). As shown in detailed view FIG. 39B, the rings 842 will each a serpentine pattern. Although a simple serpentine pattern comprising struts 846 joined by crowns 848 is illustrated in FIG. 39B, the rings 842 may comprise any cell patterns described herein or otherwise known in the art.

[00278] FIGS. 39C to 39E are rotated side views of the expandable scaffold 840 of FIG. 39A. The view of the scaffold 840 as shown in FIG. 39D is rotated 90° in a first rotational direction relative to the view in FIG. 39C while view shown in FIG. 39E is rotated 90° in the opposite rotational direction. The curves 852 in rings 842 of scaffold 840 cause the observed inclination of each ring 842 to shift back-and-forth as the scaffold is rotated relative its longitudinal axis, as can be seen by comparing the imaged in FIGS. 39C, 39D, and 39E.

[00279] FIG. 40 is “rolled-out” view of a ring pattern comprising rings 880 having S-shaped expandable elements 882 joined by non-extendable circumferential links 884 shown prior to expansion.

[00280] FIG. 41 is “rolled-out” view of a ring pattern comprising rings 890 formed from a wire bent into a serpentine pattern having integrated cantilevered supporting elements 892 formed by tight U-shaped turns that are glued, soldered, welded or otherwise bonded together to prevent separation.

[00281] Referring now to FIGS. 42A to 42C, a balloon-expandable vascular prosthesis 900 is delivered to a target aneurysm AS in a cerebral artery CA on a balloon 902 of a balloon catheter 904. The vascular prosthesis 900 may be any of the balloon-expandable embodiments or designs described previously, and will initially be in its radially constricted, delivery configuration when introduced through sheath 906 over a guide wire 908 using a conventional Seidinger technique, as shown in FIG. 42A. After the vascular prosthesis 900 is positioned across a neck N of the aneurysmal sac AS, the balloon 900 is expanded to cover the neck N of the aneurysmal sack with the body of the vascular prosthesis 900, as shown in FIG. 42B. The balloon catheter 906 may then be withdrawn from the vascular prosthesis 900 through the sheath 906, as shown in FIG. 42C, and the sheath 906 then removed from the patient in a conventional manner.

[00282] Referring now to FIGS. 43 A to 43C, a self-expanding vascular prosthesis 920 is delivered to a target aneurysm AS in a cerebral artery CA through a lumen of a microcatheter catheter 922. The vascular prosthesis 920 may be any of the self-expanding embodiments or designs described previously. The microcatheter 922 is introduced through a sheath 924 placed in a conventional manner to have a distal end 926 end proximate the neck N of the target aneurysmal sac AS. The vascular prosthesis 920 will initially be in its radially constricted, delivery configuration when introduced (typically by pushing with a pusher noy shown) through the lumen of microcatheter 922, as shown in FIG. 43 A. After the distal end 926 of microcatheter 922 is located at the aneurysmal neck N, as shown in FIG. 43B, the vascular prosthesis 920 will be pushed out of the distal end 926 while the microcatheter is retracted to locate the vascular prosthesis 920 across the aneurysmal neck, as shown in FIG. 43C. The microcatheter 922 may then be withdrawn through the sheath 924, and the sheath 924 then removed from the patient in a conventional manner.

[00283] Although certain aspects, or examples of the disclosure have been described in detail, variations and modifications and combinations of all or in part of these aspects and examples are within the scope of the present invention and will be apparent to those skilled in the art, including aspects, embodiments or examples that may not provide all the features and benefits described herein. It will be understood by those skilled in the art that the present disclosure extends beyond the specifically disclosed aspects, embodiments, or examples to other alternative or additional examples or embodiments and/or uses and obvious modifications and equivalents thereof. In addition, while a number of variations have been shown and described in varying detail, other modifications, which are within the scope of the present disclosure, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the aspects, embodiments and/or examples may be made and still fall within the scope of the present disclosure. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes or examples of the present disclosure. Thus, it is intended that the scope of the present disclosure herein disclosed should not be limited by the disclosed embodiments or examples described above. For all of the embodiments and examples described above, the steps of any methods for example need not be performed sequentially.

Claims

WHAT IS CLAIMED IS:

1. An intravascular prosthesis comprising: a scaffold including a plurality of radially expandable circumferential rings arranged along a longitudinal axis with circumferential gaps therebetween, wherein at least some of the radially expandable circumferential rings comprise cells including struts joined by crowns; wherein midpoints in the struts of the cells have a radius R measured from a longitudinal axis of the scaffold; wherein midpoints in the gaps between circumferentially adjacent cells have a radius r measured from a longitudinal axis of the scaffold; wherein an outer surface of the scaffold maintains a circularity of at least 97% measured as r/R x 100 after the scaffold is radially expanded by up to 200% from the delivery radius; and wherein the scaffold is configured to be radially expanded from a delivery configuration to a deployed configuration in a target blood vessel.

2. The intravascular prosthesis of claim 1, wherein the radially expandable circumferential rings are arranged continuously, end-to-end in a helical pattern.

3. The intravascular prosthesis of claim 1 or 2, wherein the scaffold is balloon expandable.

4. The intravascular prosthesis of claim 1 or 2, wherein the scaffold is selfexpanding.

5. The intravascular prosthesis of any one of claims 1 to 4, wherein the outer surface of the membrane maintains a circularity of at least 97% measured as r/R x 100 after the scaffold is radially expanded by up to 100% from the delivery radius.

6. The intravascular prosthesis of any one of claims 1 to 4, wherein the outer surface of the membrane maintains a circularity of at least 97% measured as r/R x 100 after the scaffold is radially expanded by up to 50% from the delivery radius.

7. The intravascular prosthesis of any one of claims 1 to 4, wherein the outer surface of the membrane maintains a circularity of at least 98% measured as r/R x 100 after the scaffold is radially expanded from the delivery radius.

8. The intravascular prosthesis of any one of claims 1 to 4, wherein the outer surface of the membrane maintains a circularity of at least 98.5% measured as r/R x 100 after the scaffold is radially expanded from the delivery radius.

9. The intravascular prosthesis of any one of claims 1 to 8, wherein the scaffold is open and the intravascular prosthesis comprises a stent.

10. The intravascular prosthesis of any one of claims 1 to 8, further comprising a membrane attached over at least a portion of the scaffold and wherein the intravascular prosthesis comprises a stent-graft.

11. The intravascular prosthesis of claim 10, wherein the membrane comprises a non-porous material.

12. The intravascular prosthesis of claim 10, wherein the membrane comprises a porous material.

13. The intravascular prosthesis of any one of claims 10 to 12, wherein the membrane is perforated.

14. The intravascular prosthesis of any one of claims 10 to 13, wherein the membrane is configured to extend fully over the scaffold or coil.

15. The intravascular prosthesis of any one of claims 10 to 13, wherein the membrane is configured to extend over a central portion of the scaffold or coil leaving terminal end regions uncovered.

16. The intravascular prosthesis of any one of claims 10 to 15, wherein the membrane carries a pharmaceutically active agent.

17. An intravascular prosthesis, comprising: an expandable coil comprising successive helical turns disposed along a longitudinal axis, the expandable coil comprising undulating bends and struts and the successive helical turns having a gap therebetween, wherein the successive helical turns are inclined at an acute pitch angle in a range from 85° to 89.9°, preferably from 86° to 89° degrees, and more from 86° to 88° relative to the longitudinal axis relative to the longitudinal axis; and wherein the expandable coil is configured to be radially expanded from a delivery configuration having a radially constricted diameter to a deployed configuration having a radially expanded configuration.

18. The intravascular prosthesis of claim 17, wherein: the helical turns have a radius R measured from the longitudinal axis of the coil; wherein flat facets in an outer surface of a membrane attached over at least a portion of the coil and spanning the gaps between circumferentially adjacent helical turns have a radius r measured from a longitudinal axis of the scaffold; and wherein the outer surface of the membrane maintains a circularity of at least 97% measured as r/R x 100 after the scaffold is radially expanded by up to 200% from the delivery radius.

19. The intravascular prosthesis of claims 17 or 18, wherein at least some the helical turns have a distance from peak to peak of helical turns in a ring (helical turn amplitude) in a range from 0.05 mm to 0.35 mm when the radially expandable distal tip is at its delivery radius.

20. The intravascular prosthesis of any one of claims 17 or 18, wherein at least some the helical turns have a distance from peak to peak of helical turns in a ring (helical turn amplitude) in a range from 0.1 mm to 0.25 mm when the radially expandable distal tip is at its delivery radius.

21. The intravascular prosthesis of any one of claims 17 or 18, wherein at least some the helical turns have a distance from peak to peak of helical turns in a ring (helical turn amplitude) in a range from 0.1 mm to 0.2 mm when the radially expandable distal tip is at its delivery radius.

22. The intravascular prosthesis of any one of claims 17 to 21, wherein the expandable coil is balloon expandable.

23. The intravascular prosthesis of any one of claims 17 to 21, wherein the expandable coil is self-expanding.

24. The intravascular prosthesis of any one of claim 17 to 23, wherein the expandable coil is open and the intravascular prosthesis comprises a stent.

25. The intravascular prosthesis of any one of claim 17 to 23, further comprising a membrane attached over at least a portion of the expandable coil and wherein the intravascular prosthesis comprises a stent-graft.

26. The intravascular prosthesis of claim 25, wherein the membrane comprises a non-porous material.

27. The intravascular prosthesis of claim 25, wherein the membrane comprises a porous material.

28. The intravascular prosthesis of any one of claims 25 to 27, wherein the membrane is perforated.

29. The intravascular prosthesis of any one of claims 25 to 28, wherein the membrane is configured to extend fully over the expandable coil.

30. The intravascular prosthesis of any one of claims 25 to 29, wherein the membrane is configured to extend over a central portion of the expandable coil leaving terminal end regions uncovered.

31. The intravascular prosthesis of any one of claims 25 to 30, wherein the membrane carries a pharmaceutically active agent.

32. An intravascular prosthesis, comprising: a scaffold including a plurality of radially expandable circumferential rings arranged along a longitudinal axis with circumferential gaps therebetween, wherein at least some of the radially expandable circumferential rings comprise serpentine or zig-zag structures including struts joined by crowns; and a multiplicity of supporting elements, each supporting element having a base end and a free end, wherein the base ends of the supporting elements are attached to an inner side of the crowns and the free ends are disposed between adjacent struts attached to the crown.

33. The intravascular prosthesis 32, wherein at least some of the free ends of the supporting elements are recessed within the circumferential rings and do not protrude into the circumferential gaps prior to radial expansion of the distal tip.

34. The intravascular prosthesis of claim 32 or 33, wherein at least some of the free ends of the supporting elements protrude into the circumferential gaps after expansion of the distal tip.

35. The intravascular prosthesis of any one of claim 32 to 34, wherein the supporting elements are configured to lie within a cylindrical envelope defined by the scaffold.

36. The intravascular prosthesis of any one of claims 32 to 35, wherein the scaffold is balloon expandable.

37. The intravascular prosthesis of any one of claims 32 to 35, wherein the scaffold is self-expanding.

38. The intravascular prosthesis of claim 32 to 37, wherein the scaffold is open and the intravascular prosthesis comprises a stent.

39. The intravascular prosthesis of claim 32 to 37, further comprising a membrane attached over at least a portion of the scaffold and wherein the intravascular prosthesis comprises a stent-graft.

40. The intravascular prosthesis of claim 39, wherein the membrane comprises a non-porous material.

41. The intravascular prosthesis of claim 39, wherein the membrane comprises a porous material.

42. The intravascular prosthesis of any one of claims 39 to 41, wherein the membrane is perforated.

43. The intravascular prosthesis of any one of claims 39 to 42, wherein the membrane is configured to extend fully over the scaffold or coil.

44. The intravascular prosthesis of any one of claims 39 to 42, wherein the membrane is configured to extend over a central portion of the scaffold or coil leaving terminal end regions uncovered.

45. The intravascular prosthesis of any one of claims 39 to 44, wherein the membrane carries a pharmaceutically active agent.

46. An intravascular prosthesis delivery system comprising: an elongate catheter body having a distal end, a proximal end, and an inflatable balloon at the distal end; and a balloon expandable intravascular prosthesis according to any one of the preceding claims, mounted over the inflatable balloon.

47. An intravascular prosthesis delivery system comprising: an elongate sheath having a distal end and a proximal end; and a self-expanding intravascular prosthesis according to any one of the preceding claims, constricted within a lumen at the distal end of the elongate sheath.

48. A method for delivering an intravascular prosthesis into a patient’ s vasculature, the method comprising: coupling an intravascular prosthesis as in any one of the proceeding claims in its radially constricted configuration to a distal end of a delivery device; positioning the distal end of the delivery device at a target aneurysm within a patient’s vasculature; and deploying the intravascular prosthesis to span the target aneurysm.

49. The method of claim 48, wherein deploying comprises expanding the intravascular prosthesis with an inflatable balloon.

50. The method of claim 48, wherein deploying comprises releasing the intravascular prosthesis from radial constraint within a delivery sheath.