O
`Umted States Patent
`
`[19]
`
`US005707386A
`
`[11] Patent Number:
`
`5,707,386
`
`Schnepp-Pesch et al.
`[45] Date of Patent:
`Jan. 13, 1998
`
`
`[54] STENT AND METHOD OF MAKING A
`STENT
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4/1992 Wo1fi_
`5,104,404
`8/1992 Hillstead .
`5,135,536
`5,158,548 10/1992 Lau et a1. .................................. 604/96
`5,421,955
`6/1995 Lau et al.
`606/198
`5,514,154
`5/1996 Lau et al. ....
`..... 606/195
`FOREIGN PATENT DOCUMENTS
`540290A3
`5/1993 European Pat. Off. .
`1766921
`1/1970 Germany.
`
`
`
`Primary Examiner—Michae1Bu1'z
`Assistant Examiner——Kevin Truong
`Attome}; Agent; or Firm-—A11tone]li, Terry, Stout, & Ktaus,
`LLP
`ABSTRACT
`[57]
`:ig:::;::§;;?.;‘::,:"k.?::::‘,:::.."::::‘,:::3;””.:?,:::
`paths (2,2a,2b,2c) successively arranged in the axial direc-
`22:21:: ;::u:“;:$g,,:::‘(§;,,c:<:“;‘;§i‘:::,:.:‘::;$:
`by connecting areas (4,4a,4b.4c), of the meander paths
`1 (2,2a,2b,2c) "11 th circumf
`ntial dir
`ti
`(U)th
`t
`least mo fa(:ing,en0n_inteI-Eifnnectcd
`(3,3a’;f:§,r)° Sf
`each meander Path (230, 2b,1c)_
`6
`
`16 Claims, 3 Drawing Sheets
`
`U-——-an-—
`
`[75]
`
`Inventors: Wolfram Schnepp-Pesch; Josef
`Lindenberg, both of Karlsruhe,
`Y
`German
`
`[73] Assignee: Angiomed Gmbli & Company
`12}/Iedizintechnik KG, Karlsruhe,
`ermany
`
`[21] App1.No.:
`
`495,625
`
`[22] PCI‘ Filed:
`
`Jan. 22, 1994
`
`PCT/EP94/00168
`[85] PCT N0-3
`Sep. 21, 1995
`§371 Date:
`§ 102(e) Date: Sep. 21, 1995
`an Per Pub»
`PCI‘ Pub. Date: Aug. 18, 1994
`romgnmoaw am
`xsm
`Feh.4, 1993
`[DE]
`Germany .......................... 43 03 131.1
`[51]
`Int. Cl.“ .................................................... A61M 29/00
`[52] U.S. Cl. ..............
`.. 606/194' 606/191
`
`[58] Field of Search ..................................... 606/191, 192,
`606/194, 198; 623/1, 12; 604/96, 97, 106
`
`001
`
`_
`
`EX. 101 1
`ENDOLOGIX, INC
`
`001
`
`

`
`U.S. Patent
`
`Jan. 13, 1998
`
`Sheet 1 of 3
`
`5,707,386
`
`4
`3
`3a
`54
`4:
`5b
`
`FIG. 1
`
`U L/A/ 2
`2
`5
`
`23
`3'3
`
`3b
`
`4b
`
`4C
`
`4d
`
`22
`3
`5
`3a
`2a
`33'
`3b
`2b
`
`5c‘
`
`4b
`4c
`4d
`
`002
`
`002
`
`

`
`U.S. Patent
`
`Jan. 13, 1998
`
`Sheet 2 of 3
`
`5,707,386
`
`003
`
`003
`
`

`
`vGI
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`j.5
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`004
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`

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`5,707,386
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`1
`STENT AND METHOD OF MAKING A
`STENT
`
`FIELD OF THE INVENTION
`
`BACKGROUND OF THE INVENTION
`
`Such stents or implantable catheters, which can be
`inserted in a body cavity, a vessel or the like, can be made
`from plastic or an inert metal, such as steel or nickel-
`titanium alloys. Such stents are in particular known as
`endovascular or endoluminal stents or intraluminal tubes.
`The stents are e.g. used for widening the ureter in the
`prostate region in the case of benign prostate hyperplasia
`(BPH) or in the case of sclerotic blood vessels for widening
`and keeping open the same. The stents have material areas
`and gaps between them. Thus, the parietal tissue of the organ
`kept open can grow round the stent. Stents can have a spiral
`construction or can be in the form of a helically wound coil.
`They can also be made from woven, knitted or braided wire
`or plastic material. Such stents can have memory
`characteristics, such as e.g. occur with certain nickel-
`titanium alloys (nitinol).
`A problem with such stents is their limited bendability,
`particularly on introducing through narrow organs, such as
`blood ves sels, at the point where a widening can take place.
`There is a risk that on bending the stent it bends in in the
`center as a result of the action of axially vertically directed
`forces, in that its cross-sectional area is reduced in the
`direction of the acting forces, but is widened perpendicular
`thereto and to the axial direction thereof. This can make
`insertion more diflicult and can also damage the surrounding
`tissue, particularly if the stent is to be inserted in a bend area
`of the vessel or the like. Stents are relatively still’ and
`inflexible. This more particularly applies with stents having
`arhombic structure, which are e.g. produced by cutting from
`nickel-titanium sheeting and have memory characteristics.
`
`SUMMARY OF THE INVENTION
`
`The problem of the invention is consequently to provide
`a stent, which has a high bending flexibility in the case of
`axially vertically acting forces and which is in particular
`subject to no deformations of its contour, particularly suf-
`fering no cross-sectional changes in the case of bending.
`According to the invention this problem is solved by a
`stent, which is characterized in that it has several axially
`succeeding meander paths extending over its circumference,
`that between axially facing areas of the meander paths
`interconnected by connecting portions in the circumferential
`direction there are at least two facing, non-interconnected
`areas of each meander path.
`Due to the fact that with such a stent and with several
`axially succeeding material paths guided in meander-like
`man11er over the circumference facing or directed towards
`one another, adjacent areas of two adjacent meander paths
`are not interconnected in all cases, but instead between such
`interconnected areas there are circumferentially at least two
`non-interconnected areas, a higher flexibility is obtained
`than would be the case with a stent in which all the facing,
`adjacent areas of two adjacent meander paths were firmly
`interconnected. This not only leads to a higher flexibflity, but
`it is in particular achieved that no cross-sectional deforma-
`tion occurs at bends under the action of axially vertical
`forces.
`
`An important advantage of the invention is that a high
`bendability is achieved without multilayer material crossing
`points, such as is the case in knitted, woven and braided
`
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`005
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`2
`structures. Due to the fact that there are no such material
`crossing points, the stent according to the invention grows
`better into the tissue. It also significantly reduces or elimi-
`nates the risk of the occurrence of thromboses, particularly
`in the vascular region.
`According to a preferred development the connecting
`portions of axially succeeding meander paths are recipro-
`cately displaced in the circumferential direction and in
`particular the connecting portions are circumferentially dis-
`placed by half a meander period, so that the desired axial
`strength is retained or obtained.
`The meander paths can be formed in numerous dilferent
`ways. Thus, according to preferred developments, the mean-
`der paths are zig-zag-like (with peaks), the meander paths
`are sinusoidal and that the meander paths have an oval
`construction. According to further preferred developments
`facing areas of the meander paths are aligned in the axial
`direction and/or that the width of the connecting areas in the
`circumferential direction is no larger than the width of the
`legs of the meander paths.
`The stent is preferably self-expanding and is made from
`a memory metal material. In the low temperature state (well
`below body temperature),
`the individual meander legs
`engage with one another, whereas in the high temperature
`state (below but closer to body temperature) the stent is
`radially widened.
`Further advantages and features of the invention can be
`gathered from the claims and the following description of
`the inventive stent with reference to the attached drawings.
`
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`BRIEF‘ DESCRIPTION OF DRAWINGS
`
`FIG. 1 is a preferred development of the stent according
`to the invention in its low temperature or insertion configu-
`ration.
`
`35
`
`FIG. 2 is the stent of FIG. 1 in its high temperature or
`positioning configuration.
`FIG. 3 is a diagrammatic representation of a stent sepa-
`rated longitudinally at its welding positions and laid out flat
`in order to better illustrate the connection of the successive,
`axial, zig-zag meander paths.
`FIG. 4 is a slotted plate for producing a stent according to
`the invention.
`
`DETAILED DESCRIPTION OF DISCLOSED
`EMBODIMENT
`
`In the represented embodiment the stent 1 according to
`the invention has a cylindrical shape, the outer contour of the
`stent being indicated by broken lines S in FIG. 2.
`In place of a cylindrical design the stent 1 can also have
`a conical, biconical, fi'ust11m-shaped or other contour. It
`always has an axis of symmetry A, which determines the
`axial direction. The circumferential direction is indicated by
`the arrow U.
`
`As can in particular be gathered fiom FIGS. 2 end 3, the
`stent 1 according to the invention comprises a number of
`meander paths 2, 2a, 2b succeeding one another in the axial
`direction A. In the circumferential direction the meander
`paths 2, 2a, 2b are arranged in such a way that in each case
`facing, adjacent peak areas 3, 3a or 3'a, 3b of in each case
`juxtaposed meander paths 2, 2a, 2b are axially aligned.
`FIGS. 2 and 3 clearly show that not all the facing, adjacent
`peak areas 3, 3a, 3‘a, 3b of the meander paths 2, 2a, 2b are
`interconnected by connecting areas 4, 4a, 4b, 4c, 4d, but
`between such connecting areas 4 to 4d of two adjacent
`
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`

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`5,707,386
`
`3
`
`meander paths 2, 2a are circumferentially provided several
`gaps 5, 5', 5a, 5b, Sb’. This leads to a high flexibility of the
`stent according to the invention. It is in particular achieved
`that when the stent 1 is bent at right angles to its longitudinal
`axis A the central area does not bend in in such a way that
`it loses its cross-sectionally, substantially circular contour
`and is pressed flat in the center in the action direction of the
`forces and perpendicular to the action direction of the forces
`is not widened in the center of its longitudinal extension as
`is the case with conventional stents, where all the facing,
`adjacent peak areas 3, 3a etc. of juxtaposed meander turns
`are firmly linked by connecting areas 4, 4a etc.
`The connecting areas 4, 4a etc. are in one piece with the
`remaining part of the stent, particularly the meander paths 2,
`2a etc. and their adjacent areas 3, 3a.
`It can be gathered from FIG. 1 that the substantially
`rhombic free spaces formed between the legs of the meander
`paths 2,2a etc. in the high temperature setting taper to slots
`in the low temperature setting and the legs of the meander
`paths 2, etc. are substantially parallel to one another.
`,1
`FIG. 3 also shows that the circumferential thickness of the
`connecting areas 4, 4a, 4b, 4c is no greater than the thickness
`of the individual legs of the meander paths 2, 2a, etc. The
`areas 7, 7' or 7a, 7a’ are welded areas, which in the closed
`position of the stent shown in FIG. 3 are interconnected by
`welded joints.
`FIG. 4 shows a slotted plate from which the stent accord-
`ing to the invention can be produced, The stent is made from
`a nickel-titanium alloy, such as nitinol. In a flat plate the
`openings or slots 11, as shown in FIG. 4, are produced in that
`circurnferentially adjacent slots are in each case displaced by
`approximately half their length in the axial direction A. In
`the central area of each slot 11 the latter is provided with a
`widening 12, so that the material bounding the widening 12
`in the circumferential direction is reduced roughly to the
`width of the material left between the slots. If the portions
`13 are left, they later form the connecting portions 4, 4a, etc.,
`or in the areas where the portions 13 are removed, the free
`spaces or gaps 5, 5a, etc. are created.
`After producing the plate in the form shown in FIG. 4
`initially all the portions 13 are left. Only to the left is it
`indicated in FIG. 4 how subsequently, i.e. after producing
`the stent, as shown in FIGS. 1 and 2, the separations are
`formed for creating the gaps 5.
`The plate shown in FIG. 4 is bent to form a cylinder, so
`that the two edges 14,15 are in contact. At the welding points
`7, 7' the welding joints are made and as a result initially a
`stent is formed in its low temperature position corresponding
`to FIG. 1. This is followed by a heat treatment, so as to give
`memory characteristics to the resulting stent, so that after
`raising the temperature to a predetermined ambient
`temperature, which is below the temperature of the human
`body, it can widen to its high temperature position corre-
`sponding to FIG. 2.
`After producing and heat treating the stent in this way, the
`bridges 13 are removed in the desired manner, so that the
`connecting areas or webs 4, 4a, etc. or free spaces 5, 5', 5a,
`etc. are formed, in the manner described hereinbefore. In
`FIG. 3 between two circumferentially succeeding connect-
`ing areas or webs 4, 4a are in each case formed two free
`spaces 5 of adjacent, facing areas 3, 3a of the meander turns
`2, 2a. The portions between the joining areas 4 in the
`circumferential direction can also be made larger. As arule,
`there should be at least two free spaces 5 between two
`circurnferentially succeeding webs 4.
`The invention provides a highly flexible stent, which can
`follow all the bends without any deterioration.
`
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`We claim:
`
`4
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`1. A stent comprising a plurality of succeeding meander
`paths, which succeed one another in an axial direction of
`said stent and extend over a circumference of said stent, each
`of said meander paths having legs which are connected with
`one another along their associated meander path by turns of
`said meander paths which form peaks of the meander paths
`in the axial direction, axially adjacent meander paths having
`oppositely directed peaks axially facing one another at a
`plurality of locations spaced about the circumference of the
`stent, which peaks are interconnected by connecting por-
`tions of the meander paths, and wherein between axially
`facing peaks, interconnected by said connecting portions, of
`the meander paths are provided in the circumferential direc-
`tion two axially facing, non-interconnected peaks of each
`meander path which are closely spaced from corresponding
`peaks of the adjacent meander path by relatively small gaps
`to form a plurality of‘ substantially closed free spaces
`between successive peaks in the circumferential direction.
`2. Stent according to claim 1, wherein the connecting
`portions of axially succeeding meander paths are recipro-
`cately displaced in the circumferential direction.
`3. Stent according to claim 2, wherein the connecting
`portions are displaced by half a meander period in the
`circumferential direction.
`4. Stent according to claim 1, wherein the meander paths
`have a zig-zag construction.
`5. Stent according to claim 1, wherein the meander paths
`are sinusoidal.
`
`6. Stent according to claim 1, wherein the meander paths
`are oval.
`
`7. Stent according to claim 1, wherein the facing peaks of
`the adjacent meander paths are aligned in the axial direction.
`8. Stent according to claim 1, wherein the width of the
`connecting areas in the circumferential direction is no
`greater than the width of the legs of the meander paths.
`9. Method for producing a stent from a memory alloy,
`comprising making slots in a flat plate formed of a memory
`metal material in such a way that perpendicular to their
`extension direction adjacent slots are displaced by approxi-
`mately half their length in the extension direction, bending
`the thus worked plate to form a cylinder with edges of the
`plate contacting each other,
`interconnecting contacting.
`edges of said cylinder by welding at weld points and heat
`treating the welded cylinder to give the stent memory
`characteristics, so that after raising its temperature to above
`ambient temperature, but below the body temperature of the
`human body, it widens in a high temperature position.
`10. Method according to claim 9, wherein in the central
`region of each slot the slot is provided with a widening, so
`that the material bounding the widening in the direction
`perpendicular to the extension direction of the slots roughly
`has the width of the material left between the slots.
`11. Method according to claim 9 and 10,
`including
`forming welding areas on the lateral edges of the flat plate
`before bending said plate to form a cylinder, said welding
`areas being welded to interconnect the contacting edges after
`said bending of said plate.
`12. Method according to claim 9, wherein each of said
`slots made in the flat plate defines a closed free space, and
`wherein after said slotted flat plate is bent and welded to
`form said welded cylinder, said method including in a plane
`perpendicular to the extension direction of the slots, partly
`removing webs left behind between two succeeding slots in
`the extension direction thereof so as to create free spaces or
`gaps extending between each of adjacent closed, free spaces
`in said plane.
`
`006
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`5,707,386
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`13. Method according to claim 12, wherein free spaces or
`gaps are provided between at least two circumferentially
`following webs.
`14. Method according to claim 12, wherein the webs are
`left in axially succeeding planes with a circumferential
`displacement.
`15. A stent comprising a plurality of succeeding of mean-
`der paths, which succeed one another in an axial direction of
`said stent and extend over a circumference of said stent, each
`of said meander paths having legs which are connected with
`one another along their associated meander path by turns of
`said meander paths which form peaks of the meander paths
`in the axial direction, axially adjacent meander paths having
`oppositely directed peaks axially facing one another at a
`pl1n'ality of locations spaced about the circumference of the
`stent, which peaks are interconnected by connecting por-
`tions of the meander paths, and wherein between axially
`facing peaks interconnected by said connecting portions, of
`the meander paths are provided in the circumferential direc-
`tion at least two axially facing non-interconnected peaks of
`each meander path which are closely spaced from corre-
`sponding peaks of the adjacent meander path by relatively
`small gaps to form a plurality of substantially closed free
`spaces between successive peaks in the circumferential
`direction, said stent being made by a method comprising
`making slots in a flat plate fonned of a memory metal metal
`material in such a way that perpendicular to their extension
`direction adjacent slots are displaced by approximately half
`their length in the extension direction, bending the thus
`worked plate to form a cylinder with edges of the plate
`contacting each other, interconnecting contacting edges of
`said cylinder by welding at weld points and heat treating the
`welded cylinder to give the stent memory characteristics, so
`
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`that after raising its temperature to above ambient
`temperature, but below the body temperature of the human
`body, it widens in a high temperature position, wherein each
`of said slots made in the flat plate defines a closed free space,
`and wherein after said slotted flat plate is bent and welded
`to form said welded cylinder, said method including in a
`plane perpendicular to the extension direction of the slots,
`partly removing webs left behind between two succeeding
`slots in the extension direction thereof so as to create said
`
`relatively small gaps extending between each of adjacent,
`closed free spaces in said plane.
`16. A stent comprising a plurality of succeeding meander
`paths, which succeed one another in an axial direction of
`said stent and extend over a circumference of said stent, each
`
`of said meander paths having legs which are connected with
`one another along their associated meander path by turns of
`said meander paths which form peaks of the meander path
`in the axial direction, axially adjacent meander paths having
`oppositely directed peaks axially facing one another at a
`plurality of locations spaced about the circumference of the
`stent, which peaks are interconnected by connecting por-
`tions of the meander paths, and wherein between axially
`facing peaks, interconnected by said connecting portions, of
`the meander paths are provided in the circumferential direc-
`tion at least two axially facing, non-interconnected peaks of
`each meander path which are closely spaced from corre-
`sponding peaks of the adjacent meander path by relatively
`small gaps to form a plurality of substantially closed free
`spaces between successive peaks in the circumferential
`direction.
`
`'
`
`007
`
`007