Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent in combination with graft
Reexamination Certificate
1999-09-09
2003-05-20
Milano, Michael J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent in combination with graft
C623S001140
Reexamination Certificate
active
06565596
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an intraluminal graft for use in treatment of aneurysms or occlusive diseases.
BACKGROUND ART
It is known to use stents and intraluminal grafts of various designs for the treatment of aneurysms such as aortal aneurysms and for the treatment of occlusive diseases such as the occlusion of blood vessels or like ducts such as the bile duct and the ureter (which are all hereinafter called “vessels”). It is known to form such an intraluminal graft of a sleeve in which is disposed a plurality of self expanding wire stents (see Balko A. et al., “Transfemoral Placement of Intraluminal Polyurethane Prosthesis for Abdominal Aortic Aneurysms”, Journal of Surgical Research 40, 305-309 (1986); Mirich D. et al, “Percutaneously Placed Endovascular Grafts for Aortic Aneurysms: Feasibility Study” Radiology, Vol. 170, No. 3, part 2, 1033-1037 (1989)). Such intraluminal grafts are inserted through the femoral artery into the aorta in a catheter. Upon the release of the graft from the catheter it expands to the size of the aorta above and below the aneurysms and bridges the aneurysms.
There are a number of problems associated with such known grafts. These include the problem of twisting or kinking of the graft when it has to extend along a non-linear path which, twisting or kinking can lead to occlusion of the lumen of the graft; lack of precise control of the expansion of the graft in the lumen; avoidance of inadvertent separation of a supporting stent and the covering sleeve; and maintaining the graft against longitudinal movement along the lumen in which it is placed. The present invention is directed to an alternative form of intraluminal graft which provides an alternative to the known grafts.
DISCLOSURE OF THE INVENTION
In a first aspect the present invention consists in an intraluminal graft comprising a tubular graft body which is circumferentially reinforced along its length by a plurality of separate, spaced-apart, maleable wires, each of which has a generally closed sinusoidal or zig-zag shape, one of the wires being located adjacent to one end of the graft body such that alternate crests or apices of the wire projects beyond at least part of that end.
In another aspect the invention relates to a method for positioning an intraluminal graft as defined above comprising introducing a catheter into a vein, artery or other vessel in the body, causing an intraluminal graft as defined above to be carried through the catheter on an inflatable balloon until the graft extends into the vessel from the proximal end of the catheter, inflating the balloon to cause the alternate crests or apices of the one wire to be urged into contact with the wall of the vessel, deflating the balloon and withdrawing the balloon and the catheter from the vessel.
In preferred embodiments of the invention each end of the graft will be provided with a wire which has alternate crests or apices extending beyond the adjacent end of the graft body. While the graft will normally have wires at each end of the graft with their crests extending beyond the graft body it may be necessary or desirable for a surgeon to shorten a graft and this may be achieved by cutting off part of the graft body. In this case the graft will have extending crests at only one end.
The projection of alternate crests or apices of the end wire or wires beyond at least part of the end or ends of the graft body is an important feature of this invention. As the graft is expanded by a balloon the expansion of the wires, and of the balloon, will be limited by the diameter of the tubular graft body except in the region of the alternate crests or apices of the end wire or wires. The balloon will be able to expand these crests slightly more than the remainder of the wire so that they bell outwardly away from the adjacent end of the graft body. The crests are forced into contact with the wall of the vessel and thereby become at least partly embedded into the vessel wall. This belling out of the crests of the wires at one or both ends of the graft body into contact with the inside surface of the vessel wall and then being at least partly embedded in the wall will assist in resisting any tendency for the graft to move longitudinally within the vessel after insertion. The wire crests may extend across the lumen of a vessel opening into the vessel in which the graft is being placed without occluding that lumen. This allows the intraluminal graft to be used in situations in which the aneurysm to be bridged commences closely adjacent divergent blood vessels. In most cases there will be crests of wire actually projecting totally beyond the end of the graft materials. It would, however, be possible to have flaps of graft material protruding up the outside of each crest even though intermediate the crests the end of the graft stops well short of the crests. In this latter arrangement the crests are still free to bell outwardly as has been described above even though the crests do not extend absolutely beyond the end of the graft.
It is preferred that the one wire has a greater amplitude than at least the next adjacent one or two wires. This allows the wires at the end of the graft to be positioned more closely together than would be the case if they were all of the same amplitude. It is desirable to space the wires adjacent the end of the graft that will be placed “upstream” in the patient as close together as is possible as the neck of the aneurysm with which the graft is engaged can be quite short. Close spacing of the wires maximises the number of wires reinforcing that part of the graft in contact with the neck of the aneurysm. The spacing of the rest of the wires is desirably greater than those adjacent the one end of the graft as this avoids unnecessarily reducing the flexibility of the graft.
The wavelength of the wires in the graft is preferably substantially the same when compressed however when expanded the end wires will have a shorter wavelength than the intermediate wires as the intermediate wires will not bear against the arterial wall and may therefore be more fully expanded.
It is preferred that the edge of the one end of the graft is scooped out or scalloped between each projecting crest of the one wire. This reduces the possibility that a piece of the graft between those crests could project into the arterial lumen and partially occlude it or direct blood around the outside of the graft.
The tubular graft body is preferably formed of a thin biocompatible material such as Dacron or PTFE. The tube material is preferably crimped along its length to increase its flexibility, however, uncrimped material may be used in suitable circumstances. In preferred embodiments of the invention the graft body may be formed from a material having a limited amount of diametric elasticity to ensure that it can be expanded into contact with the vessel wall. The length and diameter of the graft body will be determined by the individual circumstances of the application to which the intraluminal graft is to be put. Typically, the vessel will be assessed by X-ray or other similar examination and a suitably dimensioned graft selected for that application.
The wires are preferably formed of stainless steel or another metal or a plastic which is maleable and is biocompatible. Each wire is preferably woven into the fabric of the graft body to integrate the body and the reinforcing wires. This prevents any possibility of the wire reinforcement separating from the graft body during introduction of the graft or throughout its life. If the graft body is of a woven material the wires may be interwoven with the graft body during its production or alternatively they may be interwoven with the graft body after its manufacture. If the graft body is not woven but is knitted or of an impervious sheet material then the wires may be threaded through suitable holes formed in the graft body. The interweaving of the wires with the graft body has been found to be particularly desirable as it prevents separation of the wires from the graft b
White Geoffrey H.
Yu Weiyun
Endogad Research Pty Limited
Milano Michael J.
Phanijphand Gwen
LandOfFree
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