US20090082803A1 - Braided vascular devices having no end clamps - Google Patents

Abstract

In some embodiments, a medical device may include one or more of the following features: (a) a metal fabric formed of braided metal strands, (b) the medical device having a collapsed configuration for delivery through a channel in a patient's body and having a generally dumbbell-shaped expanded configuration with two expanded diameter portions separated by a reduced diameter portion formed between opposed ends of the device and unsecured metal strand ends at the opposed ends, and (d) a thrombogenic agent located on the metal fabric.

Description

FIELD OF THE INVENTION
• Embodiments of the present invention generally relate to intravascular devices for treating medical conditions. Particularly, embodiments of the present invention relate to intravascular devices for treating vascular conditions. More particularly, embodiments of the present invention relate to intravascular devices for selective occlusion of a vessel and/or shunting or restricting flow in a vessel or organ within the body's circulatory system.
BACKGROUND
• A wide variety of intravascular devices are used in various medical procedures. Certain intravascular devices, such as balloon catheters, diagnostic catheters, stent delivery catheters, and guidewires are generally used simply to deliver fluids or other medical devices to specific locations within a patient's body, such as a selective site within the vascular system. Other frequently more complex, devices are used in treating specific conditions, such as devices used in removing vascular occlusions or for treating septal defects and the like.
• In certain circumstances, it may be necessary to occlude a patient's vessel, chamber, channel, hole, or cavity such as to stop blood flow there through. In other cases it may be necessary to create a flow restriction or to shunt flow from one vessel to another to treat abnormal cardiovascular conditions. Examples of selective occlusion are without limitation, closure of a Patent Ductus Arteriosus (PDA), Atrial Septal Defect (ASD), Ventricular Septal Defect (VSD), Patent Foreman Ovale (PFO), Arterial Venous Fistula (AVF), or an Arterial Venous Malformation (AVM).
• Mechanical embolization devices are well known in the art and sold commercially for occlusion of vessels in various locations within the vasculature. Intravascular occlusion devices can be fabricated from Nitinol (NiTi) wire strands that have been braided to form a tubular fabric which is then heat set in a mold to an expanded shape, but which can be compressed for delivery through a catheter to a treatment site whereby the device, when urged out of the delivery catheter, self-expands within the vasculature to occlude blood flow at the treatment site. The details of the various designs and configurations as well as methods of fabricating and using the devices are known in the art.
• An example of a shunting procedure is shunting of blood between the portal vein and the hepatic vein; know as a Transjugular Intrahepatic Portosystemic Shunt (TIPS). Certain forms of congenital disease may require a communication between the right atrium and left atrium. Shunting may also be required for treating specific abnormal conditions, such as bi-passing vascular occlusions within an internal passageway.
• Congenital heart defects are examples of the necessity for flow restriction where holes in the septum allow blood to flow from the high pressure left ventricle to the lower pressure right ventricle causing excess blood flow to the lungs. The body's natural reaction is to constrict the vessels to the lungs to restrict blood flow. Over time, this causes a thickening of the pulmonary arteries and ultimately leads to closure of smaller lung arteries and further complications if left untreated. The treatment involves early mechanical flow restriction of blood to the lungs until a surgical fix can be accomplished.
• The occluding, shunting, and flow restricting devices described above use similar technology for fabrication. Each device is formed from a plurality of resilient metal strands of a shape memory alloy woven into a braided fabric to create a resilient material which can be heat treated to substantially set a desired shape. In performing the heat treatment step, the braided fabric is first deformed to generally conform to a molding surface of a molding element and the braided fabric is then heat treated in contact with the surface of the molding element at an elevated temperature. The time and temperature of the heat treatment is selected to substantially set the braided fabric in its deformed state. After the heat treatment, the fabric is removed from contact with the molding element and will substantially retain its shape in the deformed state. The braided fabric so treated defines an expanded state of a medical device, but which can be longitudinally stretched to reduce its cross-sectional profile so that it can be deployed through a catheter into a channel in a patient's body. The device connects to a delivery device by a threaded connection. Once the delivery catheter's distal end with the device contained within its lumen is placed at the treatment site, the device is urged out of the delivery catheter and self-expands to its expanded preset configuration. Once the device is positioned as desired, the delivery device is unthreaded and the delivery catheter and delivery device are removed from the body.
• One limitation of these devices is the need to clamp the ends of the wire strands at each end of the device to prevent unraveling. In such untreated NiTi fabrics, the strands will tend to return to their unbraided configuration and the braid can unravel fairly quickly unless the ends of the length of braid that has been cut to form the device, are constrained relative to one another. One method which has proven to be useful to prevent the braid from unraveling is to clamp the braid at two locations and cut the braid to leave a length of the braid having clamps at either end, thereby effectively defining an empty space within a sealed length of fabric. These clamps will hold the ends of the cut braid together and prevent the braid from unraveling.
• Alternatively, one can solder, braze, weld or otherwise affix the ends of the desired length together (e.g., with a biocompatible cementitious organic material) before cutting the braid. Although soldering and brazing of NiTi alloys have proven to be fairly difficult, the ends can be welded together, such as by spot welding with a laser welder.
• Devices marketed using these technologies include the braided metal clamps to prevent unraveling of the metal strands. The clamps add to the diameter of the collapsed device for delivery through a catheter as well as project outward from some configurations of the device. These outward projections are often in the blood flow path and could be a source of clot formation or result in flow disruption.
• Some have provided a recess in each end surface of the device where each braided end of the device is held together with a clamp. The clamps are recessed into the expanded diameter portion of the device, thereby reducing the overall length dimension of the device and creating a low profile occluder. However, the recessed clamps cause the fabric to reverse direction in the heat-set state. In the compressed state, the wires are higher stressed and exert an increased outward drag against the wall of the delivery catheter making it more difficult to push the device through the catheter.
• In the case of a flow restrictor or shunt device, the braided wire end clamps make the device configuration bulky and un-necessarily complex, since the natural placement of the clamps is in a co-axial position to the braided tube, which ideally, is where the flow path should be. The designs described require extra manufacturing steps to create the flow path. In addition the manufacturing cost of the device is higher than need be if the clamps were not used.
• With reference toFIGS. 1A-C,2,3, and4, prior occluders, shunts, and flow restrictors are shown respectively.FIGS. 1A-C illustrate an occluder design that may he described as having a flanged or disc shape at each end, connected by a smaller diameter portion between them.FIGS. 2 & 3 are two views of a shunt device.FIG. 4 is an example of a flow restrictor.
• FIG. 1A shows the design of an occluder10 having enlarged diameter discs orflanges11 &12 at each end and a small connecting diameter between the ends. Each end of the device has a wire end clamp. Thedistal clamp14 andproximal clamp13 hold the wire ends from unraveling. The side viewFIG. 1B illustrates howclamps13 extend from the end of the device.Clamp13 containsinternal threads15 that mate withexternal threads16 ondelivery device17 as depicted inFIG. 1C. Apolyester fabric disc18 is used to improve device thrombogenicity and is sutured intodisc12. The fabric collapses with the device for delivery through a delivery catheter.
• It would be desirable for a medical device to achieve occlusion, flow restriction, or shunting of blood in the human vasculature that is:
• of a lower collapsed deliverable profile;
• deliverable through a delivery catheter with less force;
• less intensive to manufacture;
• less disruptive to blood flow; and
• can be manufactured at a reduced cost.
SUMMARY OF THE INVENTION
• In some embodiments, a collapsible medical device may include one or more of the following features: (a) at least one layer of a plurality of metal strands woven into a tubular braided metal fabric having a proximal end, a distal end, and a segment there between, (b) the tubular woven metal fabric having an expanded preset configuration shaped for treatment of an opening in a body organ, (c) the expanded preset configuration being deformable to a lesser cross-sectional dimension for delivery through a channel in a patient's body, the woven metal fabric having a memory property whereby the medical device returns to the expanded preset configuration when delivered into the patient's body, said proximal and distal ends being free of clamps and having at least a portion of the segment larger in diameter than the free wire ends in the expanded preset configuration, and (d) an occluding fiber retained within an expandable hollow central portion formed by said tubular woven fabric.
• In some embodiments, a medical device may include one or more of the following features: (a) a metal fabric formed of braided metal strands, (b) the medical device having a collapsed configuration for delivery through a channel in a patient's body and having a generally dumbbell-shaped expanded configuration with two expanded diameter portions separated by a reduced diameter portion formed between opposed ends of the device and unsecured metal strand ends at the opposed ends, and (d) a thrombogenic agent located on the metal fabric.
• In some embodiments, a method of forming a medical device may include one or more of the following steps: (a) providing a metal fabric formed of a plurality of braided strands, the strands being foaled of a metal which can be heat treated to substantially set a desired shape, (b) deforming the metal fabric to generally conform to a wall surface of a moulding element, (c) heat treating the metal fabric in contact with the surface of the moulding element at an elevated temperature, the temperature and the duration of the heat treatment being sufficient to substantially set the shape of the fabric in its deformed state, (d) removing the metal fabric from contact with the moulding element, (e) cutting the fabric adjacent the device side of the clamps after heat treatment, (f) clamping the opposite ends of the strands before deforming the metal fabric, (g) cutting an appropriately sized piece of the metal fabric, and (h) forming a long tubular braid from the metal fabric.
• In some embodiments, a method for delivering a self-expanding medical device to a selected site in a vascular system may include one or more of the following steps: (a) selecting the combination of: (i) a delivery device inner catheter having a lumen extending from a proximal end to a distal end, the delivery device having an outer diameter adapted to slidingly fit within the lumen of a delivery catheter, (ii) an elongate, flexible member coaxially insertable through the lumen of the delivery device catheter, said elongate flexible member having a plunger member affixed thereto sized to at least partially fit within the lumen of the delivery device catheter when a proximally directed tension force is applied to the elongate flexible member with respect to the delivery device catheter, (iii) a braided tubular device with free ends of individual strands comprising the device captured between the plunger member and the delivery device catheter, (b) feeding the delivery device catheter with the braided tubular device attached through a lumen of the delivery catheter and out thereof, (c) moving the elongate flexible member relative to the tubular delivery device catheter to release the tubular device from the tubular delivery device catheter, (d) releasing a plunger spring located in the plunger member to capture the free ends between the plunger member and the inner delivery device catheter, (e) inserting the delivery catheter within a patient's vasculature, (f) repositioning the braided tubular device if it is not positioned properly upon release from the tubular delivery device catheter, (g) removing the delivery device from the patient's vasculature, (h) removing the delivery catheter from the patient's vasculature.
DESCRIPTION OF THE DRAWINGS
• FIG. 1A shows a perspective view of a prior art occluder.
• FIG. 1B shows a side view of the occluder design ofFIG. 1A.
• FIG. 1C shows an enlarged view of a clamp used in the occluder ofFIG. 1A along with a delivery device threaded end.
• FIG. 2 shows a side view of a prior art shunt device having an eccentric lumen and two discs with recessed securement connectors.
• FIG. 3 shows a top view of a shunt device ofFIG. 2 having an eccentric linen and two discs with recessed securement connectors.
• FIG. 4 shows a perspective view of a prior art flow restrictor.
• FIG. 5A shows a perspective view of an occluder without end clamps in an embodiment of the present invention.
• FIG. 5B shows a side view of an occluder without end clamps in an embodiment of the present invention.
• FIG. 5C shows an enlarged wire end view of an occluder without end clamps.
• FIG. 5D shows a delivery device in an embodiment of the present invention.
• FIG. 6 shows a flowchart diagram of a method of manufacturing a medical device in accordance with embodiments of the present invention.
• FIG. 7A shows a partial side cross-sectional view of a prior art occluder illustrating the clamp and clamp recess only one end of the device.
• FIG. 7B shows a frontal end view of the occluder ofFIG. 7A illustrating the clamp and clamp recess on one end of the device.
• FIG. 7C shows a partial side cross-sectional of an occluder without end clamps in an embodiment of the present invention.
• FIG. 7D shows a frontal end view of an occluder without end clamps in an embodiment of the present invention.
• FIG. 8A shows a cross-sectional view of a design for either a flow restrictor or a shunt in an embodiment of the present invention.
• FIG. 8B shows a frontal end view of a design for either a flow restrictor or a shunt in an embodiment of the present invention.
• FIG. 9 shows a side view of another occluder embodiment of the present invention.
• FIG. 10 shows a side view of an occluder shown occluding an aneurysm in an embodiment of the present invention.
• FIG. 11 shows a flow chart diagram of a method of implantation of a medical device in accordance with embodiments of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
• The following discussion is presented to enable a person skilled in the art to make and use the present teachings. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments and applications without departing from the present teachings. Thus, the present teachings are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the present teachings. Skilled artisans will recognize the examples provided herein have many useful alternatives and fall within the scope of the present teachings. It's understood that the embodiments of the present teachings can be applied to occluders, shunts, or flow restrictors.
• Embodiments of the present invention can be well suited for the selective occlusion, shunting, or flow restriction of a vessel lumen, channel, cavity, or organ within the body's circulatory system. Embodiments of the present invention disclose a vascular occlusion, flow restriction, or shunt device formed of a plurality of wire strands woven into a braided tubular metal fabric having an expanded preset configuration and an elongated collapsed reduced diameter configuration. The device can be delivered through a catheter to a treatment site and shaped to create an occlusion, flow restriction, or shunt, when placed in an opening in a body organ or vessel. The woven metal fabric can have a memory property whereby the medical device tends to return to an expanded preset configuration when unconstrained. The device can have proximal and distal unsecured wire ends and a segment there between the wire ends having at least a portion of the segment larger in diameter than the unsecured wire ends in the expanded preset configuration.
• Embodiments of the present invention can be fabricated from many various methods including those described in U.S. Pat. No. 6,123,715, titled Method of forming medical devices; intravascular occlusion devices, to Amplatz herein incorporated by reference in its entirety. Additionally, while it could be helpful to temporarily clamp or otherwise fix the wire ends during the wire cutting operation and during heat treatment to set the desired device shape, the inventors have discovered that the clamps are not needed after the heat treatment process since the heat treatment imparts a wire shape memory that resists unraveling of the braid wire ends. The elimination of the clamps reduces the device profile by elimination of the material of the clamps which surrounded the wires. In addition the wire ends may be positioned in an end wall of the device and need not be oriented outward from the device in an axial orientation as in prior devices. The recessing of the device end surfaces to hide the clamps is not required since the wire ends can be incorporated into the plane of the end surfaces of the device which simplifies the fabrication process and reduces manufacturing cost. Since the recessing of the device end surfaces is not required, the fabric reverse bends near the clamp are not required and the delivery forces are reduced during passage through the delivery catheter.
• In the case of shunt devices or a flow restrictor such fabrication methods can be used such as those described in U.S. Pat. No. 6,468,303, titled “Retrievable Self Expanding Shunt”, by Amplatz et. al. and U.S. Pat. No. 6,638,257, titled “Intravascular Flow Restrictor”, by Amplatz et. al. herein incorporated by reference in their entirety. In shunts and flow restrictors the elimination of the wire end clamps allow the axial area of the device ends to be available as a flow passage, simplifying the device design and lowering the device profile and manufacturing cost.
• In the prior art solutions described herein, at least one of the wire end clamps served as a means to connect a delivery device. This was accomplished by providing internal (female) threads in at least one clamp that mated with external (male) threads on the delivery device. However, embodiments of the present invention disclose that the clamps are no longer necessary and therefore a new delivery system is disclosed below in more detail. The new delivery system includes an outer tubular guide catheter, an inner tubular delivery (pusher) catheter coaxially disposed and slidable relative to the outer guide catheter. An elongated flexible guide wire or cable that is coaxially insertable, through thee lumen of the inner tubular catheter that has a frusto-conical bead affixed at the distal end thereof sized to at least partially fit within the lumen of the inner pusher catheter when a proximally directed tension force is applied between the elongated flexible wire or cable with respect to the pusher catheter. By inserting a compressed coiled spring between a proximal end portion of the cable, the requisite clamping force is maintained to secure the device proximal wire ends to the distal end of the pusher catheter until the compression spring force is removed. Such a delivery system and improvements there to are described by Pending Patent Application U.S. Patent Publication No. 2006/0253184, titled “System for the Controlled Delivery of Stents and Grafts”, by Amplatz et al. and by U.S. Patent Publication No. 2007/0118207, titled “System for Controlled Delivery of Stents and Grafts”, by Amplatz et al. herein incorporated by reference in its entirety.
• In one embodiment of the invention, a simplified medical device and a method of fabrication of a medical device, without the limitations inherent to having wire end clamps, for treating vascular or organ abnormalities which necessitate occlusion, flow restriction or shunting as the method of treatment is disclosed. In another embodiment of the present invention, a method of treating a medical condition requiring the occlusion, flow restriction, or shunting of blood flow in a vessel or cavity within the body's vasculature using a simplified medical device fabricated from a resilient braided metal fabric having a preset expanded configuration and a collapsed configuration for delivery through the vasculature using a novel delivery system is disclosed.
• These and other features and advantages of the inventive design will become readily apparent to those skilled in the art from a review of the drawings and the detailed description of the preferred embodiment in conjunction with the accompanying claims and drawings.
• With reference toFIGS. 5A-B, perspective views of an occluder without end clamps is shown. Embodiments of the present invention disclose anoccluder100 that can be formed of a plurality ofwire strands102 woven into abraided metal fabric104 having an expanded preset configuration as shown bydiscs112 and114 and an elongated collapsedreduced diameter configuration115 for delivery through acatheter sleeve120 to a treatment site (FIG. 5). The device can also be shaped to create a flow restrictor or shunt when placed in an opening in a body organ or vessel as discussed above in detail.Woven metal fabric104 can have a memory property wherebyoccluder100 tends to return to an expanded preset configuration when unconstrained (e.g., by catheter sleeve120).Occluder100 can have proximal and distal unsecured wire ends106 and108 and asegment109 there between, having at least a portion of the segment larger in diameter than the unsecured wire ends in the expanded preset configuration.
• Metal strands102 define two sets of essentially parallel generally helical strands, with the strands of one set having a “hand” (e.g., a direction of rotation, opposite that of the other set). This is a generallytubular fabric104, known in the fabric industry as a tubular braid. The pitch of wire strands102 (e.g., the angle defined between the turns of the wire and the axis of the braid) and the pick of fabric104 (e.g. the number of wire crossovers per unit length) may be adjusted as desired for a particular application.Wire strands102 ofmetal fabric104 used can be formed of a, material which is both resilient and which can be heat treated to substantially set a desired shape. Materials which are suitable for this purpose include a cobalt-based low thermal expansion alloy referred to in the field as Elgeloy, nickel-based high temperature-high-strength “superalloys” commercially available from Haynes International located in Kokomo, Ind. under the trade name Hastelloy, nickel-based heat treatable alloys sold under the name Incoloy by International Nickel located in Toronto, Canada, and a number of different grades of stainless steel. A factor in choosing a suitable material forwires102 is that they retain a suitable amount of the deformation induced by the molding surface when subjected to a predetermined heat treatment.
• One class of materials which meet these qualifications are so-called shape memory alloys. One particularly preferred shape memory alloy for use in the present method is a Nitinol alloy that is very elastic this alloy is said to be “superelastic” or “pseudoelastic”. This elasticity will help a device return to a preset expanded configuration for deployment.
• With reference toFIG. 6, a flowchart diagram of a method of manufacturing a medical device in accordance with embodiments of the present invention is shown.Manufacturing process200 begins atstate204 where a large piece offabric104 which is formed, for example, by braidingwire strands102 to form a long tubular braid. Atstate206, ends106 and108 can be secured. One can clamp, tape, solder, braze, weld or otherwise affix ends106 and108 to the desired length (e.g., length greater than final device length) together (e.g., with a biocompatible cementitious organic material) before cutting the braid. Atstate208, an appropriately sized piece ofmetal fabric104 is cut from the larger piece offabric104 by cutting outside the clamps, leaving the clamps to contain the braid ends of the device segment. Metal sleeves clamped or swaged onto the braid are a preferred clamp design and can be easily removed after heat treatment by cutting the fabric adjacent the clamps. Since the clamps contain braided heat set filaments set in the axial direction, the braid should be cut to place the wire ends in the plane of the device ends. Compressing the heat set shape or elongating the braid by pulling on the clamps allows the braid to be placed into a small diameter sleeve for holding purposes during the braid cutting process. A laser or mechanical cutter as well known in the art may be used to cut the braid. Mechanical cutting may require deburring of sharp wire cut ends.
• Using a temporary clamp is helpful as it can be removed easily after heat treatment. Permanent wire end bonds would need to be cut off after heat treatment. Tape can also hold the ends from unraveling during handling but will not survive the heat treatment; however, at this point in the process minor unraveling is not a factor since the final device braided fabric length will be shortened by cutting.
• Once an appropriately sized piece ofmetal fabric104 is obtained,fabric104 is deformed atstate210 to generally conform to a surface of a molding element. Deforming the fabric will re-orient the relative positions of the strands of the metal fabric from their initial order to a second, re-oriented configuration. The shape of the molding element should be selected to deform the fabric into substantially the expanded shape of the desired component of the medical device.
• Once the molding element is assembled withmetal fabric104 generally conforming to a molding surface of that element,fabric104 can be subjected to a heat treatment atstate212 while it remains in contact with that molding surface. Suitable heat treatments of Nitinol wire to set a desired shape are well known in the art. It has been found that holding a Nitinol fabric at about 500° C. to about 550° C. for a period of about 1-30 minutes, depending on the softness or harness of the device to be made, will tend to setfabric104 in its deformed state, e.g. (wherein it conforms to the molding surface of the molding element). At lower temperatures the heat treatment time will tend to be greater (e.g., about one hour at about 350° C.) and at higher temperatures the time will tend to be shorter (e.g., about 30 seconds at about 900 degrees C.). After the heat treatment and cooling,fabric104 is removed from contact with the molding element atstate214 and will substantially retain the molded shape.
• Atstep216, the fabric adjacent the device side of the clamps is cut after heat treatment. Thus cutting the fabric adjacent the clamps inherently removes the clamps. Any temporary wire clamps or other means of holding the wire ends, if used, are thus removed atstate216 after the heat treatment process by cutting the braided wire adjacent the clamps as previously explained to provide a desired final device length atstate218.
• With reference again toFIGS. 5A-C all occluder without end clamps is shown. It is noted there are no clamps for wire ends106 and108.Discs112 and114, after heat treatment and removal from the mold, can be axially elongated by compressing them such thatoccluder100 elongates and can be advanced into a cut to length fixture. The excess length from each end can be trimmed by manually cutting or using a laser to cutwires102 to length. As illustrated inFIG. 5B, the cut length can be such that wire ends106 and108 are positioned near devicecentral axis110. Alternatively, wire ends106 and108 could be cut shorter resulting in wire ends106 and108 positioned into a larger diameter. The result isoccluder100 is shorter in length compared to know prior art devices and there are no clamps. As is known in the art, apolyester fabric disc113 can be used to improve device thrombogenicity and can be sutured intodisc114. For an occluder device thefabric disk114 could have no central passage as opposed to the case for a flow restrictor or shunt device where a central flow passage infabric disk114 if used, could be fabricated to allow for controlled blood passage.
• FIG. 5D shows wire ends106 pushed into adelivery catheter sleeve120.Delivery system129 includes an outertubular guide catheter124, an inner tubular deliver (pusher)catheter121 coaxially disposed and slidable relative toouter guide catheter124. The delivery system comprises an elongatedflexible guide wire122 or cable that is coaxially insertable throughlumen131 of the innertubular catheter121 and that has a frusto-conical bead123 affixed at the distal end thereof sized to at least partially fit withinlumen131 of theinner pusher catheter121 when a proximally directed tension force is applied between the elongated flexible wire or cable with respect topusher catheter121. By inserting a compressed coiled spring between a proximal end portion ofcable122 and a fixed hub onpusher catheter121, the requisite clamping force is maintained to secureoccluder100 proximal wire ends106 to the distal end ofpusher catheter121 until the compression spring force is removed. A frusto-conical plunger123 moves axially with theshaft122 to clamp the inside of wire ends106 or108 against the inside surface ofsleeve120.Sleeve120 is attached to the distal end ofpusher catheter121.Plunger123 is spring loaded to clamp device wire ends106 or108 but can be released by advancement ofshaft122 to releaseoccluder100 when properly positioned in a body. With ends106 or108 clamped withinsleeve120,occluder100 may be drawn proximally into adelivery catheter124 coaxially arranged overpusher catheter121. Once delivercatheter124 is advanced within the vasculature adjacent the site of treatment, the delivery device may be advanced orcatheter124 withdrawn to allowoccluder100 to freely self expand to its pre-determined memorized shape. Onceoccluder100 is in place,occluder100 is released by advancing frusto-conical clamping mechanism123 relative tosleeve120. Withoccluder100 fully deployed thedelivery system129 is removed from the body, leavingoccluder100 implanted at the treatment site.
• In the embodiment shown inFIGS. 1A-C,polyester fabric18 provides an occluding surface across device10 and therefore the choice of location for cutting the wire ends is not that critical. Wire ends106 could he cut and lie anywhere inouter discs112 and114 but preferably are nearcentral axis110 to provide a double wall todiscs112 and114.
• With reference toFIG. 7A, a partial side cross-sectional view and end view of a prior art occluder portion illustrating the clamp and clamp recess on one end of the device is shown. The device ofFIG. 7A illustrates device designs whereby the surface containing the end clamp is recessed to make, the device shorter. InFIG. 7A, a cross-sectional view is provided of a recessedend30 andwire end clamp31 of a prior art device.
• With reference toFIG. 7C, a partial side cross-sectional and end view of an occluder without end clamps in an embodiment of the present invention is shown.Recess132 is eliminated in the design and wire ends134 are cut after heat treatment such that wire ends134 terminate near devicecentral axis135.Occluder130 may have anoptional polyester disc112 or114 sutured in for improved occlusion.
• With reference toFIG. 8, a side and end view respectively of a design for either a flow restrictor or a shunt in an embodiment of the present invention is shown.Braided device140 has two raisedflanges141 and142 which locate against the vessel surface to retaindevice140.Flanges141 and142 are sized to be somewhat larger (e.g., 10-30%) than the vessel inside diameter to produce an outward force against the vessel wall to anchordevice140 and prevent dislodgement. Anoptional polyester fabric143 is sutured144 across raisedflange142 diameter.Fabric143 has ahole145 in the central portion, sized to create a flow limiting area as desired for the restriction of blood flow or shunting of blood through a vessel or across a membrane. In the case of shunting blood flow through a membrane, raisedflanges141 and142 would be more disc-like in shape and the discs would be separated by the thickness of the membrane with one disc on either side of the membrane and loaded against the membrane. In either design, the clamps in the prior art devices are replaced by un-bound cut wire ends146 which are positioned to lie indevice end surface148. It is of note, that there are no clamps, recesses, or holes being forced through a braided fabric where the wires need to be manually rearranged and spaced evenly as in the prior art devices. This reduces manufacturing cost and provides a lower profile device that is easier to deliver.
• With reference toFIG. 9, a side view of another occluder embodiment of the present invention is shown. A PDA occluder is illustrated in a side view of bell shapedoccluder150. There are no clamps indevice150 and wire ends151 are cut so as to be positioned near the central axis of the device's tapered distal end. Proximal device wire ends152 are cut to length such as to lie in a recessed surface withinflange154. Optionally, wire ends152 could be cut to a longer length to end near the proximal device central axis. Apolyester fabric153 is optionally sutured across the diameter of the devicedistal flange154 to improve thrombogenicity (reduce the time to occlusion).
• With reference toFIG. 10, aside view of an occluder shown occluding an aneurysm in an embodiment of the present invention is illustrated.Occluder300 could eliminate a distal recess and distal clamp and cut wire ends299 to a length such that they are positioned near the distal axis of the device. The proximal clamp would be eliminated and proximal wire ends298 cut to a length to position the ends in the flange outer surface facing the inside of the vessel. This improved design has minimal projection into the flow stream and thus the risk of a clot forming and breaking off from a clamp an entering the blood stream is diminished.
• Further, it is anticipated that an occluder, stent, or flow restrictor could take any shape and could be offered for new applications or different anatomical conditions. In addition it is contemplated that a device may be fabricated using multiple metal fabric layers. The individual layer wire ends could be cut to the same length or have staggered cut ends. The multiple layers could increase the metal content of the device and cause quicker occluding times, thus eliminating the need for polyester or other fabric to improve throbogenicity. The multiple layers could he sutured together in a central area and generally at least one layer could be a primary structural layer while one or more layers could be of lesser radial strength and generally of smaller wire diameter and smaller pore size between filaments. The braided pitch of each layer could generally be the same to allow uniform expansion and contractions. The layers may have the same or different shapes to fill a hollow space within the outer layer. A multi-layered device may in addition include an occluding fiber within the hollow portion of the device or one or more layers may be coated with a drug to promote clotting or if desired with a drug such as heparin to inhibit thrombus formation, depending on the application.
• Those skilled in the art will appreciate that in order to speed up the occlusion of the vessel; the device may be coated with a suitable thrombogenic agent, filled with a polyester fiber or braided with an increased number of wire strands. This fiber easily collapses with the device for delivery through a catheter. This fiber is also useful for occlusion devices, although use of multiple-layers of braided fabric may function in a similar manner to the polyester fabric to speed thrombosis. The interwoven fiber by attachment to clot retains the clot firmly within the device as it forms the occlusion.
• The tubular braid used to fabricate occlusion devices for example, in embodiments of the present invention may range from wire having a diameter of 0.002 to 0.005 inch, possibly in the range of 0.003 to 0.0035 inch and for a PDA device possibly 0.003 inch diameter. The number of wires in the tubular braid may vary from 36 to 144 but it is most helpful if it is in the range of 72 to 144 and for a PDA device is preferably 144 wires. The pick count of the braid may vary from 30 to 100 and preferably from 50 to 80 and for a PDA device is preferably 70.
• With reference toFIG. 11, a flow chart diagram of a method of implantation of a medical device in accordance with embodiments of the present invention is shown. A part of a method ofimplantation301, once access has been obtained to a vessel, an introducer catheter is inserted into the vessel and maintains a position from outside the body to within a vessel such as the femoral artery atstate302. Access to the patient's vessel of treatment is obtained using the Seldinger Technique as is commonly known in the art.Delivery catheter124 can be placed into vasculature and navigated to the treatment site such that the distal end ofcatheter124 is adjacent the treatment site atstate304. A clinician could select a medical device suitable for the condition being treated atstate306. The device could be furnished separately or could be pre-loaded onto a delivery device as is illustrated inFIG. 5D. If furnished separately, a device could be in a reduced diameter sleeve with the proximal device wire ends exposed for loading into the delivery device. A delivery catheter could be selected based on the particular device and anatomical conditions. The delivery device could be first placed through the lumen of the delivery catheter until the distal end is adjacent the distal end of the catheter atstep308.
• With reference again toFIG. 5D,occluder100 having proximal wire ends106 and108 could be inserted overplunger123 intodelivery device sleeve120 atstate308 while the spring loaded frusto-conical plunger123 is advanced distally with respect tosleeve120 to open sleeve access126. Once wire ends106 or108 are inserted intosleeve120,plunger spring123 can be released to moveplunger123 proximally toward wire ends106 or108 atstate310. Spring pressure locks wire ends106 or108 betweensleeve120 and the plunger surface.Delivery device121 andoccluder100 may now be drawn together proximally to drawoccluder100 intolumen127 ofdelivery catheter124 adjacent the distal end atstate312. Sinceoccluder100 can be formed from Nitinol and can have shape memory, this reduction in diameter does not harmoccluder100.
• Delivery catheter124 can be slowly pulled proximal while holding back ondelivery device121 to allow the distal end ofoccluder100 to emerge fromdelivery catheter124 and to self expand to its pre-determined shape atstate314. Ifoccluder100 is not positioned as desiredoccluder100 may be returned todelivery catheter124 by either advancement ofdelivery device121 while holdingdelivery catheter124 stationary or holding delivery catheter stationary124 and pulling proximally ondelivery device121 atstate316. In the case of flanged or double disk devices where one disk is placed on either side of a septum,delivery catheter124 distal end is placed distal to the septum and then withdrawn partially relative to thedelivery device121 to allow the distal disk only to self expand. Thedelivery catheter124 anddelivery device121 are now pulled proximally together to locate the first expanded disk against the septum. Thedelivery catheters124 is now withdrawn proximally while holding thedelivery device121 in place to allow the second disk to self expand on the proximal side of the septum. Assumingoccluder100 is positioned as desired, fully deployedplunger123 may be displaced distally relative tosleeve120 to releaseoccluder100.Delivery catheter124 anddelivery device121 can next be removed from thebody leaving occluder100 implanted in the vessel, cavity, or treatment site atstate318.
• In an alternative method oftreatment delivery catheter124 may first be placed into the desired treatment site using a technique of advancement over a steerable guide wire as well know in the interventional medical art.Occluder100 may be connected todelivery device121 as previously stated andoccluder100 anddelivery device121 advanced into the proximal end ofdelivery catheter124 using a tear-away introducer tapered to pilot intodelivery catheter124 and coaxially placed over thedelivery device121 distal end. Onceoccluder100 is withincatheter124 the tear-away introducer is removed andoccluder100 advanced adjacent the distal end ofdelivery catheter124. In all other aspects,occluder100 placement is as previously described.Delivery catheter124 may be a guide catheter or steerable sheath in other embodiments.
• In another embodiment of the delivery device disclosed in patent application US 2007/0118207A1, thedelivery system129 replaces wire or cable122 (FIG. 5D) with a hollow tube suitable for passage of a guidewire there through. In such cases where theguide catheter124 is introduced into the vasculature over a guidewire prior to device selection, the delivery, catheter may be advanced over the guidewire within the guide catheter. In all other aspects the procedure is similar.
• Thus, embodiments of the BRAIDED VASCULAR DEVICES HAVING NO END CLAMPS are disclosed. One skilled in the art will appreciate that the present teachings can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the present teachings are limited only by the claims that follow.

Claims (25)

1. A collapsible medical device, comprising:

at least one layer of a plurality of metal strands woven into a tubular braided metal fabric having a proximal end, a distal end, and a segment there between;

the tubular woven metal fabric having an expanded preset configuration shaped for treatment of an opening in a body organ; and

the expanded preset configuration being deformable to a lesser cross-sectional dimension for delivery through a channel in a patient's body, the woven metal fabric having a memory property whereby the medical device returns to the expanded preset configuration when delivered into the patient's body, said proximal and distal ends being free of clamps and having at least a portion of the segment larger in diameter than the free wire ends in the expanded preset configuration.

2. The collapsible medical device ofclaim 1, wherein the medical device is an occluder.

3. The collapsible medical device ofclaim 1, wherein the medical device is a shunt.

4. The collapsible medical device ofclaim 1, wherein the medical device is a flow restrictor.

5. The collapsible medical device ofclaim 1, further comprising an occluding fiber retained within an expandable hollow central portion formed by said tubular woven fabric.

6. The collapsible medical device ofclaim 1, wherein the metal fabric is manufactured from an alloy selected from the group consisting of stainless steel, nickel-titanium, and cobalt-chromium-nickel.

7. The collapsible medical device ofclaim 1, wherein the device comprising the expanded preset configuration is the shape of a disc.

8. A medical device comprising:

a metal fabric formed of braided metal strands;

the medical device having a collapsed configuration for delivery through a channel in a patient's body and having a generally dumbbell-shaped expanded configuration with two expanded diameter portions separated by a reduced diameter portion formed between opposed ends of the device and unsecured metal strand ends at the opposed ends.

9. The medical device ofclaim 8, wherein the medical device can be any one of an occluder, shunt, or flow restrictor.

10. The medical device ofclaim 8, wherein the metal strand ends are unsecured from metal clamps.

11. The medical device ofclaim 8, wherein the metal strand ends do not unravel.

12. The medical device ofclaim 8, wherein the medical device is delivered to a treatment site in a patient without physical connection to a delivery device.

13. The medical device ofclaim 8, wherein the unsecured metal strand ends do not extend outside of the expanded diameter portions.

14. The medical device ofclaim 8, further comprising a thrombogenic agent located on the metal fabric.

15. A method of forming a medical device, the method comprising the steps of: providing a metal fabric formed of a plurality of braided strands, the strands being formed of a metal which can be heat treated to substantially set a desired shape;

deforming the metal fabric to generally conform to a wall surface of a moulding element;

heat treating the metal fabric in contact with the surface of the moulding element at an elevated temperature, the temperature and the duration of the heat treatment being sufficient to substantially set the shape of the fabric in its deformed state;

removing the metal fabric from contact with the moulding element; and

cutting the fabric adjacent the device side of the clamps after heat treatment.

16. The method ofclaim 15, further comprising the step of clamping the opposite ends of the strands before deforming the metal fabric.

17. The method ofclaim 15, further comprising the step of cutting an appropriately sized piece of the metal fabric.

18. The method ofclaim 17, further comprising the step of forming a long tubular braid from the metal fabric.

19. The method ofclaim 15, wherein the metal of which the strands are formed is a shape memory alloy, stainless steel, or elgiloy, the temperature and the duration of the heat treatment being selected to substantially set the strands in a deformed state.

20. A method for delivering a self-expanding medical device to a selected site in a vascular system comprising the steps of:

(a) selecting the combination of: (i) a delivery device inner catheter having a lumen extending from a proximal end to a distal end, the delivery device having an outer diameter adapted to slidingly fit within the lumen of a delivery catheter, (ii) an elongate, flexible member coaxially insertable through the lumen of the delivery device catheter, said elongate flexible member having a plunger member affixed thereto sized to at least partially fit within the lumen of the delivery device catheter when a proximally directed tension force is applied to the elongate flexible member with respect to the delivery device catheter, (iii) a braided tubular device having at least a portion of a segment larger in diameter than free wire ends in the expanded preset configuration with the free ends of individual strands comprising the device captured between the plunger member and the delivery device catheter;

(b) feeding the delivery device catheter with the braided tubular device attached through a lumen of the delivery catheter and out thereof; and

(c) moving the elongate flexible member relative to the tubular delivery device catheter to release the tubular device from the tubular delivery device catheter.

21. The method ofclaim 20, further comprising the step of releasing a plunger spring located in the plunger member to capture the free ends between the plunger member and the inner delivery device catheter.

22. The method ofclaim 20, further comprising the step of inserting the delivery catheter within a patient's vasculature.

23. The method ofclaim 20, further comprising the step of repositioning the braided tubular device if it is not positioned properly upon release from the tubular delivery device catheter.

24. The method ofclaim 20, further comprising removing the delivery device form the patient's vasculature.

25. The method ofclaim 20, further comprising removing the delivery catheter from the patient's vasculature.

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