WO2006036373A2

WO2006036373A2 - Thoracic aortic endograft

Info

Publication number: WO2006036373A2
Application number: PCT/US2005/029619
Authority: WO
Inventors: Darwin Eton
Original assignee: The University Of Miami
Priority date: 2004-09-16
Filing date: 2005-08-19
Publication date: 2006-04-06
Also published as: WO2006036373A3

Abstract

An endograft having a proximal end portion that that is curved to define an elbow or periscope configuration, to provide a more contiguous interface with the curvature of the aortic arch and thereby avoid stenosis and prevent embolism without creating streamlines that could cause the endograft to injure the underlying artery.

Description

THORACIC AORTIC ENDOGRAFT

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 60/610,207, which was filed on September 16, 2004, the disclosure of which is incorporated herein by this reference.

BACKGROUND OF THE INVENTION

The present invention relates to a device for repairing aneurysms and, more particularly, to an aortic endograft for repairing aneurysms near the aortic arch.

The aortic wall may weaken due to degeneration with aging and arteriosclerosis, congenital defects, infection, injury and other conditions. Weakening of the aortic wall generally results in a ballooning of the wall referred to as an aneurysm. Aneurysms affect the ability of the vessel lumen to conduct fluids and may be life threatening if rupture of the aortic wall results. One conventional treatment for repairing aneurysms is to surgically remove part or all of the aneurysm and implant a vessel graft section as a replacement in the vessel. Another conventional treatment is the percutaneous delivery of an endograft device to bridge the aneurysmal segment of the blood vessel.

Aortic endografts were designed in the 1990's to permit replacement of a diseased vessel segment from within the vessel (endovascularly) in lieu of open surgery. An endograft typically includes a graft material, such as Dacron or PTFE₁ and a frame or support structure such as a balloon expandable or self-expanding stent structure. The stent structure may be provided at each end of the graft or may extend along the length of the graft. Endografts are typically introduced percutaneously into the patient's circulatory system on or in a delivery device. More particularly, catheter technology is used to deliver the entire graft to the target vessel segment via an open puncture wound in the femoral artery (in the groin) or in the iliac artery (pelvis) or via an infrarenal aortic graft, or the aorta itself (in the abdomen). Once at the target aneurysmal site, the endograft either self expands or is balloon expanded to anchor the stent structure(s) above and below the aneurysm. The graft is held in place by the radial force of the stent(s) against the vessel wall, thereby sealing the weakened vessel segment from the circulatory flow. Isolating the aneurysm from the circulatory flow reduces pressure on the weakened vessel wall thereby reducing the likelihood of vascular rupture.

The repair of aneurysms located near the aortic arch is a particular challenge because of the location and the curvature of the vessel. In this regard, conventional thoracic endografts are typically provided as a simple elongated tube, supported throughout their length with a stent. When a straight, tubular endograft is stiffened by a correspondingly straight stent skeleton, as depicted in FIGURE 1 , the graft can override the inner convexity of the arch. When this happens, stenosis will result. If a substantial ledge is created, then the severe stenosis resulting may create ischemia distally. Also, the ledge can be a source for embolus and generate untoward forces on the aorta wall opposite the ledge, possibly leading to perforation.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention, to provide an endograft having a proximal end that that is curved to define an elbow or periscope configuration as an extension or expansion of the anchoring proximal neck, to provide a more contiguous interface with the curvature of the aortic arch, to avoid stenosis and prevent embolism without creating streamlines that could cause the endograft to injure the underlying artery.

Thus, the invention may be embodied in an endograft device comprising: an elongated, tubular graft main body portion having a longitudinal axis, a lumen defined therethrough and proximal and distal ends; a graft proximal end portion extending from said proximal end of said main body portion to terminate at a proximal end inlet opening, and having a lumen extending therethrough; said main body portion and said graft proximal end portion being formed of a graft material configured such that said proximal end inlet opening is disposed in a plane inclined at an angle of greater than zero degrees with respect to a transverse plane of said main body portion that is substantially perpendicular to said longitudinal axis of said main body portion. In an exemplary embodiment, the graft material is supported by a stent structure, said stent structure being provided at least to define and support a distal end of said main body portion and to define and support said graft proximal end portion, said stent structure being sufficiently rigid to define and substantially maintain a predetermined shape of said graft proximal end portion. The stent structure may be integrated with the graft material or may be disposed in the interior of the graft material. In the latter case, the endograft may be placed first and the stent material separately placed therein, or the endograft may be mounted to the stent structure before placement.

The invention may also be embodied in a thoracic aortic endograft prosthesis comprising: a tubular main body portion and an arched proximal end portion integrally formed with said tubular main body and defining an arched segment extending from a proximal end of said tubular main body portion to an open proximal end, said arched proximal end portion being one of supported by and formed from a sufficiently rigid material so as to define and maintain a predefined shape in the absence of external forces, such that said open proximal end is disposed at an angle with respect to a plane perpendicular to a longitudinal axis of said tubular main body portion.

The invention is also embodied in a method for endografting a blood vessel to repair a thoracic aortic aneurysm comprising the steps of: providing an endograft including a tubular main body portion and an arched proximal end portion integrally formed with said tubular main body and defining an arched segment extending from a proximal end of said tubular main body to an open proximal end, percutaneously delivering the endograft in an aneurysmal aortic segment so that the endograft extends across the aneurysmal segment to bridge the same; securing the endograft at least at proximal and distal ends thereof with respect to the aortic vessel; and supporting said arched proximal end portion so as to define and maintain a predefined shape in the absence of external forces, such that said open proximal end is disposed at an angle with respect to a plane perpendicular to a longitudinal axis of said tubular main body portion. In an exemplary embodiment, the endograft is supported by being one of supported by and formed from a sufficiently rigid material to define and maintain said predefined shape. For example the endograft may comprises a stent structure or have stent structure disposed within said tubular main body. In such an embodiment, said securing may comprise expanding said stent structure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of this invention, will be more completely understood and appreciated by careful study of the following more detailed description of the presently preferred exemplary embodiments of the invention taken in conjunction with the accompanying drawings, in which: FIGURE 1 is a schematic view, partly in cross-section, illustrating a prior art aortic endograft;

FIGURE 2 is a schematic view, partly in cross-section, depicting an aortic endograft provided in accordance with the invention disposed in an aneurysmal segment of the aorta;

FIGURE 3 is a schematic prospective view of an aortic endograft according to a first embodiment of the invention; and

FIGURE 4 is a schematic prospective view of a second embodiment of an aortic endograft according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an aortic endograft having a proximal end that is preformed as a curved end to conform to the aortic arch to provide better hemodynamics and eliminate graft slippage.

As noted above, conventional aortic endografts are provided as a straight tube 10 disposed in the descending portion 12 of the aortic arch 14. As schematically shown in FIGURE 1 , the curve in the aortic arch 14 presents a problem for such grafts and a stenosis can exist if the graft overrides the inner convexity of the arch, as shown at 16. To define a more contiguous interface with the aortic vessel in the vicinity of the aortic arch, to avoid stenosis and prevent embolism, the vascular aortic endograft 110 of the invention provides a periscope shaped proximal end 118 that is angled to follow the natural curvature of the aortic arch 114 and so as to terminate with an inlet opening 120 defined in a plane that is substantially perpendicular to the central axis of the aortic vessel.

Thus, with reference to the embodiment illustrated in FIGURE 2, the endograft device or assembly 110 provided in accordance with the invention may be generically characterized as comprised of an angled proximal end 118 and a generally tubular main body 122 having a support frame or stent 124, 126 for engaging the vessel adjacent the proximal or upstream and distal or downstream ends of the aneurysm to support and anchor the endograft with respect thereto. The stent structure may extend the entire length of the endograft structure or may be provided by generally discrete stent portions 124, 126 at proximal and distal ends of the endograft assembly, as in the illustrated embodiment. The stent 124, 126 may be located external or internal to the graft body, or imbedded within the graft material itself. Furthermore, the graft material may be placed and then the stent(s) placed within the graft material to define the final shape of and anchor the graft material or, in the alternative, the endograph already supported on stent(s) may be placed. The stent structure is preferably and advantageously formed from nitenol or another known temperature responsive, self-expanding memory metal. In the alternative, the stent structure may be provided as an expandable mesh, or other expandable configuration, that is adapted to be mechanically expanded at the target site in the blood vessel by, e.g., the inflatable balloon of a conventional delivery catheter. As a variety of stent/endograft delivery catheters are known in the art and may be adapted to deliver the endograft of the invention, and for clarity, the delivery catheter is not illustrated in the accompanying drawings.

In the embodiments illustrated in FIGURES 2-4, the inlet 120, 220 to the aortic endograft generally corresponds to an inner diameter of the aortic vessel 114 in which it is disposed, and the hood or elbow portion 118, 218 of the endograft 110, 210 is angled to define a gradual transition to the straight, main body portion 122, 222 of the endograft. As will be appreciated, the diameter of the endograft inlet 120, 220 generally corresponds to the diameter of the straight, main body portion of the endograft. The particular angle θ of the plane of the endograft inlet 120, 200 relative to a transverse plane of the main body of the endograft may be varied from an orientation that is generally perpendicular, as shown in FIGURE 4, to an orientation inclined with respect thereto, as shown in FIGURES 2-3. In an exemplary embodiment the plane of the endograft inlet is defined at an angle of between about 45 and 90° with respect to a transverse plane of the straight, main body portion 122, 222 of the endograft and the endograft's outer wall is continuously curved from the inlet opening to the top or proximal end of the straight portion of the endograft. Most preferably, the angle is between about 70 and 90°.

As will be understood, the stent structure that defines the shape of the endograft is preformed to define the angled, periscope or elbow shape. In a presently preferred embodiment, the endograft is made from a soft and malleable material and is supported throughout its length with a self expanding stent structure that is preformed to assume the desired periscope or elbow configuration. As an alternative, the endograft may be stent supported substantially only at its ends. In accordance with this alternative, the stent structure 126, 226 provided at the distal end may be a substantially cylindrical tube or cuff and the stent structure 124, 224 provided at the proximal end would be preformed to define the desired angled end of the endograft. Dacron is the preferred material for the endograft, but the invention is not limited to that material and other suitable materials, such as PTFE, are known and may be provided instead.

To implant the endograft of the invention, in accordance with the conventional procedure noted above, the entire graft is delivered to the target segment of the aorta via an open puncture wound in the femoral artery (in the groin) or in the iliac artery (pelvis) or via an infrarenal aortic graft, or the aorta itself (in the abdomen). The endograft of the invention is adapted to deal with aneurysms distal to the subclavian artery but the endograft is provided to bridge the entire length of the aneurysm and needs to anchor into an area of the arch which is not aneurysmal. Proximally that could be as high as to cover the origin of the subclavian artery, if necessary. The stent structure itself, whether extending the entire length of the endograft or defined only at its ends is adapted to provide a significant radial force that springs the graft open so it locks into the aorta. A balloon may be used to expand the stent graft further, if necessary for the endograft to secure to the aorta by radial force. If deemed necessary or desirable, stent anchors, such as pins on the stent, may be provided to more assuredly anchor the stent structure in position in the aorta.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. An endograft device comprising: an elongated, tubular graft main body portion having a longitudinal axis, a lumen defined therethrough and proximal and distal ends; a graft proximal end portion extending from said proximal end of said main body portion to terminate at a proximal end inlet opening, and having a lumen extending therethrough; said main body portion and said graft proximal end portion being formed of a graft material configured such that said proximal end inlet opening is disposed in a plane inclined at an angle of greater than zero degrees with respect to a transverse plane of said main body portion that is substantially perpendicular to said longitudinal axis of said main body portion.

2. An endograft device as in claim 1 , wherein the graft material is supported by a stent structure, said stent structure being provided at least to define and support a distal end of said main body portion and to define and support said graft proximal end portion, said stent structure being sufficiently rigid to define and substantially maintain a predetermined shape of said graft proximal end portion.

3. An endograft device as in claim 2, wherein said stent structure is located on the surface of the graft material.

4. An endograft device as in claim 2, wherein said stent structure is disposed in the lumen of the main body portion and in the lumen of the proximal end portion.

5.. An endograft device as in claim 2, wherein said stent structure is imbedded in the graft material.

6. An endograft device as in claim 2, wherein said stent structure extends the entire length of the graft material.

7. An endograft device as in claim 1 , wherein said angle is between about 45 and about 90 degrees.

8. An endograft device as in claim 7, wherein said angle is between about 70 and about 90 degrees.

9. An endograft device as in claim 8, wherein said angle is about

90 degrees.

10. A thoracic aortic endograft prosthesis comprising: a tubular main body portion and an arched proximal end portion integrally formed with said tubular main body and defining an arched segment extending from a proximal end of said tubular main body portion to an open proximal end, said arched proximal end portion being one of supported by and formed from a sufficiently rigid material so as to define and maintain a predefined shape in the absence of external forces, such that said open proximal end is disposed at an angle with respect to a plane perpendicular to a longitudinal axis of said tubular main body portion.

11. A thoracic aortic endograft prosthesis as in claim 10, wherein said angle is between about 45 and about 90 degrees.

12. A thoracic aortic endograft prosthesis as in claim 11 , wherein said angle is between about 70 and about 90 degrees.

13. A thoracic aortic endograft prosthesis as in claim 12, wherein said angle is about 90 degrees.

14. A thoracic aortic endograft prosthesis as in claim 10, wherein said arched proximal end portion is reinforced and supported by a stent structure.

15. A thoracic aortic endograft prosthesis as in claim 14, wherein said stent structure is formed from a self-expanding memory metal.

16. A thoracic aortic endograft prosthesis as in claim 15, wherein said stent structure is formed from Nitinol.

17. A thoracic aortic endograft prosthesis as in claim 14, wherein said stent structure also reinforces and supports said tubular main body portion.

18. A method for endografting a blood vessel to repair a thoracic aortic aneurysm comprising the steps of: providing an endograft including a tubular main body portion and an arched proximal end portion integrally formed with said tubular main body and defining an arched segment extending from a proximal end of said tubular main body to an open proximal end, percutaneously delivering the endograft in an aneurysmal aortic segment so that the endograft extends across the aneurysmal segment to bridge the same; securing the endograft at least at proximal and distal ends thereof with respect to the aortic vessel; and supporting said arched proximal end portion so as to define and maintain a predefined shape in the absence of external forces, such that said open proximal end is disposed at an angle with respect to a plane perpendicular to a longitudinal axis of said tubular main body portion.

19. A method as in claim 18, wherein said supporting comprises one of supporting the endograft with, and providing an endograft formed from, a sufficiently rigid material to define and maintain said predefined shape.

20. A method as in claim 19, wherein at least one of said tubular main body portion and said arched proximal end portion of said endograft comprises a stent structure or has a stent structure disposed therewithin, and wherein said securing may comprises expanding said stent structure.