Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Reexamination Certificate
1997-02-07
2001-04-24
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
C623S001510
Reexamination Certificate
active
06221099
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to tubular prostheses which are placed within the body.
BACKGROUND OF THE INVENTION
Tubular prostheses are used in body lumens to perform various functions. For example, a tubular stent may be used to maintain the opening of an esophagus that has been restricted by a tumor or a blood vessel restricted by plaque. Tubular grafts are used to substitute for or reinforce a weakened lumen, such as the aorta or other blood vessel that has been weakened by an aneurysm. In this latter technique, a graft of a knitted dacron may be used to advantage since the textured nature of the textile can induce blood clotting along the graft to contribute to the patency of the lumen formed by the graft.
Tubular prostheses for purposes such as the above may be positioned in the body lumen during a surgical procedure or may be delivered into the body by a catheter that supports the prosthesis in a compact form during percutaneous insertion and transport through body passageways to a desired site. Upon reaching the site, the prosthesis is expanded so that it engages the walls of the lumen. After this operation, the catheter is removed, leaving the device in the body.
The expansion technique may involve forcing the prosthesis to expand radially outwardly, for example, by inflation of a balloon carried by the catheter. Knitted, balloon expandable stents are discussed for example in Strecker U.S. Pat. No. 4,922,905, the entire content of which we hereby incorporate by reference. In another technique, the prosthesis is formed of an elastic material that can be arranged and held in a compact form for insertion and allowed to expand when in position by its own internal elastic restoring force. Knitted self-expanding stents are described in Strecker PCT EP 91/02194 and in Anderson U.S. Ser. No. 07/773,847, filed Oct. 9, 1991, the entire contents of both applications being incorporated herein by reference.
SUMMARY OF THE INVENTION
The invention provides prostheses with improved properties by forming the prostheses of multiple filaments or strands of different materials, one of which is a structural filament, preferably metal. In preferred embodiments, the strands are knit into a tubular form. In some embodiments, multiple strands of different materials are co-knit into a stent. The term “co-knit” as used herein refers to the knitting of multiple discrete strands in the knit pattern. In certain preferred embodiments, the strands are in a parallel co-knit form, by which is meant the strands of the various substances lie in parallel in all contiguous loops of the co-knit portion of the knit pattern. In other embodiments, the multiple strands of different materials are alternately knit such that adjacent rows of knit loops are of the different materials. In some embodiments, different regions of the prosthesis are formed of different sets of materials. In still further embodiments, a tubular structure of a first knit material is provided as a sheath over a second tubular structure of another knit material.
In one particular aspect, the invention features a tubular prosthesis having a tubular wall portion of loosely interlocked knitted loops constructed to function within a body lumen. The loops are formed of co-knitted strand materials where a first strand material of the loops is a metal wire that structurally defines the tubular shape of the prosthesis and maintains the shape when positioned in the lumen and a second strand material of the loops is co-knitted with the metallic strand and is formed of a predetermined substance selected to provide desired characteristics to the wall of the prosthesis.
In another particular aspect, the invention features a vascular graft prosthesis for bridging an aneurysm in an arterial lumen of the body. The graft has a tubular wall portion of loosely interlocked knitted loops constructed to function within the arterial lumen. The loops are formed of co-knitted strand materials where a first strand material of the loops is a metal wire that structurally defines the tubular shape of the prosthesis and maintains the shape when positioned in the lumen and a second strand material of the loops, co-knitted with the metallic strand, is formed of a predetermined non-metallic substance selected to provide desired characteristics to the wall of the prosthesis to enable it to perform its the function to effectively provide a patent covering over the structure of the graft.
In another particular aspect, the invention features a vascular prosthesis for use in an arterial lumen of the body. The prosthesis has a tubular wall portion of loosely interlocked knitted loops constructed to function within the arterial lumen. The loops are formed of parallel co-knitted strand materials where a first strand material of the loops is a metal wire that structurally defines the tubular shape of the prosthesis and maintains the shape when positioned in the lumen and a second strand material of the loops, co-knitted with the metallic strand, is a textured textile strand substance selected to enhance patency characteristics of the wall of the prosthesis.
In another particular aspect, the invention features a tubular prosthesis. The prosthesis has a tubular wall portion of loosely interlocked knitted loops constructed to function within a body lumen. The loops are formed of multiple strand materials where a first strand material of the loops is a metal wire that structurally defines the tubular shape of the prosthesis and maintains the shape when positioned in the lumen and a second strand material of knitted loops is formed of a predetermined substance selected to provide desired characteristics to the wall of the prosthesis.
In yet another particular aspect, the invention features a tubular prosthesis. The prosthesis has a tubular wall portion of a loosely interlocked regular pattern of strands constructed to function within a body lumen. The pattern is formed of multiple strand materials where a first strand material of the pattern is a metal wire that structurally defines the tubular shape of the prosthesis and maintains the shape when positioned in the lumen and a second strand material of the pattern, integrated with the metallic strand as part of the pattern, is formed of a predetermined substance selected to provide desired characteristics to the wall of the prosthesis.
The features of the above aspects can be combined. In addition, various embodiments may include one or more of the following features. The prosthesis has an anchoring end portion of knitted loops which are knitted integrally with at least a portion of the co-knitted wall portion and formed of a strand material adapted to make contact with the wall of the body lumen to maintain the axial position of the prosthesis in the body lumen. The anchoring end portion is formed of contiguous loops of the first, metal strand material joined integrally with the wall portion that includes the co-knit second strand. The anchoring end portion of the prosthesis is self-expanding and is formed of elastic metal strand capable of being reduced in radial size without plastic deformation and retaining self-restoring capability such that the end portion can be reduced to a relatively small size for introduction lengthwise into the lumen, and when freed can radially self-expand to tubular form to engage the wall of the lumen. The anchoring end portion is formed of the plastically deformable metal and is knit integrally with the wall portion. The anchoring end portion is formed of metal strand flared to a diameter greater than the wall portion. The prosthesis has an anchoring portion at each of its axial ends. The wall portion is expandable to desired size by means of an internal expanding force or is self-expanding. The first strand material of the wall portion is a plastically deformable metal and the wall portion is expandable to a desired size by application of an internal expanding force. The first strand is selected from tantalum and nitinol. The second strand is selected from dacron, wool, nylon, polyethyl
Andersen Erik
Strecker Ernst Peter
Boston Scientific Corporation
Fish & Richardson P.C.
Jackson Suzette J.
Willse David H.
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