United States Patent [19]
`Cragg
`
`111111111111111111111111111111111111111111111111111111111111111111111111111
`USOO5405377 A
`5,405,377
`[11] Patent Number:
`[45] Date of Patent: Apr. 11, 1995
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`[75]
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`[21]
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`[51]
`[52]
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`[58]
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`[56]
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`INTRALUMINAL STENT
`Inventor: Andrew H. Cragg, Bloomington,
`Minn.
`Assignee: EndoTech Ltd., Guernsey, Channel
`Islands
`Appl. No.: 839,911
`Filed:
`Feb. 21, 1992
`Int. Cl.6 ................................................ A61F 2/06
`U.S. Cl •.......................................... 623/1; 623/12;
`606/191; 606/194; 606/198
`Field of Search ................ 604/281; 606/108, 191,
`606/192, 194, 198; 623/1, 12; 139/387 R;
`140/11
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,868,956 3/1975 Alfidi et aI .......................... 128/345
`3,890,977 6/1975 Wilson ................................ 128/418
`3,996,938 12/1976 Clark, III ............................ 128/348
`4,149,911 4/1979 Clabburn ............................ 148/11.5
`4,306,318 12/1981 Mano et aI ............................... 3/1.4
`4,425,908 1/1984 Simon ..................................... 128/1
`4,503,569 12/1985 Dotter ..................................... 623/1
`4,512,338 4/1985 Balko et aI .............................. 128/1
`4,553,545 11/1985 Maass et aI ......................... 128/341
`4,560,374 12/1985 Hammerslag ......................... 604/49
`4,580,568 4/1986 Gianturco ........................... 128/345
`4,649,922 3/1987 Wiktor ................................ 128/344
`4,655,771 4/1987 Wallsten ................................. 623/1
`4,665,906 5/1987 Jervis .................................... 128/92
`4,665,918 5/1987 Garza et aI. ........................ 128/343
`4,681,110 7/1987 Wiktor ................................ 128/343
`4,729,766 3/1988 Bergentz et aI ........................ 623/1
`4,732,152 3/1988 Wallsten et aI ..................... 128/343
`4,733,665 3/1988 PaImaz .................................. 604/96
`4,739,762 4/1988 PaImaz ................................ 128/343
`4,762,128 8/1988 Rosenbluth ......................... 128/343
`4,768,507 9/1988 Fischell et aI ...................... 128/303
`4,776,337 10/1988 PaImaz ................................ 128/343
`4,800,882 1/1989 Gianturco ........................... 128/343
`4,820,298 4/1989 Leveen et aI ........................... 623/1
`4,830,003 5/1989 Wolff et aI .......................... 128/343
`4,856,516 8/1989 Hilstead ................................ 604/96
`4,878,906 11/1989 Lindemann et aI ..................... 623/1
`4,886,062 12/1989 Wiktor ................................ 128/343
`4,913,141 4/1990 Hillstead ............................. 606/108
`4,922,905 5/1990 Strecker .............................. 606/195
`4,969,458 11/1990 Wiktor ................................ 606/194
`5,019,090 5/1991 Pinchuk .............................. 606/194
`5,041,126 8/1991 Gianturco ........................... 606/195
`
`5,057,092 10/1991 Webster, Jr ......................... 604/282
`5,067,957 11/1991 Jervis .................................. 606/108
`5,078,736 1/1992 Behl ........................................ 623/1
`5,133,732 7/1992 Wiktor ................................ 606/195
`5,135,536 8/1992 Hillstead ............................. 606/195
`5,282,824 2/1994 Gianturco ........................... 606/198
`
`FOREIGN PATENT DOCUMENTS
`0145166 6/1985 European Pat. Off ..
`2106190 4/1983 United Kingdom.
`W09107928 6/1991 WIPO.
`W09200043 1/1992 WIPO.
`
`OTHER PUBLICATIONS
`C. Dotter, R. Buschmann, M. McKinney and J. Rosch,
`"Transluminal Expandable Nitinol Coil Stent Grafting:
`Preliminary Report," 147 Radiology at 259-60 (Apr.
`1983).
`L. Schetky, "Shape-Memory Alloys," pp. 74-82.
`K. Otsuka and K. Shimizu, "Shape-MemoryAlloys-P(cid:173)
`seudoelasticity," Metals Forum, vol. 4, No.3, at 142-52
`(1981).
`Cragg, Andrew et al., "Nonsurgical Placement of Arte(cid:173)
`rial Endoprostheses: A New Technique Using Nitinol
`Wire," Radiology, vol 147, No.1, pp. 261-263 (Apr.
`1983).
`Cragg, Andrew H. et al., "Percutaneous Arterial Graft(cid:173)
`ing," Radiology, vol. 150, No.1, pp. 45-49 (Jan. 1984).
`Duerig, T. W. et al., "An Engineer's Perspective of
`Pseudoelasticity," The Mechanism of Pseudoelasticity,
`pp. 369-393.
`Primary Examiner-Jerome L. Kruter
`Attorney, Agent, or Firm-Tilton, Fallon, Lungmus &
`Chestnut
`ABSTRACT
`[57]
`An intraluminal stent includes a continuous helix of
`zig-zag wire and loops which connect adjacent apices
`of the wire. The stent is compressible and self-expanda(cid:173)
`ble substantially to a pre-compressed configuration. A
`method of forming the stent includes bending a length
`of wire into a zig-zag configuration and a helix and
`connecting adjacent apices of the wire. A method im(cid:173)
`planting this stent includes compressing the stent radi(cid:173)
`ally, implanting it in a predetermined location of a body
`vessel, and allowing it to recoil to the configuration it
`had before compression.
`
`6 Claims, 3 Drawing Sheets
`
`001
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`u.s. Patent
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`Apr. 11, 1995
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`Sheet 1 of 3
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`5,405,377
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`u.s. Patent
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`Apr. 11, 1995
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`Sheet 2 of 3
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`5,405,377
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`u.s. Patent
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`Apr. 11, 1995
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`Sheet 3 of 3
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`5,405,377
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`

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`1
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`INTRALUMINAL STENT
`
`5,405,377
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`2
`graft is a flexible, tubular shell which allows the wire
`helix to contract and recoil.
`
`5
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`BACKGROUND OF THE INVENTION
`For a more complete understanding of this invention
`1. Field Of The Invention
`one should now refer to the embodiments illustrated in
`The present invention generally relates to a vascular
`greater detail in the accompanying drawings and de-
`prosthesis, and more particularly to an intraluminal
`scribed below by way of examples of the invention. In
`stent which has a flexible and elastic tubular construc-
`the drawings:
`tion with sufficient hoop strength to prevent elastic
`recoil of balloon-resistant strictures or to produce de- 10
`FIG. 1 is a perspective view of the intraluminal stent
`of the present invention;
`layed dilation of those strictures.
`FIGS. 2-4 are side elevation views of a suture con-
`2. Description Of The Prior Art
`nection for the stent of FIG. 1;
`The prior art includes a wide variety of intraluminal
`FIG. 5 is a sectional view of the devices used to im-
`stents and grafts. For example, Palmaz U.S. Pat. No.
`4,733,665 discloses a balloon-expandable intraluminal 15 plant the stent of FIG. 1;
`graft, including an embodiment comprising a wire mesh
`FIG. 6 is a sectional view of the sheath and catheter
`tube. Intersecting wire members, secured to one an-
`devices used to implant the stent, showing the catheter
`other at their intersections by welding, soldering or
`holding the stent in place as the sheath moves out of the
`gluing, form the wire mesh and define a diamond-like
`body vessel.
`pattern. This structure provides a relatively high resis- 20
`FIG. 7 is a side elevation view of an alternative em-
`tance to ra~ial ~o~aps~; .but it suffers a ~umber of dis~d-
`bodiment of the stent of the present invention;
`vantages. FIrst It IS a ngId structure which cannot easily
`FIG. 8 is a sectional view taken along the line 8-8 in
`assume the configuration of a curved vessel which re-
`FIG. 7'
`ceives it. Sec~nd one. must ~e a ~alloon cll:th~ter to 25
`FIG: 9 is a partial perspective view of the stent of
`expand and lIDplant It. This r~qw:ement llIDlts the
`FIG. 7, showing a suture connection for the stent; and
`length of ~e graft, as does the ngIdI.ty.
`.
`FIG. 10 is a perspective view of the mandrel used to
`Other pnor stents ha~e more fleXible. constructions;
`form the wire helix of the present invention.
`but they suffer other disadv~tages. Wiktor U.~. Pat.
`While the applicant will describe the invention in
`No. 4,886,062, for example, dIScloses a stent which has
`t'
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`This
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`mc u es a elorma e WIre en m 0 a ZIg-zag esign
`ted to those embodlIDe~ts. Furthermore, one s~ould
`and coiled in a spiral fashion. The resulting wire tube
`understand t~at. the drawmgs ar~ not necessarily ~o
`has an open configuration with a reduced hoop
`scale. ~ ce~n mstances, the applicant may have on;ut-
`strength. Each hoop lies essentially isolated from the
`adjacent hoops and does not obtain substantial support 35 ted details whi~h are ?ot necessary for an understandmg
`of the present mventIOn.
`from them. Moreover, the open configItration increases
`the risk that plaque elements may herniate through the
`DETAILED DESCRIPTION OF THE
`coil. Finally, one must use a balloon catheter to expand
`DRAWINGS
`and implant it. Thus, the length of the stent cannot
`exceed the balloon length of available balloon catheters. 40
`The intraluminal stent of the present invention avoids
`the disadvantages of the prior art stents and grafts. It
`has sufficient hoop strength to prevent elastic recoil of
`balloon-resistant strictures. The stent of the present
`invention has a flexible construction which allows it to 45
`follow the curvature of the vessel which receives it. It
`has an elastic construction which allows implantation
`without a balloon catheter. This elasticity further al(cid:173)
`lows compression of the structure and recoil upon im(cid:173)
`plantation to produce delayed dilation of the receiving 50
`vessel.
`
`C
`
`Turning now to the drawings, FIG. 1 shows the
`intraluminal stent of the present invention generally at
`10. This stent includes a wire body 11 made out of a
`predetermined length of wire having a sinuous or zig(cid:173)
`zag configItration and defming a continuous helix with
`a series of connected spirals or hoops. It also includes
`loop members 12 which connect adjacent apices of
`adjacent helix hoops to help defme the tubular stent.
`The loop members 12 may connect all or some of the
`pairs of adjacent apices.
`The wire body 11 is an elastic alloy which provides
`radial elasticity for the stent. Preferably, it is a nitinol
`alloy which has superior elasticity and fatigue resis(cid:173)
`tance. The wire has a round cross-section; but its cross(cid:173)
`section may also be anyone of a variety of shapes, e.g.,
`triangular, rectangular, etc. Alternatively, any material
`of sufficient strength and elasticity and the other prop(cid:173)
`erties identified above may form the wire body, includ(cid:173)
`ing stainless steel, tantalum, titanium, or anyone of a
`variety of plastics.
`The loop members 12 connect adjacent apices of
`adjacent hoops of the wire body 11 so that the adjacent
`apices abut each other (See FIGS. 2-4). Thus, each
`hoop receives support from adjacent hoops, increasing
`the hoop strength of the overall stent structure and
`minimizing the risk of plaque herniation. The loop
`members 12 are ligatures of suture material with the
`ends tied together to form a loop. This material is poly(cid:173)
`propylene material or any other biocompatible material
`
`SUMMARY OF THE INVENTION
`In accordance with an embodiment of the present
`invention, an intraluminal stent includes a predeter- 55
`mined length of wire having a sinuous or zig-zag config(cid:173)
`uration and defining a continuous helix with a plurality
`of connected spirals or hoops. A plurality of loop mem(cid:173)
`bers connect adjacent apices of adjacent helix hoops.
`The stent is compressible and self-expandable substan- 60
`tially to the configItration prior to compression.
`In accordance with an alternative embodiment of the
`present invention, an intraluminal stent includes the
`continuous helix and the plurality of loop members
`described above. It also includes a prosthetic graft dis- 65
`posed longitudinally of the wire helix within its central
`opening (or around the wire helix). One or more of the
`loop members secures the graft to the wire helix. This
`
`005
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`

`
`3
`of sufficient strength. Although sutures are the pre(cid:173)
`ferred connecting means, other connecting means such
`as staples and rings made of metal or plastic may pro(cid:173)
`vide the same function.
`The stent structure of the present invention allows 5
`compression prior to implantation in a human or animal
`vessel. After implantation, upon release of the compres(cid:173)
`sive force, the stent structure recoils (or sel(-expands) to
`its original configuration. Thus, it continues to provide
`dilating force in the implanted state. The structure pro- 10
`vides flexibility which allows the stent to follow the
`curvature of the vessel which receives it.
`Turning now to FIGS. 7-9, an alternative embodi(cid:173)
`ment of the present invention includes the wire body
`and suture connections described above. This alterna- 15
`tive also includes a prosthetic graft 13 disposed inside
`the central opening of the wire body. The graft 13 is a
`round, open tube made of polytetrafluoroethylene
`(PTFE), dacron or any other suitable biocompatible
`material. It has an outside diameter slightly smaller than 20
`the inside diameter of the wire body 11. One or more
`hoop members connect the graft 13 to the wire body 11
`as shown in FIG. 9. In place, the graft closes the
`diamond shaped openings of the stent structure to fur(cid:173)
`ther minimize plaque herniation and minimize the flow 25
`of fluid and cellular elements through the structure.
`Alternatively, the graft 13 may lie around the outside
`of the wire helix. Furthermore, the graft 13 may be
`co-extensive with the wire helix; or it may be shorter
`than the wire helix. Finally, the graft 13 may include a 30
`plurality of segments disposed within the wire helix or
`around the outside of the helix.
`The method of making the stent of the present inven(cid:173)
`tion includes bending a predetermined length of wire in
`a zig-zag fashion between the pins 14 of the mandrel 15 35
`and around the mandrel, thus forming a helix (See FIG.
`10). The next step includes removing the helix from the
`mandrel by removing the pins and sliding the helix off
`the mandrel. The process further includes connecting
`adjacent apices of adjacent helix hoops. A fabricator 40
`makes each connection by placing a ligature of suture
`material (or any other suitable material) around the wire
`segments which defme two adjacent apices and tying
`the ends of the ligature together to form a loop. In
`applications in which the wire body is nitinol wire, the 45
`process includes securing the ends of the wire to the
`mandrel and annealing the wire to a predetermined
`temperature (and thus imparting a thermal memory for
`the annealed shape) before removing the helix from the
`mandrel.
`The method of implanting the stent of the present
`invention includes compressing it and placing it into the
`central bore of an introducing device 16. The next step
`includes coupling the device 16 with the hub 17 of a
`sheath 18 which extends to the implantation location. 55
`The next step involves using a catheter 19 to push the
`compressed stent to the predetermined location and to
`
`50
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`5,405,377
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`4
`hold the stent at the location with the catheter, and then
`removing the sheath. The fmal step involves removal of
`the catheter to allow the stent to recoil.
`In applications in which the wire body is a nitinol
`metal, a user reduces the diameter of the stent by first
`cooling it, e.g., by submerging it in ice water. This
`cooling places the nitinol in a martensitic phase and
`facilitates manual reduction or-the diameter and inser(cid:173)
`tion of the stent in the central bore of the device 16. The
`device 16 and the sheath 18 restrain the stent until de(cid:173)
`ployment in a predetermined location. At that location
`in a subject's body, body fluids warm the nitinol and
`place it in an austenitic phase which is the stable phase
`of this metal and which corresponds to a fully opened
`or expanded configuration of the stent (to its original
`annealed diameter).
`While the above description and the drawings illus(cid:173)
`trate one embodiment and an alternative, one should
`understand, of course, that the invention is not limited
`to those embodiments. Those skilled in the art to which
`the invention pertains may make other modifications
`and other embodiments employing the principals of this
`invention, particularly upon considering the foregoing
`teachings. For example, one may use a deformable ma(cid:173)
`terial to construct the wire body 11 of the stent and then
`use a balloon catheter to deploy it. The applicant, there(cid:173)
`fore, by the appended claims, intends to cover any mod(cid:173)
`ifications and other embodiments which incorporate
`those features which constitute the essential features of
`this invention.
`What is claimed is:
`1. An intraluminal stent comprising: a predetermined
`length of elastic wire having a zig-zag configuration and
`defIDing a continuous helix with a plurality of hoops; a
`plurality of loop members for connecting adjacent api(cid:173)
`ces of adjacent helix hoops; the loop members and the
`wire being separate members and made of different
`materials, the stent being compressible and self-expand(cid:173)
`able substantially to a pre-compressed configuration.
`2. The stent of claim 1, wherein the loop members
`connect the adjacent apices of the helix hoops in abut(cid:173)
`ting relation.
`3. The stent of claim 1, wherein the elastic wire is a
`high shape memory nitinol alloy.
`4. The stent of claim 1, wherein the loop members
`have a substantially greater flexibility than the wire.
`5. An intraluminal stent comprising: a predetermined
`length of elastic wire having a zig-zag configuration and
`defIDing a continuous helix with a plurality of hoops; a
`plurality of loop members for connecting adjacent api(cid:173)
`ces of adjacent helix hoops, each said loop member
`including a single ligature of suture material tied into a
`loop; the stent being compressible and self-expandable
`substantially to a pre-compressed configuration.
`6. The stent of claim 5, wherein the suture material is
`made of polypropylene.
`* * * * *
`
`60
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`65
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`006