(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2004/0082989 A1
`(43) Pub. Date:
`Apr. 29, 2004
`Cook et al.
`
`US 20040082989A1
`
`(54) STENT GRAFT WITH IMPROVED
`PROXIMAL END
`
`(75) Inventors: William A. Cook, Bloomington, IN
`(US); Thomas A. Osborne,
`Bloomington, IN (US); Sarah E.
`Anderson, Cory, IN (US); David E.
`Hartley, Subiaco (AU)
`
`Correspondence Address:
`COOK GROUP PATENT OFFICE
`P.O. BOX 2269
`BLOOMINGTON, IN 47402
`
`(73) Assignees: COOK INCORPORATED, Blooming
`ton, IN (US); WILLIAM COOK
`EUROPE ApS, Bj aeverskov (DK)
`
`(21) Appl. No.:
`
`10/644,129
`
`(22) Filed:
`
`Aug. 20, 2003
`
`Related U.S. Application Data
`
`(60) Provisional application No. 60/404,662, ?led on Aug.
`20, 2002.
`
`Publication Classi?cation
`
`(51) rm.c1.7 ...................................................... ..A61F 2/06
`(52) U.S. c1. ........................................ ..623/1.13;623/1.36
`
`(57)
`
`ABSTRACT
`
`Disclosed is a stent graft prosthesis comprising a graft
`portion that includes a main body portion and an cuff
`portion, the cuff portion generally located at or near the
`proximal end of the main body portion and extending
`circumferentially therealong. Stents comprising the graft
`supporting structure are also attached to graft portion about
`the proximal end. In one embodiment, the cuff portion
`comprises material that is folded over the outside surface of
`the main body portion With an anchoring stent being
`attached over the cuff and main body portions, extending
`proximally therefrom. In another series of embodiments, the
`cuff portion comprises an external sealing Zone that extends
`around the outer main body portion to help prevent leakage
`of ?uids. In one example, the material of the second edge of
`the cuff portion is frayed to better engage the vessel Walls
`and promote thrombus and/or tissue groWth.
`
`3 7 J44‘.
`
`3/—-
`
`a
`
`3 6
`
`/8
`
`20
`
`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 1 of 12
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`Patent Application Publication Apr. 29, 2004 Sheet 1 0f 5
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`US 2004/0082989 Al
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`N @Q . \ QR
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`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 2 of 12
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`Patent Application Publication Apr. 29, 2004 Sheet 2 0f 5
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`US 2004/0082989 A1
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`mwt
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`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 3 of 12
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`Patent Application Publication Apr. 29, 2004 Sheet 3 0f 5
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`US 2004/0082989 A1
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`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 4 of 12
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`Patent Application Publication Apr. 29, 2004 Sheet 4 0f 5
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`US 2004/0082989 A1
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`Q Pom
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`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 5 of 12
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`Patent Application Publication Apr. 29, 2004 Sheet 5 0f 5
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`US 2004/0082989 A1
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`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 6 of 12
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`US 2004/0082989 A1
`
`Apr. 29, 2004
`
`STENT GRAFT WITH IMPROVED PROXIMAL
`END
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`[0001] This application claims priority of provisional
`application Serial No. 60/404,662 ?led Aug. 20, 2002. This
`application is related to the US. patent application Ser. No.
`10/322,862 ?led Dec. 18, 2002, entitled Stent Graft With
`Improved Adhesion.
`
`TECHNICAL FIELD
`
`[0002] This invention relates to medical devices and more
`particularly, to intraluminal graft prostheses.
`
`BACKGROUND OF THE INVENTION
`
`[0003] The top or proximal edge region of a graft pros
`thesis, particularly one used to exclude an abdominal aortic
`aneurysm
`or an aneurysm Within the thoracic arch,
`is that portion of the device Which is perhaps most critical to
`clinical success. Typically, it is the portion of the graft that
`forms the critical seal against the Walls of the aorta to
`prevent leakage of arterial blood directly into the aneurys
`mal sac (a situation knoWn as a Type I endoleak). In the case
`of a stent graft that employs a suprarenal stent or other stent
`that extends beyond the top edge of the tubular graft, (e.g.,
`the ZENITH® AAA Endovascular Graft, Cook Incorpo
`rated), the top edge region also represents the portion to
`Which the stent is seWn or otherWise attached or secured to
`the graft fabric, typically With a series of sutures. For stent
`grafts placed in the aorta, the pulsatile forces of blood being
`exerted on the device are suf?ciently great such that over
`time, the sutures may break or pull through the material,
`Which can cause the anchoring stent and graft to separate. If
`this occurs, the device may migrate or shift, resulting in the
`aneurysm no longer being excluded and making a subse
`quent rupture of the aneurysm potentially lethal to the
`patient.
`[0004] While endoleaks can occur anyWhere Where an
`aortic stent graft is placed, they can be particularly trouble
`some When the graft is placed to treat an aneurysm occurring
`in the region betWeen the renal arteries and the iliac bifur
`cation. If the neck of the aneurysm (the healthy portion or
`the vessel betWeen the aneursymal sac and renal arteries) is
`short or tortuous in shape, it may be dif?cult to get proper
`alignment, anchoring, or a good seal betWeen the graft and
`the vessel Wall, possibly resulting in a Type I endoleak in
`Which the sac may continue to be pressuriZed With blood.
`
`[0005] What is needed is an improved proximal edge
`region of the graft portion of a stent graft prosthesis or
`covered stent to help ensure secure anchoring of the sup
`porting structure or stent(s) to the fabric or material, and
`secondly, to ensure a good seal With the vessel Wall such that
`leakage of blood or ?uids does not occur along the proximal
`edge of the prosthesis.
`
`SUMMARY OF THE INVENTION
`
`[0006] The foregoing problems are solved and a technical
`advance is achieved in an illustrative intraluminal prosthe
`sis, such as a stent graft, made of a sleeve of material (e.g.,
`a tight-mesh fabric, extruded polymer, and/or a biomaterial)
`Which includes a leading edge portion having an external
`
`structure con?gured to prevent anchoring stent detachment
`and/or leakage of blood or ?uids around the graft portion. In
`one aspect of the invention, the stent graft includes a
`proximal cuff portion to Which at least the proximal stent
`may be attached, thereby providing at least a ?rst and second
`layer of material that helps provide a more secure substrate
`for the attached stent(s). The double layer is more likely to
`hold the sutures and keep them intact, as Well as being less
`likely to have a portion of the stent Wear through the fabric
`over time. A ?rst illustrative embodiment comprises a stent
`graft adapted for use in treating an aortic aneurysm, such as
`the ZENITH® AAA Endovascular Graft, in Which the most
`proximal stent extends beyond the proximal or top edge of
`the graft potion to help anchor the stent graft in the vessel.
`The prosthesis is placed at or above the iliac bifurcation With
`the proximal stent acting as a suprarenal stent, attaching to
`the healthy portion of the aorta about and above the openings
`to the renal arteries. Because this particular stent typically is
`only attached about the distal bends and strut portions, there
`are relatively feW sutures to anchor the stent to the material.
`The cuff of the present invention gives a double-thickness
`layer of graft material, such as DACRON® polyester ?ber
`(trademark of El duPont de Nemours & Co., Inc.) for
`holding the sutures intact and providing better assurance that
`the distal bends or struts of the zigzag stent Will not Wear
`through the fabric, creating a hole or causing detachment of
`the suprarenal stent at that point.
`[0007] The stent adjacent to the proximal anchoring
`(suprarenal) stent may also be partially attached to the cuff
`as Well. The proximal stent can be seWn to the cuff from the
`inside or the outside of the graft, preferably, but not neces
`sarily to both the main body and cuff portions. Additionally,
`the stent can be seWn to the graft material’s folded or leading
`edge such that the stent and graft material generally abut one
`another. This reduces thickness by not having the struts of
`the stent overlapping the material. Furthermore, the cuff can
`comprise a separate piece of the same or a different material
`that is seWn, bonded, applied, or otherWise attached to the
`main body of the graft With the anchoring stent or other
`supporting structure being attached to both layers to provide
`added support. While the cuff preferably encircles the entire
`circumference of the main body of the graft, it is Within the
`scope of the invention (and de?nition of the term ‘cuff’) to
`include a series of discrete cuff ‘?aps’ or patch-like elements
`distributed around the circumference of the main body as
`points to Which the bends or struts of the anchoring stent or
`other supporting structure are attached.
`
`[0008] In one embodiment, at least a portion of the proxi
`mal stent is attached to the graft betWeen the layers of the
`cuff to further strengthen the stent-graft attachment by
`having the folded edge provide a stop to prevent the stent,
`Which may be inserted through holes about the folded edge,
`from pulling through if becoming detached from the fabric.
`Although the folded ?rst edge of the cuff may provide a
`better substrate for preventing sutures pulling out as com
`pared to a cut edge of material, it is Within the scope of the
`invention to include a cuff in Which both the ?rst edge of the
`cuff and the ?rst end of the main graft body comprise free
`or cut edges of fabric or other material, rather than a folded
`edge to unite them.
`
`[0009] In another aspect of the invention, the cuff, Which
`comprises a ?rst edge at the leading or folded edge of the
`graft extending to second edge that comprises the free or cut
`
`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 7 of 12
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`US 2004/0082989 A1
`
`Apr. 29, 2004
`
`edge of the material, is adapted to extend outward to serve
`as an external sealing Zone to engage the vessel Wall and
`help prevent leakage of blood or ?uid around the device. In
`one illustrative embodiment of a modi?ed ZENITH® AAA
`Endovascular Graft, approximately 10 mm of the graft
`material is folded over on itself such that the free edge is on
`the outside of the graft. Approximately the distal 5 cm of the
`cuff includes a region in Which the threads and ?bers of the
`DACRON® polyester fabric have been at least partially
`separated from one another to create a frayed region that
`extends outWard from the graft and facilitates sealing by
`encouraging thrombus formation and tissue ingroWth. Graft
`material, such as DACRON® polyester ?ber, is particularly
`Well-suited to form thrombus. One advantage of the external
`sealing Zone is that the top or ?rst supporting stent, Which
`has the ability to compromise the quality of the graft-vessel
`seal if placed on the outside of the graft (such as is the case
`With the ZENITH® AAA Endovascular Graft), can be
`moved from the inside to the outside of the graft and still
`alloW for adequate sealing. This alloWs the inner lumen of
`the graft to remain smooth and stent-free. In a variation of
`this embodiment, the frayed region is folded or otherWise
`directed so that it extends proximally, thereby creating a
`third layer of graft material along the ?rst edge of the cuff.
`Additionally, the frayed region can be modi?ed to enhance
`its sealing properties, such as by adding agents to encourage
`thrombosis or cell proliferation, adding structure capable of
`stimulating the cell injury response and facilitate tissue
`ingroWth.
`[0010] In yet another aspect of the invention, the external
`sealing Zone can include separate element or series of
`elements that includes the same material and/or a second
`material Which is af?xed to the outer surface of the graft. It
`can be attached to or beloW the cuff, or the cuff can be
`eliminated completely. Some examples of materials for an
`attached external sealing Zone include bands of felt material,
`foam, lyophiliZed collagen, such as small intestinal submu
`cosa (SIS) or another extracellular matrix (ECM), or some
`other suitable material.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0011] Embodiments of the present invention Will noW be
`described by Way of example With reference to the accom
`panying draWings, in Which:
`
`[0012] FIG. 1 depicts a side vieW of an illustrative
`embodiment of the present invention in Which the graft
`portion includes a proximal cuff portion;
`
`[0013] FIG. 2 depicts a side vieW of an embodiment of the
`present invention Where the cuff portion includes an external
`sealing Zone comprising a frayed portion;
`
`[0014] FIG. 3 depicts an in situ vieW of the embodiment
`of FIG. 2;
`
`[0015] FIG. 4 depicts a cross-sectioned vieW of the cuff of
`FIG. 2;
`
`[0016] FIG. 5 depicts a detailed vieW of the free edge of
`the cuff portion of FIG. 2;
`
`[0017] FIG. 6 depicts a cross-sectional embodiment of the
`present invention Wherein the free edge of the cuff portion
`is directed toWard the ?rst end of the graft;
`
`[0018] FIG. 7 depicts a detail vieW of an alternative cuff
`embodiment Wherein a fringe is cut into the free edge of the
`graft material;
`[0019] FIG. 8 depicts an alternative embodiment ofthe
`present invention Wherein the external sealing Zone com
`prises a band of material attached to the graft;
`
`[0020] FIG. 9 depicts an alternative embodiment of the
`present invention in Which the frayed portion includes
`additional structure to promote thrombus formation and/or
`tissue ingroWth;
`
`[0021] FIG. 10 depicts an alternative embodiment of the
`present invention Wherein the cuff portion comprises a
`portion of the graft material extending over the leading edge
`of a cannula stent;
`
`[0022] FIG. 11 depicts a partially sectioned detail vieW of
`an alternative embodiment in Which the proximal anchoring
`stent is attached underneath the cuff portion;
`
`[0023] FIG. 12 depicts an enlarged side vieW of an
`alternative embodiment in Which the proximal anchoring
`stent is attached about the edge comprising the ?rst end of
`the graft material;
`[0024] FIG. 13 depicts a partially sectioned side vieW of
`an alternative embodiment in Which the cuff portion com
`prises a layer of material separate to the main body portion
`of the graft; and
`
`[0025] FIG. 14 depicts a side of an embodiment in Which
`the cuff portion comprises a plurality of ?aps.
`
`DETAILED DESCRIPTION
`
`[0026] FIG. 1 depicts a graft prosthesis 10 that includes a
`graft portion 11 having a ?rst end 13, Which typically forms
`the proximal or leading edge of the main body 12 of the
`tubular graft portion, and a second end 14, Which typically
`is the distal end Which is further doWnstream from the
`direction of blood or ?uid ?oW. The illustrative graft pros
`thesis 10 represents a modi?ed ZENITH® AAA Endovas
`cular Graft comprising a tubular graft portion 11 of
`DACRON® polyester ?ber (including a bifurcated distal
`portion in this embodiment to feed into the right and left iliac
`arteries), and a supporting structure 40 that comprises a
`series of Zig-Zag stents seWn thereto, including a proximal
`anchoring stent 18, such as the illustrative suprarenal Zig
`Zag stentWith barbs, extending from the proximal (caudal)
`end to anchor the stent graft above the aneurysmal sac. The
`prosthesis 10 further includes a cuff portion 15 comprising
`material of the main body 12 that is folded over the outside
`thereof to form a double layer of material. The cuff portion
`15 includes a ?rst edge 16 or leading edge, Which is typically
`a folded edge, that also comprises the ?rst end 13 of the graft
`portion 11, and extends distally to a second edge 17, Which
`is the free edge of the cuff. In the illustrative cuff portion 15,
`the free edge 17 is unattached to the main body 12 so that
`it is alloWed to extend or ?air outWard to comprise a lip that
`serves as an external sealing Zone 21 to help provide a better
`seal graft portion 11 and Walls of the vessel in Which the
`device is placed. It should be noted that While it may be
`preferable to form the cuff portion 15 by folding the excess
`material over upon itself, it is also Within the scope of the
`invention for the cuff portion 15 to be a separate piece that
`is secured to the main body 12 of the graft portion, such that
`
`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 8 of 12
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`US 2004/0082989 Al
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`Apr. 29, 2004
`
`the proximal edges of the main body and cuff portions 13,16
`each comprise ‘cut’ or free edges rather than a single folded
`edge. The double thickness of the cuff portion typically
`offers a better foundational substrate through Which sutures
`20 may be attached, forming knots to secure or anchor stents
`or other framework of the graft prosthesis 10. The length of
`the cuff 15 depends largely on the speci?c clinical applica
`tion and siZe of the prosthesis, but preferably the free edge
`17 does not extend more than a feW centimeters from the
`?rst end 13, especially in an endovascular stent graft Where
`the seal must be safely proximal of the aneurysm being
`excluded. The cuff portion 15, hoWever, may extend any
`length, including the entire length of the main body portion
`12, particularly if it is not utiliZed as an external sealing Zone
`21. Although it is generally preferred that the cuff be folded
`or placed over the outer surface of the main body portion 12
`so as not to interfere With blood ?ood and promote formation
`of thrombus, it may folded inWard and attached, particularly
`if the free edge 17 can be attached or bonded in such a
`manner that does not interrupt blood ?oW.
`[0027] FIG. 14 depicts an alternative embodiment of the
`cuff portion 15 in Which the cuff is con?gured as a series of
`discontinuous ?aps 55 distributed around the outer perimeter
`of the main body portion 12 of the graft. The ?aps 55 are
`spaced to correspond to the attachment points of the bends
`51 of the anchoring stent 18. Although the illustrative
`embodiments each depict a suprarenal anchoring stent 18, it
`is not necessary to the invention that the supporting structure
`40 attached to the cuff 15 comprise an anchoring stent
`extending from the proximal end 13 of the graft 11.
`[0028] The illustrative ZENITH® AAA Endovascular
`Graft represents but one exemplary embodiment of the
`present invention. As such, the stent graft material 11 and
`supporting structure 40 may include otherWell-knoWn mate
`rials and designs. For example, other biocompatible fabrics
`and non-Woven materials, such as expanded polytetra?uo
`roethylene (ePTFE) may be used as Well as biomaterials,
`such as cross-linked collagen and remodelable collagen
`materials, e.g, a tube formed from a single or multiple ply
`tube of a extracellular collagen matrix material (SIS being
`an example commercially available from Cook Biotech,
`Inc., West Lafayette, Ind.).
`[0029] The suture 20 used to attached supporting structure
`40 to the graft material 11 may be made of any biocompat
`ible ?ber suitable for the application, including but not
`limited to, mono?lament or braided multi-?lament polyes
`ter, nylon, polyaramid, polypropylene, and polyethylene.
`Braided polyester 4-0 suture material is preferred for attach
`ing internal stents to grafts, While mono?lament suture
`material is preferred for attaching top stents to grafts. The
`polyester 4-0 suture material is nonabsorbable and has limits
`of 0.150 to 0.199 mm (metric siZe 1.5). This Well-knoWn
`material is commercially available from a number of com
`panies. The suture material may be attached to a holloW
`needle used to thread the suture through the graft, thus
`attaching the stent to the graft using any suitable type of
`knot. It is not necessary to the invention that ?ber suture be
`used to attach the supporting structure to the graft material.
`Wire, staples, clips, bonding agents, or other methods also
`may be used to achieve a secure attachment of the graft
`material and stents.
`[0030] To further enhance the sealing properties of the
`external sealing Zone 21, the free edge may be modi?ed to
`
`increase its ability to conform With the vessel, promote
`thrombus formation, and/or encourage tissue ingroWth into
`the graft material. FIG. 2 depicts an embodiment of the
`present invention in Which the cuff 15 includes a frayed
`portion 22 located about the free end 17 thereof, the frayed
`portion 22 comprising about 5 mm of threads and ?bers (of
`an approximately 10 mm cuff) that have been at least
`partially separated from one another or unraveled such that
`they extend outWard from the main graft body 12 and
`circumferentially therearound. Alternatively, the frayed por
`tion 22 may extend the entire length of the cuff portion 15.
`The frayed portion 22 is particularly Well adapted to make
`contact With the vessel and alloW thrombocytes to collect
`and tissue to groW thereinto, thus improving the ef?cacy of
`the seal. FIG. 3 depicts the illustrative embodiment of FIG.
`2 deployed in an abdominal aorta 32 to exclude an aneurysm
`33 that has formed beloW the renal arteries 34, usually above
`or at the iliac bifurcation 41. The external sealing Zone 21
`comprising the frayed portion 22 is positioned Within the
`neck 35 of the aneurysm 33 Where it helps the stent graft 10
`seal against the healthy aortic Wall tissue so that an endoleak
`does not occur around the proximal end 16 of the graft. The
`proximal anchoring stent 18 is placed across the renal
`arteries Where it is anchored to the vessel 32 by a plurality
`of barbs 36. In other embodiments, the proximal anchoring
`stent 18 may include hooks or other structure that extend
`beyond or through the graft material 38 to engage the vessel
`and help anchor the prosthesis in place.
`
`[0031] FIG. 4 depicts a cross-sectional vieW taken about
`the proximal end 16 of the graft portion 11, including the
`cuff portion 15 and proximal anchoring stent 18. The proxi
`mal anchoring stent 18 is attached to the inner surface 37 of
`the graft material 38 and secured With sutures 20 that are
`passed through both the main graft body 12 (inner) and the
`cuff portion 15 (outer) layers of material 38, preferably
`through the proximal or anchoring portion 31 of the cuff
`portion 15. In particular, a series of interconnecting (run
`ning) or separate sutures 42 anchor the proximal anchoring
`stent 18 to the cuff portion 15 at the bends 51 and struts 52
`of the stent 18, the later being sutured about the proximal or
`folded edge 16 of the cuff. Additionally, the ?rst adjacent
`supporting stent 19 is attached to the outer surface 39 of the
`main graft body 12 With a another series of sutures 43. The
`illustrative example depicts the frayed portion 22 extending
`through and around the struts to minimiZe direct contact of
`the stent With the vessel Wall, thus resulting in a better seal
`than Would otherWise be possible With an externally placed
`stent.
`
`[0032] FIG. 11 depicts an alternative embodiment of the
`present invention in Which the proximal anchoring stent 18
`is attached to the graft portion 11 betWeen the main body 12
`and cuff portion 15, such that the bends 51 and distal
`portions of the struts 52 being sandWiched betWeen graft
`material 38, providing a more secure anchoring of the stent.
`One skilled in the medical arts Would appreciate thatthere
`are multiple methods of forming the embodiment of FIG.
`11. One method is to feed an end of an unassembled
`proximal anchoring stent through a series of holes 53 formed
`through the graft material until all of the bends 51 are looped
`underneath the cuff portion 15, as shoWn. The stent 18 is
`then joined together With cannula and solder, spot or laser
`Welding, etc., and secured With a series of sutures 42. The
`illustrative method of attachment provides a backup means
`
`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 9 of 12
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`US 2004/0082989 A1
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`Apr. 29, 2004
`
`of preventing the proximal anchoring stent 18 from com
`pletely detaching from the graft portion 11 in the event of
`suture 20 failure.
`
`[0033] FIG. 12 depicts an embodiment in Which the
`proximal anchoring stent 18 is attached at the proximal
`(folded) edge 16 of the cuff portion 15 by a plurality of
`sutures 20 (either multiple sutures or multiple loops of a
`single suture) such that no portion of the bends 51 or struts
`overlaps With the stent graft material 11. This advanta
`geously reduces the pro?le of the graft prosthesis 10 during
`the loading process.
`
`[0034] While the cuff portion 15 of the illustrative
`embodiments is shoWn as a free edge 17 that is folded over
`itself (the tubular prosthesis 12) to create a double thickness
`of material (neW folded leading edge 16), it is Within the
`scope of the invention for the cuff portion to be a separate
`element that is attached to the main body 12 of the graft
`(FIG. 13), such as When the sutures 20 penetrated both
`layers to attach the anchoring stent 18 or other supporting
`structure 40. Adhesives, laser/thermal bonding, or other
`methods may be used supplement or achieve attachment of
`the tWo layers of material 12,15. The separate ring-like outer
`cuff portion 54 comprising the outer portion of the cuff 15
`may be of the same material of the main body 12, or a
`different material, particularly one having advantageous
`properties such as better durability, thinner pro?le, remod
`elability/tissue ingroWth facilitation (e.g., an ECM), or supe
`riorability to elute medicaments or agents, etc., Without
`regard to Whether the second material is particularly suitable
`to prevent the leakage of blood therethrough. Furthermore,
`the separate outer cuff portion 54 can comprise a material,
`such as a polymer. that is printed, sprayed, painted, dipped,
`or otherWise applied to the surface of the graft prosthesis to
`improve the attachment betWeen stent and graft material.
`The illustrative embodiment of FIG. 13 further includes a
`frayed portion 22 located at the leading edge 16 of the cuff
`portion 15 to facilitate sealing thereat. Alternatively, the
`optional frayed portion 22 may be located at the second edge
`17 of the cuff 15, similar to the embodiment of FIG. 2, or
`it may be located at the ?rst edge 13 of the main body 12,
`or any combination of the three free edges 13,16,17. By
`being separate pieces, the outer cuff portion 54 and main
`body may be used to form a sandWich of material to secure
`the anchoring stent 18 therebetWeen (not shoWn), similar to
`the embodiment of FIG. 11. Although the illustrative sepa
`rate outer cuff 54 completely encircles the main body 12 to
`Which it is attached, it may be divided into discrete sections
`that are located at the attachment points of the stent bends 51
`to provide a double thickness of material.
`
`[0035] FIG. 5 depicts an enlarged vieW of the frayed
`portion 22 and hoW it is formed from material 38 of the cuff
`portion 15. The illustrative TWILLWEAVETM graft material
`38 (SelZer-Vascutek Ltd., Inchinnan, Scotland, UK) com
`prises a Woven DACRON® polyester fabric Which is frayed
`by separating the longitudinal threads 46 from one another
`and from the cross threads 47 With Which they are interWo
`ven. Once the ends 23 of the threads 46 are separated,
`typically using a tool or machine suitable for creating a
`frayed portion 22 of the desired length, the ?bers 24 that
`comprise the individual longitudinal threads 46 are prefer
`ably, but not necessarily, also unraveled and separated from
`one another, alloWing the frayed portion 22 to assume a
`‘fuZZier’ con?guration that enhances the sealing properties
`
`of the external sealing Zone 21 and provides an improved
`substrate for tissue ingroWth thereinto. Generally, it is pre
`ferred that the portion in Which the ?bers 24 are separated
`from one another, comprises at least a substantial portion of
`the frayed portion 22. The length of frayed portion 22 of a
`typical stent graft comprises at least 2 cm of the cuff portion
`15 (preferably 5 mm or more).
`
`[0036] FIG. 6 depicts an embodiment in Which the exter
`nal sealing Zone 21, including the illustrative frayed portion
`22, is con?gured such that the free edge 17 of the cuff
`portion 15 is directed proximally (toWard the ?rst or folded
`edge 16), to produce a fold 44 that creates gutter-like pocket
`45 that is able to collect any blood passing around the
`leading edge 16 of the graft 11 to prevent an endoleak and
`promote thrombus formation. The pocket 45 can be created
`by any means knoWn to those in the medical arts, including
`treating and forming the cuff material using a chemical
`agent, heat, etc. such that it can maintain such a shape; or by
`adding Wires or other supporting structure (not shoWn) that
`reshapes the cuff portion 15 into the illustrative pocket 45
`con?guration.
`[0037] Although DACRON® polyester ?ber and other
`selected fabrics usable in medical applications are generally
`able to be unraveled to create a frayed portion 22, some
`fabrics and unWoven materials potentially suitable for medi
`cal applications, such as polymer sleeves, biomaterials, etc.,
`cannot be frayed in the same manner. FIG. 7 depicts an
`external sealing Zone 21 created by creating a series of
`closely adjacent cuts 26 or slices through the material to
`form fringe elements 27 about the free edge 17 of the
`material. The length, Width, and con?guration of the fringe
`elements 27 (fringed portion) are largely determined by the
`clinical application and type of material 38 comprising the
`cuff portion 15.
`
`[0038] In addition to the external sealing Zone 21 com
`prising the free edge 17 of the cuff portion 15, as With each
`of the embodiments described above, FIG. 8 depicts an
`embodiment Wherein the external sealing Zone 21 comprises
`a band 28 of separate material such as open-cell foam or
`another suitable biocompatible material (e.g., a lyophiliZed
`orsponge-form collagen material such as SIS) and con?gu
`ration Which is attached to the outer surface 39 of the graft.
`Such materials should be effective for creating a seal With
`vessel Wall and/or encouraging cell ingroWth. Such a band
`of material 28 can be af?xed over the cuff portion 15, such
`as over the free edge 17, as shoWn, attached beloW the cuff
`15 to further take advantage of the free edge 17 for sealing,
`or the cuff portion 15 may be eliminated entirely if not
`needed for additional anchoring support. While the illustra
`tive embodiments depicts an external sealing Zone 21/frayed
`portion 22 that encircles the graft 11 in a ring-like manner,
`it may assume other con?gurations, such as a helically or
`serpentine shaped strips of material, discrete staggered
`patches of material/fringe, etc.
`
`[0039] The external sealing Zone 21 may be augmented
`With additional structure, materials, or agents that further
`enhance its sealing properties. One example includes tissue
`engaging elements 29, such as the illustrative barbs depicted
`in FIG. 9. The barbs 29 may be con?gured to help anchor
`the graft prosthesis 10 in the vessel, or their primary function
`may be limited to providing irritation or trauma to the vessel
`Wall for stimulating cell proliferation into the external
`
`Edwards Lifesciences Corporation, et al. Exhibit 1106, Page 10 of 12
`
`

`

`US 2004/0082989 A1
`
`Apr. 29, 2004
`
`sealing Zone 21. The tissue engaging elements 29 may
`comprise any suitable structure, such as a plurality of small
`diameter Wires, Which are interwoven into the cuff portion
`15, or attached in any suitable manner, such as the illustra
`tive method in Which the barbs 29 originate from a common
`basal element 48 that encircles the graft portion 11 and is
`design to be collapsible (e. g., a Zig-Zag shaped element). The
`tissue-engaging elements 29 may also con?gured to bias the
`cuff portion toWard the Wall during delivery (e.g., by adding
`springs or other biasing mechanisms about the common
`basal element 48). For example, the prosthesis 10 may be
`loaded such that the cuff portion could be loaded such it
`extends proximally from the main body portion 12. As the
`graft prosthesis is unsheathed for delivery, the embedded
`elements 29 spring back and ?ip the cuff portion distally to
`engage the Walls of the vessel. This has the advantage of
`eliminating the extra thickness of the cuff portion 15 during
`loading, yet retaining the advantages it provides folloWing
`deployment.
`[0040] Besides tissue-engaging structures 29, the external
`sealing Zone 21 may be impregnated With a bioactive or
`pharmacological agent that enhances sealing properties,such
`as thrombin poWder or another agent for stimulating throm
`bus formation about the external sealing Zone 21. Other
`possible materials or agents, include, but are not limited to,
`groWth factors or biomaterials for stimulating tissue
`ingroWth, materials that sWell in the presence of