MXPA00008590A - Endoluminal vascular prosthesis - Google Patents

Abstract

Disclosed is a tubular endoluminal vascular prosthesis (42), useful in treating, for example, an abdominal aortic aneurysm. The prosthesis (42) comprises a self-expandable wire support structure (46) surrounded by a flexible tubular membrane (44). A delivery catheter and methods are also disclosed.

Description

ENDOLUMINAL VASCULAR PROSTHESIS Background of the Invention The present invention relates to endoluminal vascular prostheses and, in one application, to self-expanding endoluminal vascular prostheses for use in the treatment of abdominal aortic aneurysms. An abdominal aortic aneurysm is a sac or balloon caused by an abnormal dilation of the wall of the aorta, a major artery of the body, as it passes through the abdomen. The abdomen is that portion of the body that lies between the thorax and the pelvis. It contains a cavity, known as the abdominal cavity, separated by the diaphragm of the thoracic cavity and lined with a serous membrane, the peritoneum. The aorta is the main branch or artery, from which the systemic arterial system proceeds. This arises from the left ventricle of the heart, passes upwards, flexes and passes down through the thorax and through the abdomen approximately at the level of the fourth lumbar vertebra, where it divides into the two common iliac arteries.

REF .: 122922 The aneurysm usually arises in the infrarenal portion of the diseased aorta, for example, below the kidneys. When left untreated, the aneurysm may sooner or later cause rupture of the sac with subsequent fatal hemorrhage in a very short time. The high mortality associated with the rupture initially led to transabdominal surgical repair of abdominal aortic aneurysms. Surgery involving the abdominal wall, however, is a major undertaking with high associated risks. There is considerable mortality and morbidity associated with this magnitude of surgical intervention, which essentially involves the replacement of the diseased and aneurysmal segment of the blood vessel with a prosthetic device that is typically a synthetic tube, or graft, usually made of polyester, urethane, P , DACRON®, TEFLON®, or other suitable material. To perform the surgical procedure requires exposure of the aorta through an abdominal incision which can extend from the box of the ribs to the pubis. The aorta should be closed above and below the aneurysm, so that the aneurysm can then be opened and the thrombus, or blood clot, and the arteriosclerotic waste removed. The small arterial branches from the posterior wall of the aorta are ligated. The DACRON® tube, or graft, of approximately the same size as the normal aorta is sutured in place, thereby replacing the aneurysm. The blood flow is then restored through the graft. It is necessary to move the intestines in order to have access to the posterior wall of the abdomen before pinching the aorta. If the surgery is performed before the rupture of the abdominal aortic aneurysm, the survival rate of the treated patients is markedly higher than if the surgery is performed after the rupture of the aneurysm, although the mortality rate is still very high. If the surgery is performed before the rupture of the aneurysm, the mortality rate is typically less than 10%. Conventional surgery performed after the rupture of the aneurysm is significantly higher, with one study reporting a mortality rate of 66.5%. Although abdominal aortic aneurysms can be detected from routine examinations, the patient does not experience any pain from the condition. In this way, if the patient is not receiving routine exams, it is possible that the aneurysm progresses to the rupture stage, where the mortality rates are significantly higher. The disadvantages associated with conventional prior art surgery, in addition to the high mortality rate include the prolonged recovery period associated with such surgery; difficulties in suturing the graft, or tube, to the aorta; the loss of the existing wall of the aorta and thrombosis to support and reinforce the graft;, the non-adequacy of surgery for many patients who have abdominal aortic aneurysms; and the problems associated with performing surgery on an emergency basis after the aneurysm has ruptured. A patient can expect to take one to two weeks in the hospital after surgery, a larger portion of which is spent in the intensive care unit, and a convalescence period in the home of two to three months, particularly if the The patient has other diseases such as cardiac, pulmonary, hepatic, and / or renal disease, in which case the stay in the hospital is prolonged as well. Since the graft must be secured, or sutured, to the remaining portion of the aorta, it is often difficult to perform the suture step due to the thrombosis present on the remnant portion of the aorta, and that remaining portion of the wall of the aorta. Aorta can often be friable or easily crumbly. Since many patients who have abdominal aortic aneurysms have other chronic diseases, such as heart, lung, liver, and / or kidney disease, coupled with the fact that many of these patients are elderly, the average age of Approximately 67 years, these patients are not ideal candidates for such major surgery. More recently, a significantly less invasive clinical procedure to repair the aneurysm, known as an endovascular graft, has been developed. Parodi et al provide one of the first clinical descriptions of this therapy. Parodi, J.C. and collaborators "Transfemoral Intraluminal Graft Implantation for Abdominal Aortic Aneurysms", 5 Annals of Vascular Surgery 491 (1991). Endovascular grafting involves the transluminal placement of a prosthetic arterial graft in the endoluminal position (within the lumen or lumen of the artery). By this method, the graft is coupled to the inner surface of an arterial wall by means of coupling devices (expandable stents), typically one above the aneurysm and a second stent below the aneurysm. Stents allow the fixation of a graft to the inner surface of a seamless arterial wall or an open surgical procedure. The expansion of radially expandable stents is conventionally carried out by dilation of a balloon at the distal end of a balloon catheter. In U.S. Patent No. 4,776,337, for example, Palmaz discloses a balloon expandable stent for endovascular treatments. Self-expanding stents are also known, such as are described in U.S. Patent No. 4,655,771 to Wallsten. Notwithstanding the foregoing, a need remains for a transluminally implantable stent, such as to encompass an abdominal aortic aneurysm. Preferably, the tubular prosthesis can be self-expanded at the site to treat the abdominal aortic aneurysm.

Brief Description of the Invention An endoluminal prosthesis is provided according to one aspect of the present invention. The endoluminal prosthesis comprises a tubular wire holder having a proximal end, a distal end and a central lumen extending therethrough. The wire support comprises at least a first and a second axially adjacent tubular segments, joined by a connector extending between them. The first and second segments and the connector are formed from a single length of wire. In one embodiment, the wire in each segment comprises a series of proximal bends, a series of distal bends, and a series of wall segments (strut) that connect the proximal bends and distal bends to form a tubular segment wall. Preferably, at least one proximal fold on a first segment is connected to at least one corresponding distal bend on a second segment. The connection can be provided by a metal joint, a suture, or other means of connection known in the art. Preferably, the endoluminal prosthesis further comprises a polymeric layer such as a tubular PTFE sleeve, on the support. According to yet another aspect of the present invention, a method for the fabrication of an endoluminal prosthesis is provided. The method comprises the steps of providing a wire length, and forming the wire into two or more zigzag sections, each zigzag section connected by a connection or link. The wire formed is thereafter wound around an axis to produce a series of tubular elements positioned along the axis, such that each tubular element is connected to the adjacent tubular member by a connection. Preferably, the method further comprises the step of placing a tubular polymer sleeve concentrically over at least a portion of the endoluminal prosthesis. According to yet another aspect of the present invention, a multi-zone endoluminal prosthesis is provided. The multi-zone prosthesis comprises a tubular wire support having a proximal end, a distal end and a central lumen extending therethrough. The wire support comprises at least a first and a second axially adjacent tubular segments, joined by a connector extending between them. The first tubular segment has a different radial resistance than the second tubular segment. In one embodiment, the prosthesis further comprises a third tubular segment. At least one of the tubular segments has a radial resistance different from that of the other two tubular segments. In yet another embodiment, a proximal end of the prosthesis is self-expanding to a larger diameter than a central region of the prosthesis. According to yet another aspect of the present invention, an endoluminal prosthesis is provided. The prosthesis comprises an elongate flexible wire, formed in a plurality of axially adjacent tubular segments, spaced along an axis. Each tubular segment comprises a zigzag section of wire, having a plurality of proximal bends and distal bends, with the wire continuing between each adjacent tubular segment creating an integral structural support system along the entire longitudinal distance of the device. The prosthesis is radially collapsible or collapsible in a first, transverse, reduced configuration for the implant within a lumen of the body, and self-expandable to a second, enlarged, transverse configuration at a treatment site in a lumen of the body. Preferably, the prosthesis further comprises an outer tubular sleeve that surrounds at least a portion of the prosthesis. One or more side perfusion gates can be provided through the tubular sleeve. In one embodiment, the prosthesis has an expansion ratio of at least about 1: 5, and preferably at least about 1: 6. The prosthesis in yet another embodiment has an expanded diameter of at least about 20 mm in unconstrained expansion, and the prosthesis is implantable using a catheter no greater than about 16 French. Preferably, the prosthesis has an expanded diameter of at least about 25 mm, and is implantable on a delivery device having a diameter of no more than about 16 French.

In accordance with a further aspect of the present invention, a method for implanting an endoluminal vascular prosthesis is provided. The method comprises the steps of providing an endoluminal, self-expanding vascular prosthesis having a proximal end, a distal end, and a central lumen extending therethrough. The prosthesis is expandable from a first reduced diameter to a second enlarged diameter. The prosthesis is mounted on a catheter, such that when the prosthesis is in the reduced diameter configuration on the catheter, the diameter of the catheter through the prosthesis is no greater than about 16 French. The catheter is then inserted into the lumen of the body and positioned such that the prosthesis is in a treatment site in the lumen of the body. The prosthesis is released at the treatment site, such that it expands from the first diameter to the second diameter, where the second diameter is at least about 20 mm. Additional features and advantages of the present invention will become apparent to those skilled in the art in view of the description herein, when considered in conjunction with the accompanying drawings and claims.

Brief description of the drawings Figure 1 is a schematic representation of an endoluminal vascular prosthesis according to the present invention, placed within a symmetric abdominal aortic aneurysm. Figure 2 is an exploded view of an endoluminal vascular prosthesis according to. the present invention, which shows a self-expanding wire support structure, separated from an outer tubular sleeve. Figure 3 is a plan view of a wire formed, useful for winding around an axle in a multi-segment support structure, in accordance with the present invention. Figure 4 is an enlarged detail view of a portion of the formed wire, illustrated in Figure 3. Figure 5 is a cross-sectional view taken along lines 5-5 of Figure 4.

Figure 6 is an alternative cross-sectional view taken along lines 5-5 of Figure 4. Figure 7 is a fragmentary view of an alternative arrangement or arrangement of wires according to a further aspect of the present invention. Figure 8 is an elevation view of a crosslinked wire arrangement according to the present invention. Figure 8A is a plan view of a wire arrangement formed useful for forming the cross-linked embodiment of Figure 8. Figure 9 is a fragmentary view of an alternate wire arrangement in accordance with a further aspect of the present invention. Figure 10 is a fragmentary view of an alternating wire arrangement according to a further aspect of the present invention. Figure 11 is a fragmentary view of a vertex according to an aspect of the present invention. Figure 12 is a fragmentary view of an alternative embodiment of a vertex according to the present invention.

Figure 13 is a further embodiment of a vertex according to the present invention. Fig. 14 is a fragmentary view of an additional wire arrangement according to the present invention. Fig. 14 is a fragmentary view of an additional wire arrangement according to the present invention. Figure 15 is a fragmentary view of an additional wire arrangement according to the present invention. Figure 16 is a fragmentary view of an additional wire arrangement according to the present invention. Figure 17 is a schematic illustration of a delivery catheter according to the present invention, placed within an abdominal aortic aneurysm. Figure 18 is an illustration as Figure 17, with the endoluminal prosthesis partially deployed from the delivery catheter. Figure 19 is a cross sectional view taken along lines 19-19 of Figure 17.

Figure 20 is a detailed fragmentary view of a tapered wire embodiment according to a further aspect of the present invention. Figure 21 is a schematic representation of the abdominal aortic anatomy, with an endoluminal vascular prosthesis of the present invention, placed within each of the right renal artery and the right common iliac artery.

Detailed Description of the Preferred Modality With reference to figure 1, a schematic representation of the abdominal part of the aorta and its main branches is described. In particular, the abdominal aorta 30 is characterized by a right renal artery 32 and the left renal artery 34. The large terminal branches of the aorta are the right and left common iliac arteries, 36 and 38, respectively. Additional vessels (eg, second lumbar, testicular, inferior mesenteric, middle sacral) have been omitted for simplification. A generally symmetric aneurysm 40 is illustrated in the infrarenal portion of the diseased aorta. An expanded endoluminal vascular prosthesis 42, according to the present invention, is illustrated as encompassing aneurysm 40. Although the characteristics of the endoluminal vascular prosthesis of the present invention may be modified for use in a bifurcation aneurysm, such as the iliac bifurcation. Commonly, the endoluminal prosthesis of the present invention will be described herein primarily in terms of its application in the rectus segment of the abdominal aorta, or the thoracic or iliac arteries. The endoluminal vascular prosthesis 42 includes a polymeric sleeve 44 and a tubular wire holder 46, which are illustrated in FIG. 1 in Fig. 1. The sleeve 44 and the wire holder 46 are more easily visualized in the exploded view shown in FIG. Figure 2. The endoluminal prosthesis 42 illustrated and described herein, discloses an embodiment in which the polymeric sleeve 44 is concentrically located outside the tubular wire holder 46. However, other embodiments may include a sleeve located instead of concentrically , inside the wire support or on the internal part and the external part of the wire support. Alternatively, the wire support may be embedded within a polymer matrix constituting the sleeve. Regardless of whether the sleeve 44 is inside or outside the wire holder 46, the sleeve can be coupled to the wire support by any of a variety of means, including laser bonding, adhesives, staples, sutures, dipping or spraying or other , depending on the composition of the sleeve 44 and the complete design of the graft. The polymeric sleeve 44 can be formed from any of a variety of synthetic polymeric materials, or combinations thereof, including PTFE, PE, PET, Urethane, Dacron, nylon, polyester or woven textiles. Preferably, the sleeve material exhibits relatively low inherent elasticity, or low elasticity outside the intended enlarged diameter, of the wire grid 46. The material of the sleeve preferably has a thin profile, such as no greater than about 50.8 μm (0.002 inches) to about 127 μm (0.005 inches). In a preferred embodiment of the invention, the material of the sleeve 44 is sufficiently porous to allow the inward growth of the endothelial cells, thereby providing safer anchorage of the prosthesis and potentially reducing the flow resistance, the forces of cutting, and leakage of blood around the prosthesis. The porosity in the polymeric sleeve materials can be estimated by measuring the water permeability as a function of the hydrostatic pressure, which will preferably be in the range of 0.211 to 0.422 kg / cm2 (approximately 3 to 6 psi). The porosity characteristics of the polymeric sleeve 44 can be either homogeneous along the entire axial length of the prosthesis 42, or may vary according to the axial position along the prosthesis 42. For example, with reference to Figures 1 and 2, the different physical properties will be mentioned in different axial positions along the prosthesis 42 in use . At least a proximal portion 55 and a distal portion 59 of the prosthesis 42 will be seated against the wall of the native vessel, proximal and distally of the aneurysm. In these proximal and distal portions, the prosthesis preferentially promotes endothelial development or, at least, allows endothelial development to infiltrate the portions of the prosthesis in order to increase anchoring and minimize leakage. A central portion 57 of the prosthesis spans the aneurysm, and anchoring is less than a problem. Rather, the minimization of blood flow through the wall of the prosthesis becomes a primary objective. Thus, in a central zone 57 of the prosthesis 42, the polymeric sleeve 44 can be either non-porous, or provided with pores of no more than about 60% to 80%. A multi-zone prosthesis 42 can also be provided in accordance with the present invention by placing a tubular sleeve 44 over a central portion 57 of the prosthesis, such that it encompasses the aneurysm to be treated, but leaving an area of proximal coupling 55 and a distal coupling area 59 of the prosthesis 42, having wires exposed from the wire support 46. In this embodiment, the exposed wires 46 are placed in contact with the proximal vessel wall and distally of the aneurysm, such that the wire, over time, becomes embedded in the cellular development on the inner surface of the vessel wall. In one embodiment of the prosthesis 42, the sleeve 44 and / or the wire holder 46 is tapered, having a relatively larger expanded diameter at the proximal end 50 compared to the distal end 52. The tapered design may allow the prosthesis to be conforms best to the distal, naturally decreasing cross section of the vessel, to reduce the risk of graft migration and potentially create better flow dynamics. The tubular wire support 46 is preferably formed from a single continuous length of round wire (shown in Figure 5) or flattened (shown in Figure 6). The wire support 46 is preferably formed in a plurality of discrete segments 54, connected to each other and oriented around a common axis. Each pair of adjacent segments 54 is connected to a connector 66 as will be discussed later. The connectors 66 collectively produce a generally axially extending spinal column, which adds axial strength to the prosthesis 42. The adjacent segments can be connected by the spinal column, as well as by other structures, including the circumferentially extending structures 56. (illustrated in Figures 1 and 2), weld joints, wire loops and any of a variety of interlocking ratios. The structure can be made from any of a variety of biocompatible polymeric materials or alloys, such as nylon, polypropylene, or stainless steel. Other means of securing the segments 54 to one another are discussed below (see figure 8). The segmented configuration of the tubular wire holder 46 facilitates a large amount of flexibility. Each segment 54, although linked to the adjacent segments, can be independently designed to produce the desired parameters. Each segment may be in the range in axial length from about 0.3 to about 5 cm. In general, the shorter its length the greater the radial resistance. An endoluminal prosthesis may include from about 1 to about 50 segments, preferably from about 3 to 10 segments. For example, while a short graft patch, according to the invention, can comprise only 2 segments and cover a total of 2 to 3 cm, a complete graft can comprise 4 or more segments and encompass the entire aortic aneurysm.

In addition to the flexibility and other functional benefits available through the use of different longitudinal segments, additional flexibility can be achieved through adjustments in the number, angle or configuration of the wire bends associated with the tubular support. The potential bending or bending configurations are discussed in more detail later (see Figures 4-16). A variety of additional advantages can be achieved through the multi-segment configuration of the present invention. For example, with reference to Figure 2, the wire cage 46 is divisible into a proximal zone 55, a central zone 57 and a distal area 59. As discussed, the wire cage 46 can be configured to tape from a relatively larger diameter in the proximal zone 55 to a relatively smaller diameter in the distal area 59. In addition, the wire cage 46 can have a tapered transitional and / or stepped diameter within a given area. The cage 46 can also be provided with a proximal zone 55 and a distal area 59 having a larger diameter relatively expanded than the central zone 57, as illustrated in Figure 2. This configuration can desirably resist migration of the prosthesis inside the vessel. In the proximal zone 55 and / or the distal area 59 can be left without an outer covering 44, with the outer sleeve 44 covering only the central area 57. This allows the proximal and distal 55, 59 areas to be in direct contact with the tissue proximally and distally to the lesion, which may facilitate the development of endothelial cells. In addition to having different diameters expanded in the different areas of the prosthesis 42, different areas with a different radial expansion force can be provided, such as in the range of about 90.7 g (0.2 pounds) to about 362.8 g (8 pounds). In one embodiment, the proximal zone 55 is provided with a greater radial force than the central zone 57 and / or the distal area 59. Greater radial force can be provided in any of a variety of ways discussed hereinafter, such as through the use of one or two or three or more additional proximal bends or bends 60, distal bends 62 and wall sections 64 compared to a reference segment 54 in the central zone 57 or in the distal area 59. Alternatively, the Additional spring force can be achieved in the proximal zone 55 through the use of the same number of proximal bends 60 as in the rest of the prosthesis, but with a larger gauge wire. The radial force beyond the boundary of the expanded diameter of the central zone 57 can be achieved by tightening the suture 56 as illustrated in Figure 2, such that the central zone 57 is retained under compression even in the expanded configuration. When omitting a suture at the proximal end and / or at the distal end of the prosthesis, the proximal end and the distal end will widen radially outwardly to a fully expanded configuration as illustrated in Figure 2. The wire may be made from any of a variety of different alloys, such as elgiloy, nitinol or MP35N, or other alloys including nickel, titanium, tantalum, or stainless steel, alloys of high Co-Cr content or other temperature-sensitive materials. For example, an alloy comprising 15% nickel, 40% cobalt, 20% chromium, 7% molybdenum and the balance of iron can be used. The tensile strength of the suitable wire is generally greater than 21,092 kg / cm 2 (300 K psi) and frequently between approximately 21,092 kg / m2 and approximately 23,094 kg / cm 2 (340 K psi and 340 K psi) for many embodiments. In one embodiment, a chromium-nickel-molybdenum alloy such as that marketed under the name Conichrom (Fort Wayne Metals, Indiana) has a tensile strength in the range of 21, 092 kg / cm2 up to 22,498 Kg / cm2 (300 to 320 K psi), elongation from 3.5 to 4.0% and load to break up to approximately 36.28 kg to 31.75 kg (80 pounds to 70 pounds). The wire can be treated with a plasma coating and can be provided with / without coating such as: PTFE, Teflon, Perylene, and Drugs. In addition to the segment length and bending configuration, discussed above, another determinant of radial resistance is the wire gauge. The radial resistance, measured at 50% of the collapsed profile, is preferably in the range of about 90.7 g to 362.8 g (0.2 pounds to 0.8 pounds), and generally about 181.4 g (0.4 pounds) to about 226.8 g (0.5 pounds) or more. Preferred wire diameters according to the present invention are in the range of about 101.6 μm (0.040 inches) to about 504 μm (0.020 inches). More preferably, the wire diameters are in the range of about 152 μm (0.006 inches) to about 457.2 μm (0.018 inches). In general, the larger the diameter of the wire, the greater the radial resistance for a given wire arrangement. In this way, . the wire gauge can be varied depending on the application of the finished graft, in combination with / or separated from the variation in other design parameters (such as the number of poles, or proximal bends or bends 60 and distal bends or bends 62 segment), as will be discussed later. A wire diameter of approximately 457.2 μm (0.018 inches) can be useful in a graft that has four segments each having a length of 2.5 cm per segment, with each segment having six poles designed for use in the aorta, while a diameter Smallest such as 152 μm (0.006 inches) can be useful for a 0.5 cm segment graft that has 5 posts per segment designed for the iliac artery. The length of the cage 42 could be as long as approximately 28 cm. In one embodiment of the present invention, the diameter of the wire is tapered from the ends proximal to the distal. Alternatively, the diameter of the wire may be tapered in increments or stepped down, or stepped up, depending on the radial resistance requirements of each particular clinical application. In one embodiment, designed for the abdominal aortic artery, the wire has a cross section of approximately 457.2 μm (0.018 inches) in the proximal zone 55, and the wire tapers down to a diameter of approximately 152 μm (0.006 inches) in the distal region 59 of the graft 42. The dimensions of the end point and the tapering proportions can be varied widely, within the spirit of the present invention, depending on the desired clinical performance. Referring to Figure 3, a plan view of a simple formed wire used to wind around a longitudinal axis is illustrated to produce a four-segment tubular wire support. The wire formed shows different segments, each corresponding to an individual tubular segment 54 in the tubular support (see figures 1 and 2). Each segment has a repetitive pattern of proximal bends or bends 60 connected to corresponding distal bends 62 by wall sections 64 that extend in a generally zigzag configuration when segment 54 is radially expanded. Each segment 54 is connected to the adjacent segment 54 through a connector 66, except at the terminal ends of the graft. The connector 66 in the illustrated embodiment comprises two wall sections 64 which are connected to a proximal fold 60 on a first segment 54 with a distal bend 62 on a second adjacent segment 54. The connector 66 may further be provided with a fold 68 of connector, which can be used to impart increased radial resistance to the graft and / or provide a binding site for a circumferentially extending suture. With reference to figure 4, an enlarged view of the wire support illustrating a connecting portion 66 between the adjacent segments 54 is shown. In the embodiment shown in Figure 4, a proximal fold 60 comprises approximately an arc of 180 degrees, which has a radial diameter of ( w) in the range of 1,778 μm to 228.6 μm (0.070 to 0.009 inches), depending on the diameter of the wire, followed by a relatively short length of parallel wire spanning an axial distance of di. The parallel wires thereafter diverge outwardly from each other and form the post sections 64, or the proximal half of a connector 66. At the distal end of the post sections 64, the wire forms a distal fold 62, which preferably has identical characteristics as the proximal flexion 60, except that it is concave in the opposite direction. The axial direction component of the distance between the vertices of the corresponding proximal and distal bends 60, 62 is designated as (d) and represents the axial length of that segment. The total expanded angle defined by the bend 60 and the diverging pole sections 64 is represented by a. After compression to a collapsed state, such as when the graft is within the deployment catheter, the angle a is reduced to a '. In the expanded configuration, a is generally within the range of about 35 ° to about 45 °. The expanded circumferential distance between any two adjacent distal bends 62 (or proximal bends 60) is defined as (s). In general, the diameter W of each proximal fold 60 or distal fold 62 is within the range of about 228 μm (0.009 inches) to about 1,778 mm (0.070 inches) depending on the diameter of the wire. The diameter W is preferably as small as possible for a given wire diameter and the given characteristics of the wire. As will be appreciated by those of skill in the art, as the distance W is reduced to approximate twice the cross section of the wire, the bend 60 or 62 will exceed the yield strength of the wire, and the radial strength of the finished segment will be lost. The determination of a minimum value for W, in the context of a particular wire diameter and a particular wire material, can be easily determined through routine experimentation by those of skill in the art. Similarly, although at least a distance of di is desired, from the vertex to the first bend in the wall section 64, the distance di is preferably minimized within the performance requirements of desired radial strength. As it increases, it can disadvantageously increase the collapsed profile of the graft. As will be appreciated from Figures 3 and 4, the sum of the distances (s) in a plane transverse to the longitudinal axis of the finished graft will correspond to the circumference of the finished graft in that plane. For a given circumference, a number of proximal bends 60 or distal bends 62 is directly related to the distance (s) in the corresponding plane. Preferably, the finished graft in any single transverse plane will have from about 3 to about 10 dimensions (s), preferably from about 4 to about 8 dimensions (s), and more preferably, about 5 or 6 dimensions (s) for an aortic application . Each dimension (s) corresponds to the distance between any two adjacent bends 60-60 or 62-62 as will be apparent from the discussion herein. Each segment 54 can thus be visualized as a series of triangles extending circumferentially around the axis of the graft, defined by a proximal fold 60 and two distal folds 62 or the inverse. By modifying the wire support parameters (such as d, di, s, alpha and alpha ') the manufacturer enjoys tremendous design control with respect to the total axial length, to the axial and radial flexibility, to the radial force and to the proportions of expansion, and consequently to the operation of the prosthesis. For example, an increase in the dimension (w) translates directly into a collapsed, increased profile, since the circumference of the collapsed profile can be no less than the sum of the distances (w) in a given transverse plane. Similarly, an increase in the number of proximal bends 60 in a given segment can increase the radial strength, but similarly increase the collapsed profile. Since the primary radial force comes from the proximal bends 60 and the distal bends 62, the wall sections 64 act as a lever arm to translate that force into radial resistance. As a consequence, the decrease in the length of the post sections 64 for a given number of proximal folds 60 but may require additional segments to maintain the full length of the graft. Where a minimum entry profile is desired, the radial strength is best achieved by decreasing the length of the wall sections 64 instead of increasing the number of proximal bends 60. On the other hand, the increase in the number of segments 54 (shorter ) in a given full-length graft will increase the degree of axial shortening on the radial expansion of the graft. Thus, in a mode where axial shortening is to be avoided, the increased radial resistance can be optimized through the selection of the wire material or the wire gauge and other parameters, while minimizing the total number of segments in the graft. Other geometry consequences of the present invention will be apparent to those of skill in the art in view of the description herein. In one embodiment of the type illustrated in Figure 8A, it is approximately 2.0 mm ± 1 mm for a wire diameter of 4572 mm (0.018 inches). DI is approximately 3 mm ± 1 mm, d is approximately 20 mm ± 1 mm, c is approximately 23 mm ± 1 mm, g is approximately 17 mm ± 1 mm, in a variety of ways as it will be apparent to those skilled in the art. technique in view of the description herein. In the illustrated embodiment, the connection is achieved through the use of a connection or link 72. The connection 72 may be a metal curl such as stainless steel, a suture, a welded joint or other type of connection. Preferably, the connection 72 comprises a metal loop or ring that allows pivotal movement of a proximal segment 76 with respect to the distal segment 78. In an example of an endoluminal vascular prosthesis according to the present invention, the proximal segment '76 is provided with 6 distal bends 62. The corresponding distal segment 78 is provided with six proximal bends 60 such that there is a one-to-one correspondence. A connection 72 may be provided in each pair of corresponding bends 60, 62, such that there are six connections 72 in a plane transverse to the Longitudinal axis of the graft at the interface between the proximal segment 76 and the distal segment 78. Alternatively, they may be provided connections 72 in less than all corresponding bends, such as each second bend, each third bend, or only on opposite sides of the graft. The distribution of the connections 72 in any given mode may be selected to optimize the desired flexibility characteristics and other performance criteria in a given design. The use of connectors such as cross-linking or cross-linking 72 makes possible the improved tracking of the graft around the curved sections of the vessel. In particular, the wire cage 46 as illustrated in Figure 8 can be bent around a smooth curve, such that it will retain the curved configuration and will preserve the lack of obstruction of the central lumen extending axially therethrough. The modality illustrated in figure 2 may be more difficult to track the curved anatomy, while maintaining a lack of complete obstruction of the central lumen. The ability to maintain the lack of complete obstruction while extending around a curve may be desirable in certain anatomies, such as where the aorta fails to follow the linear infrarenal path illustrated in Figure 1.

With reference to Figure 8a, a plan view of a formed wire, useful for winding around an axis, is illustrated to produce a multi-segment support structure of the type illustrated in Figure 8. In general, the wire formed of Figure 8a is similar to that illustrated in Figure 3. However, while any portion of distal bends 62 and corresponding proximal bends 60, of the embodiment of Figure 3 overlap in the axial direction to facilitate threading a suture circumferential through it, the corresponding distal fold 62 and the proximal fold 60 of the embodiment illustrated in Figure 8a may abut end-to-end against one another or one close to the other, as illustrated in Figure 8 to receive a connector 72 about these. The proper axial placement of a distal fold 62, relative to a corresponding proximal fold 60 can be achieved in a variety of ways, most conveniently by properly forming the connector fold 68 between the adjacent segments of the wire cage.

Figures 9-16 illustrate alternative bending modalities according to the present invention. Figure 9 shows a modality having proximal and distal folds as eyelets, but the fold 68 of the connector remains in the usual configuration. The modality illustrated in Figure 10 has the proximal and distal bends as well as the connector fold in the eyelet configuration. Various eyelet designs according to the present invention are shown in greater detail in Figures 11-13, including a circular double loop eyelet (figure 11), a triangular double loop eyelet (figure 12), and a triangular eyelet of simple curl (figure 13). The eyelets can be used to receive a circumferentially extending suture or a wire as described. Additional embodiments of the wire configuration are illustrated in Figures 14-16. Figure 14 shows a modality of the proximal 60 and distal 62 bends in which double bends are used to increase flexion. Alternatively, Figure 15 shows the triangular bends having a more pronounced length (di) of parallel wire, and consequently shorter wall sections 64. Yet another modality of the proximal and distal bends is shown in Figure 16, where the triangular bends include additional bending points in the form of wall segment bends 70. With reference to Figures 17 and 18, a device and a deployment method according to a preferred embodiment of the present invention is illustrated. A distribution catheter 80, having a dilator tip 82, is advanced along a guide wire 84 until the proximally (anatomically) end 50 of the collapsed endoluminal vascular prosthesis 86 is placed between the renal arteries 32 and 34 and the aneurysm 40. The collapsed prosthesis according to the present invention has a diameter in the range of about 2 to about 10 mm. Preferably, the diameter of the collapsed prosthesis is in the range of about 3 to 6 mm (12 to 18 French). More preferably, the delivery catheter including the prosthesis will be 16 F or 15 F, or 14 F, or smaller. The prosthesis 86 is maintained in its collapsed configuration by the restriction walls of the tubular distribution catheter 80, such that removal of this restriction could allow the prosthesis to self-expand. The radio-opaque marker material can be incorporated into the delivery catheter 80, and / or the prosthesis 86, at least at the proximal and distal ends, to facilitate periodic verification of the position of the prosthesis. The dilator tip 82 is attached to an internal core 92 of the catheter, as illustrated in FIG. 18, wherein the inner core 92 of the catheter and the partially expanded prosthesis 88 are disclosed as the outer shield or shield of the delivery catheter 80 is retracted The inner core 92 of the catheter is also described in the cross-sectional view of FIG. 19. As the shell or outer shield is retracted, the collapsed prosthesis 86 remains substantially axially fixed relative to the inner core 92 of the catheter and consequently self-expands into a predetermined vascular site as illustrated in Figure 18. Continuous retraction of the outer shell results in the complete deployment of the graft. After deployment, the expanded endoluminal vascular prosthesis has radially self-expanded to a diameter anywhere in the range of about 20 to 40 mm, corresponding to the expansion ratios of about 1: 2 to 1:20. In a preferred embodiment, the expansion ratios are in the range of from about 1: 4 to 1: 8, more preferably from about 1: 4 to 1: 6. In addition to, or in lieu of, the above-described outer shell or shield, the prosthesis 86 may be maintained in its collapsed configuration by a restriction cord, which may be woven through the prosthesis or wrapped around the outside of the prosthesis. the prosthesis in the reduced diameter, collapsed. After placement of the prosthesis at the treatment site, the cord can be proximally retracted from the prosthesis, thereby releasing it to self-expand at the treatment site. The cord may comprise any of a variety of materials, such as sutures, PTFE strips, FEP, polyester fiber, and others, as will be apparent to those skilled in the art in view of the description herein. The restriction cord may extend proximally through a lumen or lumen in the delivery catheter or out of the catheter to a proximal control. The control can be a pull tab or ring, a rotating reel, a slide switch or other structure to allow proximal retraction of the cord. The cord can extend continuously along the entire length of the catheter, or it can be attached to another axially movable member such as a pull wire. In general, the expanded diameter of the graft according to the present invention can be any useful diameter for the lumen or hollow organ in question, in which the graft is to be deployed. For most arterial vascular applications, the expanded size will be in the range of about 10 to about 40 mm. Abdominal aortic applications will generally require a graft having an expanded diameter within the range of about 20 to about 28 mm, and for example, a graft of the order of about 45 mm may be useful in the thoracic artery. The above dimensions refer to the expanded size of the graft in an unconstrained configuration, such as on the table. In general, the graft will be placed within an artery having an interior cross section slightly smaller than the expanded size of the graft. This makes it possible for the graft to maintain a slight positive pressure against the wall of the artery, to assist graft retention for the period of time prior to endothelialization of the polymeric sleeve 44. The radial force exerted by the proximal segment 94 of the Prosthesis against the walls of the aorta 30 provides a seal against leakage of blood around the Vascular prosthesis and tends to prevent axial migration of the deployed prosthesis. As discussed above, this radial force can be modified as required through the manipulation of various design parameters, including the axial length of the segment and the bend configurations. In yet another embodiment of the present invention, the radial tension may be increased at the proximal end upstream, by changes in the wire gauge as illustrated in FIG. 20. Note that the wire gauge increases approximately along the length of the wire. the wall segments 64 from TI in the proximal folds 60 to T2 in the distal folds 62. Accordingly, the radial flexion exerted by the distal folds 62 is greater than that exerted by the proximal folds 60 and the radial tension is thereby increased at the proximal end 50 of the prosthesis. TI may be in the range of about 25.4 μm to 254 μm (0.001 to 0.01 inches) while T2 may be in the range of about 254 μm to 762 μm (0.01 to 0.03 inches). An alternative embodiment of the wire arrangement could cause the radial tension to progressively decrease from the proximal segments to the distal segments, involving a progressive or gradual decrease in the wire gauge along the entire length of the wire support, from approximately 254 μm to 762 μm (0.01 to 0.03 inches) at the proximal end to approximately 50.8 μm to 254 μm (0.002 to 0.01 inches) at the distal end. Such modality can be used to create a tapered prosthesis. Alternatively, the wire gauge may be thicker at the proximal and distal ends, in order to ensure greater radial tension and thus sealing capacity. Thus, for example, the wire gauge in the proximal and distal segments can be from about 254 μm to 762 μm (0.01 to 0.03 inches), while the intervention segments can be constructed of thinner wire, in the range of about 25.4 μm to 254 μm - (0.001 to 0.01 inches). With reference to Figure 21, two alternative deployment sites for the endoluminal vascular prosthesis 42 of the present invention are illustrated. For example, a symmetric aneurysm 33 illustrates in the right renal artery 32. An expanded endoluminal vascular prosthesis 42, in accordance with the present invention, is illustrated encompassing that aneurysm 33. Similarly, an aneurysm of the right common iliac artery 37 is shown, with a prosthesis 42 deployed to encompass the iliac aneurysm 37. Referring to Fig. 22, a modified embodiment of the stent 96 according to the present invention is illustrated. In the embodiment illustrated in Figure 22, stent 96 is provided with a wire cage 46 having six segments 54 axially aligned. As with the previous embodiments, however, the stent 96 may be provided at any site, with from about 2 to about 10 or more segments 54 axially spaced or adjacent, depending on the clinical performance objectives of the particular embodiment. The wire support 46 is provided with a tubular polymer sleeve 44 as discussed. In the present embodiment, however, one or more lateral perfusion ports or ports are provided in the polymeric sleeve 44, such as an infusion gate 98 of the right renal artery and a perfusion gate 100 of the left renal artery, such as it is illustrated. Perfusion gates in the polymeric sleeve 44 may be desirable in the embodiments of the stent 96 in a variety of clinical settings. For example, although Figures 1 and 22 illustrate a generally symmetric aneurysm 40 placed within a linear infrarenal portion of the abdominal, axially spaced aorta of the bilaterally symmetric right and left renal arteries, and the right and left common iliac, bilaterally symmetrical , the position and symmetry of the aneurysm 40 as well as the arrangement of the abdominal aortic architecture can differ significantly from patient to patient. As a consequence, the stent 96 may need to extend through one or both of the renal arteries in order to properly anchor the stent 96 and / or encompass the aneurysm 40. The provision of one or more lateral perfusion gates makes It is possible that the endovascular stent 96 encompasses the renal arteries, while allowing perfusion through it, which prevents the "stent imprisonment" of the renal arteries. Lateral perfusion through the endovascular stent 96 may also be provided, if desired, for a variety of other arteries including the second lumbar, testicular, inferior mesenteric, sacral medial and the like, as will be well understood by those skilled in the art. . The stent 96 is preferably provided with at least one, and preferably two or more radiopaque markers, to facilitate proper placement of the prosthesis 96 within the artery. In a modality having perfusion gates 98 and 100 such as in the illustrated design, prosthesis 96 must be adequately axially and rotationally aligned, whereby the ability to visualize the axial and rotational position of the device is required. Alternatively, provided that the design of the delivery catheter shows sufficient torque transmission, the rotational orientation of the graft can be coordinated with an indexed or regulated marker, over the proximal end of the catheter, so that the catheter can be rotated and determined by an external indication of the rotational orientation, to be properly aligned with the right and left renal arteries. In an alternative embodiment, the polymeric sleeve 44 extends through the aneurysm 40, but terminates in the infrarenal zone. In this embodiment, a proximal zone 55 on the prosthesis 96 comprises a wire cage 46 but not the polymeric sleeve 44. In this embodiment, the prosthesis 96 still achieves the function of anchoring through the renal arteries, and does not materially interfere with renal perfusion. In this way, the polymeric sleeve 44 can cover anywhere from about 50% to about 100% of the axial length of the prosthesis 96, depending on the desired length of the wire cage 46, uncovered, such as for anchoring purposes and / or lateral perfusion. In particular embodiments, the polymeric sleeve 44 can cover within the range of about 70% to about 80%, and, in a fourth segment embodiment having a simple exposed segment, 75%, of the full length of the prosthesis 96. The open wire cage 46 may reside only at a single end of the prosthesis 96, such as to pass through the renal arteries. Alternatively, the exposed portions of the wire cage 46 may be provided at both ends of the prosthesis such as for anchoring purposes. In a further alternative, a polymeric sleeve 44 of two parts is provided. A first distal part encompasses the aneurysm 40, and has a proximal end that ends distally of the renal arteries. A second proximal portion of the polymeric sleeve 44 is carried by the proximal portion of the wire cage 46 that is positioned superiorly of the renal arteries. This leaves an annular lateral flow path through the lateral wall of the vascular prosthesis 96, which can be axially aligned with the renal arteries, without considering the rotational orientation. The axial length of the free space between the proximal and distal segments of the polymeric sleeve 44 can be adjusted depending on the size of the anticipated transverse section of the renal artery ostium, as well as the potential axial misalignment between the right and left renal arteries. Although the right renal artery 32 and the left renal artery 34 are illustrated in figure 22 being concentrically placed on opposite sides of the abdominal aorta, the point of intake for the right or left renal arteries from the abdominal aorta may be spaced along the abdominal aorta as will be familiar to those skilled in the art. In general, the diameter of the ostium of the renal artery, measured in the axial direction along the abdominal aorta, falls within the range of approximately 7 cm to approximately 20 cm for a typical adult patient. The clinical and design challenges, which are satisfied by the present invention, include the provision of a sufficient seal between the upstream end of the vascular prosthesis and the arterial wall, providing a sufficient length to encompass the abdominal aortic aneurysm, providing sufficient wall strength or support through the amplitude of the aneurysm, and providing a sufficient expansion ratio, such that a minimum percutaneous axis diameter can be utilized for the introduction of the vascular prosthesis into its collapsed configuration. The prior art methods currently use a 7 mm (18 French) introducer that involves a surgical procedure for the introduction of the graft delivery device. In accordance with the present invention, the introduction profile is significantly reduced. The embodiments of the present invention can be constructed having a 16 French or 15 French or 14 French profile or smaller (for example 3-4 mm) with which it becomes possible to place the endoluminal vascular prosthesis of the present invention in a manner of a percutaneous procedure. In addition, the endoluminal vascular prosthesis of the present invention does not require post-implant balloon dilation, can be constructed to have minimal axial shrinkage after radial expansion, and avoids the disadvantages associated with nitinol grafts. While a number of preferred embodiments of the invention and variations thereof have been described in detail, other modifications and methods of use and medical applications for it will be apparent to those skilled in the art. Accordingly, it should be understood that various applications, modifications and substitutions of the equivalents may be made, without departing from the spirit of the invention or the scope of the claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Claims (34)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. An endoluminal prosthesis, characterized in that it comprises: a tubular wire support having a proximal end, a distal end and a central lumen extending therethrough; a wire support comprises at least a first and a second axially adjacent tubular segments, joined by a connector extending between them; wherein the first and second segments and the connector are formed from a simple length of wire.

2. An endoluminal prosthesis according to claim 1, characterized in that it comprises at least three segments and two connectors.

3. An endoluminal prosthesis according to claim 1, characterized in that it comprises at least five segments and four connectors.

4. An endoluminal prosthesis according to claim 1, characterized in that the wire in each segment comprises a series of proximal folds, a series of distal folds, creating a series of pole segments that connect the proximal folds and the distal folds to form a wall of tubular segment.

5. An endoluminal prosthesis according to claim 4, characterized in that at least some of the pole segments are substantially linear.

6. An endoluminal prosthesis according to claim 4, characterized in that it also comprises an eyelet on at least some of the folds.

7. An endoluminal prosthesis according to claim 6, characterized in that one or more eyelets on a distal end of the first tubular segment are connected to one or more corresponding eyelets on a proximal end of the second tubular segment.

8. An endoluminal prosthesis according to claim 7, characterized in that the corresponding eyelets are connected with a suture, or ring.

9. An endoluminal prosthesis according to claim 4, characterized in that each segment comprises from approximately 4 proximal bends to approximately 12 proximal bends.

10. An endoluminal prosthesis according to claim 1, characterized in that it has at least one proximal segment, an intermediate segment and a distal segment, wherein the prosthesis is expandable from a reduced cross section to an expanded cross section.

11. An endoluminal prosthesis according to claim 10, characterized in that at least a portion of the proximal segment and the distal segment is larger in cross section than the central segment when the prosthesis is in the expanded cross section.

12. An endoluminal prosthesis according to claim 1, characterized in that it also comprises a polymer layer on the wire support.

13. An endoluminal prosthesis according to claim 12, characterized in that the layer comprises a PTFE tubular sleeve that surrounds at least a central portion of the prosthesis.

14. A method for the fabrication of an endoluminal prosthesis, characterized in that it comprises the steps of: the provision of a length of wire; the formation of the wire in two or more zigzag sections, each zigzag section is separated by a cross-linking; the winding of the wire formed around an axis, to produce a series of tubular elements positioned along the axis such that each tubular element is connected to the adjacent tubular element by a connection.

15. A method according to claim 14, characterized in that it also comprises the step of placing a tubular polymer sleeve concentrically on at least one of the tubular elements.

16. A method according to claim 15, characterized in that the laying step comprises placing the tubular polymer sleeve concentrically on the outer surface of the tubular element.

17. A method according to claim 16, characterized in that the tubular polymeric sleeve comprises PTFE.

18. A multi-zone endoluminal prosthesis, characterized in that it comprises: a tubular wire support having a proximal end, a distal end, and a lumen or central lumen extending therethrough; the wire support comprises at least a first and a second axially adjacent tubular segments, connected with a connector extending between them; wherein the first tubular segment has a different radial resistance than the second tubular segment.

19. An endoluminal prosthesis according to claim 18, characterized in that it further comprises a third tubular segment, wherein at least one of the tubular segments has a different radial resistance than the other two tubular segments.

20. An endoluminal prosthesis according to claim 19, characterized in that a proximal end of the prosthesis is self-expanding to a larger diameter than a central region of the prosthesis.

21. An endoluminal prosthesis, comprising an elongate flexible wire, formed in a plurality of axially adjacent tubular segments spaced along an axis, each tubular segment comprising a zigzag section of the wire, having a plurality of proximal folds and distal bends, with the wire that continues between each adjacent tubular segment, wherein the prosthesis is radially compressible in a first reduced transverse configuration for implantation in a body lumen, and self-expandable to a second enlarged transverse configuration at a treatment site in a body lumen.

22. An endoluminal prosthesis according to claim 21, characterized in that it comprises at least three segments formed from said wire.

23. An endoluminal prosthesis according to claim 22, characterized in that it further comprises an outer tubular sleeve that surrounds at least a portion of the prosthesis.

24. An endoluminal prosthesis according to claim 23, characterized in that the sleeve further comprises at least one lateral perfusion gate extending therethrough.

25. An endoluminal prosthesis according to claim 22, characterized in that the prosthesis has a proximal end and a distal end, and at least one of the proximal end and the distal end is expandable to a larger diameter than a central section of the prosthesis in an expansion unconstrained

26. An endoluminal prosthesis according to claim 21, characterized in that at least one distal fold on a first segment is connected to at least one proximal fold from an adjacent segment.

27. An endoluminal prosthesis according to claim 26, characterized in that the connection comprises a connection that moves in pivot.

28. An endoluminal prosthesis according to claim 27, characterized in that the connection comprises a metallic connection.

29. An endoluminal prosthesis according to claim 27, characterized in that it comprises a suture.

30. An endoluminal prosthesis according to claim 21, characterized in that the prosthesis has an expansion ratio of at least about 1: 4.

31. An endoluminal prosthesis according to claim 30, characterized in that the prosthesis has an expansion ratio of at least about 1: 5.

32. An endoluminal prosthesis according to claim 21, characterized in that the prosthesis has an expanded diameter of at least about 20 mm to 30 mm in an unconstrained expansion, and the prosthesis is implantable using a catheter no greater than about 16 French.

33. A prosthesis according to claim 32, characterized in that the prosthesis has an expanded diameter of at least about 25 mm, and is implantable on a dispensing device having a diameter no greater than about 16 French.

34. A method for the implantation of an endoluminal vascular prosthesis, characterized in that it comprises the steps of: the provision of a self-expanding endoluminal vascular prosthesis, having a proximal end, a distal end and a central lumen extending through these, the prosthesis it is expandable from a first reduced diameter to a second enlarged diameter; the mounting of the prosthesis on a catheter, such that when the prosthesis is in the reduced diameter configuration on the catheter, the diameter of the catheter through the prosthesis is no greater than about 16 French; the introduction of the catheter into a body lumen, and placement of the prosthesis in a treatment site in the body lumen; the release of the prosthesis at the treatment site, such that the prosthesis expands from the first diameter to the second diameter; wherein the second diameter is at least about 20 mm