Bifurcated stent grafts, stents, and methods

Abstract

The stent has a first wire and a second wire. The first wire is helically wound along the axis of the main body portion of the stent and along the axis of the first side branch portion of the stent. The second wire is helically wound along the axis of the main body portion of the stent and along the axis of the second side branch portion of the stent. The first wire and the second wire are encased within a graft member. A method of fabricating the stent includes helically winding the first wire around the body portion of a bifurcated mandrel and the first leg portion of the bifurcated mandrel. The method includes helically winding the second wire around the body portion of the bifurcated mandrel and the second leg portion of the bifurcated mandrel. The first wire and the second wire can be laminated within a graft material.

Description

[Technical field]

[0001] One or more exemplary embodiments of the present disclosure relate to stents, stent-grafts, and methods of manufacturing such stents and stent-grafts, and in particular embodiments, 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 claims priority to U.S. Provisional Patent Application No. 62 / 750,667, filed October 25, 2018, which is incorporated by reference in its entirety. [Background technology]

[0003] Aortoiliac occlusion (AIOD) is an obstruction of the abdominal aorta where it transitions into the common iliac arteries. This obstruction is typically caused by the buildup or deposition of plaque within the aortic vessel wall. For example, FIG. 1 is a cross-sectional view of an exemplary anatomy of the abdominal aorta 10 with the center of aortoiliac occlusion located at the aortic bifurcation 11. In FIG. 1, the aorta 10 branches into two iliac arteries 12, 13 at the aortic bifurcation 11. Often, plaque 18 accumulates on the inner wall of the aorta 10 above the aortic bifurcation 11 and in the iliac arteries 12, 13 as well as 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 organs in the pelvis.

[0004] Treatment of AIOD generally involves open surgical repair or endoluminal repair. Open surgical repair is often highly successful in patients who are otherwise fairly healthy and have no significant comorbidities. However, such open surgical procedures are problematic because access to the abdominal aorta is difficult to obtain and the aorta must be clamped, which places a significant strain on the patient's heart. On the other hand, successful endoluminal procedures have a much shorter recovery period than open surgical procedures.

[0005] Regarding endoluminal procedures, two treatment modalities are commonly used to treat AIOD, including kissing stents and covered endovascular reconstruction. Kissing stents are a procedure in which two stents are placed at the aortic bifurcation so that the two stents cross (or kiss (touch)) each other above the aortic bifurcation. Similarly, covered endovascular reconstruction is a procedure in which a stent graft body is implanted in the aorta above the aortic bifurcation, and separate stent graft side branches for each iliac artery are implanted above the aortic bifurcation so that they cross each other within the stent graft body. However, both of these treatment modalities require multiple separate stent grafts to be used to recreate the bifurcation above the diseased aortic bifurcation, and thus suffer from areas of potential leakage as the separate stent grafts are sutured or otherwise joined together. This is commonly referred to as "radial mismatch" and can result in thrombosis and neointimal hyperplasia. Additionally, both of these treatment modalities create flow dividers that can adversely affect patency. Furthermore, these stents are typically larger than the occluding vessel lumen diameter and expand within the vessel, widening the vessel to remain patent, which can result in accidental rupture. If vessel rupture occurs in combination with a leak channel, there can be residual damage to the patient. Furthermore, the technical success of these procedures can also be difficult, as device placement (or device offset) and competition between the stents for intraluminal space can result in occlusion by the stents.

[0006] Recently, off-label use of bifurcated stent grafts designed for the treatment of abdominal aortic aneurysms (AAA) has been used in experimental treatments for some cases of AIOD. For example, the Endologix AFX® Endovascular AAA System, a single-unit bifurcated stent graft designed to treat AAA, has been used to treat some cases of AIOD. However, off-label use of bifurcated AAA implant devices can create difficulties in treating AIOD. For example, aneurysm stents are constructed to reduce radial strength so that excessive force is not applied to diseased tissue. For occlusive disease, high strength is typically desired. Due to this mismatch, off-label use of AAA devices can result in insufficient radial strength and require additional ballooning or stent reinforcement to maintain patency. Also, the graft materials and stents of such AAA devices are not attached along the entire length of the device (e.g., they are attached only at the ends), and often such AAA devices are not sized accordingly (e.g., too long and / or too large in diameter for many patients). Thus, once an AAA device is placed into a narrow, e.g., occluded, anatomy, it can be difficult to thread it back through without becoming entangled in 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 spirally wound along the axis of the body portion of the stent and along the axis of the first side branch portion of the stent. The second wire is spirally wound along the axis of the body portion of the stent and along the axis of the second side branch portion of the stent. In various embodiments, 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 body portion of the stent bifurcates into a first side branch portion and a second side branch portion at a bifurcation portion of the stent.

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

[0009] In various embodiments, the first wire is an undulating wire and the second wire is an undulating wire. In some embodiments, the undulations of the first wire have a first side and a second side that meet at a peak, and the length of the first side is less 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 meet at a peak, and the length of the first side is equal to the length of the second side.

[0010] In various embodiments, the first wire contacts the second wire at two contact regions. In other embodiments, the first wire does not contact the second wire. In some embodiments, the first wire is welded to the second wire at the contact regions. In some embodiments, the first wire is crimped to the second wire at the contact regions. In various embodiments, a first distance between adjacent turns of the first wire along the body portion of the stent is greater than a second distance between adjacent turns 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 main 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 the one or more stent members for the main 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 graft member is bifurcated at the bifurcation portion of the stent graft to provide the first side branch portion and the second side branch portion. In various embodiments, the one or more stent members for the main 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 stacked within the graft member.

[0012] In one embodiment, the method includes spirally winding a first wire of the stent around a body portion of a bifurcated mandrel and a first leg portion of the bifurcated mandrel, and spirally winding a second wire of the stent around a body portion of the bifurcated mandrel and a second leg portion of the bifurcated mandrel. In various embodiments, the method further includes laminating the first wire and the second wire in a graft material. In some embodiments, the first wire is an undulating wire and the second wire is an undulating wire. Also, in some embodiments, the undulations of the first wire have a first side and a second side that meet at a peak, and the length of the first side is less than the length of the second side. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of an exemplary anatomy of the abdominal aorta with the epicenter of an aortoiliac occlusion located at the aortic bifurcation. [Diagram 2]FIG. 1 illustrates a stent graft according to an exemplary embodiment. [Figure 3A] FIG. 1 is a perspective view of a stent according to an exemplary embodiment. [Figure 3B] FIG. 3B is an enlarged view of portion A of the stent shown in FIG. 3A according to an exemplary embodiment. [Figure 3C] 3B shows the stent of FIG. 3A stacked in various embodiments to form a graft member of a stent graft. [Figure 4A] 1A-1D illustrate tooling instruments used in the process of forming a stent of a stent graft according to an exemplary embodiment. [Figure 4B] 1A-1D illustrate tooling instruments used in the process of forming a stent of a stent graft according to an exemplary embodiment. [Figure 5A] 1A-1C illustrate one tooling instrument having different prong shapes and angles according to various exemplary embodiments. [Figure 5B] 11A-11C show alternative tooling instruments having different prong shapes and angles according to various exemplary embodiments. [Figure 6A] 11A-11C show alternative tooling instruments having different prong shapes and angles according to various exemplary embodiments. [Figure 6B] 11A-11C show alternative tooling instruments having different prong shapes and angles according to various exemplary embodiments. [Figure 7A] FIG. 1 illustrates one geometric shape of undulating wire used to form a stent according to various embodiments. [Figure 7B] 1A-1C illustrate alternative undulating wire geometries used to form stents in accordance with various embodiments. [Figure 8] 4 is a flow diagram of a method of manufacturing a stent graft according to an exemplary embodiment. [Figure 9] FIG. 13 shows a stent graft according to another exemplary embodiment. [Figure 10]FIG. 13 shows a stent graft according to another exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, like symbols typically indicate like items unless otherwise specified. The illustrative embodiments set forth in the detailed description and drawings are not meant to limit the invention. Other embodiments may be utilized and other changes may be made without departing from the spirit or scope of the invention as presented herein. As will be readily understood, the aspects of the invention generally described and illustrated herein can be arranged, substituted, combined and designed in a wide variety of configurations, all of which are expressly contemplated and form a part of the present invention. An aspect described in connection with 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 for manufacturing the same. 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 stacked within a graft member such that each of the first and second side branches are integrally encapsulated or stacked with the body. Thus, according to various embodiments, a potential leak area at the bifurcated portion of the stent graft can be reduced or eliminated compared to other endoluminal implant systems in which multiple stent grafts are sewn or otherwise joined together to form a bifurcated portion.

[0016] 2 illustrates an exemplary embodiment of a stent graft 200. In some embodiments, the stent graft 200 is a bifurcated stent graft having a first side branch section 205 (or first leg) and a second side branch section 210 (or second leg). The stent graft 200 includes 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, and 220u. In some embodiments, stent members 220a, 220c, 220e, 220g, 220i, 220p, 220q, 220r, 220s, 220t, and 220u are connected to each other via a single first stent, and stent members 220b, 220d, 220f, 220h, 220j, 220k, 220l, 220m, 220n, and 220o are connected to each other via a single second stent. In other embodiments, stent members 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, and 220i are connected to each other via a single first stent, stent members 220j, 220k, 220l, 220m, 220n, and 220o are connected to each other via a single second stent, and stent members 220p, 220q, 220r, 220s, 220t, and 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, and 220u are separated from one another (e.g., as 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 that is helically wound along an axis in an open tubular configuration, and each of the stent members 220b, 220d, 220f, 220h, 220j, 220k, 220l, 220m, 220n, 220o is made of a second wire that is helically wound along an axis in an open tubular configuration. In some embodiments, the helically wound wire can be an undulating wire having zigzags with peaks and valleys. For example, stent member 220c is shown as having a number of peaks 221 facing toward the proximal end 250 of the stent graft 200 and a number of valleys 222 facing toward the distal end 260 of the stent graft 200. In various embodiments, each of 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 number 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 from, for example, a nickel titanium alloy (NiTi), such as NITINOL, stainless steel, or any other suitable material, including, but not limited to, a cobalt-based alloy, such as ELGILOY, platinum, gold, titanium, tantalum, niobium, and / or combinations thereof. In some embodiments, each of 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. Although the exemplary embodiment of FIG. 2 shows a particular number of stent members, it should be understood that any suitable number of stent members may be used in various embodiments.

[0019] In some embodiments, 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 layered within graft member 215. In some embodiments, graft member 215 extends from proximal end 250 to distal end 260 (e.g., the end of first side branch section 205 and the end of second side branch section 210). In some other embodiments, graft member 215 does not cover the entire length of stent graft 200, for example, leaving proximal end 250, distal end 260, or both uncovered. In some embodiments, 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 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 graft member 215 with the main body portion 270 of stent graft 200. In this way, 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 sewn or otherwise joined together.

[0020] In various embodiments, the graft member 215 includes 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 yet some other embodiments, the stent graft 200 may include 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 invention is not so limited and the graft member 215 may include 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, a 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 an undulating wire. The first wire 302 is spirally wound down the axis of the stent 320 and through a first side branch (or leg) portion 305 in an open tubular configuration 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 section 305. The second wire 304 spirals down the axis of the stent 320 and through the second side branch (or leg) section 310 in an open tubular configuration 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 section 310.

[0022] In some embodiments, the first and second wires 302, 304 are spirally 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 side branch section 305 has first stent members 302i, 302j, 302k, 302l, 302m, 302n wound along the axis of the first side branch section 305, and the second side branch section 310 has second stent members 304i, 304j, 304k, 304l, 304m, 304n wound along the axis of the second side branch section 310.

[0023] In some embodiments, the spacing between adjacent ones of the first stent members 302a, 302b, 302c, 302d, 302e, 302f, 302g, 302h is greater than the spacing between adjacent ones of the first stent members 302i, 302j, 302k, 302l, 302m, 302n forming the first side 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 greater than the spacing between adjacent ones of the second stent members 304i, 304j, 304k, 304l, 304m, 304n forming the second side 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 points. For example, as shown in FIG. 3B, the first wire 302 contacts the second wire 304 at only the first contact area 306 and the second contact area 308. In some embodiments, the first wire 302 does not contact (or is entirely separated from) the second wire 304 other than at the two contact areas 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 point. For example, in this case, the first wire 302 may be circularly wound to form the proximal-most first stent member (e.g., 302a) and then subsequently spirally wound to form the remaining first stent members. The second wire 304 may contact the first wire 302 at only one contact point at a portion of the proximal-most first stent member, and then this second wire may be spirally wound from this to form a second stent member that is alternating with the first stent member. In various embodiments, the first wire 302 is coupled to the second wire 304 at one or more contact areas (e.g., 306, 308) by welding, crimping, etc. In yet another example, the first wire 302 may be completely separated from (does not contact) the second wire 304.

[0025] 3A and 3B, one embodiment of a stent 320 includes a first wire 302 and a second wire 304. The first wire 302 is spirally wound along the axis of the body portion 330 of the stent 320 and along the axis of the first side branch portion 305 of the stent 320. The second wire 304 is spirally wound along the axis of the body portion 330 of the stent 320 and along the axis of the second side branch portion 310 of the stent 320. In various embodiments, the body portion 330 of the stent 320 is tubular, the first side branch portion 305 of the stent 320 is tubular, and the second side branch portion 310 of the stent 320 is tubular. The body portion 330 of the stent 320 branches into the first side branch portion 305 and the second side branch portion 310 at a 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 alternate with the windings of the first wire 302 along the body portion 330 of the stent 320. Figure 3C illustrates a graft member 350 of a stent-graft according to one embodiment. With reference to Figures 3A, 3B, and 3C, in some embodiments, the first wire 302 and the second wire 304 are encased within the graft member 350 along the body portion 330, the first wire 302 is encased within the graft member 350 along the first side branch portion 305, and the second wire 304 is encased within the graft member 350 along the second side branch portion 310, thereby forming a stent-graft. Also, in some embodiments, the windings of the first wire 302 are present only along the body portion 330 and first side branch portion 305 of the stent 320, and the windings of the second wire 304 are present only along the body portion 330 and second side branch portion 310 of the stent 320. In various embodiments, the graft member 350 is a single unit with no sutures.

[0027] In various embodiments, the first wire 302 contacts the second wire 304 at two contact locations, e.g., first contact location 306 and 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 the contact area, e.g., first contact area 306. In some embodiments, the first wire 302 is crimped to the second wire 304 at the contact area. In various embodiments, a first distance between adjacent turns of the first wire 302 along the body portion 330 of the stent 320 is greater than a second distance between adjacent turns of the first wire 302 along the first side branch portion 305 of the stent 320.

[0028] 4A and 4B show a tooling tool used in the process of forming a stent for a stent graft according to an exemplary embodiment. Referring initially to FIG. 4A, a first undulating wire 402 is spirally 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 number 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 alignment. The first undulating wire 402 is spirally 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 winding (or first stent member) of the first undulating wire 402 along the body portion 415 is separated from an adjacent winding (or first stent member) by a first distance d1. In some embodiments, each winding (or first stent member) of the first undulating wire 402 along the first leg portion 405 is separated from an adjacent winding (or first stent member) by a second distance d2. In some embodiments, the first distance d1 is greater than the second distance d2, although the invention is not limited thereto and in other embodiments d1 may be equal to d2 or even less than d2 depending on considerations of stiffness or flexibility of the stent graft body and / or side branch.

[0029] 4B, the second undulating wire 404 is spirally wound around the bifurcated mandrel 400 shown in FIG. 4A after the first undulating wire 402 is arranged. As shown in FIG. 4B, the second undulating wire 404 is spirally wound along the body portion 415 of the bifurcated mandrel 400 between the first undulating wire 402 spaced apart by the second distance d1 and along the second leg portion 410 of the bifurcated mandrel 400. In some embodiments, the windings of the second undulating wire 404 (or second stent members) alternate with the windings of the first undulating wire 402 (or first stent members) along the body portion 415 of the bifurcated mandrel 400. In some embodiments, each winding (or first stent member) of the first undulating wire 402 is separated from an adjacent winding (or second stent member) of the second undulating wire 404 on the body portion 415 by a third distance d3. In some embodiments, distance d3 is greater than or equal to distance d2, although the invention is not limited thereto and in other embodiments d3 may be less than d2 depending on stiffness or flexibility considerations of the stent graft body and / or side branch.

[0030] In some embodiments, after the first and second undulating wires 402, 404 are aligned, the alignment is baked or otherwise heat treated to define the configuration of the first and second undulating wires 402, 404. In various embodiments, the entire stent, including the stent formed by alternating windings of the first and second undulating wires 402, 404 on the body portion 415 and the first and second side branches formed by windings of the first and second undulating wires 402, 404, respectively, on the first and second leg portions 405, 410 of the bifurcated mandrel 400, is encased in graft material to form a single-unit bifurcated stent graft (e.g., as shown in FIG. 2). Although the exemplary embodiment of Figures 4A and 4B shows a particular number of windings (or stent members) of the first and second undulating wires 402, 404, it should be understood that in various embodiments, any suitable number of windings (or stent members) may be used.

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

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

[0033] 5A, 5B, 6A, and 6B, the shape and size of the leg or body portion of the mandrel can also be varied to adjust the shape and size of the side branch and body portions of the bifurcated stent graft formed using the mandrel. For example, the mandrel 500 can have a more gradual tapered shape between the body and leg portions 505, 510 shown in the side view 525 and rear view 575 as compared to the mandrel 600 as shown in the side view 625 and rear view 675. Additionally, the mandrel 600 can be of a more rounded shape for the body up to the side branch portion transition as shown in the bottom view 650 as compared to the mandrel 500 shown in the bottom view 550. Thus, the shape and size of the bifurcated stent graft formed using the mandrels 500, 600 can be varied to correspond to the shape and size of the mandrel used to form the bifurcated stent graft.

[0034] 7A and 7B show various zigzag geometries of the undulating wire used to form a stent according to various embodiments. In various embodiments, the length of the zigzag and / or the angle of the windings can be adjusted to spirally wind the undulating wire used to form a stent. For example, as shown in FIG. 7A, one undulation of the undulating wire can 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 can be less than the length of the second side 704. In this case, when the undulating wire is spirally wound, the resulting structure gradually lengthens in the winding direction. Similarly, in some embodiments, the distance between the windings of the undulating wire can be adjusted by the length of the sides of the undulation.

[0035] On the other hand, in some embodiments, as shown in FIG. 7B, one undulating portion of the undulating 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, if the undulating wire is wound in a direction perpendicular to the axis of the stent graft body, the undulating wire will be wound in a circular shape. On the other hand, if the undulating wire is wound at an angle with respect to this perpendicular direction, the undulating wire will be longer in the winding direction. Similarly, in some embodiments, the distance between the windings of the undulating wire can be adjusted by the angle of the winding with respect to this perpendicular direction. Thus, in various embodiments, the undulating wire can be spirally wound to form a stent by defining different lengths of zigzags, by adjusting the angle with respect to the perpendicular direction, and / or by a combination thereof.

[0036] 3A and 7A, in various embodiments, the first wire 302 is an undulating wire and the second wire 304 is an undulating wire. In some embodiments, the undulations of the first wire 302 have a first side 702 and a second side 704 that meet at a peak 703, and the length of the first side 702 is less than the length of the second side 704. With reference to FIGS. 3A and 7B, in some embodiments, the undulations of the first wire 302 have a first side 706 and a second side 708 that meet at a peak 707, and the length of the first side 706 is equal to the length of the second side 708.

[0037] Figure 8 is a flow diagram of a method of manufacturing a stent graft according to an example embodiment. With reference to Figure 8, method 800 begins by providing a bifurcated mandrel having a body portion, a first leg portion, and a second leg portion at block 805. For example, in various embodiments, the bifurcated mandrel may be the same as or similar to any of mandrels 400, 500, or 600 shown in Figures 4A, 5A, or 6A.

[0038] 8, at block 810, a first wire is spirally wound along the length of the body portion and along the length of the first leg portion. In some embodiments, the first wire is an undulating wire having peaks and valleys. In some embodiments, the spacing between adjacent turns of the first wire along the body portion is greater than the spacing between adjacent turns of the first wire along the first leg portion.

[0039] At block 815, a second wire is spirally wound along the length of the body portion and along the length of the second leg portion. In some embodiments, the second wire is an undulating wire having peaks and valleys. 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 interleaved 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 or 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 or second leg portion.

[0040] In some embodiments, the spacing between the windings is adjustable based on the angle of the windings relative 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 the windings can be adjusted based on the distance of the zigzags of the undulating wire. In some embodiments, the spacing between the windings can be adjusted based on a combination of the angle and length of the zigzags.

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

[0042] Figures 9 and 10 show various examples of such bifurcated stent grafts in accordance with other exemplary embodiments. With reference to Figure 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 a first side branch (or leg), and the third stent 915 may form a stent for a second side branch (or leg). In some embodiments, the first stent 905 may be formed by a first undulating wire helically wound along the axis of the stent graft body, the second stent 910 may be formed by a second undulating wire helically wound along the axis of the first side branch, and the third stent 915 may be formed by a third undulating wire helically 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 stacked, encased or otherwise attached within 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 may not cover the entire length of the stent graft 900, for example, leaving the proximal end, the distal end, or both uncovered. In some embodiments, each of the first, second and third stents 905, 910, 915 are all stacked or fused within the graft member 920 to form a single-unit bifurcated stent graft 900 in which the side branch portion formed by the second and third stents 910, 915 together with the main body portion formed by the first stent 905 are integrally encapsulated by the graft member 920. In this way, the risk of leakage at the bifurcated portion of the stent graft 900 may be reduced or eliminated, which may occur when multiple stent grafts are sewn or otherwise joined together to form the bifurcated portion.

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

[0045] In some embodiments, each of the first, second, and third stents 1005, 1010, 1015 may be stacked, encased, 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 may not cover the entire length of the stent graft 1000, for example, leaving the proximal end, the distal end, or both uncovered. In some embodiments, each of the first, second and third stents 1005, 1010, 1015 are all laminated or fused within the graft member 1020 to form a single-unit bifurcated stent graft 1000 in which the side branch portions formed by the second and third stents 1010, 1015 together with the main body portion formed by the first stent 1005 are integrally encapsulated by the graft member 1020. In this manner, the risk of leakage at the bifurcated portion of the stent graft 1000 may be reduced or eliminated, which may occur when multiple stent grafts are sewn or otherwise joined together to form the bifurcated portion.

[0046] In the figures, relative dimensions of elements, layers, and regions may be exaggerated and / or simplified for clarity. Spatially relative terms, such as "below", "downward of", "downward", "under", "on", "above", and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as shown. As will be understood, these spatially relative terms include different orientations of the device in use or operation in addition to the orientation shown. For example, if the device depicted in the figures were inverted, elements described as "below", or "downward", or "below" other elements or features would then be oriented "above" these other elements or features. Thus, the illustrative terms "below" or "below" may include both an orientation of "above" and "below". The device may be oriented differently (e.g., rotated 90 degrees or otherwise oriented) and the spatially relative descriptive terms used herein should be interpreted accordingly.

[0047] It is understood that the terms "first," "second," "third," etc. may be used herein 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, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section described above may be referred to as a second element, component, region, layer, or section without departing from the spirit and scope of the present invention.

[0048] It will be understood that when an element or layer is referred to as being "on," "connected to," or "bonded to" another element or layer, the element or layer can be directly on, connected to, or bonded to the other element or layer, or one or more intervening elements or layers may be present. In addition, when an element or layer is referred to as being located "between" two elements or two layers, it will also be understood that such element or layer can be the only element or layer between the two elements or 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 and is not intended to be limiting of the present invention. As used herein, the singular forms "a" and "an" include the plural unless expressly specified otherwise. It is further understood that, when used in the original specification, the terms "comprises", "comprising", "includes", "including", "has", "have", and "having" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. When an expression precedes a listed element in the original specification, such as "at least one of," (which in the translation would follow the element as "at least one of"), modifies the entire list of elements.

[0050] As used herein, the terms "substantially," "about," and similar terms are used in terms of approximation, not degree, and are intended to take into account inherent variations in measurements or calculations recognized by those of ordinary skill in the art. Additionally, the use of the term "may" in describing embodiments of the present invention means "one or more embodiments of the present invention." As used herein, the terms "using," "with," and "used" may be considered synonymous with "utilizing," "utilizing," and "utilized," respectively. Additionally, the term "exemplary" is intended to mean an example or an illustrated example.

[0051] Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. It is further understood that terms, such as those defined in commonly used dictionaries, should be understood to have meanings consistent with their meanings in the relevant field and / or in the context of this specification, and should not be interpreted in an idealized or overly formal sense unless otherwise expressly stated in this specification.

[0052] The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive of the present invention. The present invention is not limited in any respect 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

1. 1. A stent comprising: a first wire helically wound along the axis of the body portion of the stent and along the axis of a first side branch portion of the stent; a second wire helically wound along the axis of the body portion of the stent and along the axis of a second side branch portion of the stent; the body portion of the stent is tubular; the first side branch portion of the stent is tubular; the second side branch portion of the stent is tubular; the body portion of the stent bifurcates into the first side branch portion and the second side branch portion at a bifurcation portion of the stent; the undulations of the first wire have first and second sides that meet at a peak, the first side having a length less than the second side; The stent, wherein an end of the first wire is connected to the second wire at a contact region.

2. 2. The stent of claim 1, wherein the windings of the second wire along the body portion of the first wire alternate with the windings of the stent along the body portion of the stent.

3. the first wire and the second wire are encased within a graft member along the body portion; the first wire is encased within the graft member along the first side branch section; The stent of claim 1 , wherein the second wire is encased within the graft member along the second side branch section.

4. 2. The stent of claim 1, wherein the first wire windings are present only along the main body portion and the first side branch portion of the stent, and the second wire windings are present only along the main body portion and the second side branch portion of the stent.

5. The stent of claim 1 , wherein the end of the first wire is connected to the second side of the second wire.

6. the first wire undulation has a first side and a second side that meet at a peak; The stent of claim 1 , wherein the length of the first side is equal to the length of the second side.

7. 2. The stent of claim 1, wherein the first wire is connected to the second wire at two separate contact areas near the proximal end of the body portion.

8. The stent of claim 1 , wherein the first wire does not contact the second wire.

9. The stent of claim 1 , wherein the first wire is welded or crimped to the second wire at a contact area.

10. 2. The stent of claim 1, wherein an end of the first wire is connected to the second wire at a first contact area and an end of the second wire is connected to the first wire at a second contact area, the first contact area and the second contact area being separate.

11. 1. A stent graft comprising: two or more undulating stent members for a body portion of the stent graft; one or more undulating stent members for a first side branch section of the stent graft; one or more undulating stent members for a second side branch section of the stent graft; a graft member which is a single unit and which retains the two or more stent members for the main 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 graft member is bifurcated at a bifurcation portion of the stent graft to provide the first side branch portion and the second side branch portion; A stent graft, wherein the two or more undulating stent members for the body portion of the stent graft are alternately wound around the body portion.

12. The stent graft of claim 11, wherein two or more stent members for a main body portion of the stent graft, one or more stent members for a first side branch portion of the stent graft, and one or more stent members for a second side branch portion of the stent graft are stacked within the graft members.

13. 1. A method comprising: helically winding a first wire of a stent around a body portion of a bifurcated mandrel and a first leg portion of said bifurcated mandrel; and helically winding a second wire of the stent around the body portion of the bifurcated mandrel and around a second leg portion of the bifurcated mandrel; the undulations of the first wire have first and second sides that meet at a peak, the first side having a length less than the second side; A method, wherein the connection of the end of the first wire is made to the second wire at a contact area.

14. The method of claim 13 , further comprising laminating the first wire and the second wire within a graft material.

15. 14. The method of claim 13, wherein the connection of the end of the first wire is made to the second side of the second wire, the undulations of the second wire having first and second sides that meet at a peak, and the length of the first side is less than the length of the second side.

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