Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Bifurcated
Reexamination Certificate
2001-02-28
2003-12-16
Milano, Michael J. (Department: 3731)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Bifurcated
Reexamination Certificate
active
06663665
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the endoluminal repair of abdominal aortic aneurysms at the aortic and iliac bifurcation, and more particularly, to a deployment system used to deploy a self-expanding prosthesis.
Endoluminal repair or exclusion of aortic aneurysms has been performed for the past several years. The goal of endoluminal aortic aneurysm exclusion has been to correct this life threatening disease in a minimally invasive manner in order to effectuate a patient's quick and complete recovery. Various vascular grafts exist in the prior art that have been used to exclude aortic aneurysms. These prior art grafts have met varying degrees of success.
Initially, straight tube grafts were used in the infrarenal abdominal aorta to exclude the aneurysmal sac from the blood stream thereby resulting in the weakened aortic wall being protected by the graft material. These straight tube grafts were at first unsupported, meaning that they employed stents at their proximal and distal ends to anchor the proximal and distal ends of the graft to the healthy portions of the aorta, thereby leaving a midsection of the graft or prosthesis that did not have any internal support. Although this type of graft at first appeared to correct the aortic aneurysm, it met with many failures. The unsupported nature of its midsection allowed the graft to migrate distally as well as exhibit significant proximal leakage due to the enlargement of the aorta without adaptation of the graft, such as enlargement of the graft, to accommodate the change in diameter of the aorta.
Later, technical improvements in stent design led to “self-expanding” stents. In addition, later improvements produced “Nitinol” stents that had a “memory” that was capable of expanding to a predetermined size. Coincidentally, graft designers began to develop bifurcated grafts having limbs that extended into the iliac arteries. The development of bifurcated grafts allowed for the treatment of more complex aneurysms. With the advent of bifurcated grafts, the need for at least a 1.0 cm neck from the distal aspect of the aneurysmal sac to the iliac bifurcation in order to treat the aneurysm with an endoluminal graft was no longer needed. However, proximal necks of at least 0.5 to 1.0 cm distance from the renal arteries to the most proximal aspect of the aneurysm are still generally required.
Some bifurcated grafts are of a two-piece design, in which an aorta and ipsilateral iliac segment is connected with a contralateral iliac branch in situ. The two-piece designs require the insertion of a contralateral limb through a separate access site. These types of grafts are complex to deploy and have the potential for leakage at the connection site of the two limbs of the graft.
One-piece bifurcated grafts are also known in the art. For example, U.S. Pat. No. 2,845,959 discloses a one-piece seamless woven textile bifurcated tube for use as an artificial artery. Yams of varying materials can be used to weave the bifurcated graft including nylon and plastic yams. U.S. Pat. Nos. 3,096,560 and 3,029,9819 issued to Liebig and Starks, respectively, disclose woven one-piece bifurcated grafts which are constructed by performing specific types of winding and weaving about a smooth bifurcated mandrel.
U.S. Pat. No. 4,497,074 describes a one-piece bifurcated graft that is made from a preformed support in the shape of the bifurcated graft. In a first stage, a gel enabling a surface state close to that of the liquid-air interface to be obtained at the gel-air interface is deposited by dipping or coating the preform with a sol which is allowed to cool. A hardenable flexible material such as a silicone elastomer is applied by dipping or spraying the material on the mold in a second stage. Finally, after hardening of the material, the prosthesis is removed from the mold. In U.S. Pat. No. 4,816,028 issued to Kapadia et al., there is shown a one-piece woven bifurcated vascular graft having a plurality of warp threads running in the axial direction and a plurality of weft threads running in the transverse direction. Further, U.S. Pat. No. 5,108,424 issued to Hoffman, Jr. et al. discloses a one-piece bifurcated collagen-impregnated Dacron graft. The bifurcated graft includes a porous synthetic vascular graft substrate formed by knitting or weaving with at Cast three applications of dispersed collagen fibrils.
The Herweck et al. patent, U.S. Pat. No. 5,197,976, discloses a continuous one-piece bifurcated graft having plural longitudinally parallel tube structures which are attached to one another over at least a portion of their longitudinal exteriors. The tube structures can be manually separated to form a branched tubular structure. The prosthesis is manufactured by paste forming and stretching and/or expanding highly crystalline unsintered polytetrafluoroethylene (PTFE). Paste forming includes mixing the PTFE resin with a lubricant, such as mineral spirits, and then forming the resin by extrusion into shaped articles.
Although all of the above-described one-piece bifurcated grafts have eliminated the problems of leakage and graft failure at the suture or juncture site associated with two piece bifurcated grafts which join together two separate grafts to form the bifurcated graft, problems still exist with these one-piece bifurcated grafts. For example, the previously described one-piece bifurcated grafts do not include an integral support structure to prevent the deformation, twisting or collapse of the graft limbs. Further, the same problems with graft migration that existed with straight tube grafts still exist with the one-piece bifurcated grafts. Accordingly, there is a need for a stable and durable transluminally implantable bifurcated vascular graft that is structured to prevent the migration and deformation of the graft and obstruction of the blood flow through the limbs of the bifurcated graft.
Endoluminal implantation is an increasingly accepted technique for implanting vascular grafts. Typically, this procedure involves percutaneously inserting a vascular graft or prosthesis by using a delivery catheter. This process eliminates the need for major surgical intervention thereby decreasing the risks associated with vascular and arterial surgery. Various catheter delivery systems for prosthetic devices are described in the prior art.
For example, bifurcated vascular grafts have been created by combining grafts with stents on delivery systems in order to secure the graft ends to the blood vessel thereby stabilizing the bifurcated graft. In U.S. Pat. No. 5,360,443 issued to Barone et al., a method for repairing an abdominal aortic aneurysm is described. The method comprises the steps of (1) connecting an expandable and deformable tubular member, such as a stent, to each of the tubular passageways of a bifurcated graft, (2) disposing the bifurcated graft and deformable tubular members within the aortic and iliac arteries, and (3) expanding and deforming each deformable tubular member with a catheter to secure each tubular passageway of the bifurcated graft within the appropriate artery. This reference only discloses a catheter delivery method for deploying the aortic portion of the bifurcated graft. The same catheter is supposedly used to also expand and secure the associated stents within the iliac arteries.
The Palmaz et al. patent, U.S. Pat. No. 5,316,023, describes a method and apparatus for repairing an abdominal aortic aneurysm in an aorta at the iliac arteries. This method includes the steps of connecting a first tubular graft to a first deformable and expandable tubular member, connecting a second tubular graft to a second deformable and expandable tubular member, disposing the first tubular graft and first tubular member upon a first catheter having an inflatable portion, disposing the second tubular graft and second tubular member upon a second catheter having an inflatable portion, intraluminally delivering the first and second tubular grafts, tubular members and catheters to the aorta and disposing at least a portion
Madrid Gilbert
Nguyen Thanh Van
Pham To Van
Pham Trinh Van
Shaolian Samuel M.
Davis Daniel Jacob
Endologix, Inc.
Knobbe Martens Olson & Bear LLP
Milano Michael J.
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