United States Patent [19]
`Andersen et al.
`
`US005366504A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,366,504
`Nov. 22, 1994
`
`[54]
`[75]
`
`[73]
`
`[21]
`[22]
`
`[63]
`
`[51]
`[52]
`[58]
`
`[56]
`
`Inventors:
`
`TUBULAR MEDICAL PROSTHESIS
`Erik Andersen, Roskilde, Denmark;
`Ernst P. Strecker, Karlsruhe,
`Germany
`Assignee: Boston Scienti?c Corporation,
`Watertown, Mass.
`912,902
`Jul. 13, 1992
`
`Appl. No.:
`Filed:
`
`Related U.S. Application Data
`Continuation-impart of Ser. No. 886,518, May 20,
`1992.
`
`Int. Cl.5 ........................ .. A61F 2/02; A61F 2/06;
`A61M 29/02
`U.S. Cl. .................................... .. 623/11; 606/194;
`623/ 1
`Field of Search ....................... .. 623/1, l1, 12, 66;
`606/ 191-200; 600/36
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,657,744 4/1972 Ersek .
`4,130,904 12/1978 Whalen .
`4,164,045 8/ 1979 Bokros et al. .
`4,300,244 11/1981 Bokros .
`4,327,736 5/1982 Inoue .
`4,626,255 12/1986 Reichart et a1. .
`4,708,141 ll/ 1987 Inoue et al. .
`4,717,387 l/ 1988 Inoue et a1. .
`4,733,665 3/1988 Palmaz .
`4,739,762 4/1988 Palmaz .
`4,776,337 10/1988 Palmaz .
`4,798,585 1/1989 Inoue et a1. .
`4,816,029 3/1989 Penny, III et al. .
`4,840,635 6/1989 Smith et a1. .
`4,922,905 5/ 1990 Strecker .
`4,990,158 2/ 1991 Kaplan et a1. ........................ .. 623/1
`4,994,071 2/ 1991 MacGregor .
`5,147,400 9/1992 Kaplan et a1. ...................... .. 623/ 13
`
`FOREIGN PATENT DOCUMENTS
`0335341 10/1989 European Pat. Off. .
`0364787 4/ 1990 European Pat. Off. .
`0441516 5/ 1991 European Pat. Off. .
`
`0461791A1 12/1991 European Pat. Off. .
`1173811 12/ 1969 United Kingdom .
`2225034 5/ 1990 United Kingdom .
`
`OTHER PUBLICATIONS
`Applicant’s knowledge of knit ?shing lures.
`Lawrence, David D. Jr., “Percutaneous Endovascular
`Graft: Experimental Evaluation”, Radiology, vol. 163,
`No. 2, May 1987, pp. 357-360.
`Guidoin et al., “Albumin Coating of a Knitted Polyester
`Arterial Prosthesis: An Alternative to Preclotting” The
`Annals of Thoracic Surgery, vol. 37, No. 6, Jun. 1984, pp.
`457-465.
`Mitchell et al., “Comprehensive Assessment of the
`Safety, Durability, Clinical Performance, and Healing
`Characteristics of a Double Velour Knitted Dacron
`Arterial Prosthesis”, Vascular Surgery, vol. 14, No. 3
`May/Jun. 1980, 197-212.
`Koopmann et al., “Degenerative Changes in Dacron
`External Velour Vascular Prostheses”, J. Cardiovas
`Surg., vol. 21, No. 2, Man-Apr. 1980, pp. 159-162.
`Kim et al., “Dilation of Synthetic Grafts and J unctional
`Aneurysms”, Arch. Surg., vol. 114, No. 11, Nov. 1979,
`pp. 1296-1303.
`May et al., “Multiple Aneurysms in Dacron Velour
`Graft”, Arch Surg., vol. 113, No. 3, Mar. 1978, pp.
`320-321.
`
`(List continued on next page.)
`
`Primary Examiner-Randall L. Green
`Assistant Examiner-Debra S. Brittingham
`Attorney, Agent, or Firm—Fish & Richardson
`
`ABSTRACT
`[57]
`A tubular prosthesis including a tubular wall portion of
`loosely interlocked pattern, e.g. of knitted loops, con
`structed to function within a body lumen. The loops are '
`preferably formed of co-knitted strand materials. A ?rst
`strand material is a metal strand that structurally de?nes
`the tubular shape of the prosthesis and maintains the
`shape when positioned in the lumen. A second strand
`material is a predetermined substance selected to pro
`vide desired characteristics to the wall of the prosthesis.
`
`29 Claims, 11 Drawing Sheets
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-1
`
`

`

`5,366,504
`
`I
`
`Page 2
`
`OTHER PUBLICATIONS
`Robicsek et al., “Indium Ill-labeled platelet deposition
`in woven and knitted Dacron bifurcated aortic grafts
`with the same patient as a clinical model”, Journal of
`Vascular Surgery, vol. 5, N0. 6, Jun. 1987, pp. 833-837.
`Rousseau et al., “Self-expanding Endovascular Pros
`thesis: An Experimental Study”, Radiology, vol. 164,
`No. 3, Sep. 1987, pp. 709-714.
`Carson et al., “Recurrence of Femoral Anastomotic
`Aneurysms”, The American Journal of Surgery, vol. 146,
`(1983), pp. 774-778.
`Harris et al., “A Comparative Study of Selected Physi
`cal Properties of Aortic Homografts and Heterografts”,
`Journal of Thoracic and Cardiovascular Surgery, vol. 57,
`No. 6, Jun. 1969, pp. 830-833.
`Schatz et al., “Report of a New Articulated Balloon
`Expandable Intravascular Stent (ABEIS)”, Circulation
`Supplement, vol. 78, No. 4, Oct. 1988, p. 11-449.
`Schatz et al., “Report of a New Radiopaque Balloon
`Expandable Intravascular Stent (RBEIS) in Canine
`Coronary Arteries”, Circulation Supplement, vol. 78,
`No. 4, Oct. 1988, p. II-448.
`Alvarado et al., “Evaluation of Polymer-Coated Bal
`loon-Expandable Stents in Bile Ducts”, Radiology, vol.
`170. No. 3, Mar. 1989, pp. 975-978.
`Bailey et al., “Polymer Coating of Palmaz-Schatz Stent
`Attenuates Vascular Spasm After Stent Placement”,
`Circulation Supplement‘, vol. 82, No. 4, Oct. 1990, p.
`III-541.
`Kram et al., “Optical Synthetic Grafts for Aortic Re
`
`placement”, W. B. Saunders Company, pp. 339-350.
`Wesolowski et al., “The Compound Prosthetic Vascu
`lar Graft: A Pathologic Survey”, Surgery, vol. 53, Jan
`.—Jun., 1963, pp. 1944.
`Chapman et al., “A Bioabsorbable Stent: Initial Experi
`mental Results”, Supplement III Circulation, vol. 82,
`No. 4, Oct. 1990, p. 0283.
`Waller et al., “Vessel Wall Pathology After Angio
`plasty”, Cardio, Aug. 1990, pp. 57-72.
`Kinley et al., “Compliance: A Continuing Problem with
`Vascular Grafts”, J. Cardiovas. Surg., vol. 21, No. 2,
`Man-Apr. 1980, pp- 163-170.
`Clark et al., “Mismatch of Mechanical Properties as a
`Cause of Arterial Prostheses Thrombosis”, Surgical
`‘Forum, pp. 208-210.
`Noldge et al., “Modelling of Transjugular Intrahepatic
`Portosystemic Shunts (T IPSS) With Stents”, Radiology
`vol. 31, No. 3, Mar. 1991, pp. 102-107.
`Sauvage et al., “Future Directions in the Development
`of Arterial Prostheses for Small and Medium Caliber
`Arteries”, Surgical Clinics of North America, vol. 54, No.
`1, Feb. 1974, pp. 213-228.
`Hall et al., “Velour Fabrics Applied to Medicine”, J.
`Biomed. Mater. Res., vol. 1, No. 2, Jun. 1967, pp.
`179-196.
`Lindenauer, “The Fabric Vascular Prosthesis”, V/Vas
`cular Gra?g pp. 450-460.
`‘
`Medi-tech, Boston Scienti?c Corporation, Strecker
`Stent product literature.
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-2
`
`

`

`US. Patent
`
`Nov. 22, 1994
`
`Sheet 1 of 11
`
`5,366,504
`
`1,4
`
`I
`is;
`
`24
`
`16 1a {"12
`
`_
`
`.’
`
`D
`
`38
`
`FIG. 1
`
`4°
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-3
`
`

`

`US. Patent
`
`Nov. 22, 1994
`
`Sheet 2 of 11
`
`5,366,504
`
`24
`
`I’
`dgT
`
`18
`
`16
`*
`
`{/26
`
`28
`
`FIG. 2
`
`28’
`
`FIG. 4
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-4
`
`

`

`US. Patent
`
`Nov. 22, 1994
`
`Sheet 3 of 11
`
`5,366,504
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-5
`
`

`

`US. Patent
`
`Nov. 22, 1994
`
`Sheet 4 of 11
`
`5,366,504
`
`'70
`76’
`73 /“ f
`
`F-vb
`
`L'b Y7'5
`
`FIG. 5
`
`FIG. 5a
`
`FIG. 5b
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-6
`
`

`

`U.S. Patent
`
`Nov. 22, 1994
`
`Sheet 5 of 11
`
`5,366,504
`
`FIG. 6b
`
`FIG. 66
`
`FIG. 6d
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-7
`
`

`

`US. Patent
`
`Nov. 22, 1994
`
`Sheet 6 of 11
`
`5,366,504
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-8
`
`

`

`US. Patent
`
`Nov. 22, 1994
`
`Sheet 7 of 11
`
`5,366,504
`
`IV.
`
`om
`
`mm
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-9
`
`

`

`U.S. Patent
`
`Nov. 22, 1994
`
`Sheet 8 of 11
`
`5,366,504
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-10
`
`

`

`US. Patent
`
`Nov. 22, 1994
`
`Sheet 9 of 11
`
`5,366,504
`
`I
`
`I
`
`nNw
`
`8
`
`ow
`
`‘ an .0E
`
`wm
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-11
`
`

`

`US. Patent
`
`Nov. 22, 1994
`
`Sheet 10 of 11
`
`5,366,504
`
`FIG. 7c
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-12
`
`

`

`US. Patent
`
`Nov. 22, 1994
`
`\ Sheet 11 of 11
`
`5,366,504
`
`FIG. 7d
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-13
`
`

`

`1
`
`15
`
`40
`
`TUBULAR MEDICAL PROSTHESIS
`
`5,366,504
`2
`some embodiments, different regions of the prosthesis
`are formed of different sets of materials. In still further
`embodiments, a tubular structure of a ?rst knit material
`CROSS-REFERENCE TO RELATED
`is provided as a sheath over a second tubular structure
`APPLICATIONS
`of another knit material.
`In one particular aspect, the invention features a tubu
`This application is a continuation—in-part of US. Ser.
`lar prosthesis having a tubular wall portion of loosely
`No. 07/886,518, ?led May 20, 1992, still pending, enti
`interlocked knitted loops constructed to function within
`tled “Device with a Prosthesis Implantable in the Body
`of a Patien ”, by Ernst Peter Strecker which is incorpo- 1
`0 a body lumen. The loops are formed of co-knitted
`rated herein by reference.
`strand materials where a ?rst strand material of the
`loops is a metal wire that structurally de?nes the tubular
`FIELD OF THE INVENTION
`shape of the prosthesis and maintains the shape when
`This invention relates to tubular prostheses which are
`positioned in the lumen and a second strand material of
`placed within the body.
`the loops is co-knitted with the metallic strand and is
`formed of a predetermined substance selected to pro
`BACKGROUND OF THE INVENTION
`vide desired characteristics to the wall of the prosthesis.
`Tubular prostheses are used in body lumens to per
`In another particular aspect, the invention features a
`form various functions. For example, a tubular stent
`vascular graft prosthesis for bridging an aneurysm in an
`may be used to maintain the opening of an esophagus
`arterial lumen of the body. The graft has a tubular wall
`that has been restricted by a tumor or a blood vessel
`portion of loosely interlocked knitted loops constructed
`restricted by plaque. Tubular grafts are used to substi
`to function within the arterial lumen. The loops are
`tute for or reinforce a weakened lumen, such as the
`formed of co-knitted strand materials where a ?rst
`aorta or other blood vessel that has been weakened by
`strand material of the loops is a metal wire that structur
`an aneurysm. In this latter technique, a graft of a knitted
`ally de?nes the tubular shape of the prosthesis and main
`dacron may be used to advantage since the textured
`tains the shape when positioned in the lumen and a
`nature of the textile can induce blood clotting along the
`second strand material of the loops, co~knitted with the
`graft to contribute to the patency of the lumen formed
`metallic strand, is formed of a predetermined non-met
`by the graft.
`allic substance selected to provide desired characteris
`Tubular prostheses for purposes such as the above
`tics to the wall of the prosthesis to enable it to perform
`may be positioned in the body lumen during a surgical
`its the function to effectively provide a patent covering
`procedure or may be delivered into the body by a cathe
`over the structure of the graft.
`ter that supports the prosthesis in a compact form dur
`In another particular aspect, the invention features a
`ing percutaneous insertion and transport through body
`vascular prosthesis for use in an arterial lumen of the
`passageways to a desired site. Upon reaching the site,
`body. The prosthesis has a tubular wall portion of
`the prosthesis is expanded so that it engages the walls of
`35
`loosely interlocked knitted loops constructed to func
`the lumen. After this operation, the catheter is removed,
`leaving the device in the body.
`tion within the arterial lumen. The loops are formed of
`The expansion technique may involve forcing the
`parallel co-knitted strand materials where a ?rst strand
`prosthesis to expand radially outwardly, for example,
`material of the loops is a metal wire that structurally
`by in?ation of a balloon carried by the catheter. Knit
`de?nes the tubular shape of the prosthesis and maintains
`ted, balloon expandable stents are discussed for example
`the shape when positioned in the lumen and a second
`in Strecker US. Pat. No. 4,922,905, the entire content of
`strand material of the loops, co-knitted with the metallic
`which we hereby incorporate by reference. In another
`strand, is a textured textile strand substance selected to
`technique, the prosthesis is formed of an elastic material
`enhance patency characteristics of the wall of the pros
`that can be arranged and held in a compact form for
`thesis.
`insertion and allowed to expand when in position by its
`In another particular aspect, the invention features a
`own internal elastic restoring force. Knitted self
`tubular prosthesis. The prosthesis has a tubular wall
`expanding stents are described in Strecker PCT EP
`portion of loosely interlocked knitted loops constructed
`91/02194 and in Anderson U.S. Ser. No. 07/773,847,
`to function within a body lumen. The loops are formed
`?led Oct. 9, 1991, the entire contents of both applica
`of multiple strand materials where a ?rst strand material
`tions being incorporated herein by reference.
`of the loops is a metal wire that structurally de?nes the
`tubular shape of the prosthesis and maintains the shape
`SUMMARY OF THE INVENTION
`when positioned in the lumen and a second strand mate
`The invention provides prostheses with improved
`rial of knitted loops is formed of a predetermined sub
`properties by forming the prostheses of multiple ?la
`stance selected to provide desired characteristics to the
`ments or strands of different materials,.one of which is
`wall of the prosthesis.
`a structural ?lament, preferably metal. In preferred
`In yet another particular aspect, the invention fea
`embodiments, the strands are knit into a tubular form. In
`tures a tubular prosthesis. The prosthesis has a tubular
`some embodiments, multiple strands of different materi
`wall portion of a loosely interlocked regular pattern of
`als are co-knit into a stent. The term “co-knit” as used
`strands constructed to function within a body lumen.
`herein refers to the knitting of multiple discrete strands
`The pattern is formed of multiple strand materials
`in the knit pattern. In certain preferred embodiments,
`where a ?rst strand material of the pattern is a metal
`the strands are in a parallel co-knit form, by which is
`wire that structurally de?nes the tubular shape of the
`meant the strands of the various substances lie in paral
`prosthesis and maintains the shape when positioned in
`lel in all contiguous loops of the co-knit portion of the
`the lumen and a second strand material of the pattern,
`knit pattern. In other embodiments, the multiple strands
`integrated with the metallic strand as part of the pat
`of different materials are alternately knit such that adja
`tern, is formed of a predetermined substance selected to
`cent rows of knit loops are of the different materials. In
`
`50
`
`55
`
`60
`
`65
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-14
`
`

`

`5,366,504
`3
`provide desired characteristics to the wall of the pros
`FIG. I is a side view, in magni?ed scale, of an aortic
`graft prosthesis according to the invention using two
`thesis.
`The features of the above aspects can be combined. In
`different strand materials co-knit into a tubular struc
`ture in parallel co-knit fashion, while FIG. 1a is a
`addition, various embodiments may include one or
`greatly expanded view of adjacent loops in the wall
`more of the following features. The prosthesis has an
`portion of the graft of FIG. 1;
`anchoring end portion of knitted loops which are knit
`ted integrally with at least a portion of the co-knitted
`FIG. 2 is a side view of another prosthesis according
`wall portion and formed of a strand material adapted to
`to the invention;
`make contact with the wall of the body lumen to main
`FIG. 3 is a side view of another prosthesis according
`tain the axial position of the prosthesis in the body lu
`to the invention, while FIG. 3a is an enlarged view of a
`men. The anchoring end portion is formed of contigu
`portion of the prosthesis of FIG. 3;
`ous loops of the ?rst, metal strand material joined inte
`FIG. 4 is a side view of another prosthesis according
`grally with the wall portion that includes the co-knit
`to the invention;
`second strand. The anchoring end portion of the pros
`FIG. 5 is a side view of another prosthesis according
`thesis is self-expanding and is formed of elastic metal
`to the invention, while FIG. 5a is an end-on view along
`strand capable of being reduced in radial size without
`lines aa and FIG. 5b is a cross-sectional view along the
`plastic deformation and retaining self-restoring capabil
`lines bb, respectively in FIG. 5 and FIG. 5c is an en
`larged view of a portion of the prosthesis of FIG. 5.
`ity such that the end portion can be reduced to a rela
`tively small size for introduction lengthwise into the
`FIG. 6 is a diagrammatic view of a circular knitting
`machine con?gured for alternate knitting while FIGS.
`lumen, and when freed can radially self-expand to tubu
`lar form to engage the wall of the lumen. The anchoring
`6a—6d illustrate the operation of a needle used in a circu
`end portion is formed of the plastically deformable
`lar knitting machine and FIG. 6e illustrates a circular
`knitting machine con?gured for parallel co-knitting.
`metal and is knit integrally with the wall portion. The
`anchoring end portion is formed of metal strand ?ared
`FIGS. 7-7d illustrate schematically, on a reduced
`to a diameter greater than the wall portion. The pros
`scale, placement of an embodiment of an aortic graft
`prosthesis in the body.
`thesis has an anchoring portion at each of its axial ends.
`The wall portion is expandable to desired size by means
`DESCRIPTION
`of an internal expanding force or is self-expanding. The
`?rst strand material of the wall portion is a plastically
`Referring to FIGS. 1 and 1a, an embodiment of a
`deformable metal and the wall portion is expandable to
`prosthesis according to the invention is a graft 10 which
`a desired size by application of an internal expanding
`may be positioned in the abdominal aorta 38 within an
`force. The ?rst strand is selected from tantalum and
`aneurysm 40. The graft 10, of overall length L1, e.g.,
`nitinol. The second strand is selected from dacron,
`about 8 cm, includes a wall portion 12, of length L2,
`wool, nylon, polyethylene and teilon. The material of
`e. g., about 5 cm, that spans the aneurysm 40 and anchor
`the second strand is textured to induce blood clotting.
`ing end portions 14, 14' each of length L3, e.g., about 1.5
`35
`The prosthesis is sized for use as an aortic graft having,
`cm, that engage healthy portions of the aorta to anchor
`for example a porosity of about 4000 ml/min or more at
`the prosthesis in the lumen. As illustrated, the graft 10 is
`implantation. The second strand is formed of a body
`formed of loosely interlocked knitted loops of material.
`fluid-dissolvable suture material. The second strand is
`The diameter d1 of the graft 10 and the respective
`an absorbing member that includes a drug. The second
`lengths are variable, as discussed below, to accommo
`strand material is a metal, such as a dense metal that
`date various aorta diameters and aneursym conditions.
`enhances the radiopacity of the prosthesis. The co-knit
`For example, the diameters may be in the range of
`strands are in a parallel co-knit pattern. The ?rst strand
`10-20 mm and prosthesis lengths L1 in the range of
`material and second strand material are continuously,
`about 4-8 cm.
`single knitted to form regions of the tubular knit struc
`Referring particularly to FIG. 1a, in the wall portion
`ture formed of the ?rst material and regions of the knit
`12, the loops are formed by parallel co-knitting of a ?rst
`structure formed of the second material. The ?rst and
`strand material 16, a metal, and a second strand material
`second strand materials are alternately knitted to form
`18, preferably of texturized ?lament or ?ber. The ?rst
`successive alternating loop rows of the ?rst and second
`strand material substantially de?nes the tubular struc
`material. The ?rst and second strand materials are
`ture of the graft and is a selected metal strand of wire
`formed as separate knitted loop tubular structures and
`such as tantalum. The second strand material 18 is pref
`the second strand knitted loop structure extends coaxi
`erably non-metallic, e.g. a polymer or natural textile
`ally with the ?rst strand knitted loop structure and
`?ber or the like, such as a textile yarn, selected to pro
`extends over an end of the ?rst strand knitted loop
`vide a desired characteristic of the prosthesis to enable
`structure to form a cuff to secure the ?rst knitted struc
`it to perform a desired function. In the case of an aortic
`graft, the second material is selected for its capability of
`ture to the second knitted structure. Rather than knit
`ting, the tubular prosthesis pattern is formed by co
`inducing the clotting of blood. In these embodiments,
`weaving or co-crocheting the strands, such as into a
`the second strand material 18 is preferably a texturized
`pattern formed of multiple parallel strands.
`material such as dacron yarn formed of crimped or
`The invention also includes methods for manufacture
`texturized multiple mono?laments, typically in excess
`and use of the prostheses described. Still other aspects
`of about 20, with multiple, randomly extending seg
`of the invention will be understood from the following
`ments 22 that extend into the open area 25 between
`adjacent knitted loops.
`description and from the claims.
`The anchoring portions 14, 14’ are formed of wire
`knitted strand 24, that does not include a co-knit strand.
`Strand 24 is integral with the wall portion 12 and may
`be a knitted extension of the metal strand material 16.
`(Alternately, the anchoring end portions may be a co
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`We ?rst briefly describe the drawings.
`Drawings
`
`60
`
`65
`
`20
`
`25
`
`40
`
`45
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-15
`
`

`

`5
`
`25
`
`35
`
`5,366,504
`5
`6
`properties which enhance performance. In general, at
`knit structure which may be the same or different from
`the co-knit structure of the central wall portion.)
`least one of the strands will be selected for its structural
`A particular aspect of this embodiment is parallel
`properties to enable the stent to maintain an open pas
`co-knitting to form rather loosely interlocked loops
`sage. In many preferred embodiments such strands are
`with selected, loop length, L4, e.g. about 1.8 m that
`of selected metal. The metal strand material may be of
`provides substantial open area 25. This design facilitates
`a metal selected to enhance radiographic visualization
`wrapping the prosthesis into small size for delivery
`of the prosthesis during the delivery through a body
`intralumenally. Wrapping produces a sliding action of
`lumen, the positioning at a desired site and the assessing
`adjacent loops within the open area that avoids stress
`of the efficacy of treatment. Particular advantages are
`concentrations in the wires, yet the size of the open area
`achieved when the metal strand is formed of a highly
`and texturized nature and number of strands formed of
`radiopaque metal such as tantalum. The metal strand
`the second material provides strand components that
`material also may be selected for features relating to its
`extend within the open areas of the loops. By suitable
`expandability, to enable a single size-prosthesis to be
`selection, these components can be suf?cient to produce
`manufactured for use in lumens of somewhat varying
`clotting in a suf?ciently short time that excessive bleed
`size as may be encountered from patient to patient. The
`ing through the graft will not occur when the graft is
`metal strand material may be a metal capable of yielding
`placed inside the lumen. A particular bene?t of this
`when the stent is expanded in the lumen by an internal
`design is that, generally, the graft need not be pre-clot
`radial force, such as by balloon expansion. Such a pros
`ted before placement. Over time in the body, the graft
`thesis is therefore size-selectable for the desired applica
`accepts cells, endothelializes and becomes a patent por
`tion. In other cases, the metal strand material is selected
`tion of the artery. The porosity of the graft may be, e.g.,
`to form an elastically self-expanding prosthesis which
`about 4000 ml/ min or more at implantation. This degree
`may be reduced to a small diameter for introduction
`of porosity facilitates migration of cells (e.g. ?broblasts
`into the body and allowed to expand at a desired site by
`and endothelial cells) into and through the knit struc
`release of a restraint. Embodiments in this case would
`ture such that cellular structure can be formed. (Graft
`use an elastic metal strand such as nitinol wire, which
`porosity as measured by water ?ltration testing is dis
`also can enhance maintenance of the elasticity of the
`cussed, for example, in Wesolowski, S. A. Dennis, G,
`vessel in which it is placed and can be used to widen an
`Fundamentals of Vascular Grafting, New York,
`occluded vessel. For example, the prosthesis may be
`McGraw-Hill, 1963.)
`used as a stent in the biliary duct or the esophagus to
`Further, the loosely interlocked loops formed by the
`widen these ducts in the cases where they have been
`co-knitting process of metal wire and the other selected
`occluded by tumors. In the case of stents formed by
`co-knitting another strand with a self-expanding elastic
`substance are free to slide with respect to each other
`metal, the co-knit portions may still require balloon
`while in use in the body. This ability for the loops to
`expansion because of the restraining effect of the second
`slide enhances the ability of the device to maintain its
`axial working length and resist migration when the
`strand, or to ensure good seating. The metal strand may
`prosthesis is locally radially compressed. Under such
`also comprise a two component cored material as dis
`compression the loop structure may locally lengthen or
`cussed in US. Ser. No. 07/861,253, ?led Mar. 31, 1992,
`the entire contents of which are hereby incorporated by
`shorten to accommodate similar changes in the vessel in
`reference.
`which it is installed, as may occur for instance if the
`aorta is stretched. The loosely co-knitted structure also
`The second strand material may be a wool, nylon,
`allows the graft to negotiate tortuous vasculature dur
`polyester, polyethylene or te?on, selected e.g. for the
`ing delivery on a catheter because of its flexibility longi
`degree of texture desired. Various embodiments may
`tudinally.
`also include a strand adapted for drug delivery. The
`The co-knitting has other advantages as well. For
`second strand material may also be a dissolvable suture
`instance, it provides a mechanism for attachment of
`45
`material or an absorbent such as hollow absorbent mate
`rial carrying drug that inhibits body rejection of the
`multiple strand materials without need for additional
`prosthesis or inhibits hyperplasia. The drug may be
`means such as tie strands and the like, although these
`optionally may be employed.
`slowly releasable as the strand dissolves, ?nally leaving
`only the thin metal ?rst strand to provide desired rein
`One embodiment of a graft as in FIG. 1 and 1a em
`forcing structure through the loops of which healthy
`ploys, in parallel with the metal strand, four parallel
`50
`strands of dacron (44DTEX), each strand consisting of
`endothelial tissue can gradually grow without the chaff
`ing or grinding effects that might occur at points of
`27 ?laments, full drawn R02 medical grade (available
`from E. I. DuPont de Nemours and Co., Wilmington,
`intersection of the strands that have dissolved. In other
`Del.). Before co-knitting, the strands are texturized by
`embodiments, both the ?rst and second strands are met~
`false twisting and set by radiation heating. Parallel co
`als that provide different desirable properties. For ex
`knitting with a tantalum wire strand (0.10 mm) is car
`ample, one strand may be an elastic material such as
`nitinol and the second strand a dense radiopaque strand
`ried out to produce a 10 mm diameter (d1) graft with a
`such as tantalum that enhances the ?uoroscopic visibil
`circumferential loop count of 12 loops and a wall por
`ity of the device. Preferably, in these latter embodi
`tion of 4 cm length (L2) consisting of 29 co-knit rows
`and anchoring end portions, of 10 single knit rows of
`60
`ments, one or both of the metal strands include a poly
`tantalum. The loop length of the knitted loops in the
`mer coating to avoid electrolytic corrosion induced by
`contact of dissimilar metals in an aqueous body ?uid
`axial direction is about 1.8 mm.
`environment. The coating may be selected to be dissolv
`Other Embodiments
`able. A drug may be incorporated in the coating so that,
`Generally, the principle of combining different
`by the dissolving action, the drug is released over time.
`strands to form a prosthesis provides a ready ability to
`The rate of dissolution of a coating may be selected so
`adapt the properties of the stent to suit various applica
`that removal of the coating occurs at a desired time, to
`tions, the respective strands being selected to provide
`enable electrolytic corrosion to dissolve one of the
`
`40
`
`55
`
`65
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-16
`
`

`

`25
`
`5,366,504
`7
`8
`strands, thereby to reduce the amount of metal remain
`lected for its elastic properties and the second strand is
`ing in the body. The coating may also be seeded with
`a radiopaque metal, with one or both of the metals
`?brin on the surface to control a ?brin layer with the
`including a coating to inhibit, at least temporarily, the
`aim of forming neuro intima. A strand material employ
`electrolytic degradation of the strands, as mentioned
`ing a semipermeable membrane for drug delivery can
`above.
`also be used. One such material is described in EP
`Referring to FIG. 4, in another embodiment, rather
`0441516, published Aug. 8, 1991, the entire contents of
`than parallel co-knitting, stent 60 is formed by continu
`which is hereby incorporated by reference.
`ous knitting of a ?rst strand 62, preferably a metal such
`Different portions of a prosthesis can be tailored with
`as tantalum and a second strand 64 such as dacron in
`speci?c, different properties, to achieve different func
`alternating regions, to perform speci?c functions. Metal
`tions, by using various strands of different materials at
`strand 62 in the end regions provide anchoring portions
`different locations, which are easily implemented dur
`while textile strand 64 provides a patent graft region.
`ing the knitting process. As illustrated above in FIGS. 1
`Referring to FIGS. 5-50, in another embodiment,
`and 1a, the anchoring portions 14, 14’ can be, for exam
`rather than parallel co-knitting, a graft 70 is provided
`ple, axial knitted extensions of the metal strand material
`that is formed of a ?rst, separately knitted tubular struc
`16 which may be produced by ceasing co-knitting of the
`ture 72 formed of a ?rst strand 73, e. g. tantalum, and a
`second strand material at a desired point in production.
`second separately tubular knitted structure 74, assem
`In some cases a second metal strand which can be of the
`bled coaxially within the ?rst structure 72 and formed
`same or different properties from the ?rst metal can be
`of a second strand 75, e.g. dacron. At the ends 76, 76’,
`added in this region to strengthen the anchoring por
`20
`the second tubular knit structure 74 is rolled over the
`tions or for other purposes.
`outside of the ?rst knit structure to form a cuff, to se
`In certain cases of an aortic graft, as discussed above
`cure the assembly together. The ?rst and second tubular
`with respect to FIGS. 1 and 1a, it is particularly advan
`knit structures may also be secured by sewing them
`tageous not to have clot-producing strands in the an
`together. In an alternative construction, the second
`choring region so that substantial clotting will not be
`tubular knitted structure of dacron could be a continu
`induced at the end portions where it is not necessary
`ously co-knitted extension of the first metal tubular
`and the mechanical properties of the metal strand can
`structure and the dacron knitted structure is pulled
`perform their function unimpeded to provide secure
`through the center of the metal structure. In other em
`anchorage. The strands at the end portions may be
`bodiments, the fabric knitted structure is on the outside
`selected to be elastic, self-expanding, or plastically de
`of the metal knitted structure or is sandwiched between
`forrnable.
`two metal structures or the metal knitted structure is
`Alternatively, the metal strand at the anchoring ends
`between two fabric knitted structures. In another em
`may be a different strand material than either the ?rs