WO2009145913A1

WO2009145913A1 - Kink-resistant stent graft

Info

Publication number: WO2009145913A1
Application number: PCT/US2009/003305
Authority: WO
Inventors: Steven J. Charlebois; William Kurt Dierking
Original assignee: MED Institute Inc
Current assignee: Cook Research Inc
Priority date: 2008-05-30
Filing date: 2009-05-29
Publication date: 2009-12-03
Anticipated expiration: 2010-11-30

Abstract

A kink-resistant tubular prosthesis with radially expansive landing zones, at least one corrugated segment adjacent to one of the landing zones, and at least one kink-resistant segment adjacent the at least one corrugated segment.

Description

KINK-RESISTANT STENT GRAFT

Description

Technical Field

The present invention relates to novel stent graft fabric designs.

Background Art

Over the past 10 years, endovascular aneurysm repair has become the treatment of choice for abdominal aortic aneurysms (AAA) with favorable post-op results compared to open repair. The move from open to endovascular treatments of AAA has involved a significant learning curve that has exposed specific problems and complications. Iliac artery elongation, tortuosity, and dilation are common in patients with aortic aneurysms. The loss of elastin may reduce support within the artery, thus leading to elongation and tortuosity, even in non-aneurysmal parts of the artery.

Disclosure Of The Invention

An endoluminal tubular prosthesis that may include a tubular graft material, two radially expansive landing zones, at least one corrugated segment and at least one kink-resistant segment, is provided. The landing zones may be located at the proximal end of the tubular prosthesis and at the distal end and/or of the tubular prosthesis. The at least one corrugated segment in the tubular graft material may be substantially free of any support structure and may be adjacent to at least one of the landing zones. The at least one kink-resistant segment in the tubular graft material may include at least one free stent adjacent the at least one corrugated segment.

According to an aspect of the present invention there is provided an endoluminal tubular prosthesis comprising tubular graft material; a radially expansive proximal landing zone; a radially expansive distal landing zone; at least one corrugated segment in the tubular graft material between the landing zones, said corrugated segment being substantially free of any support structure; and at least one kink-resistant segment in the tubular graft material comprising at least one free stent, said kink-resistant segment being adjacent the at least one corrugated segment.

Also provided is a flexible, kink-resistant endoluminal tubular prosthesis for use with a tubular bifurcated prosthesis. The prosthesis may include a first landing zone for coupling with a leg of the tubular bifurcated prosthesis and a second landing zone for placement in an iliac artery. Both landing zones may be radially expansive. There may be a segmented middle section that includes graft material with at least one corrugated segment substantially free of any support structure and at least one kink-resistant segment adjacent to the at least one corrugated segment.

According to a further aspect of the present invention there is provided a flexible kink resistant endoluminal tubular prosthesis for use with a tubular bifurcated prosthesis comprising a first landing zone for coupling with a leg of the tubular bifurcated prosthesis and a second landing zone for placement in an iliac artery, where both landing zones are radially expansive; and a segmented middle section between the landing zones comprising graft material having at least one corrugated segment free of any support structure and at least one kink-resistant segment adjacent to the at least one corrugated segment.

According to a further aspect of the present invention, there is provided a bifurcated, kink-resistant endoluminal tubular prosthesis for treatment of an abdominal aortic aneurysm comprising tubular graft material comprising a bifurcation and two distal branches; a radially expansive proximal landing zone; at least one corrugated segment in the tubular graft material and at least one kink-resistant segment in the tubular graft material adjacent to the at least one corrugated segment; and where at least one of the two distal branches comprises a distal landing zone comprising a radially expansive sealing portion, at least one stent, and is configured for coupling with a secondary prosthesis.

A bifurcated, kink-resistant endoluminal tubular prosthesis for treatment of an abdominal aortic aneurysm also is provided. The prosthesis may include a tubular graft material that includes a bifurcation and two distal branches, a proximal landing zone, at least one corrugated segment, and at least one kink-resistant segment. The proximal landing zone may be radially expansive. The bifurcation may be in communication with the two distal branches. The at least one kink-resistant segment in the tubular graft material may be adjacent to the at least one corrugated segment. At least one of the two distal branches includes a distal landing zone that is radially expansive, at least one stent, and is for coupling with a secondary prosthesis.

The provided devices advantageously overcome the elongation problems of some stent grafts and the difficulties faced by stent grafts when dealing with highly tortuous iliac arteries. The provided devices also are less prone to kinking and minimize graft occlusion.

Brief Description Of The Drawings

Figure 1 A is a coaxially extended view of a kink-resistant stent graft.

Figure 1B is a view of the proximal landing zone with stents.

Figure 2 is a partial cross-sectional view of an abdominal aortic aneurysm with a stent graft of the present invention deployed within.

Figure 3A is a view of a bifurcated kink-resistant stent graft with corrugated and kink-resistant sections above the bifurcation.

Figure 3B is a view of a bifurcated kink-resistant stent graft with corrugated and kink-resistant sections above and below the bifurcation. - A -

Description Of The Preferred Embodiments

The term "prosthesis" means any replacement for a body part or for a function of that body part or any device that enhances or adds functionality to a physiological system.

The term "graft or graft material" means a generally cannular or tubular member which acts as an artificial vessel or prosthesis. A graft by itself or with the addition of other elements, such as structural components, may be an endoluminal prosthesis. The graft includes a single material, a blend of materials, a weave, a non-woven, a laminate, or a composite of two or more materials.

The graft material is a biocompatible material that is both flexible and abrasion resistant. The woven graft material may be a woven polyester. The woven graft material may be a polyethylene terephthalate (PET), such as DACRON® (DUPONT, Wilmington, DE) or TWILLWEAVE MICREL® (VASCUTEK, Renfrewshire, Scotland). Woven polyesters, such as Dacron, possess varying degrees of porosity, where the degree of porosity may be selectively controlled based on the weaving or knitting process that is used to produce the woven polyester. Consequently, depending on the application, the porosity may be adjusted to encourage incorporation of a patient's tissue into the woven graft material, which in turn may more securely anchor the prosthesis within the patient's vessel or lumen. Furthermore, the degree of porosity also may be adjusted to provide a woven graft material that is impermeable to liquids, including blood or other physiological fluids.

The term "stent" means any device that provides some rigidity, expansion force or support to a prosthesis, such as a stent graft. In one configuration, the stent may be a plurality of discontinuous devices. In another configuration, the stent may be a unitary device. Stents may have a wide variety of configurations and may be balloon-expandable or self- expanding. Typically, stents have a circular cross-section when fully expanded, so as to conform to the generally circular cross-section of a body lumen. In one example, a stent may include struts (elongate portions) and acute bends (curvilinear portions) that are arranged in a zigzag configuration in which the struts are set at angles to each other and are connected by the acute bends. One example of a stent configuration is a Z-stent. The stents as described in this disclosure may be attached to the exterior of the graft, the interior of the graft, and/or may be sandwiched between two or more layers of graft material.

A variety of biocompatible materials may be employed to construct the stent, or portions of the stent, including metals and/or alloys, medically- acceptable polymers and/or bioabsorbable polymers or materials. The metals and/or alloys may, among other things, include stainless steel, tantalum, nitinol, gold, silver, tungsten, platinum, inconel, cobalt-chromium alloys and iridium, all of which are commercially available metals or alloys used in the fabrication of medical devices. In a preferred configuration, the stent is constructed from nitinol, stainless steel and/or cobalt-chromium alloys.

Throughout this specification, when discussing the application of this invention to the aorta or other blood vessels, the term "distal", with respect to a prosthesis, is intended to refer to a location that is, or a portion of the prosthesis that when implanted is, further downstream with respect to blood flow. The term "distally" means in the direction of blood flow or further downstream. The term "proximal" is intended to refer to a location that is, or a portion of the prosthesis that when implanted is, further upstream with respect to blood flow. The term "proximally" means in the direction opposite to the direction of blood flow or further upstream.

Disclosed here is an endoluminal tubular prosthesis that has flexibility, conformability, and kink resistance. It may be particularly useful in patients with highly tortuous iliac anatomies. The endoluminal tubular prosthesis may include tubular graft material. The prosthesis may include a landing zone that includes a radially expansive sealing portion at a proximal end of the tubular prosthesis. There also may be a landing zone that includes a radially expansive sealing portion at a distal end of the tubular prosthesis. The endoluminal tubular prosthesis also may include at least one corrugated segment in the tubular graft material free of any support structure (such as a stent) adjacent to at least one of the proximal landing zone or distal landing zone. The prosthesis may include at least one kink-resistant segment in the tubular graft material that includes at least one free stent, said segment being adjacent the at least one corrugated segment.

Figure 1A shows a kink-resistant tubular prosthesis 10 in an expanded configuration having alternating corrugated segments 13 and kink resistant segments 15. The proximal landing zone 25 and the distal landing zone 27 are located at or near the extremities of the prosthesis 10. The radially expansive landing zones 25, 27 may be self-expanding or made expansive by stents, as shown in Figure 1 B, or lengthwise or radially oriented folds 11 , as shown in Figure 1C. A landing zone 25, 27 with radially oriented folds 11 may be adjacent to a kink-resistant segment 15 or a corrugated segment 13. The landing zones may comprise standard thickness (Zenith) graft fabric. The proximal landing zone 25 may be joined with one of the distal legs of a bifurcated stent graft 19 as shown in Figure 2. The distal landing zone 27 may be implanted in an iliac artery 55 or another artery branching off from a main artery. The proximal 25 and distal 27 landing zones may include a stent 20. The landing zones 25, 27 may have an inner surface with a stent attached to the inner surface. When a stent is attached to the inner surface of the landing zone 25, 27, the exterior of the landing zone may be sealed flatly against a vessel wall or the wall of another endoluminal prosthesis in which the landing zone is placed such as a bifurcated stent. Such a seal may help prevent an endoleak.

The prosthesis includes a segmented middle section that may include kink-resistant 15 and corrugated segments 13. The middle section may have at least one corrugated segment 13 and at least one kink- resistant segment 15. The kink-resistant segment 15 includes non- corrugated graft material and may further comprise a stent 22 as shown in Figure 2. This stent may be placed either internally or externally in the segmented middle section. The kink-resistant segment 15 is adjacent to the corrugated segment 13. The kink-resistant segment 15 and the corrugated segment 13 may be non-adjacent in some circumstances.

The graft fabric in the stent supported kink-resistant segments 15 of the prosthesis may be non-corrugated and resistant to kinking due to the fabric's attachment to a wire stent 22. The fabric in this segment typically has a smooth texture and comprises low profile graft fabric. The stent 22 may be a Z-stent, typically 1cm long. The graft fabric segment between the kink-resistant stent segments 15 may be fashioned into corrugated segments 13. The corrugated segments 13 may be radially wavelike, have circumferential folds, or have a corrugated pleat configuration as shown in Figures 1A and 1 B. The corrugated segments 13 may be included to improve resistance to "infolding' or kinking when the prosthesis 10 is used to treat an aneurysm that is distorted or bent around a tight radius. The corrugated segment 13 also may comprise multi-dimensional crimps that provide for longitudinal expansion and contraction. The segmented middle section allows this prosthesis 10 to negotiate curves, such as curve 40, and tight radii due to optimized stent spacing and pleated fabric in some instances. This helps to avoid occlusion due to infolding. Where there are several alternating kink resistant segments 15 and corrugated segments 13 (such as in Fig. 1A) the stents 22 are typically spaced from about 2mm to about 6mm apart.

The diameters of the landing zones 25, 27 may be greater than the middle diameter of the kink-resistant segments 15. The greater diameters of the landing zones 25, 27 exert pressure on a vessel wall or the wall of another prosthesis 19 to give a fluid tight seal. Lengthwise or radial oriented folds added to the landing zones 25, 27 may serve also to increase the pull-out resistance of the prosthesis. The kink-resistant prosthesis 10 may be used to treat an aneurysm 50, such as an abdominal aortic aneurysm (AAA) or a thoracic aortic aneurysm (TAA). Figure 2 depicts prosthesis 10 in an AAA. A bifurcated prosthesis 19 has been implanted just distal the renal arteries 58 in the AAA. The proximal landing zone 25 of the prosthesis 10 is implanted in a leg 18 of the bifurcated prosthesis 19 and the distal landing zone 27 is implanted into iliac artery 55. The overlap region (whereby the landing zone 25 is in the leg 18) may comprise 2 to 3 stents. Stents 20 (dashed lines) are attached to the interior of both landing zones 25, 27 so that the graft material in the zones is in direct contact with the bifurcated prosthesis 19 and the iliac artery 55 wall.

The corrugated segments 13 may be pleated graft material being from about 2 mm to about 8 mm in length or any combination or subcombination therein. The corrugated segments 13 may be also from about 4 mm to about 6 mm in length or any combination or subcombination therein. The kink-resistant segment 15 may be from about 5 mm to about 15 mm in length or up to about 10 mm in length or any combination or subcombination therein.

Figures 3A and 3B show bifurcated kink-resistant prostheses 30. The proximal landing zones 48 and distal landing zones 42 are shown without stents but may include stents on the interior or exterior wall of the prosthesis. A corrugated segment 33 is adjacent the proximal landing zone 48 followed by a kink-resistant segment 35. Figure 3A shows a prosthesis having the corrugated 33 and the kink-resistant 35 segments above the bifurcation 60. In Figure 3B, the left distal leg 40 includes a segmented section below the bifurcation 60 that includes corrugated 33 and kink-resistant 35 segments. Both the proximal 48 and distal 42 landing zones may be radially expansive. Stents or lengthwise folds may be used in the landing zones 42, 48.

It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.

Claims

1. An endoluminal tubular prosthesis comprising: tubular graft material; a radially expansive proximal landing zone; a radially expansive distal landing zone; at least one corrugated segment in the tubular graft material between the landing zones, said corrugated segment being substantially free of any support structure; and at least one kink-resistant segment in the tubular graft material comprising at least one free stent, said kink-resistant segment being adjacent the at least one corrugated segment.

2. The endoluminal tubular prosthesis of claim 1 wherein the corrugated segment comprises circumferential folds in the graft material.

3. The endoluminal tubular prosthesis of claim 1 wherein the corrugated segment comprises multi-dimensional crimps in the graft material.

4. The endoluminal tubular prosthesis of claim 1 wherein the at least one kink-resistant segment comprises non-corrugated graft material.

5. The endoluminal tubular prosthesis of claim 1 wherein the support structure is attached to an inner surface of at least one of the landing zones.

6. The endoluminal tubular prosthesis of claim 1 wherein the prosthesis is bifurcated.

7. The endoluminal tubular prosthesis of claim 1 wherein a circumference of at least one of the landing zones is greater than a circumference of the at least one kink-resistant segment.

8. The endoluminal tubular prosthesis of claim 1 comprising any two or more of the following: a corrugated segment comprising circumferential folds in the graft material; a corrugated segment comprising multi-dimensional crimps in the graft material; at least one kink-resistant segment comprising non- corrugated graft material; a support structure comprising a stent; landing zones comprising an inner surface and where the support structure is attached to the inner surface of at least one of the landing zones; wherein the prosthesis is bifurcated; and wherein the circumference of at least one of the landing zones is greater than the circumference of the at least one kink-resistant segment.

9. A flexible, kink-resistant endoluminal tubular prosthesis for use with a tubular bifurcated prosthesis comprising; a first landing zone for coupling with a leg of the tubular bifurcated prosthesis and a second landing zone for placement in an iliac artery, where both landing zones are radially expansive; and a segmented middle section between the landing zones comprising graft material having at least one corrugated segment free of any support structure and at least one kink-resistant segment adjacent to the at least one corrugated segment.

10. The flexible, kink-resistant endoluminal tubular prosthesis of claim 9 where the at least one kink-resistant segment comprises non- corrugated graft material.

11. The flexible, kink-resistant endoluminal tubular prosthesis of claim 9 wherein a circumference of at least one of the landing zones is greater than a circumference of the at least one kink-resistant segment.

12. The flexible, kink-resistant endoluminal tubular prosthesis of claim 9 where the first or second landing zones comprise at least one stent.

13. The flexible, kink-resistant endoluminal tubular prosthesis of claim 12 wherein the support structure is attached to an inner surface of at least one of the landing zones.

14. The flexible, kink-resistant endoluminal tubular prosthesis of claim 9 comprising any two or more of the following: at least one kink-resistant segment comprising non- corrugated graft material; wherein a circumference of at least one of the landing zones is greater than a circumference of the at least one kink-resistant segment; the support structure comprises a stent; first or second landing zones comprising at least one stent; and wherein the support structure is attached to an inner surface of at least one of the landing zones.

15. A bifurcated, kink-resistant endoluminal tubular prosthesis for treatment of an abdominal aortic aneurysm comprising: tubular graft material comprising a bifurcation and two distal branches; a radially expansive proximal landing zone; at least one corrugated segment in the tubular graft material and at least one kink-resistant segment in the tubular graft material adjacent to the at least one corrugated segment; and where at least one of the two distal branches comprises a distal landing zone comprising a radially expansive sealing portion, at least one stent, and is configured for coupling with a secondary prosthesis.

16. The bifurcated, kink-resistant endoluminal tubular prosthesis of claim 15 where at least one of the two distal branches comprises at least one corrugated segment and at least one kink-resistant segment.

17. The bifurcated, kink-resistant endoluminal tubular prosthesis of claim 15 where the corrugated segment comprises circumferential folds in the graft material.

18. The bifurcated, kink-resistant endoluminal tubular prosthesis of claim 15 where the corrugated segment comprises multi-dimensional crimps in the graft material.

19. The bifurcated, kink-resistant endoluminal tubular prosthesis of claim 15 where the at least one kink-resistant segment comprises a stent.

20. The bifurcated, kink-resistant endoluminal tubular prosthesis of claim 15 comprising any two or more of the following: at least one of the two distal branches comprising at least one corrugated segment and at least one kink-resistant segment; a corrugated segment comprising circumferential folds in the graft material; a corrugated segment comprising multi-dimensional crimps in the graft material; and at least one kink-resistant segment comprising a stent.