Bifurcated stent graft, stent, and method

Abstract

To provide a bifurcated stent graft.SOLUTION: A stent includes a first wire and a second wire. The first wire is helically wound along an axis of a main body portion of the stent and along an axis of a first branch portion of the stent. The second wire is helically wound along the axis of the main body portion of the stent and along an axis of a second branch portion of the stent. The first wire and the second wire are encapsulated in a graft member. A method for making a stent includes a step for winding a first wire helically along a main body portion of a bifurcated mandrel and a first leg portion of the bifurcated mandrel. The method further includes a step for winding a second wire helically along the main body portion of the bifurcated mandrel and a second leg portion of the bifurcated mandrel. The first and second wires can be laminated within a graft material.SELECTED DRAWING: Figure 3A

Description

Technical Field

[0001] One or more exemplary embodiments of the present disclosure (the present invention) relate to stents, stent grafts, and methods of manufacturing such stents and stent grafts, and in certain embodiments, to stents, stent grafts, and methods of manufacturing such stents and stent grafts for treating aortoiliac occlusive disease (AIOD).

[0002] [Description of Related Applications] This application is a claim for priority of U.S. Provisional Patent Application No. 62 / 750,667, filed on October 25, 2018, which is hereby incorporated by reference in its entirety and made a part of this specification.

Background Art

[0003] Aortoiliac occlusive disease (AIOD) is an occlusion of the abdominal aorta as it transitions into the common iliac arteries. This occlusion is typically caused by the deposition or accumulation of plaque within the aortic vessel wall. For example, FIG. 1 is a cross-sectional view of an exemplary anatomical structure of the abdominal aorta 10 where the center of aortoiliac occlusive disease is located at the aortic bifurcation 11. In FIG. 1, the aorta 10 bifurcates into two iliac arteries 12, 13 at the aortic bifurcation 11. Often, plaque 18 accumulates on the aortic bifurcation 11 and within the iliac arteries 12, 13 and on the inner wall of the aorta 10 below the renal arteries 15, 16. As a result of the plaque 18, the diameter of the flow lumen in the iliac arteries 12, 13 is reduced, thereby restricting blood flow to the patient's legs and the organs within the pelvis.

[0004] The treatment of AIOD generally includes open surgical repair or endovascular repair. Open surgical repair often has a very high success rate in patients who are otherwise quite healthy and have no major co-morbidities. However, such open surgical procedures are problematic because it is difficult to access the abdominal aorta and the aorta has to be clamped, thereby imposing a significant burden on the patient's heart. On the other hand, successful endovascular procedures have a much shorter recovery period than open surgical procedures.

[0005] Regarding endoluminal techniques, generally two treatment modalities are used to treat AIOD, and such two treatment modalities include kissing stents and covered endovascular reconstruction. A kissing stent is a technique in which two stents are attached at the aortic bifurcation, and these two stents cross (or kiss (touch)) each other above the aortic bifurcation. Similarly, covered endovascular reconstruction is a technique in which a stent graft body is implanted into the aorta above the aortic bifurcation, and separate stent graft branches for each iliac artery are implanted to cross each other within the stent graft body above the aortic bifurcation. However, both of these treatment modalities require a number of separate stent grafts used to reproduce the bifurcation above the diseased aortic bifurcation, and thus are troubled by areas where potential leaks occur because the separate stent grafts are sutured or joined together in different ways. This is commonly referred to as "radial mismatch", which may result in thrombus formation and neointimal hyperplasia. In addition, both of these treatment modalities can result in a flow divider that may have an adverse effect on patency. Furthermore, these stents are typically larger than the occlusive vascular lumen diameter and expand within the blood vessel so that the blood vessel remains patent and dilated, and as a result, accidental fractures may occur. If a blood vessel fracture occurs in combination with a leak channel, complications may occur in the patient. Additionally, the technical success of these techniques can also be difficult because stent occlusion may occur due to the placement (or offset) and competition of instruments between stents with respect to the endoluminal space.

[0006] In recent years, off-label use of bifurcated stent grafts designed for the treatment of abdominal aortic aneurysms (AAA) has been used during experimental treatment for some cases of AIOD. For example, the AFX® endovascular AAA system manufactured by Endologix is a single-unit type bifurcated stent graft designed to treat AAA, but has been used to treat some cases of AIOD. However, off-label use of bifurcated AAA implant devices can present difficulties during the treatment of AIOD. For example, aneurysm stents are assembled to have a reduced radial strength so that excessive force is not applied to diseased tissue. In the case of occlusive diseases, typically, a large force is desired. Due to this discrepancy, as a result of off-label use of AAA devices, the radial force is insufficient, and additional ballooning (inflating) or stent reinforcement may be required to maintain patency. Also, such graft materials and stents of AAA devices are not attached throughout the length of the device (e.g., they are attached only at the ends), and often, such AAA devices are not formed in sizes corresponding thereto (e.g., they are too long and / or too large in diameter for many patients). Thus, once an AAA device is placed within a narrow anatomical structure, e.g., an occluded anatomical structure, it may be difficult to return the device through the stent without becoming entangled within the stent. SUMMARY OF THE INVENTION

[0007] A stent according to one embodiment has a first wire and a second wire. The first wire is helically wound along the axis of the body portion of the stent and along the axis of the first branch portion of the stent. The second wire is helically wound along the axis of the body portion of the stent and along the axis of the second branch portion of the stent. In various embodiments, the body portion of the stent is tubular, the first branch portion of the stent is tubular, and the second branch portion of the stent is tubular. The body portion of the stent branches into a first branch portion and a second branch portion at the branch portion of the stent.

[0008] In various embodiments, the windings of the second wire along the body portion of the stent are positioned alternately with the windings of the first wire along the body portion of the stent. In some embodiments, the first wire and the second wire are enclosed within the graft member along the body portion, the first wire is enclosed within the graft member along the first side branch portion, and the second wire is enclosed within the graft member along the second side branch portion. Also, in some embodiments, the windings of the first wire are present only along the body portion and the first side branch portion of the stent, and the windings of the second wire are present only along the body portion and the second side branch portion of the stent.

[0009] In various embodiments, the first wire is a wire with undulations, and the second wire is a wire with undulations. In some embodiments, the undulations of the first wire have a first side and a second side that merge at the peak, and the length of the first side is shorter than the length of the second side. In some embodiments, in various embodiments, the undulations of the first wire have a first side and a second side that merge at the peak, and the length of the first side is equal to the length of the second side.

[0010] In various embodiments, the first wire is in contact with the second wire at two contact regions. In other embodiments, the first wire is not in contact with the second wire. In some embodiments, the first wire is welded to the second wire at the contact region. In some embodiments, the first wire is crimped to the second wire at the contact region. In various embodiments, the first distance between adjacent windings of the first wire along the body portion of the stent is longer than the second distance between adjacent windings of the first wire along the first side branch portion of the stent.

[0011] A stent graft according to one embodiment has one or more stent members for the body portion of the stent graft, one or more stent members for the first side branch portion of the stent graft, and one or more stent members for the second side branch portion of the stent graft. The stent graft is a single unit and further has a graft member that holds one or more stent members for the body portion of the stent graft, one or more stent members for the first side branch portion of the stent graft, and one or more stent members for the second side branch portion of the stent graft. The graft member bifurcates at the branch portion of the stent graft to provide the first side branch portion and the second side branch portion. In various embodiments, one or more stent members for the body portion of the stent graft, one or more stent members for the first side branch portion of the stent graft, and one or more stent members for the second side branch portion of the stent graft are laminated within the graft member.

[0012] A method according to one embodiment includes the steps of helically winding a first wire of a stent along the body portion of a bifurcated mandrel and along the first leg portion of the bifurcated mandrel, and helically winding a second wire of the stent along the body portion of the bifurcated mandrel and along the second leg portion of the bifurcated mandrel. In various embodiments, the method further includes the step of laminating the first wire and the second wire within a graft material. In some embodiments, the first wire is a wire with undulations, and the second wire is a wire with undulations. Also, in some embodiments, the undulations of the first wire have a first side and a second side that merge at the peak, and the length of the first side is shorter than the length of the second side.

Brief Description of the Drawings

[0013]

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[0014] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, like symbols typically represent like items unless otherwise specified. The exemplary embodiments described in the detailed description and the drawings are not meant to limit the present invention. Other embodiments can be utilized and other changes can be made without departing from the spirit or scope of the present invention as presented herein. As will be readily understood, the various aspects of the present invention generally described and illustrated herein can be arranged, substituted, combined, and designed in a wide variety of forms, and all such forms are clearly contemplated and form a part of the present invention. One aspect described in relation to a particular embodiment is not necessarily limited to such embodiment and can be embodied in any other embodiment or configuration.

[0015] One or more aspects of the exemplary embodiments relate to a single-unit bifurcated stent graft and a method of manufacturing this stent graft. In various embodiments, the single-unit bifurcated stent graft has a body, a first side branch, and a second side branch, and the single-unit bifurcated stent graft is encapsulated or laminated within a graft member such that each of the first and second side branches is integrally encapsulated or laminated together with the body. Thus, according to various embodiments, compared to other endoluminal implant systems in which multiple stent grafts are sutured together or joined in a different manner to form a bifurcated portion, the potentially leaking regions at the bifurcated portion of the stent graft can be reduced or eliminated.

[0016] Figure 2 shows a stent graft 200 according to an exemplary embodiment. In some embodiments, the stent graft 200 is a bifurcated stent graft having a first side branch portion 205 (or first leg) and a second side branch portion 210 (or second leg). The stent graft 200 has a graft member 215 and stent members 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 220i, 220j, 220k, 220l, 220m, 220n, 220o, 220p, 220q, 220r, 220s, 220t, 220u. In some embodiments, the stent members 220a, 220c, 220e, 220g, 220i, 220p, 220q, 220r, 220s, 220t, 220u are connected to each other via a single first stent, and the stent members 220b, 220d, 220f, 220h, 220j, 220k, 220l, 220m, 220n, 220o are connected to each other via a single second stent. In other embodiments, the stent members 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 220i are connected to each other via a single first stent, the stent members 220j, 220k, 220l, 220m, 220n, 220o are connected to each other via a single second stent, and the stent members 220p, 220q, 220r, 220s, 220t, 220u are connected to each other via a single third stent. In yet another embodiment, each of the stent members 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 220i, 220j, 220k, 220l, 220m, 220n, 220o, 220p, 220q, 220r, 220s, 220t, 220u is separated from each other (e.g., separate circular rings).

[0017] In some embodiments, each of the stent members 220a, 220c, 220e, 220g, 220i, 220p, 220q, 220r, 220s, 220t, 220u is made of a first wire helically wound along an axis in an open tubular form, and each of the stent members 220b, 220d, 220f, 220h, 220j, 220k, 220l, 220m, 220n, 220o is made of a second wire helically wound along an axis in an open tubular form. In some embodiments, the helically wound wire may be a corrugated wire having a zigzag with peaks and valleys. For example, the stent member 220c is shown as having a plurality of peaks 221 facing towards the proximal end 250 of the stent graft 200 and a plurality of valleys 222 facing towards the distal end 260 of the stent graft 200. In various embodiments, each of the stent members 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 220i, 220j, 220k, 220l, 220m, 220n, 220o, 220p, 220q, 220r, 220s, 220t, 220u forms a crown with a plurality of peaks and valleys.

[0018] In various embodiments, each of the wires forming the stent members 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 220i, 220j, 220k, 220l, 220m, 220n, 220o, 220p, 220q, 220r, 220s, 220t, 220u may be made of, for example, a nickel-titanium alloy (NiTi), such as Nitinol, stainless steel, or any other suitable material, and examples of such any other suitable material include, but are not limited to, cobalt-based alloys, such as Elgiloy, platinum, gold, titanium, tantalum, niobium, and / or combinations thereof. In some embodiments, each of the stent members 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 220i, 220j, 220k, 220l, 220m, 220n, 220o, 220p, 220q, 220r, 220s, 220t, 220u may be balloon-expandable or self-expandable. The exemplary embodiment of FIG. 2 shows a specific number of stent members, but it should be understood that in various embodiments, any suitable number of stent members may be used.

[0019] In some embodiments, the stent members 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 220i, 220j, 220k, 220l, 220m, 220n, 220o, 220p, 220q, 220r, 220s, 220t, 220u are attached to or laminated within the graft member 215. In some embodiments, the graft member 215 extends from the proximal end 250 to the distal end 260 (e.g., the ends of the first side branch portion 205 and the second side branch portion 210). In some other embodiments, the graft member 215 does not cover the entire length of the stent graft 200, and for example, the proximal end 250, the distal end 260, or both may be left uncovered. In some embodiments, the stent members 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 220i, 220j, 220k, 220l, 220m, 220n, 220o, 220p, 220q, 220r, 220s, 220t, 220u are all laminated or fused within the graft member 215, thereby forming a single unit bifurcated stent graft 200, in which the first and second side branch portions 205, 210 are integrally encapsulated by the graft member 215 at the body portion 270 of the stent graft 200. In this case, the risk of leakage at the bifurcated portion 275 of the stent graft 200 can be reduced or eliminated, which may occur when multiple stent grafts are sutured or joined together in different ways.

[0020] In various embodiments, the graft member 215 comprises a graft material made of one or more polymers or other suitable materials. In some embodiments, the graft member 215 is made of polytetrafluoroethylene (PTFE). In some embodiments, the graft member 215 is made of expanded polytetrafluoroethylene (ePTFE). In still some other embodiments, the stent graft 200 may have at least one additional polymer layer, such as a drug eluting layer, that elutes a bioactive agent from the stent graft 200 after implantation. However, the present invention is not limited thereto, and the graft member 215 may comprise or be made of any suitable graft material.

[0021] FIG. 3A is a perspective view of a stent according to an exemplary embodiment, and FIG. 3B is an enlarged view of portion A of the stent shown in FIG. 3A. Referring to FIGS. 3A and 3B, the stent 320 has a first wire 302 and a second wire 304. In some embodiments, each of the first and second wires 302, 304 is a wavy wire. The first wire 302 is spirally wound downward along the axis of the stent 320 and through a first side branch (or leg) portion 305 in an open tubular form to form first stent members 302a, 302b, 302c, 302d, 302e, 302f, 302g, 302h, 302i, 302j, 302k, 302l, 302m, 302n. The first stent members 302i, 302j, 302k, 302l, 302m, 302n formed by the first wire 302 form the stent of the first side branch portion 305. The second wire 304 is spirally wound downward along the axis of the stent 320 and through a second side branch (or leg) portion 310 in an open tubular form to form second stent members 304a, 304b, 304c, 304d, 304e, 304f, 304g, 304h, 304i, 304j, 304k, 304l, 304m, 304n. The second stent members 304i, 304j, 304k, 304l, 304m, 304n formed by the second wire 304 form the stent of the second side branch portion 310.

[0022] In some embodiments, the first and second wires 302, 304 are helically wound along the axis of the stent 320 such that the first stent members 302a, 302b, 302c, 302d, 302e, 302f, 302g, 302h alternate with the second stent members 304a, 304b, 304c, 304d, 304e, 304f, 304g, 304h along the axis of the stent 320. On the other hand, the first branch portion 305 has first stent members 302i, 302j, 302k, 302l, 302m, 302n wound along the axis of the first branch portion 305, and the second branch portion 310 has second stent members 304i, 304j, 304k, 304l, 304m, 304n wound along the axis of the second branch portion 310.

[0023] In some embodiments, the spacing between adjacent ones of the first stent members 302a, 302b, 302c, 302d, 302e, 302f, 302g, 302h is longer than the spacing between adjacent ones of the first stent members 302i, 302j, 302k, 302l, 302m, 302n forming the first branch portion 305, such that the second stent members 304a, 304b, 304c, 304d, 304e, 304f, 304g can be wound alternately between the first stent members 302a, 302b, 302c, 302d, 302e, 302f, 302g, 302h. Similarly, in some embodiments, the spacing between adjacent ones of the second stent members 304a, 304b, 304c, 304d, 304e, 304f, 304g, 304h is longer than the spacing between adjacent ones of the second stent members 304i, 304j, 304k, 304l, 304m, 304n forming the second branch portion 310, such that the first stent members 302a, 302b, 302c, 302d, 302e, 302f, 302g can be wound alternately between the second stent members 304a, 304b, 304c, 304d, 304e, 304f, 304g, 304h.

[0024] In some embodiments, the first wire 302 contacts the second wire 304 at only two or fewer contact locations. For example, as shown in FIG. 3B, the first wire 302 contacts the second wire 304 only at the first contact region 306 and the second contact region 308. In some embodiments, the first wire 302 does not contact (or is entirely separated from) the second wire 304 except at the two contact regions 306, 308. Similarly, in other embodiments, it should be understood that the first wire 302 may contact the second wire 304 at only one contact location. For example, in this case, the first wire 302 may be wound circularly to form the most proximal first stent member (e.g., 302a), and then helically wound thereafter to form the remaining first stent members. The second wire 304 may contact the first wire 302 at only one contact location at a portion of the most proximal first stent member, and then be helically wound therefrom to form second stent members that are alternately positioned with the first stent members. In various embodiments, the first wire 302 is connected to the second wire 304 at one or more contact regions (e.g., 306, 308) by welding, crimping, etc. In yet another example, the first wire 302 may be completely separated from (and not in contact with) the second wire 304.

[0025] Referring to FIGS. 3A and 3B, a stent 320 according to one embodiment has a first wire 302 and a second wire 304. The first wire 302 is helically wound along the axis of the body portion 330 of the stent 320 and along the axis of the first branch portion 305 of the stent 320. The second wire 304 is helically wound along the axis of the body portion 330 of the stent 320 and along the axis of the second branch portion 310 of the stent 320. In various embodiments, the body portion 330 of the stent 320 is tubular, the first branch portion 305 of the stent 320 is tubular, and the second branch portion 310 of the stent 320 is tubular. The body portion 330 of the stent 320 branches into the first branch portion 305 and the second branch portion 310 at the bifurcated portion 340 of the stent 320.

[0026] In various embodiments, the windings of the second wire 304 along the body portion 330 of the stent 320 are positioned alternately with the windings of the first wire 302 along the body portion 330 of the stent 320. FIG. 3C shows a graft member 350 of a stent graft according to one embodiment. Referring to FIGS. 3A, 3B, and 3C, in some embodiments, the first wire 302 and the second wire 304 are wrapped within the graft member 350 along the body portion 330, the first wire 302 is wrapped within the graft member 350 along the first branch portion 305, and the second wire 304 is wrapped within the graft member 350 along the second branch portion 310, thereby forming a stent graft. Also, in some embodiments, the windings of the first wire 302 exist only along the body portion 330 and the first branch portion 305 of the stent 320, and the windings of the second wire 304 exist only along the body portion 330 and the second branch portion 310 of the stent 320. In various embodiments, the graft member 350 is a single unit without suturing.

[0027] In various embodiments, the first wire 302 contacts the second wire 304 at two contact locations, such as the first contact location 306 and the second contact location 308. In other embodiments, the first wire 302 does not contact the second wire 304. In some embodiments, the first wire 302 is welded to the second wire 304 at a contact region, such as the first contact region 306. In some embodiments, the first wire 302 is crimped to the second wire 304 at a contact region. In various embodiments, a first distance between adjacent turns of the first wire 302 along the body portion 330 of the stent 320 is longer than a second distance between adjacent turns of the first wire 302 along the first side branch portion 305 of the stent 320.

[0028] Figures 4A and 4B illustrate a tooling apparatus used in the process of forming a stent of a stent graft according to an exemplary embodiment. First, referring to FIG. 4A, a first undulating wire 402 is helically wound around a bifurcated mandrel 400. The bifurcated mandrel 400 has a first leg portion 405, a second leg portion 410, and a body portion 415. In some embodiments, the bifurcated mandrel 400 has a plurality of pins 420 at the proximal end of the bifurcated mandrel 400 and at the distal ends of the first and second leg portions 405, 410 to hold the undulating wire in a desired array state. The first undulating wire 402 is helically wound along the length of the body portion 415 and along the first leg portion 405 of the bifurcated mandrel 400. In some embodiments, each turn (or first stent member) of the first undulating wire 402 along the body portion 415 is separated from an adjacent turn (or first stent member) by a first distance d1. In some embodiments, each turn (or first stent member) of the first undulating wire 402 along the first leg portion 405 is separated from an adjacent turn (or first stent member) by a second distance d2. In some embodiments, the first distance d1 is longer than the second distance d2, but the present invention is not limited thereto, and in other embodiments, d1 may be equal to d2, or rather, depending on considerations regarding the stiffness or flexibility of the stent graft body and / or side branches, d1 may be shorter than d2.

[0029] Referring to FIG. 4B, a second corrugated wire 404 is helically wound around the bifurcated mandrel 400 shown in FIG. 4A after arranging the first corrugated wire 402. As shown in FIG. 4B, the second corrugated wire 404 is helically wound along the body portion 415 of the bifurcated mandrel 400 between the first corrugated wire 402 at a second distance d1 and also helically wound along the second leg portion 410 of the bifurcated mandrel 400. In some embodiments, the winding of the second corrugated wire 404 (or the second stent member) is alternately positioned with the winding of the first corrugated wire 402 (or the first stent member) along the body portion 415 of the bifurcated mandrel 400. In some embodiments, each of the windings of the first corrugated wire 402 (or the first stent member) is separated from the adjacent winding of the second corrugated wire 404 (or the second stent member) on the body portion 415 by a third distance d3. In some embodiments, the distance d3 is greater than or equal to the distance d2, but the present invention is not limited thereto. In other embodiments, d3 may be shorter than d2 depending on considerations for the stiffness or flexibility of the stent graft body and / or the side branches.

[0030] In some embodiments, after arranging the first and second corrugated wires 402, 404, the assembly is annealed or heat treated in a different manner to define the arrangement state of the first and second corrugated wires 402, 404. In various embodiments, a stent formed on the body portion 415 by alternately positioned windings of the first and second corrugated wires 402, 404, and first and second side branches formed by windings of the first and second corrugated wires 402, 404 on the first and second leg portions 405, 410 of the bifurcated mandrel 400, respectively, are encapsulated with a graft material such that a single unit type bifurcated stent graft is formed (e.g., as shown in FIG. 2). The exemplary embodiments of FIGS. 4A and 4B show a specific number of windings (or stent members) of the first and second corrugated wires 402, 404, but it should be understood that in various embodiments, any suitable number of windings (or stent members) can be used.

[0031] FIGS. 5A, 5B, 6A, and 6B show various tooling devices having different branch shapes and angles according to various exemplary embodiments. More particularly, FIG. 5A is a partial front view of the bifurcated portion of a mandrel 500 including a first leg portion 505, a second leg portion 510, and a branch zone 515. Similarly, FIG. 6A is a partial front view of the bifurcated portion of a mandrel 600 including a first leg portion 605, a second leg portion 610, and a branch zone 615. FIG. 5B shows a side view 525, a bottom view 550, and a rear view 575 of the branch zone 515 shown in FIG. 5A, with the first and second leg portions 505, 510 omitted. Similarly, FIG. 5B shows a side view 625, a bottom view 650, and a rear view 675 of the branch zone 615 shown in FIG. 6A, with the first and second leg portions 605, 610 omitted.

[0032] Referring to FIGS. 5A and 6A, by varying the angle between the leg portions of the mandrel, the angle between the branch portions of the stent graft formed by using the mandrel can be adjusted. For example, the mandrel 500 in FIG. 5A has a first angle θ1 between a first leg portion 505 and a second leg portion 510. The mandrel 600 in FIG. 6A has a second angle θ2 between a first leg portion 605 and a second leg portion 610. Referring to FIGS. 5A and 6A, the first angle θ1 is smaller than the second angle θ2. In this case, the bifurcated stent graft formed using the mandrel 500 has an angle between a first branch portion and a second branch portion that is smaller than the angle formed between the first branch portion and the second branch portion of the bifurcated stent graft formed using the mandrel 600.

[0033] Referring to FIGS. 5A, 5B, 6A, and 6B, the shape and dimensions of the leg portions or the body portion of the mandrel can also be varied in various ways, thereby adjusting the shape and dimensions of the branch portions and the body portion of the bifurcated stent graft formed using the mandrel. For example, the mandrel 500 can have a shape that is more gently tapered between the body portion and the leg portions 505, 510 shown in the side view 525 and the rear view 575 as compared to the mandrel 600 shown in the side view 625 and the rear view 675. Further, the mandrel 600 can be more rounded in shape up to the branch portion transition of the body as shown in the bottom view 650 as compared to the mandrel 500 shown in the bottom view 550. Therefore, the shape and dimensions of the bifurcated stent grafts formed using the mandrels 500, 600 can be variously modified corresponding to the shape and dimensions of the mandrel used to form the bifurcated stent graft.

[0034] Figures 7A and 7B show various zigzag geometries of a corrugated wire used to form a stent according to various embodiments. In various embodiments, to helically wind a corrugated wire used to form a stent, it is advisable to adjust the length of the zigzag and / or the angle of the winding. For example, as shown in Figure 7A, one corrugation of the corrugated wire may have a first side 702 and a second side 704 that define a peak 703. In some embodiments, the length of the first side 702 may be shorter than the length of the second side 704. In this case, when the corrugated wire is helically wound, the resulting structure will gently elongate in the winding direction. Similarly, in some embodiments, the distance between the windings of the corrugated wire can be adjusted by the length of the sides of the corrugation.

[0035] On the other hand, in some embodiments, as shown in Figure 7B, one corrugation of the corrugated wire may have a first side 706 and a second side 708 that define a peak 707. In some embodiments, the length of the first side 706 may be equal to the length of the second side 708. In this case, when the corrugated wire is wound in a direction perpendicular to the axis of the stent graft body, the corrugated wire will be wound in a circular shape. On the other hand, when the corrugated wire is wound at an angle with respect to this perpendicular direction, the corrugated wire will elongate in the winding direction. Similarly, in some embodiments, the distance between the windings of the corrugated wire can be adjusted by the angle of the winding with respect to this perpendicular direction. Therefore, in various embodiments, the corrugated wire can be helically wound to form a stent by defining different lengths of the zigzags, by adjusting the angle with respect to the perpendicular direction, and / or by a combination of these.

[0036] Referring to FIGS. 3A and 7A, in various embodiments, the first wire 302 is a wire with undulations, and the second wire 304 is a wire with undulations. In some embodiments, the undulation portions of the first wire 302 have a first side portion 702 and a second side portion 704 that merge at the peak portion 703, and the length of the first side portion 702 is shorter than the length of the second side portion 704. Referring to FIGS. 3A and 7B, in some embodiments, the undulation portions of the first wire 302 have a first side portion 706 and a second side portion 708 that merge at the peak portion 707, and the length of the first side portion 706 is equal to the length of the second side portion 708.

[0037] FIG. 8 is a flowchart of a method of manufacturing a stent graft according to an exemplary embodiment. Referring to FIG. 8, method 800 begins, and in block 805, a bifurcated mandrel having a body portion, a first leg portion, and a second leg portion is provided. For example, in various embodiments, the bifurcated mandrel may be the same as or similar to any of the mandrels 400, 500, or 600 shown in FIGS. 4A, 5A, or 6A.

[0038] Referring to FIG. 8, in block 810, a first wire is helically wound along the length of the body portion and along the length of the first leg portion. In some embodiments, the first wire is a wire with undulations having peaks and valleys. In some embodiments, the spacing between adjacent windings of the first wire along the body portion is greater than the spacing between adjacent windings of the first wire along the first leg portion.

[0039] In block 815, the second wire is helically wound along the length of the body portion and along the length of the second leg portion. In some embodiments, the second wire is a corrugated wire having crests and troughs. In some embodiments, the spacing between adjacent windings of the second wire along the body portion is greater than the spacing between adjacent windings of the second wire along the second leg portion. In some embodiments, the windings of the second wire along the body portion are arranged alternately with the windings of the first wire along the body portion. In some embodiments, the spacing between adjacent first and second windings is equal to the spacing between adjacent windings of the first leg portion or the second leg portion. In other embodiments, the spacing between adjacent first and second windings is greater than the spacing between adjacent windings of the first leg portion or the second leg portion.

[0040] In some embodiments, the spacing between windings is adjustable based on the angle of the winding with respect to a direction perpendicular to the axis of the body portion, the first leg portion, or the second leg portion. In some embodiments, the spacing between windings can be adjusted based on the zigzag distance of the corrugated wire. In some embodiments, the spacing between windings can be adjusted based on a combination of the zigzag angle and length.

[0041] In block 820, the first and second corrugated wires including the windings on the body portion and the windings on the first and second leg portions are laminated or encapsulated within the graft material. In some embodiments, the graft material extends from the proximal end of the body portion to the distal ends of the first and second leg portions. In some embodiments, all of the windings of the first and second wires on the body portion and on the first and second leg portions are all laminated or fused within the graft material. Thus, in some embodiments, a single-unit bifurcated stent graft is formed, and in such a single-unit bifurcated stent graft, the side branches are integrally encapsulated with the body of the bifurcated stent graft by the graft material.

[0042] Figures 9 and 10 illustrate various examples of such bifurcated stent grafts in accordance with other exemplary embodiments. Referring to FIG. 9, in some embodiments, the bifurcated stent graft 900 includes a first stent 905, a second stent 910, and a third stent 915. The first stent 905 may form a stent for the stent graft body, the second stent 910 may form a stent for the first side branch (or leg), and the third stent 915 may form a stent for the second side branch (or leg). In some embodiments, the first stent 905 may be formed by a first corrugated wire spirally wound along the axis of the stent graft body, the second stent 910 may be formed by a second corrugated wire spirally wound along the axis of the first side branch, and the third stent 915 may be formed by a third corrugated wire spirally wound along the axis of the second side branch.

[0043] In some embodiments, each of the first, second, and third stents 905, 910, 915 may be laminated within, encapsulated by, or otherwise attached to the graft member 920. In some embodiments, the graft member 920 extends from the proximal end of the first stent 905 to the distal ends of the second and third stents 910, 915. In some other embodiments, the graft member 920 does not cover the entire length of the stent graft 900 and, for example, the proximal end, the distal end, or both may be left uncovered. In some embodiments, each of the first, second, and third stents 905, 910, 915 is laminated or fused entirely within the graft member 920, thereby forming a single unit bifurcated stent graft 900, and in such a single unit bifurcated stent graft, the side branch portions formed by the second and third stents 910, 915 are integrally encapsulated by the graft member 920 together with the body portion formed by the first stent 905. In this case, the risk of leakage at the bifurcated portion of the stent graft 900 can be reduced or eliminated, which may occur when multiple stent grafts are sutured or joined in some other way to form the bifurcated portion.

[0044] Referring to FIG. 10, in some embodiments, the bifurcated stent graft 1000 includes a first stent 1005, a second stent 1010, and a third stent 1015. The first stent 1005 may form a stent for the stent graft body, the second stent 1010 may form a stent for the first side branch (or leg), and the third stent 1015 may form a stent for the second side branch (or leg). In some embodiments, each of the first, second, and third stents 1005, 1010, 1015 may be formed by laser cutting of a tubular sheet (e.g., a nitinol tubular sheet). In various embodiments, the first, second, and third stents 1005, 1010, 1015 may be connected (or brought into contact) with each other or may be spaced apart from each other.

[0045] In some embodiments, each of the first, second, and third stents 1005, 1010, 1015 may be stacked, encapsulated, or otherwise attached within the graft member 1020. In some embodiments, the graft member 1020 extends from the proximal end of the first stent 1005 to the distal ends of the second and third stents 1010, 1015. In some other embodiments, the graft member 1020 does not cover the entire length of the stent graft 1000, and for example, the proximal end, the distal end, or both may be left uncovered. In some embodiments, each of the first, second, and third stents 1005, 1010, 1015 is stacked or fused entirely within the graft member 1020, thereby forming a single-unit bifurcated stent graft 1000, and in such a single-unit bifurcated stent graft, the side branch portions formed by the second and third stents 1010, 1015 are integrally encapsulated by the graft member 1020 together with the body portion formed by the first stent 1005. In this case, the risk of leakage at the bifurcated portion of the stent graft 1000 can be reduced or eliminated, and leakage may occur when multiple stent grafts are sutured or joined in other ways to form the bifurcated portion.

[0046] In the figures, the relative dimensions of elements, layers, and regions may be exaggerated and / or simplified for clarity. Relative terms concerning space, such as "below", "beneath", "downward", "under", "above", "upward", etc., may be used in this specification to facilitate the description of the relationship of one element or feature to another element or feature as illustrated. As is understood, these spatial relative terms include different orientations of the apparatus relative to each other in use or operation in addition to the orientation shown in the figures. For example, if the apparatus described in the drawings is turned upside down, an element described as "below", or "beneath", or "under" another element or other feature will in this case be directed "above" these other elements or features. Thus, the exemplary terms "below" and "under" may include both the "above" and "below" orientations. The apparatus can be oriented differently (e.g., rotated 90° or in other orientations), and the spatially relative descriptive terms used in this specification should be interpreted accordingly.

[0047] As is understood, terms such as "first", "second", "third", etc., may be used in this specification to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, one component, one region, one layer, or one section from another element, another component, another region, another layer, or another section. Thus, the first element, the first component, the first region, the first layer, or the first section described above may also be referred to as the second element, the second component, the second region, the second layer, or the second section without departing from the spirit and scope of the present invention.

[0048] As will be appreciated, when an element or layer is referred to as being "on", "connected to" or "coupled to" another element or another layer, this element or layer can be directly on, connected to or coupled to the other element or layer, or one or more intervening elements or layers may be present. Additionally, when an element or layer is referred to as being positioned "between" two elements or two layers, it will also be understood that such element or layer may be the sole element or layer between the two elements or two layers, or one or more intervening elements or layers may also be present.

[0049] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms "a" and "an" used herein include the plural unless the context clearly dictates otherwise. Further, as will be understood, when used in the original specification, the terms "comprises" (often translated as "has"), "comprising", "includes" (often translated as "includes"), "including", "has" (often translated as "comprises"), "have", "having" identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of", when preceding the elements listed in the original specification, modify the entire list of elements.

[0050] As used herein, the terms "substantially", "about", and similar terms are used from the perspective of approximation rather than degree, and are intended to take into account the inherent variations in measured or calculated values recognized by those skilled in the art. Further, the use of the term "may be" when describing embodiments of the present invention means "one or more embodiments of the present invention". The expressions "use", "use with", and "used" as used herein may be regarded as synonymous with "utilize", "utilize with", and "utilized", respectively. Also, the term "exemplary" is intended to mean an example or an illustrative example.

[0051] Unless otherwise specified, all terms (including technical and scientific terms) used herein shall have the same meaning as commonly understood by those skilled in the art related to the present invention. Further, as will be understood, terms, such as those defined in commonly used dictionaries, should be construed to have a meaning consistent with their meaning in the context of the relevant art and / or this specification, and should not be construed in an idealized or overly formal sense unless otherwise expressly stated herein.

[0052] The embodiments disclosed herein should be regarded as illustrative in all respects and should not be regarded as limiting the present invention. The present invention is not limited in any aspect to the above-described embodiments. Various modifications and changes can be made to such embodiments without departing from the spirit and scope of the present invention.

Claims

**Claim 1** A stent, comprising: a first wire helically wound along the axis of the body portion of the stent and along the axis of the first side branch portion of the stent; and a second wire helically wound along the axis of the body portion of the stent and along the axis of the second side branch portion of the stent. **Claim 2** The body portion of the stent is tubular; the first side branch portion of the stent is tubular; and the second side branch portion of the stent is tubular. The stent according to claim 1. **Claim 3** The body portion of the stent branches into the first side branch portion and the second side branch portion at the branching portion of the stent. The stent according to claim 1. **Claim 4** The windings of the second wire along the body portion of the first wire are alternately positioned with the windings of the stent along the body portion of the stent. The stent according to claim 1. **Claim 5** The first wire and the second wire are enclosed within a graft member along the body portion; the first wire is enclosed within the graft member along the first side branch portion; and the second wire is enclosed within the graft member along the second side branch portion. The stent according to claim 1. **Claim 6** The windings of the first wire exist only along the body portion and the first side branch portion of the stent, and the windings of the second wire exist only along the body portion and the second side branch portion of the stent. The stent according to claim 1. **Claim 7** The first wire is a wire with undulations; and the second wire is a wire with undulations. The stent according to claim 1. **Claim 8** The undulations of the first wire have a first side portion and a second side portion that merge at the peak, and the length of the first side portion is shorter than the length of the second side portion. The stent according to claim 7. **Claim 9** The undulations of the first wire have a first side portion and a second side portion that merge at the peak, and the length of the first side portion is equal to the length of the second side portion. The stent according to claim 7. **Claim 10** The first wire contacts the second wire at two contact regions. The stent according to claim 1. **Claim 11** The first wire does not contact the second wire. The stent according to claim 1.

12. The stent according to claim 1, wherein the first wire is welded to the second wire at the contact region.

13. The stent according to claim 1, wherein the first wire is crimped to the second wire at the contact region.

14. The stent according to claim 1, wherein a first distance between adjacent windings of the first wire along the body portion of the stent is longer than a second distance between adjacent windings of the first wire along the first side branch portion of the stent.

15. A stent graft, comprising: one or more stent members for the body portion of the stent graft; one or more stent members for the first side branch portion of the stent graft; one or more stent members for the second side branch portion of the stent graft; a graft member that is a single unit and holds the one or more stent members for the body portion of the stent graft, the one or more stent members for the first side branch portion of the stent graft, and the one or more stent members for the second side branch portion of the stent graft; The stent graft, wherein the graft member branches at a branching portion of the stent graft to provide the first side branch portion and the second side branch portion.

16. The stent graft according to claim 15, wherein the one or more stent members for the body portion of the stent graft, the one or more stent members for the first side branch portion of the stent graft, and the one or more stent members for the second side branch portion of the stent graft are laminated within the graft member.

17. A method, comprising: spirally winding a first wire of a stent along a body portion of a bifurcated mandrel and a first leg portion of the bifurcated mandrel; spirally winding a second wire of the stent along the body portion of the bifurcated mandrel and a second leg portion of the bifurcated mandrel.

18. The method according to claim 17, further comprising laminating the first wire and the second wire within a graft material.

19. The first wire is a wire with undulating waves. The method according to claim 17, wherein the second wire is a wire having undulations in a wave shape.

20. The undulation of the first wire has a first side portion and a second side portion that are joined together at the peak, The method according to claim 19, wherein the length of the first side portion is shorter than the length of the second side portion.

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