United States Patent [19]
`Myers et al.
`
`[54] INTRALUMINAL STENT GRAFT
`
`[75] Inventors: David J. Myers, Camp Verde; James
`D. Lewis, Flagsta?; Wayne D. House,
`Flagstaff; Karl E. Schwarz. Flagstaff,
`all of Ariz.
`
`[73] Assignee: W. L. Gore 8: Associates, Inc..
`Newark, Del.
`
`[21] Appl_ No; 109,214
`
`[22] Filed:
`
`Aug. 18, 1993
`
`[51] Int. Cl.6 ................................ .. A61F 2/06; A61F 2/04
`o o
`_ ________ "
`.
`.
`E?
`dclf Se rch
`623/1’ ?ag/‘13261119918
`,
`,
`................................... ..
`606/195; 623/1- 12
`
`O
`
`a
`
`]
`
`l
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4/1972 Ersek .
`3,657,744
`3/1975 Al?di et a1. .
`3,868,956
`4/1976 Gore .
`3,953,566
`4,130,904 12/1978 Whalen .
`4,140,126 2/1979 Choudury .
`4,190,909
`3/1980 Ablaza.
`4,300,244 11/1981 Bokros .
`4,313,231
`211982 Koyamada .
`4,512,228
`4/1985 Balko et a1. .
`4,553,545 11/1985 Maass et a1. .
`4,562,596
`1/1986 Kornberg.
`4,577,631
`311986 Kreamer .
`4,655,771
`4/1987 Wallsten .
`4,681,110
`7/1987 Wiktor .
`4,740,207
`4/1988 Kreamer .
`4,776,337 10/1988 Palmaz .
`4,787,899 11/1988 Lazarus.
`4,791,966 12/1988 Ei1entropp.
`4,320,293 4/1989 Leveen et a1. .
`4,377,030 10/1989 Beck et a1. .
`4,373,906 11/1939 Lmdemm e1 31 -
`213755413‘;
`gg?kgal' ‘
`5’078’726 1119” K 3 er‘
`£08910“. 2,19” Stiles .
`5,107,852
`4/1992 Davidson et a1. .
`5,122,154
`6/1992 Rhodes .
`
`'
`
`US0057
`
`35892A
`[11] Patent Number:
`[45] Date of Patent:
`
`‘
`
`5,735,892
`Apr. 7, 1998
`
`6/1992 Lee.
`5,123,917
`9/1992 Kwan-Getl.
`5,151,105
`5,156,620 10/1992 Pigou.
`5,211,658
`5/1993 Clouse.
`5,236,447
`8/1993 Kubo et a]. .
`5,254,113 10/1993 Wilk .................................. .. 606/195 X
`5,282,823
`211994 Schwartz et al. .
`5,282,824
`211994 Gianmrco.
`FOREIGN PATENT DOCUMENTS
`
`0010293 411980 European Pat. O?. .
`461791 12/1991 European Pat. O?'. .
`464755 1/1992 European Pal. O?'. .
`466518 1/1992 European Pat. O?". .
`480667 4/1992 European Pat. 01f. .
`508473 10/l9% European Pat. Off. .
`518704 17Jl992 European Pat. 01f. .
`528039 2/1993 European P81. 011. .
`I
`European Pat.
`53%37
`0551179 7/1993 European P61. 011‘. .
`3918736 12/1990 Germany.
`55-36492
`5/1976 Japan.
`53-67109 6/1978 Japan.
`60-17230 9/1985 Japan.
`8704935 8/1987 WIPO.
`9112779 9/1991 WIPO.
`9113648 9/1991 wIPo.
`OTHER PUBLICATIONS
`
`George P J M et aL, Covered expandable metal stent for
`recurrent tracheal obstruction. The Lancet, Mar. 1990;
`335:582-584.
`(List continued on next page.)
`Primary Examiner-Gary Jackson
`Assistant Examiner—Nancy Mulcare
`Attomey, Agent, or Firm—Wayne D. House
`
`[57]
`
`ABSTRACT
`
`A tubular intraluminal graft in the form of a tubular dia
`metrically adjustable stent having a tubular covering of
`porous expanded polyten'a?uoroethylene which is less than
`0.10 mm thick. The coven'ng may be on the exterior surface
`of the stent, or on the interior surface of the stent, or both.
`The covering may be a?ixed to the stent by an adhesive
`winch is preferably ?uormated ethylene propylene.
`
`_48 Claims, 4 Drawing Sheets
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-1
`
`

`
`5,735,892
`Page 2
`
`OTHER PUBLICATIONS
`
`Kato M et al.. Development of a chronic endothelialized
`transcatheter implantable intra-aortic graft. ASAIO Journal
`1993; M518-M521.
`Lawrence D D et al.. Percutaneous Endovascular Graft:
`Experimental
`Evaluation.
`Radiology May 1987;
`l63(2):3S7-360.
`Yoshioka T et a1. Self-Expanding Endovascular Graft: An
`Experimental Study in Dogs. AJR Oct. 1988; 151:673-676.
`Sayers R D et al.. Endovascular stenting of abdominal aortic
`aneurysms. Eur J Vasc Surg 1993; 7:225-227.
`Schneck R R and Derman G H. An Instraluminal Silastic
`Stent for Small Vessel Repair. Orth Clin North Amer. Apr.
`1977; 8(2):265-271.
`Yoshida H et al.. Transcatheter Placement of an Intraluminal
`Prosthesis for the Thoracic Aorta. ANew Approach to Aortic
`Dissection. ASAIO Transactions 1991;37:M272-M-273.
`
`Balko A et al.. Transfemoral Placement of Intraluminal
`Polyurethane Prosthesis for Abdominal Aortic Aneurysm.
`Iou of Surg Research 1986; 40:305-309.
`Chuter T AM et al.. Transfemoral Endovascular Aortic Graft
`Placement. Jour of Vas Surg Aug. 1993; vol. 18(2): 185-197.
`Cragg AH. Drake M D. Percutaneous Femoropopliteal Graft
`Placement. Radiology 1993; 187(3):643-648.
`Mirich D et al.. Percutaneously Placed Endovascular Grafts
`for Aortic Aneurysms: Feasibilty Study. Radiology 1989;
`170(3):1033-l037.
`Parodi J C et al.. Transfemoral Intraluminal Graft Implan
`tation for Abdominal Aortic Aneurysms. Annals of Vascular
`Surg 1991; vol. 5(6):491-499.
`Preminger T J et al.. Transluminal vascular stenting using a
`GORE-TEX covered stent: An experimental study. Pre
`sented at the congress of Pediatric Cardiology and Cardiac
`Surgery Jun. 21-25 1993.
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-2
`
`

`
`US. Patent
`
`Apr. 7, 1998
`
`Sheet 1 of 4
`
`5,735,892
`
`/IO
`
`by’ "
`f."
`
`n
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-3
`
`

`
`US. Patent
`
`Apr. 7, 1998
`
`Sheet 2 of 4
`
`5,735,892
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-4
`
`

`
`US. Patent
`
`Apr. 7, 1998
`
`Sheet 3 of 4
`
`5,735,892
`
`FlG.4
`
`35
`
`FIGS
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-5
`
`

`
`US. Patent
`
`Apr. 7, 1998
`
`Sheet 4 0f 4
`
`5,735,892
`
`\\\\\\\\\
`
`\
`
`FIG. 7
`
`FIG, 8
`
`FIG. 9
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-6
`
`

`
`5,735,892
`
`2
`minal use which comprise a sleeve having at least two
`diametrically-expandable stents. Rhodes teaches that the
`sleeve material is to be made of conventional vascular graft
`materials such as GORE-TEX® Vascular Graft (W. L. Gore
`&Associates. Inc.. Flagstaff Ariz.) or Irnpra® Graft (Impra.
`Inc. Tempe Ariz.). Both the GORE-TEX Vascular Graft and
`Irnpra Graft are extruded and longitudinally expanded PI‘FE
`tubes. Additionally. the GORE-TEX Vascular Graft pos
`sesses an exterior helical wrapping of porous expanded
`PTFE ?lm. The di?iculty with the use of either the GORE
`TEX Vascular Graft or the Impra graft as the sleeve com
`ponent is that the relatively thick. bulky wall of the extruded.
`longitudinally expanded P'I'FE tubes limits the ability of the
`tube to be contracted into a small cross-sectional area for
`insertion into a blood vessel. For example, the wall thickness
`of a 6 mm inside diameter Thin Walled GORE-TEX Vas
`cular Graft is typically 0.4 mm. The thinness of the wall is
`limited by the dif?culty of manufacturing an extruded.
`longitudinally expanded tube having a thin wall of uniform
`thiclmess.
`
`10
`
`15
`
`1
`INTRALUMINAL STENT GRAFT
`FIELD OF THE INVENTION
`This invention relates to the ?eld of intralurninal grafts
`and particularly to thin-wall intraluminal grafts useful as an
`inner lining for blood vessels or other body conduits.
`BACKGROUND OF THE INVENTION
`Conventional vascular grafts have long been used for
`vascular repair in humans and animals. These devices are
`typically ?exible tubes of Woven or knitted polyethylene
`terephthalate or of porous polytetra?uoroethylene
`(hereinafter P'I'FE). Grafts of biological origin are also used.
`these being typically ?xed human umbilical or bovine
`arteries. These conventional vascular grafts usually require
`invasive surgical methods that expose at least both ends of
`the segment of vessel to be repaired. Frequently it is
`necessary to expose the entire length of the vessel segment.
`These types of repairs consequently cause major trauma to
`the patient with corresponding lengthy recovery periods and
`may result in occasional mortality.
`Alternative methods have evolved which use intralurninal
`vascular grafts in the form of adjustable stent structural
`supports. tubular grafts or a combination of both. These
`devices are preferably remotely introduced into a body
`cavity by the use of a catheter type of delivery system.
`Alternatively they may be directly implanted by invasive
`surgery. The intent of these methods is to maintain patency
`after an occluded vessel has been re-opened using balloon
`angioplasty. laser angioplasty. atherectomy. roto-ablation.
`invasive surgery. or a combination of these treatments.
`Intraluminal vascular grafts can also be used to repair
`aneurysmal vessels. particularly aortic arteries. by inserting
`an intraluminal vascular graft within the aneurysmal vessel
`so that the prosthetic withstands the blood pressure forces
`responsible for creating the aneurysm
`Intraluminal vascular grafts provide a new blood contact
`ing surface within the lumen of a diseased living vessel.
`Intralurninal grafts are not. however. limited to blood ves
`sels; other applications include urinary tracts, biliary ducts,
`respiratory tracts and the like.
`If the intraluminal graft used is of thin enough wall and
`adequate ?exibility. it may be collapsed and inserted into a
`body conduit at a smaller diameter location remote from the
`intended repair site. A catheter type of delivery system is
`then used to move the intraluminal graft into the repair site
`and then expand its diameter appropriately to conform to the
`inner surface of the living vessel. Various attachment meth
`ods including the use of adjustable stents may be used to
`secure the intraluminal graft at the desired location without
`the necessity of invasive surgery.
`Intraluminal vascular grafts were suggested as early as
`1912 in an article by Alexis Carrel (Results of the permanent
`intnbation of the thoracic aorta. Surg.. Gyn and Ob.
`1912;15:245-248). U.S. Pat. No. 3.657.744 to Ersek
`describes a method of using one or more adjustable stents to
`secure a ?exible fabric vascular graft intraluminally, the
`graft and stent having been introduced distally and delivered
`to the desired position with a separate delivery system.
`Choudhury. U.S. Pat. No. 4.140.126. describes a similar
`method of repairing aortic aneurysms whereby a polyethyl
`ene terephthalate vascular graft is ?tted at its ends with metal
`anchoring pins and pleated longitudinally to collapse the
`graft to a size small enough to allow for distal introduction.
`Rhodes. U.S. Pat. No. 5.122.154 and Lee. U.S. Pat. No.
`5.123.917. describe endovascular bypass grafts for intralu
`
`SUNIMARY OF THE INVENTION
`The present invention is a tubular intraluminal graft
`comprising a tubular. diametrically adjustable stent having
`an exterior surface. a lurninal surface and a wall having a
`multiplicity of openings through the wall. and further having
`a tubular covering of porous expanded PTFE ?lm aflixed to
`the stent. said covering being less than about 0.10 mm thick.
`Porous expanded PTFE ?lm has a microstructure of nodes
`interconnected by ?brils and is made as taught by U.S. Pat.
`Nos. 3.953.566; 4.187.390 and 4.482.516. As will be
`described further. the ?brils may be uniaxially oriented. that
`is, oriented in primarily one direction. or multiaxially
`oriented. that is. oriented in more than one direction. The
`term expanded is used herein to refer to porous expanded
`PTFE. The terms expand. expanding and expandable we
`used herein to refer to diametrically adjustable intralurninal
`stents. More speci?cally. the term balloon-adjustable refers
`to stents of the Palmaz type as taught by U.S. Pat. No.
`4,776,337 which typically require a balloon catheter to
`increase the diameter of the stent within a blood vessel. The
`term self-expanding refers to stents which increase in diam
`eter by various other means. Stents of this type include stents
`of braided wire made as taught by Wallsten, U.S. Pat. No.
`4.544.771; and stents of formed wire made as taught by
`Gianturco. U.S. Pat. No. 4.580.568. Stents of this type
`expand to a larger diameter after being released from a
`constraining force which restricts them to a smaller diam
`eter. Self-expanding stents also include stents formed from
`Nitinol wire made as taught by PC!‘ U.S. Ser. No. 92103481.
`These stents expand in diameter when exposed to a slight
`increase in temperature.
`The tubular covering of porous expanded PI‘FE ?lm may
`be a?ixed to either the exterior surface or the luminal surface
`of the stent Alternatively. a ?rst tubular covering of porous
`expanded PTFE ?lm may be a?ixed to the exterior surface
`of the tubular diametrically adjustable stent and a second
`tubular covering of porous expanded PI‘FE ?lm may be
`a?ixed to the luminal surface of the tubular diametrically
`adjustable stent. The ?rst and second tubular coverings of
`porous expanded P'I'FE ?lrn may be a?ixed to each other
`through the openings through the wall of the stent.
`The porous expanded P'I‘FE ?lrn may be a?ixed to the
`stent with an adhesive. The adhesive may be a thermoplastic
`adhesive and more preferably a thermoplastic ?uoropolymer
`adhesive such as ?uorinated ethylene propylene (hereinafter
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-7
`
`

`
`5,735,892
`
`3
`FEP) or per?uoroalkoxy (hereinafter PFA). Where ?rst and
`second tubular coverings of expanded PI‘FE ?lm are a?ixed
`to each other through the multiplicity of openings in the stent
`wall. the two coverings may be af?xed by heating them
`above the crystalline melt point of the PTFE ?lm adequately
`to cause them to thermally adhere. or alternatively they may
`be a?ixed by an adhesive such as FEP.
`
`4
`enlarged schematic representations of alternative micro
`structures of porous expanded PTFE ?lms that may also be
`used for making the present invention. These microstruc
`tures have nodes interconnected by ?brils wherein the ?brils
`are oriented in at least two directions which are substantially
`perpendicular to each other. FIG. 3A describes a microstruc
`ture 30 of nodes 11 and ?brils 13 and 15 wherein the ?brils
`13 and 15 are biaxially-oriented ?brils which are oriented in
`two di?’erent directions that are substantially perpendicular
`to each other. Those microstructures may contain some
`?brils 17 which are not oriented in the two dilferent direc
`tions. FIG. 33 describes another alternative microstructure
`35 wherein the ?brils 21 are multiaxially-oriented ?brils
`oriented in virtually all directions within the plane of the
`sheet material. Either of these ?lms may be made by having
`been expanded two directions that are perpendicular to each
`other. The microstructure 30 of multiaxially~oriented ?brils
`21 may also have been made by being expanded in more
`than two directions as shown by FIG. 3B. The manufacture
`of these ?lms is taught by US. Pat. Nos. 3.953.566; 4.198.
`390 and 4.482.516.
`The ?bril lengths of the porous expanded P'I'FE ?lms
`referred to herein were estimated mean values obtained by
`examining scanning electron photomicrographs of these
`?lms. For multiaxialIy-oriented ?lms. these estimates
`included consideration of ?brils oriented in all directions.
`The mean ?bril lengths of the ?lms used to construct the
`intraluminal grafts of the present invention are preferred to
`be within the range of about 5 to about 120 microns.
`although ?bril lengths beyond this range may also be useful.
`Wall thickness measurements of intraluminal graft stent
`coverings were determined by cutiing away a portion of the
`covering that covered an opening through the stent wall. The
`thickness of the sample portion was measured by placing the
`sample portion between the pads of a Mitutoyo model no.
`804-10 snap gauge having a part no. 7300 frame. and gently
`easing the pads into contact with the sample portion until the
`pads were in full contact with the sample portion under the
`full force of the spring-driven snap gauge pads. Film density
`measurements were based on the bulk volume of a ?lm
`sample using the snap-gauge thickness measurement.
`The following examples of intraluminal stent grafts are
`intended to be illustrative only and are not intended to limit
`the scope of the invention to only the constructions
`described by these examples.
`
`EXAMPLEI
`A Nitinol wire stent 10 (Nitinol Medical Technologies.
`Boston. Mass.) of the type described by FIG. 1 was provided
`with both a luminal covering and an exterior covering of
`expanded PI‘FE ?lm. This 3 cm long stent was formed from
`0.25 mm diameter Nitinol wire into a tubular shape of
`interlocking hexagons. The luminal and exterior coverings
`were both made from a uniaxially-oriented ?lm having
`?brils oriented substantially in a single direction wherein the
`?brils were all substantially parallel to each other. The
`luminal covering was provided with the ?brils oriented
`parallel to the longitudinal axis of the tubular stent; the
`exterior covering was provided with the ?brils oriented
`substantially circumferential to the tubular stent. The ?lm
`used for both the luminal and exterior coverings was a
`porous expanded PTFE ?lm having a discontinuous. porous
`coating of FEP applied to one side of the porous expanded
`P'I'FE ?lm. Examination f the FEP coated side of the ?lm by
`scanning electron microscopy revealed FEP on only small
`portions of the nodes and ?brils at the surface of the ?lm. It
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a side view of a typical diametrically adjustable
`stent.
`FIG. 2 is an enlarged schematic representation of the
`microstructure of porous expanded P'I'FE ?lm having a
`microstructure with uniaxially-oriented ?brils as used to
`construct Examples 1 and 3.
`FIGS. 3A and 3B describe enlarged schematic represen
`tations of the rnicrostructure of porous expanded P'I'FE ?lm
`having mia'ostructures of multiaxially-oriented ?brils as
`used to construct Example 2.
`FIG. 4 is a transverse cross section of the stent of Example
`1 having a luminal layer of porous expanded I’I'FE ?lm with
`longitudinally-oriented ?brils and an exterior layer of porous
`expanded P'I'FE ?lm with circumferentially-oriented ?brils.
`FIG. 5 is a transverse cross section of the stent of Example
`2 having a luminal layer of porous expanded P'I'FE ?lm with
`biaxially-oriented ?brils.
`FIG. 6 is a transverse cross section of the stent of Example
`3 having an exterior layer of porous expanded PI'FE ?lm
`30
`with circumferentially-oriented ?brils.
`FIG. 7 describes a method of collapsing a previously
`outwardly adjusted balloon-expandable stent.
`FIG. 8 describes the ?tting of a single trrbular sleeve to
`both the exterior and luminal surfaces of a stent.
`FIG. 9 describes the removal a covered. braided wire stent
`of the self-expanding type from a manufacturing mandrel by
`evening the braided wire, thereby placing the covering on
`the luminal surface of the stent.
`
`20
`
`25
`
`35
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`FIG. 1 is a side view of a typical diametrically adjustable
`stent. The stent is shown as it would appear implanted into
`a body conduit with its diameter adjusted beyond the col
`lapsed pre-implantation diameter. While the stent shown is
`made from metal wire. a perforated sleeve having perfora
`tions of suitable shape. size and quantity may also be used.
`Various suitable stents are described by US. Pat. No.
`4.776.337 to Palmaz and PCI‘ U.S. Ser. No. 9W0348l to
`Hess. These stents may be made from implantable metals
`such as titanium. stainless steel. or Nitinol.
`The stent may be provided with an exterior covering of
`porous expanded PI‘FE ?lm. or a luminal covering of porous
`expanded PTFE ?lm. or with both exterior and luminal
`coverings. Uniaxially-oriented ?lms having a microstructure
`of uniaxially-oriented ?brils wherein substantially all of the
`?brils are oriented parallel to each other may be used.
`Multiaxially-oriented ?lms having a microstructure of biaxi
`ally or multiaxially-oriented ?brils wherein the ?brils are
`oriented in at least two directions which are substantially
`perpendicular to each other may also be used.
`FIG. 2 describes an enlarged schematic representation of
`the microstructure of nodes 11 connected by ?brils 12 of a
`?lm 20 wherein the uniaxially-oriented ?brils 12 are sub
`stantially parallel to each other. FIGS. 3A and 3B describe
`
`45
`
`55
`
`65
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-8
`
`

`
`5
`was estimated that less than 10% of the available node and
`?bril surface area exposed at the surface of the ?lm was
`covered by FER The presence of the FEP adhesive thus had
`little or no adverse etfect on the porosity of the porous P'I'FE
`?lm.
`The FEP-coated porous expanded PI‘FE ?lm was made
`by a process which comprises the steps of:
`a) contacting a porous PI'FE ?lm with another layer
`which is preferably a ?lm of FEP or alternatively of
`another thermoplastic polymer;
`b) heating the composition obtained in step a) to a
`temperature above the melting point of the thermoplas
`tic polymer;
`c) stretching the heated composition of step b) while
`maintaining the temperature above the melting point of
`the thermoplastic polymer; and
`d) cooling the product of step c).
`In addition to FEP. other thermoplastic polymers includ
`ing thermoplastic ?uoropolymers may also be used to make
`this coated ?lm. The adhesive coating on the porous
`expanded PTFE ?lm may be either continuous (non-porous)
`or discontinuous (porous) depending primarily on the
`amount and rate of stretching, the temperature during
`stretching. and the thickness of the adhesive prior to stretch
`ing.
`The discontinuously FEP-coated porous expanded PTFE
`?lm used to construct this example was of about 0.01 mm
`thickness and had a density of about 0.3 g/cc. The micro
`structure of the porous expanded P'I'FE contained ?brils of
`about 50 micron mean ?bril length.
`A 3.0 cm length of film 20 having uniaxially-oriented
`?brils was wrapped as a single layer 41 around a hollow,
`tubular. 1.5 cm outside diameter mandrel 43 of non-porous
`PTFE to form a seam 45 as described by the cross section of
`FIG. 4. The seam edges 45 overlapped as shown by about 3
`mm. The ?brils of the ?lm were oriented parallel to the
`longitudinal axis of the mandrel; the FEP-coated side of the
`?lm faced away from the surface of the mandrel. The Nitinol
`stent was carefully ?tted over the ?lm-wrapped portion of
`the mandrel. The 3 cm length of the stent was centered over
`the 3.0 cm length of ?lm-wrapped mandrel. The stent was
`then provided with an exterior covering 47 of a 3.0 cm wide
`tape of the ?lm described above by wrapping the tape
`circumferentially around the exterior surface of the maadrel
`so that the edges of the circumferentially-wrapped tape
`overlapped by about 3 mm to form seam 49. The circum
`ferentially wrapped covering was oriented so that the FEP
`coated side of the tape faced inward in contact with the
`exterior surface of the stent and the outward facing FEP
`coated surface of the luminal layer of ?lm exposed through
`the openings in the stent. Except for the overlapped seam
`edges 49. the circumferentially-wrapped covering was only
`one ?lm layer thick. The uniaxially-oriented ?brils of the
`microstructure of the circumferentially-wrapped tape were
`circumferentially-oriented about the exterior stent surface.
`The ?lm-wrapped mandrel assembly was placed into an
`oven set at 360° C. for a period of 4 minutes after which the
`?lm-wrapped mandrel was removed from the oven and
`allowed to cool. Following cooling to approximately ambi
`ent temperature, the mandrel was removed from the ?lm
`wrapped stent. The amount of heat applied was adequate to
`melt the FEP-coating on the porous expanded P'I'FE ?lm and
`thereby cause adjacent layers of ?lm to adhere to each other.
`Thus the luminal layer of ?lm was adhered to the exterior
`circumferentially wrapped layer through the openings
`between the adjacent wires of the stent. The combined
`thickness of the luminal and exterior coverings was about
`0.005 mm.
`
`35
`
`45
`
`55
`
`65
`
`5,735,892
`
`6
`The ?lm-covered stent was then chilled in a bath of ice
`water while being rolled between human ?ngers applying
`compression diametrically across the stent. This reduced the
`outside diameter of the stent to about 0.3 cm. The collapsed
`stent was then heated by immersion in about 40° C. water.
`thereby increasing the stent diameter to about 1.5 cm. The
`?lm covering showed no visible adverse e?ects from the
`process of shrinln'ng and increasing the stent diameter.
`
`10
`
`EXAMPLE 2
`A Nitinol wire stent of the same type used for Example 1
`was provided with a luminal covming of a porous expanded
`P'I'FE ?lm having a microstructure of biaxially-oriented
`?brils as shown by FIG. 3A. This was accomplished by
`wrapping a hollow tubular mandrel of non-porous PTFE
`with a layer of porous expanded PTFE ?lm having a
`continuous (non-porous) coating of FEP with the FEP
`coated side of the ?lm facing outwardly away from the
`mandrel surface. This ?lm was about 0.02 mm thick; the
`porous expanded PI‘FE had a microstructure of uniaxially
`oriented ?brils with the ?brils oriented circumferentially
`about the exterior surface of the mandrel. The Nitinol stent
`was carefully ?tted over the ?lm-wrapped portion of the
`mandrel. The mandrel assembly was then placed into an
`oven set at 360° C. for four minutes. After removal from the
`oven and subsequent cooling. the mandrel was removed
`from the stent leaving the wrapped ?lm adhered to the
`luminal surface of the stent. This ?lm was then peeled from
`the luminal stent surface. leaving the FEP-coating and some
`small shreds of residual porous expanded P'I'FE adhered to
`the luminal surface of the stent wires. By removing the ?lm
`and leaving the FEP adhesive on the luminal stent surface.
`the ?lm served only as a release substrate for the application
`of the adhesive to the stent surface.
`As shown by FIG. 5. the mandrel 43 was then provided
`with a single layer 51 wrapping of a porous expanded PTFE
`?lm 35 having a microstructure of biaxially-oriented ?brils.
`This ?lm was of about 30 micron ?bril length. about 0.08
`mm thickness, about 0.3 g/cc density and did not have an
`FEP coating. The biaxially-oriented ?brils were oriented to
`be substantially parallel to the longitudinal axis of the
`mandrel and to the circumference of the mandrel.
`The ?lm was overlapped adequately to form a 2 mm wide.
`longitudinally oriented seamline 45 parallel to the longitu
`dinal axis of the mandrel. A sheet of polyamide ?lm was
`temporarily placed over the sm'face of the seam and then
`contacted with the surface of a hand-held iron set at 400° C.
`to cause the P'I'FE ?lm seam edges to adhere to each other.
`Excess material beyond the 2 mm wide seam was trimmed
`away and discarded. The stent was again carefully ?tted over
`the ?lm-covered mandrel. The resulting assembly was
`placed into an oven set at 380° C. for three minutes and then
`removed and allowed to cool. after which the mandrel was
`removed from the stent. The porous expanded PTFE ?lm
`appeared to be well adhered to the luminal surface of the
`wire stent by the FEP coating left from the ?rst. previously
`removed. layer of ?lm. The wall thickness of the PTFE ?lm
`covering was about 0.08 mm.
`The ?lm-covered stent was then chilled in a bath of ice
`water while being rolled between human ?ngers applying
`compression diametrically across the stent. This reduced the
`outside diameter of the stent to about 0.3 cm. The collapsed
`stent was then heated by immersion in about 40° C. water.
`thereby increasing the stent diameter to about 1.5 cm. The
`?lm covering showed no visible adverse effects from the
`process of shrinking and increasing the stent diameter.
`
`W.L. Gore & Associates, Inc.
`Exhibit 1024-9
`
`

`
`5,735,892
`
`7
`EXAMPLE 3
`A Palrnaz stent of the balloon-expandable type (part no.
`P830. Johnson & Johnson Interventional Systems, Inc..
`Warren. NJ.) was adjusted from its collapsed outside diam
`eter of 3.4 mm to an enlarged outside diameter of 8.0 mm by
`inserting a tapered stainless steel mandrel followed by a
`straight 8.0 mm diameter stainless steel mandrel. This stent
`was then provided with a single layer exterior wrapping of
`the same discontinuously FEP-coated porous expanded
`PTFE coating used for the exterior wrapping of the stent of
`Example 1. This was accomplished by wrapping the ?lm
`about the exterior surface of the mandrel with the uniaxially
`oriented ?brils of the ?lm microstrucmre oriented parallel to
`the longitudinal axis of the stent. This exterior covering 61
`is described by the transverse cross section of FIG. 6. A 2
`mm wide seam 45 was formed from the overlapped edges of
`the porous expanded PTFE ?hn 20 by temporarily placing a
`thin sheet of polyarnide ?lm over these edges and applying
`heat from a hand-held iron with a surface temperature of
`about 400° C. The ?lm~wrapped stent 65 was then placed
`into an oven set at 380° C. for 3 minutes, after which it was
`removed and allowed to cool. The ?lm appeared to be well
`adhered to the exterior surface of the stent. ‘The wall thick
`ness of the ?hn covering was about 0.01 mm. The enlarged
`stent was then collapsed by the following process.
`A series of 20 cm long 6-0 sutures were tied individually
`to each of the closed metal stent openings adjacent to one
`end of a stent. The ?lm-covered stent was provided with a
`temporary non-adhered additional wrapping of
`longitudinally-oriented ?lm without FEP and having a
`rnicrostructure of uniaxially-oriented ?brils. This temporary
`wrapping was intended as a dry lubricant. As described by
`FIG. 7 which omits the exterior ?lm covering for clarity, the
`enlarged stent 71 was then pulled by these sutures 77
`35
`through a tapered die 75 of round cross section and 2.5 cm
`length, the die having a tapered ori?ce with a 9.5 rmn
`diameter bore at its entrance 78 and a 4.5 mm diameter bore
`at its exit 79. The result was that the stent was collapsed back
`to an outside diameter of 4.5 mm. The lubricity of the
`temporary covering of porous expanded PI‘FE ?lm aided in
`making it possible to pull the stent through the die. This
`temporary covering was removed after completion of the
`collapsing process. It is anticipated that the use of a tapered
`die having an appropriately sized, smaller diameter exit bore
`would result in collapsing the stent to its original collapsed
`diameter. The ?lm-covered stent was again enlarged to a
`diameter of 8 rmn using a balloon catheter followed by a
`tapered stainless steel mandrel. The covering of porous
`expanded P'I'FE ?lm appeared to be fully intact after the
`collapsing and enlarging of the ?lm-covered stent.
`Stent coverings may be a?ixed to a stent surface by
`variations on this method. For example, a tubular sleeve may
`be made from a ?lm of porous expanded P'TFE and inverted
`back into itself and ?tted over the inner and outer surfaces
`of a stent as shown by FIG. 8. The inner 83 and outer 85
`portions of the tubular sleeve 81 may be thermally adhered
`to each other througi the openings in the stent wall. or may
`be adhered to the stent surfaces by an adhesive such as FEP.
`or may be a?ixed to the stent by sunning the open ends 87
`of the tube together.
`
`25
`
`45
`
`8
`cut from a sheet of porous expanded PTFE ?lm. The tape
`used was 6 mm wide. 0.01 mm thick, 0.3 g/ec density. and
`had uniaxially-oriented ?brils of about 50 micron ?bril
`length. This tape-covered wire was then heated by pulling
`the wire through the 0.14 mm diameter ori?ce of a 2.5 cm
`long die heated to 400° C., at a rate of 1.5 meters per minute.
`thereby adhering the overlapped edges of the tape together
`and thereby adhering the tape to the wire. This wire was then
`cut into shorter lengths and spooled onto 16 bobbins. These
`bobbins were used to supply the wire to a model D-5600
`Steeger braider.
`A 12 meter length of 1.75 mm diameter non-porous PTFE
`mandrel was then fed into the braider where a braided
`covering of the above wire was applied at a density of about
`16 pickslcrn. An additional covering of tape cut from a sheet
`of porous expanded P'I'FE ?lm was then helically wrapped
`over the surface of the wire-braided PTFE mandrel. The tape
`used for this helical wrapping was of 0.01 mm thickness, 0.3
`g/cc density, about 50 micron ?bril length and 12 mm width.
`Adjacent edges of the helical wrapping were overlapped by
`approximately 1 mm. The wire-braided Te?on mandrel was
`then placed into an oven set at 380° C. for four minutes, after
`which it was removed and allowed to cool. As shown by
`FIG. 9, the wire-braided stent 91 with the exterior covering
`of porous expanded P'I'FE tape was then removed from the
`non-porous PI‘FE mandrel 93 by folding the ends 95 of the
`braided wires back on themselves and pulling on these
`everted ends. The exterior covering of porous expanded
`PI'FE ?lm is omitted from FIG. 9 for clarity. By applying
`tension on these everted ends in a direction parallel to the
`longitudinal axis of the mandrel and from the everted end
`back toward the opposite, non-everted end, the entire
`braided construction was everted and simultaneously
`removed from the mandrel. This evertin