Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
2000-02-16
2001-04-03
Jackson, Gary (Department: 3731)
Surgery
Instruments
Internal pressure applicator
Reexamination Certificate
active
06210422
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a bifurcated graft and an apparatus and method for delivering the same within the body of a patient using a minimally invasive procedure. More particularly, the present invention includes a bifurcated vascular graft having two hollow cylindrical limb grafts of an equal first diameter attached to one another along a portion of their circumferences at their first ends and a third hollow cylindrical body graft of a larger diameter circumferentially positioned over the first two hollow cylindrical limb grafts such that the remaining unconnected end circumferences of the first two hollow cylindrical limb grafts are connected about an end circumference of the third hollow cylindrical body graft thereby bisecting the diameter of the third hollow cylindrical body graft in half.
The present invention also includes an apparatus and method for delivering the bifurcated vascular graft of the present invention which includes first and second hollow limb tubes of approximately equal diameter and varying lengths for containing the two hollow cylindrical limb grafts, a third hollow body tube having a larger diameter than the first and second hollow limb tubes for containing the hollow cylindrical body graft, a metal tube for containing a guide wire, and a hollow delivery tube which is capable of encompassing the first and second hollow limb tubes, the hollow body tube, and the metal tube.
BACKGROUND OF THE INVENTION
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 which have been used to exclude aortic aneurysms. These prior art grafts have been met with varying degrees of success.
Initially, straight tube grafts were used in the 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 or stented 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, latter improvements produced “Nitinol” stents which had a “memory” that was capable of expanding to a pre-determined size. Coincidentally, graft designers began to develop bifurcated grafts having limbs which 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 one centimeter 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 centimeter distance from the renal arteries to the most proximal aspect of the aneurysm are still required.
Many bifurcated grafts are of a two piece design. These 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 have also been designed. However, there deployment is still somewhat complicated and has torsion tendencies.
One piece bifurcated grafts are well 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. Yarns of varying materials can be used to weave the bifurcated graft including nylon and plastic yarns. U.S. Pat. Nos. 3,096,560 and 3,029,819 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 which is made from a preformed support in the shape of the bifurcated graft (i.e. mould). 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 by dipping or spraying the material on the mould in a second stage. Finally, after hardening of the material, the prosthesis is removed from the mould. 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 least 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 manufactures 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 bifurcated vascular graft which is structured to prevent the migration of the graft and the deformation and obstruction of the blood flow through the limbs of the bifurcated graft.
Endoluminal implantation is a common 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
Endologix, Inc.
Jackson Gary
Knobbe Martens Olson & Bear LLP
Trinh (Vikki) Hoa
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