Bifurcated graft with a superior extension

Details Bifurcated graft with a superior extension Bifurcated graft with a superior extension

2002-07-01

2003-12-09

Willse, David H. (Department: 3738)

Prosthesis (i.e., artificial body members), parts thereof, or ai

Arterial prosthesis

Stent structure

Reexamination Certificate

active

06660033

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to bifurcated intraluminal grafts, particularly for repairing defects in arteries and other lumens within the body. More particularly, the present invention relates to modular systems for forming bifurcated grafts and to methods for delivering and assembling same in situ for repairing defective body lumens, and particularly abdominal aortic aneurysms.
BACKGROUND OF THE INVENTION
An abdominal aortic aneurysm is a sac caused by an abnormal dilation of the wall of the aorta as it passes through the abdomen. The aorta is the main artery of the body, supplying blood to all organs and parts of the body except the lungs. It arises from the left ventricle of the heart, passes upward, bends over and passes down through the thorax and through the abdomen, and finally divides into the two iliac arteries which supply blood to the pelvis and lower extremities.
The aneurysm ordinarily occurs in the portion of the aorta below the kidneys. When left untreated, the aneurysm will eventually cause the sac to rupture with ensuing fatal hemorrhaging in a very short time. The repair of abdominal aortic aneurysms has typically required major abdominal surgery in which the diseased and aneurysmal segment of the aorta is removed and replaced with a prosthetic device, such as a synthetic graft.
As with all major surgeries, there are many disadvantages to the foregoing surgical technique, the foremost of which is the high mortality and morbidity rate associated with surgical intervention of this magnitude. Other disadvantages of conventional surgical repair include the extensive recovery period associated with such surgery; difficulties in suturing the graft to the aorta; the loss of the existing thrombosis to support and reinforce the graft; the unsuitability of the surgery for many patients, particularly older patients exhibiting co-morbid conditions; and the problems associated with performing the surgical procedure on an emergency basis after the aneurysm has already ruptured.
In view of the foregoing disadvantages of conventional surgical repair techniques, techniques have been developed for repairing abdominal aortic aneurysms by intraluminally delivering an aortic graft to the aneurysm site through the use of a catheter based delivery system, and securing the graft within the aorta using an expandable stent. Since the first documented clinical application of this technique was reported by Parodi et al in the Annals of Vascular Surgery, volume 5, pages 491-499 (1991), the technique has gained more widespread recognition and is being used more commonly. As vascular surgeons have become more experienced with this endovascular technique, however, certain problems have been encountered. One problem has been the difficult nature of the procedure. Particularly complex is the step of transferring one leg of the graft from one iliac artery to the other, which requires the careful manipulation of numerous catheters and guide wires. Another problem has been the kinking and/or twisting of the graft both during and after the graft has been implanted. Still other problems relate to the need for accurate preoperative measurements to be made on the morphology of the aneurysm and the surrounding arterial structure, including the length of the aneurysm, the infrarenal aortic length and diameter, the length and diameter of the aorta between the aneurysm and the iliacs, the diameter of the iliacs, and the angle between the iliacs and the aorta. The difficulty in making these measurements accurately and the wide variations in these measurements among patients mandates that the bifurcated grafts be available in a wide range of sizes and configurations.
There therefore exists a need for a bifurcated graft and an implantation method which will overcome the foregoing deficiencies of the prior art. More particularly, there exists a need for a modular graft system which will more accurately accommodate the widely varying arterial sizes in patients, as well as the other size considerations faced by the surgeon. There also exists a need for a method for delivering and implanting a bifurcated graft which avoids the complex procedure for implanting prior art bifurcated grafts.
SUMMARY OF THE INVENTION
The present invention addresses the needs.
One aspect of the present invention provides a modular prosthesis for repairing a tubular anatomical structure consisting of a base member foldable radially between a collapsed configuration and an expanded configuration and extending longitudinally between a proximal end and a distal end, a primary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, and joining means for intraluminally joining the distal end of the primary limb to the proximal end of the base member. Preferably, the joining means includes a friction fit engagement between the distal end of the primary limb in the expanded configuration and the proximal end of the base member in the expanded configuration.
In accordance with one embodiment of the modular prosthesis, the primary limb may have a first diameter at its proximal end and a second diameter less that the first diameter at its distal end. In this regard, the diameter of the primary limb may decrease from the proximal end toward the distal end at an angle of taper between about 2 degrees and about 15 degrees. In preferred embodiments, the primary limb may have a diameter at its proximal end of between about 16 mm and about 36 mm in the expanded configuration and a diameter at its distal end of between about 16 mm and about 25 mm in the expanded configuration. The primary limb may also have a length from its proximal end to its distal end of between about 6 cm and about 15 cm. Desirably, the primary limb includes an annular sleeve at its distal end, the annular sleeve having a substantially uniform diameter. The primary limb may also include securing means at its proximal end for securing the primary limb to the tubular anatomical structure.
The base member may have a first diameter at its proximal end and a second diameter greater than the first diameter at its distal end. In preferred embodiments, the base member may have a diameter at its proximal end of between about 16 mm and about 25 mm in the expanded configuration. The base member may also include an annular sleeve at its proximal end, the annular sleeve having a substantially uniform diameter. Preferably, the annular sleeve has a length between about 2 cm and about 15 cm.
The base member and the primary limb may both consist of a flexible layer which is radially supported along substantially its entire length by an expandable stent. In one embodiment, the expandable stent may be formed from a high shape-memory material. In another embodiment, the expandable stent may be formed from a low shape-memory material.
In accordance with another embodiment hereof, the base member may include dividing means for forming first and second passageways communicating between the proximal and distal ends of the base member. The dividing means may include a line of stitching joining one surface of the base member to an opposite surface of the base member. Alternatively, the dividing means may include a web of material arranged longitudinally inside the base member and defining a first substantially round aperture adjacent the distal end of the base member and a second substantially round aperture at a spaced distance from the distal end of the base member. Preferred embodiments may further include at least one secondary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, and connecting means for connecting the proximal end of the secondary limb to the distal end of the base member.
In accordance with a further embodiment of the present invention, a modular prosthesis for repairing a tubular anatomical structure consists of a base member foldable radially between a collapsed configuration and an expan

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