JP2007526803A - Ribbon-shaped vascular prosthesis with stress relief joint and method of use - Google Patents

Abstract

A vascular prosthesis is provided having a self-expanding radial distal section connected to a ribbon-shaped helical section by a stress relief joint. The stress relief joint preferably comprises a first coupling member and a second coupling member, each having a hinge and interconnected between the distal section and the helical section, the first coupling member The proximal ends of the coupling member and the second coupling member are also interconnected by a hinge to allow the joint to rotate and compress relative to the distal and helical sections.

Description

(Technical field)
The present invention relates to an implantable vascular ribbon prosthesis having a helical section and at least one anchor section, wherein the anchor section is coupled to the helical section by a stress relief overlapping joint.

(Background technology)
There are today a wide range of endovascular prostheses marketed for use in the treatment of aneurysms, stenosis and other vascular abnormalities. Balloon expandable and self-expanding stents are well known, for example, to restore patency in constricted blood vessels after an angioplasty procedure, and the use of coils and stents is well known for treating aneurysms Technique.

  Previously known self-expanding stents are generally held in a reduced delivery configuration using an outer sheath and then self-expanding when the sheath is retracted. Such stents have several disadvantages in common, for example, they can experience large length changes during expansion (referred to as “shortening”) and are associated with the vessel wall. Before joining, it can shift within the blood vessel, resulting in improper placement. Furthermore, many self-expanding stents have a relatively large delivery profile. This is because the form of these struts limits further compression of the stent. Thus, such stents may not be suitable for use in smaller blood vessels such as cerebral blood vessels and coronary arteries.

  Other disadvantages associated with the use of coils or stents in the treatment of aneurysms may have a tendency to straighten or otherwise remodel delicate cerebrovascular when these devices are deployed, , Can cause further bad results. Furthermore, such devices may not adequately reduce blood flow from the cerebral blood vessels to the aneurysm sac, which may increase the likelihood of rupture. In general, if a larger surface area is employed to cover the sac, the delivery profile of the device can be compromised due to the increased surface area, and the device can also be more rigid, And it can cause blood vessel remodeling.

  For example, U.S. Patent No. 5,677,096 to Rivelli describes a stent that includes a mesh coil having a plurality of bends and includes a lattice having a plurality of pores. The grid is tapered along its length. In operation, the multiple turns are wound into a reduced diameter helical shape and then contracted into the delivery sheath. The delivery sheath is retracted, exposing the distal portion of the stent and anchoring the distal end of the stent. As the delivery sheath is further retracted, the next individual bend in the stent is unwound to match the vessel wall diameter.

  The stent described in the above publication has several disadvantages. For example, due to friction between the bend and the sheath, when the delivery sheath is retracted, the individual bends of the stent may gang up or overlap each other. Further, once the delivery catheter sheath is fully retracted, the bow of the ribbon stent may shift within the vessel before engaging the vessel wall, resulting in improper placement of the stent. Still further, ambiguity regarding the accuracy of stent placement may occur because the distal portion of the stent may provide poor engagement with the vessel wall during the remaining subsequent retraction of the sheath.

In view of these shortcomings of previously known devices, US patent application Ser. No. 10 / 342,427, filed Jan. 13, 2003, co-pending and assigned to the same person, It has been proposed to provide an implantable vascular prosthesis comprising a ribbon-shaped stent body coupled to a radially expandable anchor. As described in this application, this radially expandable anchor is first deployed to anchor the most distal portion of the ribbon-shaped stent body, thereby increasing the placement accuracy of the prosthesis. Increase.
International Publication No. 00/62711 Pamphlet

  Although the prosthetic devices described in the above-mentioned applications overcome many of the disadvantages of previously known ribbon stents, the connection between the helical section and the anchor provides a high level of stress during stent deployment. It has become recognized that you can experience. Such stress levels can exceed the elastic range of the stent material, resulting in sub-optimal deployment, or even stent fracture. Accordingly, it may be desirable to provide a vascular prosthesis having a distal anchor and a helical section connected by a stress relief joint.

  It would further be desirable to provide a ribbon-shaped stent with a distal anchor where the stress relief feature allows the planar hinge element to withstand axial compression in a direction perpendicular to the plane of the hinge element. obtain.

  It may also be desirable to provide a ribbon-shaped stent with a distal anchor having stress mitigating features that allow movement of high torsional loads while reducing the risk of generating inelastic strains.

  To provide a ribbon-shaped stent with a distal anchor having a joint that allows distribution of torsional load over an enlarged area, and to some extent to ensure that the helical and anchor sections of the stent cannot be separated It may be further desired to provide additional margin.

(Disclosure of the Invention)
In view of the foregoing, it is an object of the present invention to provide a vascular prosthesis having a distal anchor and a helical section connected by a stress relief joint.

  It is an object of the present invention to provide a ribbon-shaped stent with a distal anchor wherein the stress relief feature allows a planar hinge element to withstand axial compression in a direction perpendicular to the plane of the hinge element. Another purpose.

  It is also an object of the present invention to provide a ribbon-type stent with a distal anchor having stress mitigating features that allow movement of high torsional loads while reducing the risk of generating inelastic strains.

  Ribbon-shaped stent with a distal anchor having a joint that allows distribution of torsional load over an enlarged area, and to some extent to ensure that the helical and anchor sections of the stent cannot be separated It is a further object of the present invention to provide a ribbon-shaped stent that includes a sufficient number of connections.

  This and other objects of the present invention are achieved by providing a vascular prosthesis comprising a ribbon-shaped helical section that is coupled at its distal end to a radially expandable anchor. The section is connected to the anchor by a stress relief joint.

  In a preferred embodiment, the vascular prosthesis comprises a self-expanding helical ribbon section connected to a self-expanding anchor portion comprising either approximately a zigzag or cell-like strut configuration, wherein the anchor portion is initially Deployed to secure the most distal end of the stent within the vessel. According to the principles of the present invention, the helical section and the distal section are connected by at least one connecting member having a hinge. More preferably, the helical section and the distal section are connected by at least two connecting members each having a hinge, thereby allowing for the distribution of torsional load over a larger area of adjacent sections. Furthermore, the presence of multiple connecting members increases the safety of this vascular prosthesis by ensuring that the helical and distal sections cannot become separated.

  In one preferred embodiment, the distal anchor comprises a cell-like configuration having substantially straight axially oriented struts connected by a zigzag portion. Each zigzag preferably includes a bend having a “C” shaped semi-circular form. According to the invention, the first coupling member defines a distal edge of the helical section of the vascular prosthesis and is aligned with or relative to the longitudinal axis of the prosthesis. It includes a substantially straight portion extending from the apex of the bend so as to be disposed at an oblique angle. The first connecting member further comprises a planar hinge having a “C” shaped semi-circular portion similar to that of the bend connecting adjacent zigzag portions of the anchor section.

  A second coupling member extending from the adjacent bend apex of the anchor section may also be provided and secured at its proximal end, at the proximal end of the distal edge of the helical section, or at its particular midpoint Is done. This second connecting member preferably comprises a planar hinge that is substantially similar to the hinge provided in the first connecting member. This second coupling member distributes the torsional load imposed on the anchor section during deployment of the helical section and helps stabilize the distal edge of the helical section during deployment.

  For example, a method of using the vascular prosthesis of the present invention in the treatment of an aneurysm or stenosis is also provided.

  Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.

(Best Mode for Carrying Out the Invention)
The present invention is used in a wide range of applications such as treating aneurysms, maintaining vascular patency after angioplasty, or providing controlled delivery of therapeutic agents to the vessel wall The invention relates to an implantable vascular prosthesis in the form for. The vascular prosthesis of the present invention comprises a helical ribbon portion that is coupled via a stress relief joint to an anchor portion that radially self-expands at its distal end. This joint provides improved axial flexibility, improved distribution and stabilization of torsional stress, increased safety and accuracy in delivering the stent, and carelessness of the helical portion during deployment. Provide by reducing the risk of axial movement.

  With reference to FIGS. 1A and 1B, a first embodiment of a vascular prosthesis suitable for use with the stress relief joint of the present invention will be described. Vascular prosthesis 10 is described in co-pending and commonly assigned US patent application Ser. No. 10 / 342,427, filed Jan. 13, 2003, and each can be in a contracted and deployed state. A helical section 12 and a distal section 14. In FIGS. 1A and 1B, helical section 12 and distal section 14 are each depicted in their respective deployed states.

  The vascular prosthesis 10 is preferably formed from a solid tubular member that includes a shape memory material, such as a nickel-titanium alloy (generally known in the art as Nitinol). This solid tubular member is then laser cut into the desired deployed configuration as depicted in FIG. 1 using techniques known per se in the art. Appropriate heat treatment known per se in the art can then be applied to the solid region 16 of the vascular prosthesis 10 while the device is held in the desired deployed configuration (eg, on a mandrel). The processing of the shape memory material allows the vascular prosthesis 10 to self-expand into the desired deployed configuration, depicted in FIG. 1, for purposes described hereinafter.

  The distal section 14 preferably has a generally zigzag configuration in the deployed state, wherein the zigzag configuration is preferably formed by laser cutting a solid tube and has a plurality of bends 20. A pattern having a plurality of support posts 18 disposed therebetween is formed. The distal section 14 is designed to be initially deployed from the stent delivery catheter to secure the distal end of the stent at a desired known location within the blood vessel, whereby the next to the helical section 12 of the stent. Deployment can be achieved with greater accuracy.

  The helical section 12 preferably comprises a helical mesh form including a plurality of substantially flat bends 22. The plurality of bends 22 may include a plurality of openings provided in different shapes and sizes, as indicated by a larger rectangular opening 24, a smaller rectangular opening 26 and a small circular opening 28. Although the plurality of openings are disposed between solid regions 16 of the shape memory material used to form the vascular prosthesis 10, the form of the helical section 12 depicted herein is merely For illustrative purposes. The helical section 12 is coupled to the distal section 14 at a connection 30.

  With reference to FIGS. 2A and 2B, an alternative embodiment of a vascular prosthesis suitable for use with the stress relief joint of the present invention will be described. The vascular prosthesis 40 includes a helical section 42 and a distal section 44 that are joined at a connection 46. The distal section 44 comprises a radially self-expanding cell-like configuration comprising a pair of zigzags 48a, 48b connected by struts 48c. The cell configuration of FIG. 2 is expected to be more rigid than the single zigzag configuration of the embodiment of FIG. 1, and therefore can apply and withstand greater radial forces. The helical section 42 preferably comprises a helical ribbon that includes a plurality of bends 50 having a plurality of openings 52 provided in varying shapes and sizes.

  A vascular prosthesis 60 of the present invention will now be described with reference to FIGS. The prosthesis 60 is coupled to this distal section by a distal section 62 that is similar in design to that of FIG. 2 and a stress relief joint 66 of the present invention (shown in more detail in FIGS. 4A and 4B). Includes section 64. The distal section 62 comprises a plurality of cells defined by a pair of zigzags 68a, 68b connected by struts 68c, wherein adjacent portions of each zigzag preferably have a “C” shaped semi-circular form They are connected by a bend 68d. The helical section 64 preferably comprises a helical ribbon formed from a plurality of spirals 69.

  In accordance with the principles of the present invention, stress reducing joint 66 includes a first coupling member and second coupling members 70a and 70b, respectively. The connecting member 70 a preferably comprises a substantially straight portion that defines the distal edge of the helical section 64. This straight portion can be aligned either at an angle α parallel to or oblique to the longitudinal axis of the prosthesis. As better shown in FIG. 4, the connecting member 70a includes a hinge 72 connected to the proximal apex 73 of the zigzag 68b. Hinge 72 preferably has a flat “C” shaped semi-circular shape similar to that of bend 68d.

  The connecting member 70 b also includes a substantially straight portion 73 and a hinge 74. The hinge 74 is similar in design to the hinge 72 but has a concave surface opposite to the hinge 72. The connecting member 70b is bent at one end by a hinge 74 to the bend 68d of the proximal apex 75 of the zigzag 68b, the adjacent apex 73, and at the other end by the hinge 76 to the proximal end of the connecting member 70a ( Or at that particular intermediate position). Hinge 76 also preferably has the “C” shape configuration of hinges 72 and 74.

  The connection of the connecting members 70a and 70b via the respective hinges 72 and 74 to the bends 68d of the adjacent cusps 73 and 75 of the zigzag 68b is the long axis of the prosthesis of the accompanying zigzag section 68c Allows relative rotation and compression relative to the directional axis (as shown by the dotted line in FIG. 4A for connecting member 70a). This arrangement and the connection of the proximal ends of the connecting members 70a and 70b by the hinge 76 allows for the relatively independent movement of the components of the distal and helical sections, while the distal anchor section 62 and the helical section. It is expected to apply minimal stress to the connection between 64. The possible rotational movement caused by compression of the joint and its adjacent components is indicated by arrows in FIGS. 4A and 4B.

  Such an arrangement is advantageously expected to more evenly distribute the loads and stresses experienced during the deployment of individual sections of the prosthesis. The use of the first and second coupling members 70a and 70b can also reduce the risk of inelastic strain or fracture at the connection between the distal anchor and the helical section between the distal anchor and the helical section. Provide extra connectivity. In addition, the presence of the connecting member 70b connected to the proximal end (or a specific intermediate position) to the connecting member 70a is expected to stabilize the movement of the distal edge of the helical section of the prosthetic device during deployment. Is done.

  It can be appreciated by those skilled in the art that the advantages of the foregoing arrangement can be achieved using hinges other than the planar “C” shape semicircular form described above. For example, some or all of bend 68d and planar hinges 72, 74, and 76 may be replaced by a spiral portion similar to spiral 69 that defines helical section 64 of the prosthesis. As a further alternative, some or all of the hinges 72, 74, and 76 may include separately formed coil springs that are coupled to the distal and helical sections, for example, by welding. Still further, the hinges 72 and 74 need not be coupled to the cell apex of the distal section 62, but may instead be coupled to other portions of the proximal zigzag 68b.

  5 and 6, a preferred delivery catheter suitable for deploying the vascular prosthesis of the present invention will now be described. In FIG. 5, the inner member 80 of this delivery catheter is depicted, while FIG. 6 shows the inner member holding the vascular prosthesis of the present invention that is contracted onto the inner member 80 by a retractable sheath 92.

  Still referring to FIG. 5, the inner member 80 includes a shaft 81 that is typically used in catheter manufacture and includes a tough flexible material such as polyethylene, and is attached to the atraumatic tip 83. It includes a balloon 82 disposed adjacent to it. A radiopaque marker 84 is fixed adjacent to the tip 83 of the shaft 81 so that the distal end of the shaft is visible under fluoroscopic imaging. Balloon 82 may be formed from a stretchable or semi-extensible material such as nylon or PEBAX and is inflated through lumen 85. Lumen 85 can be pressurized with fluid from a syringe or inflator 86 that can be selectively coupled to the proximal end of shaft 81 as is known in the art.

  Inner member 81 includes a polymer layer 87 that engages the distal end of the distal section of the vascular prosthesis to prevent it from moving proximally when sheath 92 is retracted. The polymer layer 87 is preferably treated, for example, by formulation, mechanical friction, chemically or by heat treatment to increase the polymer tackiness or otherwise tighten the material. The polymer layer 87 may comprise the proximal shoulder of the balloon 82, or alternatively may be formed or applied separately from the balloon 82. As yet a further alternative, the balloon 82 may be omitted and the polymer layer 87 may be disposed adjacent to the distal end of the inner member.

  With reference to FIG. 6, delivery catheter 90 is shown preloaded with a vascular prosthesis 100 of the type shown in FIG. 3, wherein the prosthesis is constrained between inner member 80 and sheath 92. . The prosthesis 100 includes a distal section 102 that engages the polymer layer 87 and a helical section 104 that wraps around the shaft 81 of the inner member 80 to a small diameter. The sheath 92 restrains the vascular prosthesis 100 against the shaft 81 of the inner member 80 until the sheath is retracted proximally. Balloon 82 is shown deflated and wrapped around inner member shaft 81 in accordance with known techniques.

  The sheath 92 is depicted in its inserted configuration, where the sheath extends over the balloon 82 to a position just proximal to the distal end 83. Delivery catheter 90 may optionally include radiopaque marker bands 105, 106, and 107, respectively, on internal member 80 below the distal and proximal ends of distal section 102, and a helical section. Located at the proximal end of 104. The sheath 92 can also include a radiopaque marker 108 disposed adjacent to its distal end. The delivery catheter 90 preferably includes a guidewire lumen 109 that allows the delivery catheter to be slidably moved along the guidewire 110.

  In operation, delivery catheter 90 is advanced along the guidewire into the blood vessel containing the treatment area. The positioning of the vascular prosthesis with respect to this treatment area is confirmed using radiopaque markers 84 and 105-107. Once the delivery catheter is in the desired position, the sheath 92 is retracted proximally, allowing the vascular prosthesis 100 to deploy. The polymer layer 87 grips the distal section 102 of the stent 100 and engages the helical section 104 during withdrawal of the sheath 92 to prevent it from being pulled proximally. Instead, the polymer section 87 grips the distal section 102 for axial movement, and this distal section is radially outward for engagement with the vessel wall once the outer sheath is retracted. Allowing you to expand.

  Further, as described with respect to FIG. 7 below, the balloon 82 is expanded and contacts the vessel wall either before or after the distal section 102 is expanded to engage the vessel wall. The balloon 82 therefore anchors the distal end 83 of the delivery catheter 90 relative to the vessel wall so that there is no inadvertent axial movement of the delivery catheter during the proximal retraction of the sheath and the vascular prosthesis 100 distal sections 102 or helical sections 104 are released.

  Referring now to FIG. 7, a method for using the delivery catheter 90 of FIG. 6 to perform angioplasty and to deliver the vascular prosthesis 100 of the present invention will be described. Vascular prosthesis 100 is deployed in its delivery configuration with distal section 102 compressed around inner member 80 and held by sheath 92. The distal section 102 of the prosthesis 100 is placed in contact with the polymer layer 87 and prevents relative axial movement therebetween as described above.

  As shown in FIG. 7A, the delivery catheter 90 is percutaneously and transluminally along the guidewire 110, as determined by fluoroscopy, for example, with the catheter tip 83 attached to the body vessel V. The process proceeds until it is placed in the damage L inside. Once the balloon 82 is positioned adjacent to the injury L, the sheath 92 is aligned with the marker 105 of the inner member 80 so that the radiopaque marker 108 on the sheath 92 is thereby shown in FIG. 7B. The sheath is retracted proximally until it indicates that the sheath has been retracted beyond the balloon 82.

  With reference to FIG. 7C, once the balloon 82 is positioned adjacent to the injury L, the balloon can be inflated, expanding a portion of the blood vessel and destroying the plaque containing the injury L. The balloon 82 can then be deflated, moved to another location within the injury, and reinflated to destroy another portion of the injury L. This process is repeated until the damage is sufficiently destroyed and patency to the blood vessel is restored.

  Referring to FIG. 7D, after performing angioplasty, delivery catheter 90 is advanced such that balloon 82 is positioned adjacent to healthy tissue in the distal direction of the injury. Balloon 82 is then inflated to engage the vessel wall and prevent axial movement of the delivery catheter during subsequent retraction of sheath 92. Polymer layer 87 engages distal section 102 of vascular prosthesis 100, thereby preventing axial movement of distal section 102 during sheath 92 retraction.

  Referring to FIG. 7E, after the balloon 82 is inflated and engaged with the vessel wall, the sheath 92 is expanded until the distal section 102 self-expands into engagement with the vessel wall in the injury L or in its distal direction. Retreat proximally. Proximal movement of the sheath 92 can be stopped once the radiopaque marker 108 of the sheath 92 is substantially aligned with the radiopaque marker 106 of the inner member 80. When released from the restraint provided by the sheath 92, the struts of the distal section 102 expand radially and engage the interior of the blood vessel V. The stress relief joint comprising the coupling members 112a and 112b, in accordance with the principles of the present invention, relaxes the torsional force applied to the distal edge of the helical section 104 while the distal section 102 engages with the vessel V wall. Allow to engage.

Referring now to FIG. 7F, after the distal section 102 is secured to the distal vessel wall of the injury L, the sheath 92 is further retracted proximally and the helical section of the stent 100 is unwound, Then, it expands into the predetermined shape in the blood vessel V. During the proximal retraction of the sheath 92, each subsequent turn is unwound one at a time and engages and conforms to the inner wall of the blood vessel V in a controlled manner. Advantageously, the torsional force applied to the distal section 102 during deployment of the helical section 104 is distributed across the cells of the distal section 102 through the coupling members 112a and 112b and the associated hinges, Thereby reducing the risk of formation of inelastic strain or stress-induced fracture of the connection between the distal section 102 and the helical section 104.

  Furthermore, any torsional force imparted to the distal section 102 during withdrawal of the sheath 92 is evenly distributed over the surface of the balloon 82, thereby reducing the risk of vascular endothelium invasion. Once the last turn of the helical section of the stent 100 has been deployed, the balloon 82 is deflated and the sheath can be advanced to cover the balloon 82 as needed. The delivery catheter 90 is then withdrawn from the patient's blood vessel and the guidewire 110 is removed to complete the above procedure.

  While preferred exemplary embodiments of the present invention have been described above, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the invention. The appended claims are intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.

1A and 1B are side and perspective views, respectively, of a vascular prosthesis suitable for use with the stress relief joint of the present invention. 2A, 2B are side and perspective views, respectively, of an alternative embodiment suitable for use with the stress relief joint of the present invention. FIG. 3 is a perspective view of a vascular prosthesis including the stress reducing joint of the present invention. 4A and 4B of FIG. 4 are partial side views of the connecting member of the vascular prosthesis of FIG. FIG. 5 is a side view of an internal member of a delivery catheter suitable for use with the vascular prosthesis of the present invention. 6 is a side view, partially in section, showing the vascular prosthesis of the present invention disposed within a delivery catheter including the internal member of FIG. 7A-7G are side cross-sectional views showing a method of performing angioplasty and delivering a vascular prosthesis using the delivery catheter of FIG.

Claims (22)

A vascular prosthesis:
A distal anchor that self-expands radially;
A spiral section with multiple turns;
A vascular prosthesis comprising: a stress relief joint coupling the radially self-expanding distal anchor to the helical section. The vascular prosthesis of claim 1, wherein the radially self-expanding section comprises a zigzag configuration defining a plurality of cusps. The vascular prosthesis of claim 2, wherein each zigzag shaped apex comprises a pair of adjacent sections connected by flexion. The vascular prosthesis of claim 3, wherein the bend comprises a substantially “C” shaped semi-circular form. The stress relief joint comprises a first connecting member, the first connecting member comprising a substantially straight portion connected by a first hinge to the zigzag first point. The vascular prosthesis described in 1. The vascular prosthesis of claim 5, wherein a substantially straight portion of the first connecting member defines a distal edge of the last bend of the helical section. The vascular prosthesis of claim 5, wherein the first hinge comprises a substantially “C” -shaped semi-circular configuration. The stress relief joint further comprises a second connecting member, the second connecting member comprising a substantially straight portion connected by a second hinge to the zigzag second cusp; The vascular prosthesis of claim 5, wherein two cusps are disposed adjacent to the first cusp. The vascular prosthesis of claim 8, wherein the second hinge comprises a substantially “C” shaped semi-circular form. The vascular prosthesis of claim 8, wherein a proximal end of the first connecting member is connected to a proximal end of the second connecting member by a third hinge. The vascular prosthesis of claim 10, wherein the third hinge comprises a substantially “C” shaped semi-circular form. A vascular prosthesis:
A radially self-expanding distal anchor having a plurality of cells defined by a pair of zigzag features connected by axially oriented struts;
A spiral section with multiple turns;
A vascular prosthesis comprising at least one of the plurality of cells and a stress relief joint placed between the helical sections. The vascular prosthesis of claim 12, wherein each one of the plurality of cells includes a proximal apex. The vascular prosthesis of claim 13, wherein the proximal apex comprises a substantially “C” -shaped semi-circular form. The vascular prosthesis of claim 13, wherein the stress relief joint comprises a first coupling member coupled to a first proximal apex by a first hinge. The vascular prosthesis of claim 15, wherein the first coupling member comprises a substantially straight post. The vascular prosthesis of claim 15, wherein the first coupling member comprises a distal edge of the last bend of the helical section. The vascular prosthesis of claim 15, wherein the first hinge comprises a substantially “C” -shaped semi-circular form. The stress relief joint further comprises a second coupling member coupled to a second proximal apex by a second hinge, the second proximal apex adjacent to the first proximal apex. The vascular prosthesis according to claim 15, which is arranged as follows. The vascular prosthesis of claim 19, wherein the second hinge comprises a substantially “C” shaped semi-circular form. The vascular prosthesis of claim 19, wherein a proximal end of the first coupling member is coupled to a proximal end of the second coupling member by a third hinge. The vascular prosthesis of claim 21, wherein the third hinge comprises a substantially “C” -shaped semi-circular form.

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