US20110208288A1 - Stents and stent grafts - Google Patents

Abstract

Elastic compressible stents have a plurality of proximal and distal apices joined by struts that are essentially straight. The stent can have a polygonal cross-sectional shape, such as a dodecahedron shape. Elastic compressible stents can be made by a method that includes winding stent wire around an outer surface of a longitudinal axis of a polygonal cross-sectional shaped mandrel into a desired shape that is polygonal in an elevation orthogonal to the longitudinal axis. The stent can be formed by setting the wound stent wire in the desired polygonal final shape. The polygonal cross-sectional shape mandrel can be a mandrel having a multi-sided outer surface. Stents can include graft material attached to the stent.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• This application is a divisional of co-pending U.S. patent application Ser. No. 10/784,462, filed Feb. 23, 2004, which application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Applications Nos. 60/499,652, filed Sep. 3, 2003, and 60/500,155, filed Sep. 4, 2003, the complete disclosures of which are each hereby incorporated by reference herein in their entirety.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The invention lies in the field of endoluminal blood vessel repairs. The invention specifically relates to a method for making a non-circular stent, which can be used to endoluminally repair aneurysm and/or dissections of the thoracic transverse aortic arch, thoracic posterior aortic arch, and the descending thoracic portion of the aorta.
• 2. Description of the Related Art
• A stent graft is an implantable device made of a tube-shaped surgical graft covering and an expanding or self-expanding frame. The stent graft is placed inside a blood vessel to bridge, for example, an aneurismal, dissected, or other diseased segment of the blood vessel, and, thereby, exclude the hemodynamic pressures of blood flow from the diseased segment of the blood vessel.
• In selected patients, a stent graft advantageously eliminates the need to perform open thoracic or abdominal surgical procedures to treat diseases of the aorta and eliminates the need for total aortic reconstruction. Thus, the patient has less trauma and experiences a decrease in hospitalization and recovery times. The time needed to insert a stent graft is substantially less than the typical anesthesia time required for open aortic bypass surgical repair, for example.
• Use of surgical and/or endovascular grafts have widespread use throughout the world in vascular surgery. There are many different kinds of vascular graft configurations. Some have supporting framework over their entirety, some have only two stents as a supporting framework, and others simply have the tube-shaped graft material with no additional supporting framework, an example that is not relevant to the present invention.
• One of the most commonly known supporting stent graft frameworks is that disclosed in U.S. Pat. Nos. 5,282,824 and 5,507,771 to Gianturco (hereinafter collectively referred to as “Gianturco”). Gianturco describes a zig-zag-shaped, self-expanding stent commonly referred to as a z-stent. The stents are, preferably, made of nitinol, but also have been made from stainless steel and other biocompatible materials.
• There are various features characterizing a stent graft. The first significant feature is the tube of graft material. This tube is commonly referred to as the graft and forms the tubular shape that will, ultimately, take the place the diseased portion of the blood vessel. The graft is, preferably, made of a woven sheet (tube) of polyester or PTFE. The circumference of the graft tube is, typically, at least as large as the diameter and/or circumference of the vessel into which the graft will be inserted so that there is no possibility of blood flowing around the graft (also referred to as endoleak) to either displace the graft or to reapply hemodynamic pressure against the diseased portion of the blood vessel. Accordingly, to so hold the graft, self-expanding frameworks are attached typically to the graft material, whether on the interior or exterior thereof. Because blood flow within the lumen of the graft could be impaired if the framework was disposed on the interior wall of the graft, the framework is connected typically to the exterior wall of the graft. The ridges formed by such an exterior framework help to provide a better fit in the vessel by providing a sufficiently uneven outer surface that naturally grips the vessel where it contacts the vessel wall and also provides areas around which the vessel wall can endothelialize to further secure the stent graft in place.
• One of the significant dangers in endovascular, graft technology is the possibility of the graft migrating from the desired position in which it is installed. Therefore, various devices have been created to assist in anchoring the graft to the vessel wall.
• One type of prior art prosthetic device is a stent graft made of a self-expanding metallic framework. For delivery, the stent graft is, first, radially compressed and loaded into an introducer system that will deliver the device to the target area. When the introducer system holding the stent graft positioned in an appropriate location in the vessel and allowed to open, the radial force imparted by the self-expanding framework is helpful, but, sometimes, not entirely sufficient, in endoluminally securing the stent graft within the vessel.
• U.S. Pat. No. 5,824,041 to Lenker et al. (hereinafter “Lenker”) discloses an example of a stein graft delivery system. Lenker discloses various embodiments in which a sheath is retractable proximally over a prosthesis to be released, With regard toFIGS. 7 and 8, Lenker names components72 and76, respectively, as “sheath” and “prosthesis-containment sheath.” However, the latter is merely the catheter in which the prosthesis74 and the sheath72 are held. With regard toFIGS. 9 and 10, the sheath82 has inner and outer layers91,92 fluid-tightly connected to one another to form a ballooning structure around the prosthesis P. This ballooning structure inflates when liquid is inflated with, a non-compressible fluid medium and flares radially outward when inflated. With regard toFIGS. 13 to 15, Lenker discloses the “sheath”120, which is merely the delivery catheter, and an eversible membrane126 that “folds back over itself (everts) as the sheath120 is retracted so that there are always two layers of the membrane between the distal end of the sheath [120] and the prosthesis P.” Lenker at col.9, lines63 to66. The eversion (peeling back) is caused by direct connection of the distal end130 to the sheath120. The Lenker delivery system shown inFIGS. 19A to 19D holds the prosthesis P at both ends256,258 while an outer catheter254 is retracted over the prosthesis P and the inner sheath260. The inner sheath260 remains inside the outer catheter254 before, during, and after retraction. Another structure for holding the prosthesis P at both ends is illustrated inFIGS. 23A and 23B. Therein, the proximal holder having resilient axial members342 is connected to a proximal ring structure346.FIGS. 24A to 24C also show an embodiment for holding the prosthesis at both ends inside thin-walled tube362.
• To augment radial forces of stents, some prior art devices have added proximal and/or distal stents that are not entirely covered by the graft material. By not covering with graft material a portion of the proximal/distal ends of the stent, these stents have the ability to expand further radially than those stents that are entirely covered by the graft material. By expanding further, the proximal/distal stent ends better secure to the interior wall of the vessel and, in doing so, press the extreme cross-sectional surface of the graft ends into the vessel wall to create a fixated blood-tight seal.
• One example of such a prior art exposed stent can be found in United States Patent Publication US 2002/0198587 to Greenberg et al. The modular stent graft assembly therein has a three-part stent graft: a two-part graft having anaortic section12 and an iliac section14 (with four sizes for each) and a contralateral iliac occluder80.FIGS. 1,2, and4 to6 show theattachment stent32. As illustrated inFIGS. 1,2, and4, theattachment stent32, while rounded, is relatively sharp and, therefore, increases the probability of puncturing the vessel.
• A second example of a prior art exposed stent can be found in U.S. Patent Publication 2003/0074049 to Hoganson et al. (hereinafter “Hoganson”), which discloses a coveredstent10 in which the elongated portions orsections24 of the ends20aand20bextend beyond the marginal edges of thecover22. See Hoganson atFIGS. 1,3,9,11a,11b,12a,12b, and13. However, these extending exposed edges are triangular, with sharp apices pointing both upstream and downstream with regard to a graft placement location. Such a configuration of the exposed stent20a,20bincreases the possibility of puncturing the vessel. In various embodiments shown inFIGS. 6a,6b,6c,10,14a, Hoganson teaches completely covering the extended stent and, therefore, the absence of a stent extending from thecover22. It is noted that the Hoganson stent is implanted by inflation of a balloon catheter.
• Another example of a prior art exposed stent can be found in U.S. Pat. No. 6,565,596 to White at al. (hereinafter “White I”), which uses a proximally extending stent to prevent twisting or kinking and to maintain graft against longitudinal movement. The extending stent is expanded by a balloon and has a sinusoidal amplitude greater than the next adjacent one or two sinusoidal wires. White I indicates that it is desirable to space wires adjacent upstream end of graft as close together as is possible. The stent wires of White I are actually woven into graft body by piercing the graft body at various locations. See White I atFIGS. 6 and 7. Thus, the rips in the graft body can lead to the possibility of the exposed stent moving with respect to the graft and of the graft body ripping further. Between the portions of the extending stent17, the graft body has apertures.
• The stent configuration of U.S. Pat. No. 5,716,393 to Lindenberg et al. is similar to White I in that the outermost portion of the one-piece stent—made from a sheet that is cut/punched and then rolled into cylinder—has a front end with a greater amplitude than the remaining body of the stent
• A further example of a prior art exposed stent can be found in U.S. Pat. No. 6,524,335 to Hartley et al. (hereinafter “Hartley”).FIGS. 1 and 2 of Hartley particularly disclose a proximal first stent1 extending proximally from graftproximal end4 with both the proximal and distal apices narrowing to pointed ends.
• Yet another example of a prior art exposed stent can be found in U.S. Pat. No. 6,355,056 to Pinheiro (hereinafter “Pinheiro I”). Like the Hartley exposed stent, Pinheiro discloses exposed stents having triangular, sharp proximal apices.
• Still a further example of a prior art exposed stent can be found in U.S. Pat. No. 6,099,558 to White et al. (hereinafter “White II”). The White II exposed stent is similar to the exposed stent of White I and also uses a balloon to expand the stent.
• An added example of a prior art exposed stent can be found in U.S. Pat. No. 5,871,536 to Lazarus, which discloses two support members68 longitudinally extending from proximal end to a rounded point. Such points, however, create a very significant possibility of piercing the vessel.
• An additional example of a prior art exposed stent can be found in U.S. Pat. No. 5,851,228 to Pinheiro (hereinafter “Pinheiro II”). The Pinheiro II exposed stents are similar to the exposed stents of Pinheiro I and, as such, have triangular, sharp, proximal apices.
• Still another example of a prior art exposed stent can be found in Lenker (U.S. Pat. No. 5,824,041), which shows a squared-off end of the proximal and distal exposedband members14. A portion of the exposedmembers14 that is attached to thegraft material18,20 is longitudinally larger than a portion of the exposedmembers14 that is exposed and extends away from thegraft material18,20, Lenker et al. does not describe themembers14 in any detail.
• Yet a further example of a prior art exposed stent can be found in U.S. Pat. No. 5,824,036 to Lauterjung, which, of all of the prior art embodiments described herein, shows the most pointed of exposed stents. Specifically, the proximal ends of the exposed stent are apices pointed like a minaret. The minaret points are so shaped intentionally to allow forks300 (see Lauterjung atFIG. 5) external to the stent154 to pull the stent154 from the sheath302, as opposed to being pushed.
• A final example of a prior art exposed stent can be found in U.S. Pat. No. 5,755,778 to Kleshinski. The Kleshinski exposed stents each have two different shaped portions, a triangular base portion and a looped end portion. The totality of each exposed cycle resembles a castellation. Even though the end-most portion of the stent is curved, because it is relatively narrow, it still creates the possibility of piercing the vessel wall.
• All of these prior art stents suffer from the disadvantageous characteristic that the relatively sharp proximal apices of the exposed stents have a shape that is likely to puncture the vessel wall.
• Devices other than exposed stents have been used to inhibit graft migration. A second of such devices is the placement of a relatively stiff longitudinal support member longitudinally extending along the entirety of the graft.
• The typical stent graft has a tubular body and a circumferential framework. This framework is not usually continuous. Rather, it typically takes the form of a series of rings along the tubular graft. Some stent grafts have only one or two of such rings at the proximal and/or distal ends and some have many stents tandemly placed along the entirety of the graft material. Thus, the overall stent graft has an “accordion” shape. During the systolic phase of each cardiac cycle, the hemodynamic pressure within the vessel is substantially parallel with the longitudinal plane of the stent graft. Therefore, a device having unsecured sterns, could behave like an accordion or concertina with each systolic pulsation, and may have a tendency to migrate downstream. (A downstream migration, to achieve forward motion, has a repetitive longitudinal compression and extension of its cylindrical body.) Such movement is entirely undesirable. Connecting the stents with support along the longitudinal extent of the device thereof can prevent such movement. To provide such support, a second anti-migration device can be embodied as a relatively stiff longitudinal bar connected to the framework.
• A clear example of a longitudinal support bar can be found in Pinheiro I (U.S. Pat. No. 6,355,056) and Pinheiro II (U.S. Pat. No. 5,851,228). Each of these references discloses a plurality of longitudinally extendingstruts40 extending between and directly interconnecting the proximal and distal exposed stents20a,20b. These struts40 are designed to extend generally parallel with the inner lumen15 of thegraft10, in other words, they are straight.
• Another example of a longitudinal support bar can be found in U.S. Pat. No. 6,464,719 to Jayaraman. The Jayaraman stent is formed from a graft tube21 and a supporting sheet1 made of nitinol. This sheet is best shown inFIG. 3. Theend pieces11,13 of the sheet are directly connected to one another by wavy longitudinal connecting pieces15 formed by cutting the sheet1. To form the stent graft, the sheet1 is coiled with or around the cylindrical tube21. SeeFIGS. 1 and 4. Alternatively, a plurality of connecting pieces53 with holes at each end thereof can be attached to a cylindrical fabric tube51 by stitching or sutures57, as shown inFIG. 8. Jayaraman requires more than one of these serpentine shaped connecting pieces53 to provide longitudinal support.
• United States Patent Publication 2002/0016627 and U.S. Pat. No. 6,312,458 to Golds each disclose a variation of a coiled securingmember20.
• A different kind of supporting member is disclosed in FIG. 8 of U.S. Pat. No. 6,053,943 to Edwin et al.
• Like Jayaraman, U.S. Pat. No. 5,871,536 to Lazarus discloses a plurality of straight, longitudinal support structures38 attached to the circumferential support structures36, seeFIGS. 1,6,7,8,10,11,12,14.FIG. 8 of Lazarus illustrates the longitudinal support structures38 attached to a distal structure36 and extending almost all of the way to the proximal structure36. The longitudinal structures38,84,94 can, be directly connected to thebody22,80 and can be telescopic38,64.
• United States Patent Publication 2003/0088305 to Van Schie et al. (hereinafter “Van Schie”) does not disclose a support bar. Rather, it discloses a curved stent graft using an elastic material8 connected to stents at a proximal end2 and at a distal end3 (seeFIGS. 1,2) thereof to create a curved stent graft. Because Van Schie needs to create a flexible curved graft, the elastic material8 is made of silicone rubber or another similar material. Thus, the material8 cannot provide support in the longitudinal extent of the stent graft. Accordingly, an alternative to the elastic support material8 is asuture material25 shown inFIGS. 3 to 6.
SUMMARY OF THE INVENTION
• The invention provides a method of forming a non-circular stent that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that provides a vessel repair device that implants/conforms more efficiently within the natural or diseased course of the aorta by aligning with the natural curve of the aorta, decreases the likelihood of vessel puncture, increases the blood-tight vascular connection, retains the intraluminal wall of the vessel position, is more resistant to migration, and delivers the stent graft into a curved vessel while minimizing intraluminal forces imparted during delivery and while minimizing the forces needed for a user to deliver the stent graft into a curved vessel.
• With the foregoing and other objects in view, there is provided, in accordance with the invention, method for manufacturing a stent, including the steps of providing a mandrel with an outer surface having a polygonal cross-sectional shape and a longitudinal axis, winding stent wire around the outer surface of the mandrel about the longitudinal axis into a desired final shape, the desired final shape being polygonal in an elevation orthogonal to the longitudinal axis, and forming a stent by setting the wound stent wire in the desired polygonal final shape.
• With the objects of the invention in view, there is also provided a method for manufacturing a stent, including the steps of providing a mandrel with a multiple-sided outer surface and a longitudinal axis, winding a stent wire around the outer surface of the mandrel into a desired final shape substantially corresponding to a shape of the outer surface, and forming a stent by setting the wound stent wire into the desired final shape.
• In accordance with another mode of the invention, the mandrel is provided with flat sections and rounded edge portions between the flat sections.
• With the objects of the invention in view, the stent forming step is carried out by setting the stent wire to have rounded edges corresponding to the rounded edge portions of the mandrel and with flat sides corresponding to the flat sections of the mandrel.
• With the objects of the invention in view, pins are placed on the outer surface of the mandrel longitudinally offset from one another and corresponding to desired Z-stent apex locations and Z-stent apices are formed by winding the stent wire around the pins.
• In accordance with a further mode of the invention, the pin placing step is carried out by placing the pins on the mandrel to protrude perpendicularly from the outside surface of the mandrel.
• In accordance with an added mode of the invention, pins are placed on at least some of the rounded edge portions of the mandrel longitudinally offset from one another and corresponding to desired Z-stent apex locations and Z-stent apices are formed by winding the stent wire around the pins.
• In accordance with an additional mode of the invention, the pins are placed at each of the rounded edge portions of the mandrel and the setting step is carried out to form the stent with substantially linear struts lying flat against the flat sections of the mandrel.
• In accordance with yet another mode of the invention, the mandrel is provided in a dodecahedron shape and the setting step is carried out on the mandrel to form a Z-stent having six proximal and six distal apices.
• In accordance with yet a further mode of the invention, two ends of the stent wire are fastened to one another to complete the stent.
• In accordance with yet an added mode of the invention, the stent wire is initially provided as a cold-drawn shape-memory wire and the setting step is carried out by heat-treatment. In one embodiment, the heat-treatment step is carried out by exposing the shape-memory wire to a heat-setting temperature for a period of time with subsequent quenching as required to shape set the shape-memory wire to the then-existing shape of the wire on the mandrel and obtain superelastic mechanical characteristics of the shape-memory wire.
• In accordance with yet an additional mode of the invention, the setting step by exposing the wire to a process that shapes the wire to the then-existing shape of the wire on the mandrel selected from at least one of the group consisting of a mechanical process, a thermal process, and a chemical process.
• In accordance with still a further mode of the invention, the outer surface of the mandrel is provided with a polygonal cross-sectional shape.
• In accordance with still an added mode of the invention, the desired final shape is polygonal in an elevation orthogonal to the longitudinal axis.
• In accordance with a concomitant mode of the invention, the mandrel is provided with flat sections and rounded edge portions between the flat sections; and the stent forming step is carried out by setting the stent wire to have rounded edges corresponding to the rounded edge portions of the mandrel and with flat sides corresponding to the flat sections of the mandrel.
• Other features that are considered as characteristic for the invention are set forth in the appended claims.
• Although the invention is illustrated and described herein as embodied in a method of forming a non-circular stent, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
• The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:
• FIG. 1 is a side elevational view of a stent graft according to the invention;
• FIG. 2 is a side elevational view of a stent of the stent graft ofFIG. 1;
• FIG. 3 is a cross-sectional view of the stent ofFIG. 2 with different embodiments of protrusions;
• FIG. 4 is a perspective view of a prior art round mandrel for forming prior art stents;
• FIG. 5 is a fragmentary, side elevational view of a prior art stent in a portion of a vessel;
• FIG. 6 is a perspective view of a dodecahedral-shaped mandrel for forming stents inFIGS. 1 to 3;
• FIG. 7 is a fragmentary, side elevational view of the stent ofFIGS. 1 to 3 in a portion of a vessel;
• FIG. 8 is a fragmentary, enlarged side elevational view of the proximal end of the stent graft ofFIG. 1 illustrating movement of a gimbaled end;
• FIG. 9 is a side elevational view of a two-part stent graft according to the invention;
• FIG. 10 is a fragmentary, side elevational view of a delivery system according to the invention with a locking ring in a neutral position;
• FIG. 11 is a fragmentary, side elevational view of the delivery system ofFIG. 10 with the locking ring in an advancement position and, as indicated by dashed lines, a distal handle and sheath assembly in an advanced position;
• FIG. 12 is a fragmentary, enlarged view of a sheath assembly of the delivery system ofFIG. 10;
• FIG. 13 is a fragmentary, enlarged view of an apex capture device of the delivery system ofFIG. 10 in a captured position;
• FIG. 14 is a fragmentary, enlarged view of the apex capture device ofFIG. 13 in a released position;
• FIG. 15 is a fragmentary, enlarged view of an apex release assembly of the delivery system ofFIG. 10 in the captured position;
• FIG. 16 is a fragmentary, enlarged view of the apex release assembly ofFIG. 15 in the captured position with an intermediate part removed;
• FIG. 17 is a fragmentary, enlarged view of the apex release assembly ofFIG. 16 in the released position;
• FIG. 18 is a fragmentary, side elevational view of the delivery system ofFIG. 11 showing how a user deploys the prosthesis;
• FIG. 19 is a fragmentary cross-sectional view of human arteries including the aorta with the assembly of the present invention in a first step of a method for inserting the prosthesis according to the invention;
• FIG. 20 is a fragmentary cross-sectional view of the arteries ofFIG. 19 with the assembly in a subsequent step of the method for inserting the prosthesis;
• FIG. 21 is a fragmentary cross-sectional view of the arteries ofFIG. 20 with the assembly in a subsequent step of the method for inserting the prosthesis;
• FIG. 22 is a fragmentary cross-sectional view of the arteries ofFIG. 21 with the assembly in a subsequent step of the method for inserting the prosthesis;
• FIG. 23 is a fragmentary cross-sectional view of the arteries ofFIG. 22 with the assembly in a subsequent step of the method for inserting the prosthesis;
• FIG. 24 is a fragmentary cross-sectional view of the arteries ofFIG. 23 with the assembly in a subsequent step of the method for inserting the prosthesis;
• FIG. 25 is a fragmentary, diagrammatic, perspective view of the coaxial relationship of delivery system lumen according to the invention;
• FIG. 26 is a fragmentary, cross-sectional view of the apex release assembly according to the invention;
• FIG. 27 is a fragmentary, side elevational view of the stent graft ofFIG. 1 with various orientations of radiopaque markers according to the invention;
• FIG. 28 is a fragmentary perspective view of the stent graft ofFIG. 1 with various orientations of radiopaque markers according to the invention;
• FIG. 29 is a perspective view of a distal apex head of the apex capture device ofFIG. 13;
• FIG. 30 is a fragmentary side elevational view of the distal apex head ofFIG. 29 and a proximal apex body of the apex capture device ofFIG. 13 with portions of a bare stent in the captured position;
• FIG. 31 is a fragmentary, side elevational view of the distal apex head and proximal apex body ofFIG. 30 with a portion of the proximal apex body cut away to illustrate the bare stent in the captured position;
• FIG. 32 is a fragmentary side elevational view of the distal apex head and proximal apex body ofFIG. 30 in the released position;
• FIG. 33 is a fragmentary, cross-sectional view of an embodiment of handle assemblies according to the invention;
• FIG. 34 is a cross sectional view of pusher clasp rotator of the handle assembly ofFIG. 33;
• FIG. 35 is a plan view of the pusher clasp rotator ofFIG. 34 viewed along line C-C;
• FIG. 36 is a plan and partially hidden view of the pusher clasp rotator ofFIG. 34 with a helix groove for a first embodiment of the handle assembly ofFIGS. 10,11, and18;
• FIG. 37 is a cross-sectional view of the pusher clasp rotator ofFIG. 36 along section line A-A;
• FIG. 38 is a plan and partially hidden view of the pusher clasp rotator ofFIG. 36;
• FIG. 39 is a cross-sectional view of the pusher clasp rotator ofFIG. 38 along section line B-B;
• FIG. 40 is a perspective view of a rotator body of the handle assembly ofFIG. 33;
• FIG. 41 is an elevational and partially hidden side view of the rotator body ofFIG. 40;
• FIG. 42 is a cross-sectional view of the rotator body ofFIG. 41 along section line A-A;
• FIG. 43 is an elevational and partially hidden side view of the rotator body ofFIG. 40;
• FIG. 44 is an elevational and partially hidden side view of a pusher clasp body of the handle assembly ofFIG. 33;
• FIG. 45 is a cross-sectional view of the pusher clasp body ofFIG. 44 along section line A-A;
• FIG. 46 is a cross-sectional view of the pusher clasp body ofFIG. 44 along section line B-B;
• FIG. 47 is a fragmentary, side elevational view of a portion of the handle assembly ofFIG. 33 with a sheath assembly according to the invention;
• FIG. 48 is an exploded side elevational view of a portion of the handle assembly ofFIG. 47;
• FIG. 49 is a fragmentary elevational and partially hidden side view of a handle body of the handle assembly ofFIG. 33;
• FIG. 50 is a fragmentary, exploded side elevational view of a portion of a second embodiment of the handle assembly according to the invention;
• FIG. 51 is a fragmentary, side elevational view of the portion ofFIG. 50 in a neutral position;
• FIG. 52 is an exploded view of a first portion of the second embodiment of the handle assembly;
• FIG. 53 is a fragmentary, exploded view of a larger portion of the second embodiment of the handle assembly as compared toFIG. 52 with the first portion and the sheath assembly;
• FIG. 54 is perspective view of a clasp body of the second embodiment of the handle assembly;
• FIG. 55 is an elevational side view of the clasp body ofFIG. 54;
• FIG. 56 is a cross-sectional view of the clasp body ofFIG. 55 along section line A-A;
• FIG. 57 is a plan view of the clasp body ofFIG. 54;
• FIG. 58 is a plan view of the clasp body ofFIG. 57 viewed from section line B-B;
• FIG. 59 is a fragmentary and partially hidden side elevational view of a clasp sleeve of the second embodiment of the handle assembly;
• FIG. 60 is a fragmentary, cross-sectional view of a portion the clasp sleeve ofFIG. 59 along section line A;
• FIG. 61 is a fragmentary, cross-sectional view of the clasp sleeve ofFIG. 59 along section line C-C;
• FIG. 62 is a fragmentary and partially hidden side elevational view of the clasp sleeve ofFIG. 59 rotated with respect toFIG. 59; and
• FIG. 63 is a fragmentary, cross-sectional view of the nose cone and sheath assemblies ofFIG. 10.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
• While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.
• The present invention provides a stent graft and delivery system that treats, in particular, thoracic aortic defects from the brachiocephalic level of the aortic arch distally to a level just superior to the celiac axis and provides an endovascular foundation for an anastomosis with the thoracic aorta, while providing an alternative method for partial/total thoracic aortic repair by excluding the vessel defect and making surgical repair of the aorta unnecessary. The stent graft of the present invention, however, is not limited to use in the aorta. It can be endoluminally inserted in any accessible artery that could accommodate the stent graft's dimensions.
• Stent Graft
• The stent graft according to the present invention provides various features that, heretofore, have not been applied in the art and, thereby, provide a vessel repair device that implants/conforms more efficiently within the natural or diseased course of the aorta, decreases the likelihood of vessel puncture, and increases the blood-tight vascular connection, and decreases the probability of graft mobility.
• The stent graft is implanted endovascularly before or during or in place of an open repair of the vessel (i.e., an arch, in particular, the ascending and/or descending portion of the aorta) through a delivery system described in detail below. The typical defects treated by the stent graft are aortic aneurysms, aortic dissections, and other diseases such as penetrating aortic ulcer, coarctation, and patent ductus arteriosus, related to the aorta. When endovascularly placed in the aorta, the stent graft forms a seal in the vessel and automatically affixes itself to the vessel with resultant effacement of the pathological lesion.
• Referring now to the figures of the drawings in detail and first, particularly toFIG. 1 thereof, there is shown an improved stent graft1 having agraft sleeve10 and a number ofstents20. Thesestents20 are, preferably, made of nitinol, an alloy having particularly special properties allowing it to rebound to a set configuration after compression, the rebounding property being based upon the temperature at which the alloy exists. For a detailed explanation of nitinol and its application with regard to stents, see, e.g., U.S. Pat. Nos. 4,665,906, 5,067,957, and 5,597,378 to Jervis and to Gianturco.
• Thegraft sleeve10 is cylindrical in shape and is made of a woven graft material along its entire length. The graft material is, preferably, polyester, in particular, polyester referred to under the name DACRON® or other material types like Expanded Polytetrafluoroethylene (“EPTFE”), or other polymeric based coverings. Thetubular graft sleeve10 has a framework of individual lumen-supporting wires each referred to in the art as astent20. Connection of eachstent20 is, preferably, performed by sewing a polymeric (nylon, polyester) thread around an entirety of thestent20 and through thegraft sleeve10. The stitch spacings are sufficiently close to prevent any edge of thestent20 from extending substantially further from the outer circumference of thegraft sleeve10 than the diameter of the wire itself. Preferably, the stitches have a 0.5 mm to 5 mm spacing.
• Thestents20 are sewn either to the exterior or interior surfaces of thegraft sleeve10.FIG. 1 illustrates allstents20,30 on theexterior surface16 of thegraft sleeve10. In a preferred non-illustrated embodiment, the most proximal23 and distal stents and abare stent30 are connected to the interior surface of thegraft sleeve10 and the remainder of thestents20 are connected to theexterior surface16. Another possible non-illustrated embodiment alternates connection of thestents20,30 to thegraft sleeve10 from the graft exterior surface to the graft interior surface, the alternation having any periodic sequence.
• Astent20, when connected to thegraft sleeve10, radially forces thegraft sleeve10 open to a predetermined diameter D. The released radial force creates a seal with the vessel wall and affixes the graft to the vessel wall when the graft is implanted in the vessel and is allowed to expand.
• Typically, thestents20 are sized to fully expand to the diameter D of the fully expandedgraft sleeve10. However, a characteristic of the present invention is that each of thestents20 and30 has a diameter larger than the diameter D of the fully expandedgraft sleeve10. Thus, when the stent graft1 is fully expanded and resting on the internal surface of the vessel where it has been placed, eachstent20 is imparting independently a radially directed force to thegraft sleeve10. Such pre-compression, as it is referred to herein, is applied (1) to ensure that the graft covering is fully extended, (2) to ensure sufficient stent radial force to make sure sealing occurs, (3) to affix the stent graft and prevent it from kinking, and (4) to affix the stent graft and prevent migration.
• Preferably, each of thestents20 is formed with a single nitinol wire. Of course other biocompatible materials can be used, for example, stainless steel, biopolymers, cobalt chrome, and titanium alloys.
• The preferred shape of eachstent20 corresponds to what is referred in the art as a Z-stent, see, e.g., Gianturco (although the shape of thestents20 can be in any form that satisfies the functions of a self-expanding stent). Thus, the wire forming thestent20 is a ring having a wavy or sinusoidal shape. In particular, an elevational view orthogonal to the center axis21 of thestent20 reveals a shape somewhere between a triangular wave and a sinusoidal wave as shown inFIG. 2. In other words, the view ofFIG. 2 shows that thestents20 each have alternating proximal22 and distal24 apices. Preferably, the apices have a radius r that does not present too great of a point towards a vessel wall to prevent any possibility of puncturing the vessel, regardless of the complete circumferential connection to thegraft sleeve10. In particular, the radius r of curvature of the proximal22 and distal24 apices of thestent20 are, preferably, equal. The radius of curvature r is between approximately 0.1 mm and approximately 3.0 mm, in particular, approximately 0.5 mm.
• Another advantageous feature of a stent lies in extending the longitudinal profile along which the stent contacts the inner wall of a vessel. This longitudinal profile can be explained with reference toFIGS. 3 to 7.
• Prior art stents and stents according to the present invention are formed on mandrels29,29′ by winding the wire around the mandrel29,29′ and forming theapexes22,24,32,34 by wrapping the wire over non-illustrated pins that protrude perpendicular from the axis of the mandrel. Such pins, if illustrated, would be located in the holes illustrated in the mandrels29,29′ ofFIGS. 4 and 6. Prior art stents are formed on a round mandrel29 (also referred to as a bar). Astent20′ formed on a round mandrel29 has a profile that is rounded (seeFIG. 5). Because of the rounded profile, thestent20′ does not conform evenly against the inner wall of the vessel2 in which it is inserted. This disadvantage is critical in the area of stent graft1 seal zones—areas where the ends of thegraft10 need to be laid against the inner wall of the vessel2. Clinical experience reveals thatstents20′ formed with the round mandrel29 do not lie against the vessel2; instead, only a mid-section of thestent20′ rests against the vessel2, as shown inFIG. 5. Accordingly, when such astent20′ is present at either of the proximal12 or distal14 ends of the stent graft1, the graft material flares away from the wall of the vessel2 into the lumen—a condition that is to be avoided. An example of this flaring can be seen by comparing the upper and lower portions of the curved longitudinal profile of thestent20′ inFIG. 5 with the linear longitudinal profile of the vessel2.
• To remedy this problem and ensure co-columnar apposition of the stent and vessel,stents20 of the present invention are formed on a multiple-sided mandrel. In particular, thestents20 are formed on a polygonal-shaped mandrel29′. The mandrel29′ does not have sharp edges. Instead, it has flat sections and rounded edge portions between the respective flat sections. Thus, a stent formed on the mandrel29′ will have a cross-section that is somewhat round but polygonal, as shown inFIG. 3. The cross-sectional view orthogonal to the center axis21 of such astent20 will have beveled or rounded edges31 (corresponding to the rounded edge portions of the mandrel29′) disposed between flat sides or struts33 (corresponding to the flat sections of the mandrel29′). With stents manufactured in this way, the apices remain on the circumference of the graft and do not bend into the graft interior like prior art stents—an undesirable condition as explained in the preceding paragraph. Further, the struts of the stents so manufactured (the substantially linear portions of the stent between the apices) lie in the plane of the graft material when attached thereto as shown inFIG. 7. In contrast, prior art struts are curved (seeFIG. 5) and, therefore, force the graft material inwards away from the vessel wall. As used herein, substantially linear means that the struts are sufficiently straight and level to substantially prevent displacement of an apex (which lies between two adjacent struts) towards the interior of the graft material to which the struts and apices are attached.
• To manufacture thestent20, apexes of thestents20 are formed by winding the wire over non-illustrated pins located on the rounded portions of the mandrel29′. Thus, thestruts33 lying between theapexes22,24,32,34 of thestents20 lie flat against the flat sides of the mandrel29′. When so formed on the inventive mandrel29′, the longitudinal profile is substantially less rounded than the profile ofstent20′ and, in practice, is substantially linear,
• Forstents20 having six proximal22 and six distal24 apices, thestents20 are formed on a dodecahedron-shaped mandrel29′ (a mandrel having twelve sides), which mandrel29′ is shown inFIG. 6. Astent20 fowled on such a mandrel29′ will have the cross-section illustrated inFIG. 3.
• The fourteen-apex stent20 shown inFIG. 7 illustrates astent20 that has been formed on a fourteen-sided mandrel. Thestent20 inFIG. 7 is polygonal in cross-section (having fourteen sides) and, as shown inFIG. 7, has a substantially linear longitudinal profile. Clinically, the linear longitudinal profile improves the stent's20 ability to conform to the vessel2 and press thegraft sleeve10 outward in the sealing zones at the extremities of theindividual stent20.
• Another way to improve the performance of the stent graft1 is to provide thedistal-most stent25 on the graft10 (i.e., downstream) with additional apices and to give it a longer longitudinal length (i.e., greater amplitude) and/or a longer circumferential length. When astent25 having a longer circumferential length is sewn to a graft, the stent graft1 will perform better clinically. The improvement, in part, is due to a need for the distal portion of thegraft material10 to be pressed firmly against the wall of the vessel. The additional apices result in additional points of contact between the stent graft1 and vessel wall, thus ensuring better apposition to the wall of the vessel and better sealing of thegraft material10 to the vessel. The increased apposition and sealing substantially improves the axial alignment of thedistal end14 of the stent graft1 to the vessel. As set forth above, each of thestents20 and30 has a diameter larger than the diameter D of the fully expandedgraft sleeve10. Thus, if thedistal stent25 also has a diameter larger than the diameter D, it will impart a greater radial bias on all 360 degrees of the corresponding section of the graft than stents not having such an oversized configuration.
• A typical implanted stent graft1 typically does not experience a lifting off at straight portions of a vessel because the radial bias of the stents acting upon the graft sleeve give adequate pressure to align the stent and graft sleeve with the vessel wall. However, when a typical stent graft is implanted in a curved vessel (such as the aorta), the distal end of the stent graft1 does experience a lift off from the vessel wall. The increased apposition and sealing of the stent graft1 according to the present invention substantially decreases the probability of lift off because the added height and additional apices enhance the alignment of the stent graft perpendicular to the vessel wall as compared to prior art stent grafts (no lift off occurs). The number of total apices of a stent is dependent upon the diameter of the vessel in which the stent graft1 is to be implanted. Vessels having a smaller diameter have a smaller total number of apices than a stent to be implanted in a vessel having a larger diameter. Table 1 below indicates preferred stent embodiments for vessels having different diameters. For example, if a vessel has a 26 or 27 mm diameter, then a preferred diameter of thegraft sleeve10 is 30 mm. For a 30 mm diameter graft sleeve, theintermediate stents20 will have 5 apices on each side (proximal and distal) for a total of 10 apices. In other words, the stent defines 5 periodic “waves.” Thedistal-most stent25, in comparison, defines 6 periodic “waves” and, therefore, has 12 total apices. It is noted that thedistal-most stent25 inFIG. 1 does not have the additional apex. While Table 1 indicates preferred embodiments, these configurations can be adjusted or changed as needed.

• TABLE 1
  		Stent Apices/Side
  Vessel Diameter (mm)	Graft Diameter (mm)	(Distal-most Stent #)
  19	22	5(5)
  20-21	24	5(5)
  22-23	26	5(5)
  24-25	28	5(6)
  26-27	30	5(6)
  28-29	32	6(7)
  30-31	34	6(7)
  32-33	36	6(7)
  34	38	6(7)
  35-36	40	7(8)
  37-38	42	7(8)
  39-40	44	7(8)
  41-42	46	7(8)

• To increase the security of the stent graft1 in a vessel, an exposed orbare stent30 is provided on the stent graft1, preferably, only at theproximal end12 of thegraft sleeve10—proximal meaning that it is attached to the portion of thegraft sleeve10 from which the blood flows into the sleeve, i.e., blood flows from thebare stent30 and through thesleeve10 to the left ofFIG. 1. Thebare stent30 is not limited to being attached at theproximal end12. Another non-illustrated bare stent can be attached similarly to thedistal end14 of thegraft sleeve10.
• Specifically, thebare stent30 is fixed to thegraft sleeve10 only at thedistal apices34 of thebare stent30. Thus, thebare stent30 is partially free to extend theproximal apices32 away from the proximal end of thegraft sleeve10.
• Thebare stent30 has various properties, the primary one being to improve the apposition of the graft material to the contour of the vessel wall and to align the proximal portion of the graft covering in the lumen of the arch and provide a blood-tight closure of theproximal end12 of thegraft sleeve10 so that blood does not pass between the vascular inside wall andouter surface16 of the sleeve10 (endoleak).
• The preferred configuration for the radius of curvature a of thedistal apices34 is substantially equal to the radius r of the proximal22 and distal24 apices of thestent20, in particular, it is equal at least to the radius of curvature r of the proximal apices of thestent20 directly adjacent thebare stent30. Thus, as shown inFIG. 8, a distance between theproximal apices22 of the mostproximal stent23 and crossing points of the exposed portions of thebare stent30 are substantially at a same distance from one another all the way around the circumference of theproximal end12 of thegraft sleeve10. Preferably, this distance varies based upon the graft diameter. Accordingly, the sinusoidal portion of thedistal apices34 connected to thegraft sleeve10 traverse substantially the same path as that of thestent23 closest to thebare stent30. Thus, the distance d between thestent22 and all portions of thebare stent30 connected to thegraft sleeve10 remain constant. Such a configuration is advantageous because it maintains the symmetry of radial force of the device about the circumference of the vessel and also aids in the synchronous, simultaneous expansion of the device, thus increasing apposition of the graft material to the vessel wall to induce a proximal seal—and substantially improve the proximal seal—due to increasing outward force members in contact with the vessel wall.
• Inter-positioning thestents23,30 in phase with one another, creates an overlap, i.e., theapices34 of thebare stent30 are positioned within the troughs of thestent23. A further advantage of such a configuration is that the overlap provides twice as many points of contact between the proximal opening of thegraft10 and the vessel in which the stent graft1 is implanted. The additional apposition points keep the proximal opening of thegraft sleeve10 open against the vessel wall, which substantially reduces the potential for endoleaks. In addition, the overlap of thestents23,30 increases the radial load or resistance to compression, which functionally increases fixation and reduces the potential for device migration.
• In contrast to thedistal apices34 of thebare stent30, the radius of curvature β of the proximal apices32 (those apices that are not sewn into the graft sleeve10) is significantly larger than the radius of curvature α of thedistal apices34. A preferred configuration for the bare stent apices has a radius approximately equal, to 1.5 mm for theproximal apices32 and approximately equal to 0.5 mm for thedistal apices34. Such a configuration, substantially prevents perforation of the blood vessel by theproximal apices32, or, at a minimum, makes is much less likely for thebare stent30 to perforate the vessel because of the less-sharp curvature of theproximal apices32.
• Thebare stent30 also has an amplitude greater than theother stents20. Preferably, the peak-to-peak amplitude of thestents20 is approximately 1.3 cm to 1.5 cm, whereas the peak-to-peak amplitude of thebare stent30 is approximately 2.5 cm to 4.0 cm. Accordingly, the force exerted by thebare stent30 on the inner wall of the aorta (due to thebare stent30 expanding to its native position) is spread over a larger surface area. Thus, thebare stent30 of the present invention presents a less traumatic radial stress to the interior of the vessel wall—a characteristic that, while less per square rum than an individual one of thestents20 would be, is sufficient, nonetheless, to retain theproximal end12 in position. Simultaneously, the taller configuration of thebare stent30 guides the proximal opening of the stent graft in a more “squared-off” manner. Thus, the proximal opening of the stent graft is more aligned with the natural curvature of the vessel in the area of the proximal opening.
• As set forth above, because the vessel moves constantly, and due to the constantly changing pressure imparted by blood flow, any stent graft placed in the vessel has the natural tendency to migrate downstream. This is especially true when the stent graft1 hasgraft sleeve segments18 with lengths defined by the separation of the stents on either end of thesegment18, giving the stent graft1 an accordion, concertina, or caterpillar-like shape. When such a shape is pulsating with the vessel and while hemodynamic pressure is imparted in a pulsating manner along the stent graft from theproximal end12 to the downstreamdistal end14, the stent graft1 has a tendency to migrate downstream in the vessel. It is desired to have such motion be entirely prohibited.
• Support along a longitudinal extent of thegraft sleeve10 assists in preventing such movement. Accordingly, as set forth above, prior art stent grafts have provided longitudinal rods extending in a straight line from one stent to another.
• The present invention, however, provides a longitudinal, spiraling/helical support member40 that, while extending relatively parallel to thelongitudinal axis11 of thegraft sleeve10, is not aligned substantially parallel to a longitudinal extent of the entirety of the stent graft1 as done in the prior art, “Relatively parallel” is referred to herein as an extent that is more along thelongitudinal axis11 of the stent graft1 than along an axis perpendicular thereto.
• Specifically, thelongitudinal support member40 has a somewhat S-turn shape, in that, aproximal portion42 is relatively parallel to theaxis11 of thegraft sleeve10 at a first degree41 (being defined as a degree of the 360 degrees of the circumference of the graft sleeve10), and adistal portion44 is, also, relatively parallel to theaxis11 of the tube graft, but at a differentsecond degree43 on the circumference of thegraft sleeve10. The difference between the first andsecond degrees41,43 is dependent upon the length L of thegraft sleeve10. For an approximately 20 cm (approx. 8″) graft sleeve, for example, thesecond degree43 is between 80 and 110 degrees away from thefirst degree41, in particular, approximately 90 degrees away. In comparison, for an approximately 9 cm (approx. 3.5″) graft sleeve, thesecond degree43 is between 30 and 60 degrees away from thefirst degree41, in particular, approximately 45 degrees away. As set forth below, the distance between the first andsecond degrees41,43 is also dependent upon the curvature and the kind of curvature that the stent graft1 will be exposed to when in vivo.
• Thelongitudinal support member40 has a curvedintermediate portion46 between the proximal anddistal portions42,44. By using the word “portion” it is not intended to mean that the rod is in three separate parts (of course, in a particular configuration, a multi-part embodiment is possible). A preferred embodiment of thelongitudinal support member40 is a single, one-piece rod made of stainless steel, cobalt chrome, nitinol, or polymeric material that is shaped as a fullycurved helix42,44,46 without any straight portion. In an alternative stent graft embodiment, the proximal anddistal portions42,44 can be substantially parallel to theaxis11 of the stent graft1 and thecentral portion46 can be helically curved.
• One way to describe the preferred curvature embodiment of thelongitudinal support member40 can be using an analogy of asymptotes. If there are two asymptotes extending parallel to thelongitudinal axis11 of thegraft sleeve10 at the first andsecond degrees41,43 on thegraft sleeve10, then theproximal portion42 can be on thefirst degree41 or extend approximately asymptotically to thefirst degree41 and thedistal portion44 can be on thesecond degree43 or extend approximately asymptotically to thesecond degree43. Because thelongitudinal support member40 is one piece in a preferred embodiment, thecurved portion46 follows the natural curve formed by placing the proximal anddistal portions42,44 as set forth herein.
• In such a position, the curvedlongitudinal support member40 has a centerline45 (parallel to thelongitudinal axis11 of thegraft sleeve10 halfway between the first andsecond degrees41,43 on the graft sleeve10). In this embodiment, therefore, the curved portion intersects thecenterline45 at approximately 20 to 40 degrees in magnitude, preferably at approximately 30 to 35 degrees.
• Another way to describe the curvature of the longitudinal support member can be with respect to thecenterline45. The portion of thelongitudinal support member40 between thefirst degree41 and thecenterline45 is approximately a mirror image of the portion of thelongitudinal support member40 between thesecond degree43 and thecenterline45, but rotated 180 degrees around an axis orthogonal to thecenterline45. Such symmetry can be referred to herein as “reverse-mirror symmetrical.”
• Thelongitudinal support member40 is, preferably, sewn to thegraft sleeve10 in the same way as thestents20. However, thelongitudinal support member40 is not sewn directly to any of thestents20 in the proximal portions of the graft. In other words, thelongitudinal support member40 is independent of the proximal skeleton formed by thestents20. Such a configuration is advantageous because an independent proximal end creates a gimbal that endows the stent graft with additional flexibility. Specifically, the gimbaled proximal end allows the proximal end to align better to the proximal point of apposition, thus reducing the chance for endoleak. The additional independence from the longitudinal support member allows the proximal fixation point to be independent from the distal section that is undergoing related motion due to the physiological motion of pulsutile flow of blood. Also in a preferred embodiment, thelongitudinal support member40 is pre-formed in the desired spiral/helical shape (counter-clockwise from proximal to distal), before being attached to thegraft sleeve10.
• Because vessels receiving the stent graft1 are not typically straight, the final implanted position of the stent graft1 will, most likely, be curved in some way. In prior art stent grafts (which only provide longitudinally parallel support rods), there exist, inherently, a force that urges the rod, and, thereby, the entire stent graft, to the straightened, natural shape of the rod. This force is disadvantageous for stent grafts that are to be installed in an at least partly curved manner.
• The curved shape of thelongitudinal support member40 according to the present invention eliminates at least a majority, or substantially all, of this disadvantage because the longitudinal support member's40 natural shape is curved and, therefore, imparts less of a force, or none at all, to straighten thelongitudinal support member40, and, thereby, move the implanted stent graft in an undesirable way. At the same time, the curvedlongitudinal support member40 negates the effect of the latent kinetic force residing in the aortic wall that is generated by the propagation of the pulse wave and systolic blood pressure in the cardiac cycle, which is, then, released during diastole.
• In a preferred embodiment, thelongitudinal support member40 can be curved in a patient-customized way to accommodate the anticipated curve of the actual vessel in which the graft will be implanted. Thus, the distance between the first andsecond degrees41,43 will be dependent upon the curvature and the kind of curvature that the stent graft1 will be exposed to when in vivo. As such, when implanted, the curvedlongitudinal support member40 will, actually, exhibit an opposite force against any environment that would alter its conformance to the shape of its resident vessel's existing course(es).
• Preferably, thesupport member40 is sewn, in a similar manner as thestents20, on theoutside surface16 of thegraft sleeve10.
• In prior art support rods, the ends thereof are merely a terminating end of a steel or nitinol rod and are, therefore, sharp. Even though these ends are sewn to the tube graft in the prior art, the possibility of tearing the vessel wall still exists. It is, therefore, desirable to not provide the support rod with sharp ends that could puncture the vessel in which the stent graft is placed.
• The two ends of the longitudinal,support member40 of the present invention do not end abruptly. Instead, each end of the longitudinalsupport member loops47 back upon itself such that the end of the longitudinal support member along the axis of the stent graft is not sharp and, instead, presents an exterior of a circular or oval shape when viewed from theends12,14 of thegraft sleeve10. Such a configuration substantially prevents the possibility of tearing the vessel wall and also provides additional longitudinal support at the oval shape by having two longitudinally extending sides of the oval47.
• In addition, in another embodiment, the end of the longitudinal support member may be connected to the secondproximal stent28 and to the most distal stent. This configuration would allow the longitudinal support member to be affixed to stent28 (seeFIG. 1) and the most distal stent for support while still allowing for the gimbaled feature of the proximal end of the stent graft to be maintained.
• A significant feature of thelongitudinal support member40 is that the ends of thelongitudinal support member40 may not extend all the way to the two ends12,14 of thegraft sleeve10. Instead, thelongitudinal support member40 terminates at or prior to the second-to-last stent28 at theproximal end12, and, if desired, prior to the second-to-last stent28′ at thedistal end14 of thegraft sleeve10. Such an ending configuration (whether proximal only or both proximal and distal) is chosen for a particular reason—when thelongitudinal support member40 ends before either of the planes defined bycross-sectional lines52,52′, thesleeve10 and thestents20 connected thereto respectively formgimbaled portions50,50′. In other words, when a grasping force acting upon the gimbaled ends50,50′ moves or pivots the cross-sectional plane defining each end opening of thegraft sleeve10 about thelongitudinal axis11 starting from the planes defined by thecross-sectional lines52,52′, then the movingportions50,50′ can be oriented at any angle γ about the center of the circular opening in all directions (360 degrees), as shown inFIG. 8. The natural gimbal, thus, allows the ends50,50′ to be inclined in any radial direction away from thelongitudinal axis11.
• Among other things, the gimbaled ends50,50′ allow each end opening to dynamically align naturally to the curve of the vessel in which it is implanted. A significant advantage of the gimbaled ends50,50′ is that they limit propagation of the forces acting upon the separate parts. Specifically, a force that, previously, would act upon the entirety of the stent graft1, in other words, both theend portions50,50′ and the middle portion of the stent graft1 (i.e., betweenplanes52,52′), now principally acts upon the portion in which the force occurs. For example, a force that acts only upon one of theend portions50,50′ substantially does not propagate into the middle portion of the stent graft1 (i.e., betweenplanes52,52′). More significantly, however, when a force acts upon the middle portion of the stent graft1 (whether moving longitudinally, axially (dilation), or in a torqued manner), the ends50,50′, because they are gimbaled, remain relatively completely aligned with the natural contours of the vessel surrounding therespective end50,50′ and have virtually none of the force transferred thereto, which force could potentially cause the ends to grate, rub, or shift from their desired fixed position in the vessel. Accordingly, the stent graft ends50,50′ remain fixed in the implanted position and extend the seating life of the stent graft1.
• Another advantage of thelongitudinal support member40 is that it increases the columnar strength of the graft stent1. Specifically, the material of the graft sleeve can be compressed easily along thelongitudinal axis11, a property that remains true even with the presence of thestents20 so long as thestents20 are attached to thegraft sleeve10 with a spacing between thedistal apices24 of onestent20 and theproximal apices22 of the nextadjacent stout20. This is especially true for the amount of force imparted by the flow of blood along the extent of thelongitudinal axis11. However, with thelongitudinal support member40 attached according to the present invention, longitudinal strength of the stent graft1 increases to overcome the longitudinal forces imparted by blood flow.
• Another benefit imparted by having such increased longitudinal strength is that the stent graft1 is further prevented from migrating in the vessel because the tube graft is not compressing and expanding in an accordion-like manner—movement that would, inherently, cause graft migration.
• A further measure for preventing migration of the stent graft1 is to equip at least one of any of theindividual stents20,30 or thelongitudinal support member40 withprotuberances60, such as barbs or hooks (FIG. 3). See, e.g., United States Patent Publication 2002/0052660 to Greenhalgh. In the preferred embodiment of the present invention, thestents20,30 are secured to the outercircumferential surface16 of thegraft sleeve10. Accordingly, if the stents20 (or connected portions of stent30) haveprotuberances60 protruding outwardly, then such features would catch the interior wall of the vessel and add to the prevention of stout graft1 migration. Such an embodiment can be preferred for aneurysms but is not preferred for the fragile characteristics of dissections becausesuch protuberances60 can excoriate the inner layer(s) of the vessel and cause leaks between layers, for example.
• As shown inFIG. 9, the stent graft1 is not limited to asingle graft sleeve10. Instead, the entire stent graft can be afirst stent graft100 having all of the features of the stent graft1 described above and asecond stent graft200 that, instead of having a circular extremeproximal end12, as set forth above, has aproximal end212 with a shape following the contour of the mostproximal stent220 and is slightly larger in circumference than the distal circumference of thefirst stent graft100. Therefore, an insertion of theproximal end212 of thesecond stent graft200 into thedistal end114 of thefirst stent graft100 results, in total, in a two-part stent graft. Because blood flows from theproximal end112 of thefirst stent graft100 to thedistal end214 of thesecond stent graft200, it is preferable to have thefirst stent graft100 fit inside thesecond stent graft200 to prevent blood from leaking out therebetween. This configuration can be achieved by implanting the devices in reverse order (first implant graft200 and, then,implant graft100. Each of thestent grafts100,200 can have its ownlongitudinal support member40 as needed.
• It is not significant if the stent apices of the distal-most stent of thefirst stent graft100 are not aligned with the stent apices of theproximal-most stent220 of thesecond stent graft200. What is important is the amount of junctional overlap between the twografts100,200.
• Delivery System
• As set forth above, the prior art includes many different systems for endoluminally delivering a prosthesis, in particular, a stent graft, to a vessel. Many of the delivery systems have similar parts and most are guided along a guidewire that is inserted, typically, through an insertion into the femoral artery near a patient's groin prior to use of the delivery system. To prevent puncture of the arteries leading to and including the aorta, the delivery system is coaxially connected to the guidewire and tracks the course of the guidewire up to the aorta. The parts of the delivery system that will track over the wire are, therefore, sized to have an outside diameter smaller than the inside diameter of the femoral artery of the patient. The delivery system components that track over the guidewire include the stent graft and are made of a series of coaxial lumens referred to as catheters and sheaths. The stent graft is constrained, typically, by an outer catheter, requiring the stent graft to be compressed to fit inside the outer catheter. Doing so makes the portion of the delivery system that constrains the stent graft very stiff, which, therefore, reduces that portion's flexibility and makes it difficult for the delivery system to track over the guidewire, especially along curved vessels such as the aortic arch. In addition, because the stent graft exerts very high radial forces on the constraining catheter due to the amount that it must be compressed to fit inside the catheter, the process of deploying the stent graft by sliding the constraining catheter off of the stent graft requires a very high amount of force, typically referred to as a deployment force. Also, the catheter has to be strong enough to constrain the graft, requiring it to be made of a rigid material. If the rigid material is bent, such as when tracking into the aortic arch, the rigid material tends to kink, making it difficult if not impossible to deploy the stent graft.
• Common features of vascular prosthesis delivery systems include a tapered nose cone fixedly connected to a guidewire lumen, which has an inner diameter substantially corresponding to an outer diameter of the guidewire such that the guidewire lumen slides easily over and along the guidewire. A removable, hollow catheter covers and holds a compressed prosthesis in its hollow and the catheter is fixedly connected to the guidewire lumen. Thus, when the prosthesis is in a correct position for implantation, the physician withdraws the hollow catheter to gradually expose the self-expanding prosthesis from its proximal end towards its distal end. When the catheter has withdrawn a sufficient distance from each portion of the expanding framework of the prosthesis, the framework can expand to its native position, preferably, a position that has a diameter at least as great as the inner diameter of the vessel wall to, thereby, tightly affix the prosthesis in the vessel. When the catheter is entirely withdrawn from the prosthesis and, thereby, allows the prosthesis to expand to the diameter of the vessel, the prosthesis is fully expanded and connected endoluminally to the vessel along the entire extent of the prosthesis, e.g., to treat a dissection. When treating an aneurysm, for example, the prosthesis is in contact with the vessel's proximal and distal landing zones when completely released from the catheter. At such a point in the delivery, the delivery system can be withdrawn from the patient. The prosthesis, however, cannot be reloaded in the catheter if implantation is not optimal.
• The aorta usually has a relatively straight portion in the abdominal region and in a lower part of the thoracic region. However, in the upper part of the thoracic region, the aorta is curved substantially, traversing an upside-down U-shape from the back of the heart over to the front of the heart. As explained above, prior art delivery systems are relatively hard and inflexible (the guidewire/catheter portion of the prior art delivery systems). Therefore, if the guidewire/catheter must traverse the curved portion of the aorta, it will kink as it is curved or it will press against the top portion of the aortic curve, possibly puncturing the aorta if the diseased portion is located where the guidewire/catheter is exerting its force. Such a situation must be avoided at all costs because the likelihood of patient mortality is high. The prior art does not provide any way for substantially reducing the stress on the curved portion of the aorta or for making the guidewire/catheter sufficiently flexible to traverse the curved portion without causing damage to the vessel.
• The present invention, however, provides significant features not found in the prior art that assist in placing a stent graft in a curved portion of the aorta in a way that substantially reduces the stress on the curved portion of the aorta and substantially reduces the insertion forces needed to have the compressed graft traverse the curved portion of the aorta. The delivery system of the present invention also has a very simple to use handle assembly. The handle assembly takes advantage of the fact that the inside diameter of the aorta is substantially larger that the inside diameter of the femoral arteries. The present invention, accordingly, uses a two-stage approach in which, after the device is inserted in through the femoral artery and tracks up into the abdominal area of the aorta (having a larger diameter (seeFIG. 19) than the femoral artery), a second stage is deployed (seeFIG. 20) allowing a small amount of expansion of the stent graft while still constrained in a sheath; but this sheath, made of fabric/woven polymer or similar flexible material, is very flexible. Such a configuration gives the delivery system greater flexibility for tracking, reduces deployment forces because of the larger sheath diameter, and easily overcome kinks because the sheath is made of fabric.
• To describe the delivery system of the present invention, the method for operating thedelivery assembly600 will be described first in association withFIGS. 10,11, and12. Thereafter, the individual components will be described to allow a better understanding of how each step in the process is effected for delivering the stent graft1 to any portion of the aorta700 (seeFIGS. 19 to 24), in particular, thecurved portion710 of the aorta.
• Initially, thedistal end14 of the stent graft1 is compressed and placed into a hollow, cup-shaped, or tubular-shaped graft holding device, in particular, the distal sleeve644 (see, e.g.,FIG. 25). At this point, it is noted that the convention for indicating direction with respect to delivery systems is opposite that of the convention for indicating direction with respect to stent grafts. Therefore, the proximal direction of the delivery system is that portion closest to the user/physician employing the system and the distal direction corresponds to the portion farthest away from the user/physician, i.e., towards thedistal-most nose cone632.
• Thedistal sleeve644 is fixedly connected to the distal end of thegraft push lumen642, which lumen642 provides an end face for thedistal end14 of the stent graft1. Alternatively, thedistal sleeve644 can be removed entirely. In such a configuration, as shown inFIG. 12, for example, the proximal taper of theinner sheath652 can provide the measures for longitudinally holding the compressed distal end of the graft1. As set forth in more detail below, each apex32 of thebare stent30 is, then, loaded into theapex capture device634 so that the stent graft1 is held at both its proximal and distal ends. The loadeddistal end14, along with thedistal sleeve644 and thegraft push lumen642, are, in turn, loaded into theinner sheath652, thus, further compressing the entirety of the stent graft1. The capturedbare stent30, along with the nose cone assembly630 (including the apex capture device634), is loaded until the proximal end of thenose cone632 rests on the distal end of theinner sheath652. The entirenose cone assembly630 andsheath assembly650 is, then, loaded proximally into the rigidouter catheter660, further compressing the stent graft1 (resting inside the inner sheath652) to its fully compressed position for later insertion into a patient. SeeFIG. 63.
• The stent graft1 is, therefore, held both at its proximal and distal ends and, thereby, is both pushed and pulled when moving from a first position (shown inFIG. 19 and described below) to a second position (shown inFIG. 21 and described below). Specifically, pushing is accomplished by the non-illustrated interior end face of the hollow distal sleeve644 (or thetaper653 of the inner sheath652) and pulling is accomplished by the hold that theapex capture device634 has on theapices32 of thebare stent30.
• Theassembly600 according to the present invention tracks along aguidewire610 already inserted in the patient and extending through the aorta and up to, but not into, the left ventricle of theheart720. Therefore, aguidewire610 is inserted through theguidewire lumen620 starting from thenose cone assembly630, through thesheath assembly650, through thehandle assembly670, and through theapex release assembly690. Theguidewire610 extends out the proximal-most end of theassembly600. Theguidewire lumen620 is coaxial with thenose cone assembly630, thesheath assembly650, thehandle assembly670, and theapex release assembly690 and is the innermost lumen of theassembly600 immediately surrounding theguidewire610.
• Before using thedelivery system assembly600, all air must be purged from inside theassembly600. Therefore, a liquid, such as sterile U.S.P. saline, is injected through a non-illustrated tapered luer fitting to flush the guidewire lumen at a non-illustrated purge port located near a proximal end of the guidewire lumen. Second, saline is also injected through the luer fitting612 of the lateral purge-port (seeFIG. 11), which liquid fills the entire internal co-axial space of thedelivery system assembly600. It may be necessary to manipulate the system to facilitate movement of the air to be purged to the highest point of the system.
• After purging all air, the system can be threaded onto the guidewire and inserted into the patient. Because theouter catheter660 has a predetermined length, the fixed front handle672 can be disposed relatively close to the entry port of the femoral artery. It is noted, however, that the length of theouter catheter660 is sized such that it will not have the fixedproximal handle672 directly contact the entry port of the femoral artery in a patient who has the longest distance between the entry port and the thoracic/abdominal junction742,732 of the aorta expected in a patient (this distance is predetermined). Thus, thedelivery assembly600 of the present invention can be used with typical anatomy of the patient. Of course, theassembly600 can be sized to any usable length.
• Thenose cone assembly630 is inserted into a patient's femoral artery and follows theguidewire610 until thenose cone632 reaches the first position at a level of the celiac axis. The first position is shown inFIG. 19. Thenose cone assembly630 is radiopaque, whether wholly or partially, to enable the physician to determine fluoroscopically, for example, that thenose cone assembly630 is in the first position. For example, thenose cone632 can have aradiopaque marker631 anywhere thereon or thenose cone632 can be entirely radiopaque.
• After thenose cone assembly630 is in the first position shown inFIG. 19, thelocking ring676 is placed from its neutral position N, shown inFIG. 10, into its advancement position A, shown inFIG. 11. As will be described below, placing thelocking ring676 into its advancement position A allows both thenose cone assembly630 and theinternal sheath assembly650 to move as one when theproximal handle678 is moved in either the proximal or distal directions because thelocking ring676 radially locks thegraft push lumen642 to the lumens of the apex release assembly690 (including theguidewire lumen620 and an apex release lumen640). Thelocking ring676 is fixedly connected to asheath lumen654.
• Before describing how various embodiments of thehandle assembly670 function, a summary of the multi-lumen connectivity relationships, throughout the neutral N, advancement A, and deployment D positions, is described.
• When the locking ring is in the neutral position N shown inFIG. 10, thepusher clasp spring298 shown inFIG. 48 and theproximal spring606 shown inFIG. 52 are both disengaged. This allows free movement of thegraft push lumen642 with theguidewire lumen620 and theapex release lumen640 within thehandle body674.
• When thelocking ring676 is moved into the advancement position A, shown inFIG. 11, thepusher clasp spring298 shown inFIG. 48 is engaged and theproximal spring606 shown inFIG. 52 is disengaged. The sheath lumen654 (fixedly attached to the inner sheath652) is, thereby, locked to the graft push lumen642 (fixedly attached to the distal sleeve644) so that, when theproximal handle678 is moved toward thedistal handle672, both thesheath lumen654 and thegraft push lumen642 move as one. At this point, thegraft push lumen642 is also locked to both theguidewire lumen620 and the apex release lumen640 (which are locked to one another through theapex release assembly690 as set forth in more detail below). Accordingly, as theproximal handle678 is moved to the second position, shown with dashed lines inFIG. 11, thesheath assembly650 and thenose cone assembly630 progress distally out of theouter catheter660 as shown inFIGS. 20 and 21 and with dashed lines inFIG. 11.
• At this point, thesheath lumen654 needs to be withdrawn from the stent graft1 to, thereby, expose the stent graft1 from itsproximal end12 to itsdistal end14 and, ultimately, entirely off of itsdistal end14. Therefore, movement of thelocking ring676 into the deployment position D will engage theproximal spring606 shown inFIG. 52 and disengage thepusher clasp spring298 shown inFIG. 48. At this point, thegraft push lumen642 along with theguidewire lumen620 and theapex release lumen640 are locked to thehandle body674 so as not to move with respect to thehandle body674. Thesheath lumen654 is unlocked from thegraft push lumen642. Movement of thedistal handle678 back to the third position (proximally), therefore, pulls thesheath lumen654 proximally, thus, proximally withdrawing theinner sheath652 from the stent graft1.
• At this point, only thebare stent30 of the stent graft1 is held by thedelivery assembly600. Therefore, final release of the stent graft1 occurs by releasing thebare stent30 from thenose cone assembly630, which is accomplished using theapex release assembly690 as set forth below.
• In order to explain how the locking and releasing of the lumen occur as set forth above, reference is made toFIGS. 33 to 62.
• FIG. 33 is a cross-sectional view of theproximal handle678 and thelocking ring676. Apusher clasp rotator292 is disposed between aclasp sleeve614 and thegraft push lumen642. A specific embodiment of thepusher clasp rotator292 is illustrated inFIGS. 30 through 35. Also disposed between theclasp rotator292 and thegraft push lumen642 is arotator body294, which is directly adjacent thegraft push lumen642. A specific embodiment of therotator body294 is illustrated inFIGS. 40 through 43. Disposed between therotator body294 and thesheath lumen654 is apusher clasp body296, which is fixedly connected to therotator body294 and to thelocking ring676. A specific embodiment of thepusher clasp body296 is illustrated inFIGS. 44 through 46. Apusher clasp spring298 operatively connects thepusher clasp rotator292 to the rotator body294 (and, thereby, the pusher clasp body296).
• An exploded view of these components is presented inFIG. 48, where an O-ring293 is disposed between therotator body294 and thepusher clasp body296. As shown in the plan view ofFIG. 47, acrimp ring295 connects thesheath lumen654 to thedistal projection297 of thepusher clasp body296. Ahollow handle body674, on which theproximal handle678 and thelocking ring676 are slidably mounted, holds thepusher clasp rotator292, therotator body294, thepusher clasp body296, and thepusher clasp spring298 therein. This entire assembly is rotationally mounted to thedistal handle672 for rotating the stent graft1 into position (seeFIGS. 23 and 24 and the explanations thereof below). A specific embodiment of thehandle body674 is illustrated inFIG. 49.
• Asetscrew679 extends from theproximal handle678 to contact a longitudinally helixed groove in the pusher clasp rotator292 (shown inFIGS. 36 and 38). Thus, when moving theproximal handle678 proximally or distally, thepusher clasp rotator292 rotates clockwise or counter-clockwise.
• An alternative embodiment of thelocking ring676 is shown inFIG. 50 et seq., which is the preferred embodiment because, instead of applying a longitudinal movement to rotate thepusher clasp spring298 through the cam/follower feature of theproximal handle678 andpusher clasp rotator292, arotating locking knob582 is located at the proximal end of thehandle body674. Theknob582 has three positions that are clearly shown inFIG. 51: a neutral position N, an advancement position A, and a deployment position D. The functions of these positions N, A, D correspond to the positions N, A, D of thelocking ring676 and theproximal handle678 as set forth above.
• In the alternative embodiment, asetscrew584 is threaded into theclasp sleeve614 through aslot675 in thehandle body674 and through aslot583 in theknob582 to engage the lockingknob582. Because of the x-axis orientation of theslot583 in theknob582 and the y-axis orientation of theslot675 in thehandle body674, when theknob582 is slid over the end of thehandle body674 and thesetscrew584 is screwed into theclasp sleeve614, theknob582 is connected fixedly to thehandle body674. When the lockingknob582 is, thereafter, rotated between the neutral N, advancement A, and deployment D positions, theclasp sleeve614 rotates to actuate the spring lock (seeFIGS. 48 and 52).
• Asetscrew586, shown inFIG. 53, engages agroove605 in theproximal clasp assembly604 to connect theproximal clasp assembly604 to theclasp sleeve614 but allows theclasp sleeve614 to rotate around theclasp body602. Theclasp sleeve614 is shown inFIGS. 50 and53 and, in particular, inFIGS. 59 to 62. Theproximal clasp assembly604 ofFIG. 53 is more clearly shown in the exploded view ofFIG. 52. Theproximal clasp assembly604 is made of the components including aproximal spring606, a lockingwasher608, a fastener603 (in particular, a screw fitting into internal threads of the proximal clasp body602), and aproximal clasp body602. Theproximal clasp body602 is shown, in particular, inFIGS. 54 through 58. Theproximal clasp assembly604 is connected fixedly to thehandle body674, preferably, with ascrew585 shown inFIG. 50 and hidden from view inFIG. 51 underknob582.
• Thehandle body674 has aposition pin592 for engaging in position openings at the distal end of the lockingknob582. Theposition pin592 can be a setscrew that only engages thehandle body674. When the lockingknob582 is pulled slightly proximally, therefore, the knob can be rotated clockwise or counter-clockwise to place thepin592 into the position openings corresponding to the advancement A, neutral N, and deployment D positions.
• As shown inFIG. 18, to begin deployment of the stent graft1, the user/physician grasps both thedistal handle672 and theproximal handle678 and slides theproximal handle678 towards thedistal handle672 in the direction indicated by arrow A. This movement, as shown inFIGS. 19 to 21, causes the flexibleinner sheath652, holding the compressed stent graft1 therein, to emerge progressively from inside theouter catheter660. Such a process allows the stent graft1, while constrained by theinner sheath652, to expand to a larger diameter as shown inFIG. 12, this diameter being substantially larger than the inner diameter of theouter catheter660 but smaller than the inner diameter of the vessel in which it is to be inserted. Preferably, theouter catheter660 is made of a polymer (co-extrusions or teflons) and theinner sheath652 is made of a material, such as a fabric/woven polymer or other similar material. Therefore, theinner sheath652 is substantially more flexible than theouter catheter660.
• It is noted, at this point, that theinner sheath652 contains ataper653 at its proximal end, distal to the sheath's652 connection to the sheath lumen654 (at which theinner sheath652 has a similar diameter to thedistal sleeve644 working in conjunction with thedistal sleeve644 to capture thedistal end14 of the stent graft1. Thetaper653 provides a transition that substantially prevents any kinking of theouter catheter660 when the stent graft1 is loaded into the delivery assembly600 (as in the position illustrated inFIGS. 10 and 11) and, also, when theouter catheter660 is navigating through the femoral and iliac vessels. One specific embodiment of thesheath lumen654 has a length between approximately 35 and 37 inches, in particular, 36 inches, an outer diameter of between approximately 0.20 and 0.25 inches, in particular 0.238 inches, and an inner diameter between approximately, 0.18 and approximately 0.22 inches, in particular, 0.206 inches.
• When theproximal handle678 is moved towards its distal position, shown by the dashed lines inFIG. 11, thenose cone assembly630 and thesheath assembly650 move towards a second position where thesheath assembly650 is entirely out of theouter catheter660 as shown inFIGS. 20 and 21. As can be seen most particularly inFIGS. 20 and 21, as thenose cone assembly630 and thesheath assembly650 are emerging out of theouter catheter660, they are traversing thecurved portion710 of the descending aorta. The tracking is accomplished visually by viewing radiopaque markers on various portions of the delivery system and/or the stent graft1 with fluoroscopic measures. Such markers will be described in further detail below. The delivery system can be made visible, for example, by thenose cone630 being radiopaque or containing radiopaque materials.
• It is noted that if the harderouter catheter660 was to have been moved through thecurved portion710 of theaorta700, there is a great risk of puncturing theaorta700, and, particularly, adiseased portion744 of the proximal descendingaorta710 because theouter catheter660 is not as flexible as theinner sheath652. But, because theinner sheath652 is so flexible, thenose cone assembly630 and thesheath assembly650 can be extended easily into thecurved portion710 of theaorta700 with much less force on the handle than previously needed with prior art systems while, at the same time, imparting harmless forces to the intraluminal surface of thecurved aorta710 due to the flexibility of theinner sheath652.
• At the second position shown inFIG. 21, the user/physician, using fluoroscopic tracking of radiopaque markers (e.g., marker631) on any portion of the nose cone or on the stent graft1 and/orsheath assemblies630,650, for example, makes sure that theproximal end112 of the stent graft1 is in the correct longitudinal position proximal to thediseased portion744 of theaorta700. Because the entire insertedassembly630,650 in theaorta700 is still rotationally connected to the portion of thehandle assembly670 except distal handle672 (distal handle672 is connected with theouter sheath660 and rotates independently of the remainder of the handle assembly670), the physician can rotate the entire insertedassembly630,650 clockwise or counterclockwise (indicated inFIG. 21 by arrow B) merely by rotating theproximal handle678 in the desired direction. Such a feature is extremely advantageous because the non-rotation of theouter catheter660 while theinner sheath652 is rotating eliminates stress on the femoral and iliac arteries when the rotation of theinner sheath652 is needed and performed.
• Accordingly, the stent graft1 can be pre-aligned to place the stent graft1 in the correct circumferential position—defined by placing thelongitudinal support member40 substantially at the superior longitudinal surface line of the curved aorta with respect to anatomical position).FIG. 23 illustrates thelongitudinal support member40 not in the correct superior position andFIG. 24 illustrates thelongitudinal support member40 in the correct superior position. The superior surface position is, preferably, the longest superior longitudinal line along the circumference of the curved portion of the aorta as shown inFIGS. 23 and 24. As set forth above, when thelongitudinal support member40 extends along the superior longitudinal line of the curved aorta, thelongitudinal support member40 substantially eliminates any possibility of forming a kink in the inferior radial curve of the stent graft1 during use and also allows transmission of longitudinal forces exerted along the inside lumen of the stent graft1 to the entire longitudinal extent of the stent graft1, thereby allowing the entire outer surface of the stent graft1 to resist longitudinal migration.
• In prior art stent grafts and stent graft delivery systems, the stent graft is, typically, provided with symmetrically-shaped radiopaque markers along one longitudinal line and at least one other symmetrically-shaped radiopaque marker disposed along another longitudinal line on the opposite side (180 degrees) of the stent graft. Thus, using two-dimensional fluoroscopic techniques, the only way to determine if the stent graft is in the correct rotational position is by having the user/physician rotate the stent graft in both directions until it is determined that the first longitudinal line is superior and the other longitudinal line is anterior. This required more work by the physician and is, therefore, undesirable.
• According to a preferred embodiment of the invention illustrated inFIGS. 27 and 28, uniqueradiopaque markers232,234 are positioned on the stent graft1 to assist the user/physician in correctly positioning thelongitudinal support member40 in the correct aortic superior surface position with only one directional rotation that is also the minimal rotation needed to place the stent graft1 in the rotationally correct position.
• Specifically, the stent graft1 is provided with a pair of symmetrically shaped but diametricallyopposed markers232,234 indicating to the user/physician which direction the stent graft1 needs to be rotated to align thelongitudinal support member40 to the superior longitudinal line of the curved aorta (with respect to anatomical position). Preferably, themarkers232,234 are placed at theproximate end12 of thegraft sleeve10 on opposite sides (180 degrees) of thegraft sleeve10.
• The angular position of themarkers232,234 on thegraft sleeve10 is determined by the position of thelongitudinal support member40. In a preferred embodiment, thesupport member40 is between the twomarkers232,234. To explain such a position, if themarker232 is at a 0 degree position on thegraft sleeve10 and themarker234 is at a 180 degree position, then thecenterline45 of thesupport member40 is at a 90 degree position. However, an alternative position of the markers can place themarker234 90 degrees away from the first degree41 (seeFIG. 1). Such a positioning is dependent somewhat upon the way in which the implantation is to be viewed by the user/physician and can be varied based on other factors. Thus, the position can be rotated in any beneficial way.
• Preferred ancillary equipment in endovascular placement of the stent graft1 is a fluoroscope with a high-resolution image intensifier mounted on a freely angled C-arm. The C-arm can be portable, ceiling, or pedestal mounted. It is important that the C-arm have a complete range of motion to achieve AP to lateral projections without moving the patient or contaminating the sterile field. Capabilities of the C-arm should include: Digital Subtraction Angiography, High-resolution Angiography, and Roadmapping.
• For introduction of the delivery system into the groin access arteries, the patient is, first, placed in a sterile field in a supine position. To determine the exact target area for placement of the stent graft1, the C-arm is rotated to project the patient image into a left anterior oblique projection, which opens the radial curve of the thoracic aortic arch for optimal visualization without superimposition of structures. The degree of patient rotation will vary, but is usually 40 to 50 degrees. At this point, the C-arm is placed over the patient with the central ray of the fluoroscopic beam exactly perpendicular to the target area. Such placement allows for themarkers232,234 to be positioned for correct placement of the stent graft1. Failure to have the central ray of the fluoroscopic beam perpendicular to the target area can result in parallax, leading to visual distortion to the patient anatomy due to the divergence of the fluoroscopic x-ray beam, with a resultant misplacement of the stent graft1. An angiogram is performed and the proposed stent graft landing zones are marked on the visual monitor. Once marked, neither the patient, the patient table, nor the fluoroscopic C-arm can be moved, otherwise, the reference markers become invalid. The stent graft1 is; then, placed at the marked landing zones.
• In a preferred embodiment, themarkers232,234 are hemispherical, in other words, they have the approximate shape of a “D”. This shape is chosen because it provides special, easy-to-read indicators that instantly direct the user/physician to the correct placement position for thelongitudinal support member40.FIG. 27, for example, illustrates a plan view of themarkers232,234 when they are placed in the upper-most superior longitudinal line of the curved aorta, The correct position is indicated clearly because the two hemispheres have the flat diameters aligned on top of or immediately adjacent to one another such that a substantially complete circle is formed by the two hemispherically rounded portions of themarkers232,234. This position is also indicated in the perspective view ofFIG. 28.
• Each ofFIGS. 27 and 28 have been provided with examples where themarkers232,234 are not aligned and, therefore, the stent graft1 is not in the correct insertion position. For example, inFIG. 27, twomarkers232′,234′ indicate a misaligned counter-clockwise-rotated stent graft1 when viewed from theplane236 at the right end of the stent graft1 ofFIG. 23 looking toward the left end thereof and down theaxis11. Thus, to align themarkers232′,234′ in the most efficient way possible (the shortest rotation), the user/physician sees that the distance between the two flat diameters is closer than the distance between the highest points of the hemispherical curves. Therefore, it is known that the two flat diameters must be joined together by rotating the stent graft1 clockwise.
• FIG. 28 has also been provided with twomarkers232″,234″ indicating a misaligned clockwise-rotated stent graft1 when viewed from theplane236 at the right end of the stent graft1 ofFIG. 27 looking toward the left end thereof and down theaxis11. Thus, to align themarkers232″,234″ in the most efficient way possible (the shortest rotation), the user/physician sees that the distance between the highest points of the hemispherical curves is smaller than the distance between the two flat diameters. Therefore, it is known that the two flat diameters must be joined together by rotating the stent graft1 in the direction that the highest points of the hemispherical curves point; in other words, the stent graft1 must be rotated counter-clockwise.
• A significant advantage provided by the diametrically opposedsymmetric markers232,234 is that they can be used for migration diagnosis throughout the remaining life of a patient after the stent graft1 has been placed inside the patient's body. If fluoroscopic or radiographic techniques are used any time after the stent graft1 is inserted in the patient's body, and if the stent graft1 is viewed, from the same angle as it was viewed when placed therein, then the markers'232,234 relative positions observed should give the examining individual a very clear and instantaneous determination as to whether or not the stent graft1 has migrated in a rotational manner.
• The hemispherical shape of themarkers232,234 are only provided as an example shape. Themarkers232,234 can be any shape that allows a user/physician to distinguish alignment and direction of rotation for alignment. For example, themarkers232,234 can be triangular, in particular, an isosceles triangle having the single side be visibly longer or shorter than the two equal sides.
• When the stent graft1 is in place both longitudinally and circumferentially (FIG. 21), the stent graft1 is ready to be removed from theinner sheath652 and implanted in thevessel700. Because relative movement of the stent graft1 with respect to the vessel is no longer desired, theinner sheath652 needs to be retracted while the stent graft1 remains in place, i.e., no longitudinal or circumferential movement. Such immovability of the stent graft1 is insured by, first, theapex capture device634 of thenose cone assembly630 holding the front of the stent graft1 by its bare stent30 (seeFIGS. 13,22, and23) and, second, by unlocking thelocking ring676/placing the locking ring/knob in the D position—which allows thesheath lumen654 to move independently from theguidewire lumen620,apex release lumen640, andgraft push lumen642. Theapex capture device634, as shown inFIGS. 13,14,30 and311 (and as will be described in more detail below), is holding each individualdistal apex32 of thebare stent30 in a secure manner—both rotationally and longitudinally.
• Thenose cone assembly630, along with theapex capture device634, is securely attached to the guidewire lumen620 (and theapex release lumen640 at least until apex release occurs). Theinner sheath652 is securely attached to asheath lumen654, which is coaxially disposed around theguidewire lumen620 and fixedly attached to theproximal handle678. The stent graft1 is also supported at its distal end by thegraft push lumen642 and thedistal sleeve644 or thetaper653 of theinner sheath652, (The entire coaxial relationship of thevarious lumen610,620,640,642,654, and660 is illustrated for exemplary purposes only inFIG. 25, and a portion of which can also be seen in the exploded view of the handle assembly inFIG. 50) Therefore, when theproximal handle678 is moved proximally with thelocking ring676 in the deployment position D, thesheath lumen654 moves proximally as shown inFIGS. 13,22, and23, taking thesheath652 proximally along with it while theguidewire lumen620, theapex release lumen640, thegraft push lumen642, and thedistal sleeve644 remain substantially motionless and, therefore, the stent graft1 remains both rotationally and longitudinally steady.
• The stent graft1 is, now, ready to be finally affixed to theaorta700. To perform the implantation, thebare stent30 must be released from theapex capture device634. As will be described in more detail below, theapex capture device634 shown inFIGS. 13,14, and29 to32, holds theproximal apices32 of thebare stent30 between thedistal apex head636 and the proximalapex body638. Thedistal apex head636 is fixedly connected to theguidewire lumen620. The proximalapex body638, however, is fixedly connected to theapex release lumen640, which is coaxial with both theguidewire lumen620 and thesheath lumen654 and disposed therebetween, as illustrated diagrammatically inFIG. 25. (As will be described in more detail below, thegraft push lumen642 is also fixedly connected to theapex release lumen640.) Therefore, relative movement of theapex release lumen640 and theguidewire lumen620 separates thedistal apex head636 and a proximalapex body638 from one another.
• To cause such relative movement, theapex release assembly690 has, in a preferred embodiment, three parts, adistal release part692, aproximal release part694, and an intermediate part696 (which is shown in the form of a clip inFIGS. 16 and 26). To insure that thedistal apex head636 and the proximalapex body638 always remain fixed with respect to one another until thebare stent30 is ready to be released, theproximal release part694 is formed with adistal surface695, thedistal release part692 is formed with aproximal surface693, and theintermediate part696 has proximal and distal surfaces corresponding to thesurfaces695,693 such that, when theintermediate part696 is inserted removably between thedistal surface695 and theproximal surface693, theintermediate part696 fastens thedistal release part692 and theproximal release part694 with respect to one another in a form-locking connection. A form-locking connection is one that connects two elements together due to the shape of the elements themselves, as opposed to a force-locking connection, which locks the elements together by force external to the elements. Specifically, as shown inFIG. 26, theclip696 surrounds adistal plunger699 of theproximal release part694 that is inserted slidably within a hollow698 of thedistal release part692. Theplunger699 of theproximal release part694 can slide within the hollow698, but astop697 inside the hollow698 prevents thedistal plunger699 from withdrawing from the hollow698 more than the longitudinal span of theclip696.
• To allow relative movement between thedistal apex head636 and the proximalapex body638, theintermediate part696 is removed easily with one hand and, as shown from the position inFIG. 16 to the position inFIG. 17, thedistal release part692 and theproximal release part694 are moved axially towards one another (preferably, the former is moved towards the latter). Such movement separates thedistal apex head636 and the proximalapex body638 as shown inFIG. 14. Accordingly, thedistal apices32 of thebare stent30 are free to expand to their natural position in which thebare stent30 is released against thevessel700.
• Of course, theapex release assembly690 can be formed with any kind of connector that moves theapex release lumen640 and theguidewire lumen620 relative to one another. In a preferred alternative embodiment, for example, theintermediate part696 can be a selectable lever that is fixedly connected to either one of thedistal release part692 or theproximal release part694 and has a length equal to the width of theclip696 shown inFIG. 26. Thus, when engaged by pivoting the lever between thedistal release part692 and theproximal release part694, for example, theparts692,694 cannot move with respect to one another and, when disengaged by pivoting the lever out from between theparts692,694, thedistal release part692 and theproximal release part694 are free to move towards one another.
• The apex clasp device is unique to the present invention in that it incorporates features that allow the longitudinal forces subjected on the stent graft1 to be fully supported, through thebare stent30, by both theguidewire lumen620 andapex release lumen640. Support occurs by providing thedistal apex head636 with adistal surface639 supporting theproximal apices32 of thebare stent30, which is particularly shown in the enlarged perspective view of thedistal apex head636 provided inFIG. 29. Thedistal surface639, in turn, rests on the proximalapex body638 when in the closed position, as more clearly shown inFIGS. 30 and 31. Thus, the longitudinal forces are fully transmitted to both theguidewire lumen620 andapex release lumen640, making the assembly much stronger.
• Having thedistal surface639 be the load-bearing surface of theproximal apices32 ensures expansion of the each one of thedistal apices32 from theapex release assembly690. Theproximal surface641 of thedistal apex head636 meets with the interior surfaces of the proximalapex body638 to help carry the apex load because the apices of thebare stent30 are captured therebetween when theapex capture device634 is closed. Such capture can be clearly seen in the cut-away view of the proximalapex body638 inFIG. 31. For release of theapices32 of thebare stent30, the proximalapex body638 moves to the left (with respect toFIG. 32). Because of friction occurring between theapices32 and the “teeth” of the proximalapex body638 when theapices32 are captured, theapices32 will also try to move to the left along with the proximalapex body638 and, if allowed to do so, possibly would never clear the “teeth” to allow each apex32 to expand. However, as the proximalapex body638 disengages (moves in the direction of arrow C inFIG. 31), direct contact with thedistal surface639 entirely prevents theapices32 from sliding in the direction of arrow C along with the proximalapex body638 to ensure automatic release of every capturedapex32 of thebare stent30. Because the proximalapex body638 continues to move to the left, eventually the “teeth” will clear their respective capture of theapices32 and thebare stent30 will, therefore, expand entirely. The release position of thedistal apex head636 and the proximalapex body638 is shown inFIG. 32, and corresponds to the position of theapex release assembly690 inFIG. 17. As can be seen, tapers on the distal outer surfaces of the proximalapex body638 further assist in the prevention of catching theproximal apices32 of thebare stent30 on any part of theapex capture device634.
• Simply put, theapex capture device634 provides support for load placed on the stent graft1 during advancement A of theinner sheath652 and during withdrawal of the inner sheath652 (i.e., during deployment D). Such a configuration benefits the apposition of thebare stent30 by releasing thebare stent30 after theentire graft sleeve10 has been deployed, thus reducing the potential for vessel perforation at the point of initial deployment.
• When the stent graft1 is entirely free from theinner sheath652 as shown inFIG. 23, theproximal handle678 is, then, substantially at or near the third position (deployment position) shown inFIG. 10.
• The stent graft1 is, now, securely placed within the vessel and theentire portion630,650,660 of theassembly600 may be removed from the patient.
• While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions, and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (26)

1.-22. (canceled)

23. An elastic compressible stent having a plurality of proximal and distal apices joined by struts that are essentially straight.

24. The stent ofclaim 23, wherein the stent has a polygonal cross-sectional shape.

25. The stent ofclaim 24, wherein the polygonal cross-sectional shape is a dodecahedron shape.

26. The stent ofclaim 23, wherein the stent includes at least five, six, seven or eight proximal apices and at least five, six, seven or eight distal apices.

27. The stent of claim1, wherein the stent will be in essentially co-columnar apposition with a blood vessel in which the stent is implanted.

28. The stent ofclaim 23, wherein the stent has a multiple-sided outer surface.

29. The stent ofclaim 28, wherein the stent will be in essentially co-columnar apposition with a blood vessel in which the stent is implanted.

30. The stent of claim1, further including graft material, wherein the graft material is attached to the stent.

31. An elastic compressible stent having a plurality of proximal and distal apices joined by struts are essentially straight, made by a method, comprising the steps of:

a) winding stent wire around an outer surface of a longitudinal axis of a polygonal cross-sectional shaped mandrel into a desired final shape that is polygonal in an elevation orthogonal to the longitudinal axis; and

forming a stent by setting the wound stent wire in the desired polygonal final shape.

32. The stent ofclaim 31, wherein the stent will be in essentially co-columnar apposition with a blood vessel in which the stent is implanted.

33. The stent ofclaim 31, wherein the mandrel further includes flat sections and rounded edge portions between the flat sections.

34. The stent ofclaim 31, wherein the method further includes the step of forming Z-stent apices by winding the stent wire around pins on the outer surface of the mandrel longitudinally offset from one another and corresponding to desired Z-stent apex locations.

35. The stent ofclaim 34, wherein the stent is a Z-stent that includes at least five, six, seven or eight proximal apices and at least five, six, seven or eight distal apices.

36. The stent ofclaim 31, wherein the mandrel has a dodecahedron shape.

37. The stent ofclaim 31, wherein the method further includes the step of fastening two ends of the stent wire to one another to complete the stent.

38. The stent ofclaim 31, wherein the stent wire is initially wound around the outer surface of the longitudinal axis of the mandrel as a cold-drawn shape-memory wire and formed by heat-treatment.

39. The stent ofclaim 38, wherein the heat-treatment includes exposing the shape-memory wire to a heat-setting temperature for a period of time with subsequent quenching as required to shape set the shape-memory wire to the then-existing shape of the wire on the mandrel and obtain superelastic mechanical characteristics of the shape-memory wire.

40. The stent ofclaim 31, wherein the stent wire is exposed to at least one of the group consisting of a mechanical process, a thermal process and a chemical process that shapes the wire to desired final shape on the mandrel.

41. An elastic compressible stent having a plurality of proximal and distal apices joined by struts that are essentially straight, made by a method comprising the steps of:

a) winding a stent wire around an outer surface of a longitudinal axis of a mandrel having a multiple-sided outer surface into a desired final shape substantially corresponding to a shape of the outer surface; and

b) forming a stent by setting the wound stent wire into the desired final shape.

42. The stent ofclaim 41, wherein the mandrel includes flat sections and rounded edge portions between the flat sections and the stent is formed by setting the stent wire to have rounded edges corresponding to the rounded edge portions of the mandrel and with flat sides corresponding to the flat sections of the mandrel.

43. The stent ofclaim 41, wherein the method further includes the steps of:

c) placing pins on the outer surface of the mandrel protruding perpendicularly therefrom and being longitudinally offset from one another to correspond with desired Z-stent apex locations; and

d) forming Z-stent apices of the stent by winding the stent wire around the pins.

44. The stent ofclaim 43, wherein the pins are placed on each of the rounded edge portions of the mandrel.

45. The stent ofclaim 41, wherein the method further includes the step of fastening two ends of the stent wire to one another to complete the stent.

46. The stent ofclaim 41, wherein the stent wire is initially wound around the outer surface of the longitudinal axis of the mandrel as a cold-drawn shape-memory wire and the stent is formed by heat-treatment.

47. The stent ofclaim 41, wherein the stent is formed by exposing the stent wire to at least one of the group consisting of a mechanical process, a thermal process, and a chemical process that shapes the wire to the desired final shape on the mandrel.

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