[19]
`United States Patent
`5,911,752
`[11] Patent Number:
`[45] Date of Patent: Jun. 15, 1999
`Dustrude et al.
`
`
`
`US005911752A
`
`[54] METHOD FOR COLLAPSING A STENT
`
`[75]
`
`Inventors: Mark Owen Dustrude, Minnetonka;
`James V. Donadio, III, Chaska; J.
`Edward Shapland, II, Shoreview, all
`of Minn.
`
`[73] Assignee:
`
`IntraTherapeutics, Inc., St. Paul,
`Minn.
`
`[21] Appl. No.: 08/710,245
`
`[22]
`
`Filed:
`
`Sep. 13, 1996
`
`Int. Cl.6 ........................................................ A61F 2/06
`[51]
`[52] US. Cl.
`.............................. 623/1; 606/191; 606/195;
`606/198; 606/192; 604/96
`[58] Field of Search .................................... 623/1, 11, 12;
`604/96, 104; 606/153—156, 108, 190—200;
`128/898
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`.
`
`4/1972 Ersek .
`3,657,744
`11/1985 Maass et al.
`4,553,545
`3/1988 Palmaz .
`4,733,665
`4/1988 Palmaz .
`4,739,762
`4,776,337 10/1988 Palmaz.
`4,793,348 12/1988 Palmaz.
`4,856,516
`8/1989 Hillstead.
`4,893,623
`1/1990 Rosenbluth.
`4,994,071
`2/1991 MacGregor.
`5,102,417
`4/1992 Palmaz.
`5,135,536
`8/1992 Hillstead.
`5,195,984
`3/1993 Schatz.
`5,197,978
`3/1993 Hess.
`5,266,073
`11/1993 Wall.
`5,306,294
`4/1994 Winston et al.
`5,342,348
`8/1994 Kaplan.
`.
`5,344,426
`9/1994 Lau et al.
`5,354,309
`10/1994 Schnepp—Pesch et al.
`5,366,473
`11/1994 Winston et al.
`.
`5,382,261
`1/1995 Palmaz.
`
`.
`
`.
`
`.
`
`1/1995 Cardon et al.
`5,383,892
`5/1995 Narciso, Jr.
`.
`5,419,760
`6/1995 Williams .
`5,423,885
`9/1995 Pinchasik et al.
`5,449,373
`5/1996 Lau et al.
`.
`5,514,154
`6/1997 Fischell et al.
`......................... 606/108
`5,634,928
`
`
` 8/1997 Rupp et al. ................ 604/96
`5,653,691
`..................... 604/96
`8/1997 Berthiaume et al.
`5,658,309
`FOREIGN PATENT DOCUMENTS
`
`.
`
`0 364 787
`0 423 916 A1
`WO 92/09246
`WO 94/20044
`WO 95/30385
`
`4/1990 European Pat. Off.
`4/1991
`European Pat. Off.
`6/1992 WIPO .
`9/1994 WIPO .
`11/1995 WIPO .
`
`.
`.
`
`Primary Examiner—Mickey Yu
`Assistant Examiner—Francis K. Cuddihy
`Attorney, Agent, or Firm—Merchant, Gould, Smith, Edell,
`Welter & Schmidt
`
`[57]
`
`ABSTRACT
`
`A method for implanting a stent within a body passageway
`defined by a body wall. The method includes the step of
`fabricating the stent in an initial orientation in which the
`stent has an initial diameter and an initial length. The method
`also includes the step of collapsing the stent radially inward
`from the initial orientation to a collapsed orientation in
`which the stent has a collapsed length and a collapsed
`diameter. The stent is collapsed by deforming a portion of
`the stent beyond the elastic limit of the portion of the stent.
`The method further includes the step of positioning the
`collapsed stent at a desired location within the body pas-
`sageway. Additionally,
`the method includes the step of
`expanding the stent radially outward from the collapsed
`orientation to a deployed orientation in which the stent has
`a deployed diameter and a deployed length. The deployed
`diameter and the deployed length are respectively substan-
`tially equal to the initial diameter and the initial length. The
`stent is expanding by deforming the portion of the stent
`beyond the elastic limit of the portion of the stent.
`
`6 Claims, 11 Drawing Sheets
`
`Lo
`
`
`24
`
`20
`
`/\/\/\/\ /\/\/g
`
`
`
`\A/\/ \/\/\/\/
`
`22
`
`26
`
` Edwards Lifesciences v. Boston Scientific
`
`US. Patent N0. 6,915,560
`IPR2017-00444 EX. 2038
`
`Page 1 of 17
`
`Page 1 of 17
`
`

`

`US. Patent
`
`Jun. 15, 1999
`
`Sheet 1 0f 11
`
`5,911,752
`
`FIG. lo
`
`20/‘\
`x4
`
`\
`
`FIG. lc
`
`D.
`If
`
`(”<20
`\04722
`\/
`
`FIG. Ie
`
`FIG. Ib
`Lif
`
`20
`
`
`
`24
`
`FIG. If
`Lc
`
`/\/\/\/\ /\/\/g
`\A/\/ \/\/\/\/
`
`20
`
`26
`
`22
`
`
`
`Page 2 of 17
`
`Page 2 of 17
`
`

`

`U.S. Patent
`
`Jun. 15, 1999
`
`Sheet 2 of 11
`
`5,911,752
`
`FIG. 2
`32
`
`34
`
`2?
`
`FG.2b
`36
`
`32
`
`34
`
`FIG.2c
`36
`
`32
`
`34
`
`~~~~~~~
`
`Page 3 of 17
`
`

`

`U.S. Patent
`US. Patent
`
`Jun. 15, 1999
`Jun. 15,1999
`
`Sheet 3 of 11
`Sheet 3 0f 11
`
`5,911,752
`5,911,752
`
`
`
`
`
`
`
`Page 4 of 17
`
`Page 4 of 17
`
`

`

`U.S. Patent
`US. Patent
`
`Jun. 15, 1999
`Jun. 15,1999
`FIG. 4 O
`FIG. 40
`
`Sheet 4 of 11
`Sheet 4 0f 11
`
`5,911,752
`5,911,752
`
`5O
`so
`
`2O
`20
`
`FG. 4b.
`FIG. 4b
`
`50
`
`20
`
`Page 5 of 17
`
`Page 5 of 17
`
`

`

`U.S. Patent
`US. Patent
`
`Jun. 15, 1999
`Jun. 15,1999
`
`Sheet S of 11
`Sheet 5 0f 11
`
`5,911,752
`5,911,752
`
`
`
`
`
`
`
`Page 6 of 17
`
`Page 6 of 17
`
`

`

`U.S. Patent
`US. Patent
`
`Jun.15, 1999
`Jun. 15,1999
`
`Sheet 6 of 11
`Sheet 6 0f 11
`
`5,911,752
`5,911,752
`
`FIG. 5c
`62
`
`60
`
`
`
`
`
`
`
`Page 7 of 17
`
`Page 7 of 17
`
`

`

`U.S. Patent
`US. Patent
`
`Jun. 15,1999
`Jun. 15, 1999
`
`Sheet 7 0f 11
`Sheet 7 of 11
`
`5,911,752
`5,911,752
`
`
`
`538
`
`829
`
`FIG.6
`
`229
`
`Page 8 of 17
`
`Page 8 of 17
`
`

`

`U.S. Patent
`US. Patent
`
`Jun. 15, 1999
`Jun. 15,1999
`
`Sheet 8 of 11
`Sheet 8 0f 11
`
`5,911,752
`5,911,752
`
`FIG. 7
`FIG. 7
`
`
`
`Page 9 of 17
`
`Page 9 of 17
`
`

`

`U.S. Patent
`FIG. 8
`
`Jun. 15, 1999
`
`Sheet 9 of 11
`
`5,911,752
`
`25O
`
`
`
`Page 10 of 17
`
`

`

`U.S. Patent
`US. Patent
`
`Jun. 15, 1999
`Jun. 15, 1999
`
`Sheet 10 of 11
`Sheet 10 0f 11
`
`5,911,752
`5,911,752
`
`gö L
`O)
`96..F
`
`
`
`
`
`Page11of17
`
`Page 11 of 17
`
`

`

`
`
`
`
`U.S. Patent
`US. Patent
`
`Jun. 15, 1999
`Jun.15,1999
`
`Sheet 11 of 11
`Sheet11,0f11
`
`5,911,752
`5,911,752
`
`FIG. O
`FIG. l0
`
` 09..4
`
`Page120f17
`
`Page 12 of 17
`
`

`

`5,911,752
`
`1
`METHOD FOR COLLAPSING A STENT
`
`FIELD OF THE INVENTION
`
`invention relates generally to expandable
`The present
`vascular grafts for use within body passageways. More
`particularly,
`the present
`invention relates to expandable
`stents for maintaining the patency of blood vessels and to a
`method for implanting such expandable stents within a body
`passageway.
`
`BACKGROUND OF THE INVENTION
`
`Stents are commonly used to provide mechanical rein-
`forcement for maintaining the patency of body passageways
`and cavities. Exemplary body passageways include blood
`vessels, the urethra, the bile duct, the esophagus, and the
`ureters.
`
`A common use for stents is in the treatment of coronary
`artery disease. Coronary artery disease involves the narrow-
`ing or constricting of a coronary artery such that blood flow
`through the artery is diminished. Such a situation is com-
`monly treated by balloon angioplasty procedures in which
`the afflicted artery is dilated/expanded through use of a
`balloon catheter. Without artificial reinforcement, the bal-
`loon expanded vessel has a tendency to constrict back to its
`previous obstructed internal diameter shortly after an angio-
`plasty procedure. By implanting a stent along the expanded
`portion of the vessel, the vessel is provided with sufficient
`radial reinforcement to prevent the vessel from constricting.
`Besides preventing vessel constriction, stents provide
`another important function when used in association with
`balloon angioplasty procedures. During a typical balloon
`angioplasty procedure, it is common for the afflicted artery
`to split or tear as it is expanded. The tearing of the vessel
`produces flaps of tissue that may project into the lumen of
`the vessel thereby interfering with blood flow. To prevent the
`aforementioned problem, a stent
`is implanted at
`the
`obstruction/constriction location. The stent compresses the
`flaps against the vessel to prevent interference with blood
`flow and to prevent the flaps from tearing from the vessel
`and entering the blood stream.
`Avariety of stent designs are known in the prior art. One
`category of stent design relates to self-expanding stents. Two
`types of self-expanding stents are prevalent in the medical
`field. The first type of self-expanding stent is fabricated of
`highly elastic material and exhibits elastic spring back
`characteristics. A common elastic self-expanding stent con-
`figuration comprises a helical stainless steel spring. The
`second type of self-expanding stent relates to temperature
`sensitive stents. Such temperature sensitive stents expand or
`contract in a radial direction depending upon their tempera-
`ture.
`
`An elastic self-expanding stent is typically manufactured
`in an enlarged orientation such that the stent has an enlarged
`diameter. The elastic self-expanding stent
`is then com-
`pressed to a compressed orientation in which the stent has a
`diameter sufficiently small to be inserted in a vessel. Once
`the stent is compressed to the compressed orientation, the
`stent is inserted within or on a catheter body that exerts
`sufficient radial stress upon the stent to prevent the stent
`from expanding. After the stent has been directed via the
`catheter to a desired location within a vessel, the elastic
`self-expanding stent is disengaged from the catheter. Upon
`disengagement from the catheter the radial compressive
`force provided by the catheter is removed and the stent
`automatically expands, via its elastic construction, from the
`compressed orientation to the expanded orientation. In the
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`expanded orientation, the stent radially engages the vessel
`such that the vessel is reinforced to maintain the patency of
`the vessel. Additionally, contact between the vessel and the
`stent prevents the stent from migrating within the vessel.
`A problem with elastic self-expanding stents is that they
`typically experience substantial length variations when tran-
`sitioning between the compressed and expanded orienta-
`tions. The significant length variation associated with such
`elastic self-expanding stents makes it difficult to precisely
`place the stents at a particular location within a body.
`A temperature sensitive self-expanding stent is typically
`manufactured of a two-way shape-memory alloy such as
`Nitinol. Such a stent
`is designed to have an expanded
`orientation when the stent has a temperature above a shape
`transition temperature which is typically above room tem-
`perature and may be equal to body temperature. The tem-
`perature sensitive stent is radially compressed to a con-
`stricted orientation for implantation in a body vessel via a
`catheter. Once the stent is positioned at a desired location in
`the vessel, heat absorbed from the body causes the stent to
`expand to the expanded configuration.
`In the expanded
`configuration,
`the stent engages the vessel such that the
`vessel is radially reinforced.
`Another category of stent relates to non-self-expanding
`stents. An exemplary non-self-expanding stent is disclosed
`in US. Pat. No. 4,733,665. Such stents typically are con-
`structed of a deformable material. The deformable material
`
`allows the stents to maintain their shape when expanded.
`The stents are typically pre-equipped with a manufacturing
`installed catheter balloon and are typically manufactured
`with a small diameter sized to permit insertion into a vessel.
`In use, a physician directs a non-self-expanding stent, via
`a catheter, to a desired location within a vessel. Once the
`stent reaches the desired location, the physician inflates the
`balloon in a controlled manner such that the stent is caused
`
`to expand. As the stent is expanded, the deformable material
`used to construct the stent deforms beyond its elastic limit.
`Consequently, the expanded stent has a tendency to maintain
`its expanded shape. Once expanded, the stent reinforces the
`vessel by providing radial reinforcement for maintaining the
`patency of the vessel.
`A problem with a conventional non-self—expanding stent
`is that stress generated by a vessel in which the stent is
`implanted can cause the stent to be compressed radially
`inward thereby reducing the lumen size of the vessel. One
`reason for this problem is that when the non-self-expanding
`stent is expanded/deformed from a small diameter to an
`enlarged diameter, the individual members forming the stent
`have a tendency to twist relative to one another. The relative
`twisting of the members affects the structural integrity of the
`stent thereby reducing the stent’s ability to resist vessel
`pressure.
`
`SUMMARY OF THE INVENTION
`
`The present invention relates to a method for implanting
`a stent within a body passageway. The method includes the
`step of fabricating the stent in an initial fabrication orien-
`tation. In the initial fabrication orientation, the stent has an
`initial fabrication diameter and an initial fabrication length.
`The stent is fabricated to have a predetermined flexibility
`and a radial reinforcement strength.
`After the stent
`is fabricated in the initial fabrication
`
`orientation, the stent is collapsed radially inward by deform-
`ing a portion of the stent beyond the elastic limit of the
`portion of stent. The collapsed stent has a collapsed diameter
`and a collapsed length. The collapsed diameter is sized to
`allow the stent to be inserted into the body passageway.
`
`Page130f17
`
`Page 13 of 17
`
`

`

`5,911,752
`
`3
`After the stent is collapsed, the stent is positioned at a
`desired location within the body passageway. When the stent
`is positioned at
`the desired location within the body
`passageway,
`the stent is expanded radially outward to a
`deployed orientation by deforming portions of the stent
`beyond their elastic limits. In the deployed orientation, the
`stent contacts the body passageway and has a deployed
`diameter and a deployed length that are respectively sub-
`stantially equal to the initial fabrication diameter and the
`initial fabrication length.
`the deployed diameter and the
`It
`is significant
`that
`deployed length are respectively substantially equal to the
`initial fabrication diameter and the initial fabrication length.
`Such a feature provides numerous advantages. For example,
`the similarities of the fabrication orientation and the
`
`deployed orientation facilitate a physician’s ability to select
`a stent of suitable diameter and length for a given use. Also,
`by providing the physician with the stent in the fabricated
`orientation,
`the physician can collapse the stent radially
`inward upon his or her own catheter balloon rather than
`being forced to utilize a balloon installed within the stent
`during the manufacturing process. Furthermore, because the
`deployment diameter and the deployment length are respec-
`tively substantially equal to the initial fabrication diameter
`and the initial fabrication length, there is minimal twisting of
`the individual members that form the stent when the stent is
`
`the
`actually implanted in the patient. Consequently,
`deployed stent and the initially fabricated stent demonstrate
`similar flexibility and reinforcement strength characteristics.
`Another aspect of the present
`invention relates to a
`method for collapsing a stent. The method includes the step
`of providing a stent having an expanded orientation. Next, a
`catheter balloon is placed within the stent. Finally, centrip-
`etally directed radial forces are applied substantially uni-
`formly about the perimeter of the stent. The radial forces are
`of sufficient magnitude to deform portions of the stent
`beyond their elastic limits such that
`the stent collapses
`radially inward from the expanded orientation to a collapsed
`orientation. In the collapsed orientation, the stent is com-
`pressed upon the balloon and sized for insertion within a
`body passageway.
`invention relates to a
`Another aspect of the present
`method for fabricating a stent. Generally,
`the method
`includes the step of first providing a solid tube member
`having an initial expanded diameter. The initial expanded
`diameter is substantially equal to a final expanded diameter
`which the tube member is intended to have when implanted
`in a body. Aplurality of apertures are then cut within the tube
`member while tube member maintains its initial expanded
`diameter.
`
`Afurther aspect of the present invention relates to a stent
`including a tubular stent body moveable between an
`expanded orientation and a collapsed orientation. Aplurality
`of apertures are cut within the stent body. The apertures are
`defined by a plurality of contiguous non-overlapping strut
`members. In certain embodiments, all of the strut members
`have axial components that are substantially parallel to a
`longitudinal axis of the tubular stent body to facilitate
`collapsing the stent. Portions of the strut members are
`constructed and arranged to be deformed beyond their
`elastic limits when the stent body is moved between the
`expanded and collapsed orientations.
`Avariety of additional advantages of the invention will be
`set forth in part in the description which follows, and in part
`will be obvious from the description, or may be learned by
`practice of the invention. The advantages of the invention
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`will be realized and attained by means of the elements and
`combinations particularly pointed out in the claims. It is to
`be understood that both the foregoing general description
`and the following detailed description are exemplary and
`explanatory only and are not restrictive of the invention as
`claimed.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The accompanying drawings, which are incorporated in
`and constitute a part of this specification, illustrate several
`embodiments of the invention and together with the
`description, serve to explain the principles of the invention.
`A brief description of the drawings is as follows:
`FIG. 1a shows a schematic end view of a stent as initially
`fabricated;
`FIG. 1b shows a schematic side view of the initially
`fabricated stent of FIG. 1a;
`FIG. lc shows an end view of the stent of FIG. 1a with
`a catheter inserted therein;
`FIG. 1d shows a schematic side view of the stent of FIG.
`1a with a catheter inserted therein;
`FIG. 16 shows a schematic end view of the stent of FIG.
`
`1a compressed upon a catheter;
`FIG. 1f shows a schematic side view of the stent of FIG.
`1a compressed upon a catheter;
`FIG. 1g shows a schematic end view of the stent of FIG.
`1a expanded within a body passageway;
`FIG. 1h shows a schematic side view of the stent of FIG.
`
`1a expanded within a body passageway;
`FIG. 2a schematically shows a stent prior to being forced
`through a tube having a tapered inner diameter;
`FIG. 2b shows the stent in the process of being forced
`through the tube having the tapered inner diameter;
`FIG. 2C shows the stent after having been forced through
`the tube having the tapered inner diameter;
`FIG. 3a shows an end view of a stent placed within an
`inflatable cuff, the cuff is in a non-inflated state;
`FIG. 3b shows an end view of the stent being compressed
`by the inflatable cuff, the cuff is shown in an inflated state;
`FIG. 4a shows an end view of a stent placed within a
`mechanical sleeve, the sleeve is in an expanded orientation;
`FIG. 4b shows an end view of the mechanical cuff in a
`constricted orientation;
`FIG. 5a shows a side cross-sectional view of a split collet
`mechanism for compressing a stent, the split collet mecha-
`nism is shown in an expanded orientation;
`FIG. 5b shows an end view of an inner sleeve that is
`
`incorporated within the split collet mechanism of FIG. 5a,
`the inner sleeve is shown in an expanded orientation;
`FIG. Sc shows a side cross-sectional view of the split
`collet mechanism of FIG. 5a in a constricted orientation;
`FIG. 5d shows an end view of the inner sleeve of FIG. 5b,
`the inner sleeve is shown in a constricted orientation;
`FIG. 6 is a diagrammatic illustration showing an etching
`method suitable for making stents in accordance with the
`principles of the present invention;
`FIG. 7 shows a stent having triangular openings cut
`therein;
`FIG. 8 shows a stent having hexagonal openings cut
`therein;
`FIG. 9 shows a stent having diamond-shaped openings;
`and
`
`Page 140f17
`
`Page 14 of 17
`
`

`

`5,911,752
`
`5
`FIG. 10 shows a stent including a plurality of intersecting
`elongated loop members.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`to exemplary
`Reference will now be made in detail
`embodiments of the present invention which are illustrated
`in the accompanying drawings. Wherever possible, the same
`reference numbers will be used throughout the drawings to
`refer to the same or like parts.
`FIGS. la—lh illustrate a method for implanting a stent in
`accordance with the principles of the present
`invention.
`FIGS. 1a and 1b show a stent 20 in an initial fabrication
`orientation. In the initial fabrication orientation, the stent 20
`has an initial fabrication diameter le and an initial fabrica-
`tion length Llf. The initial fabrication diameter le and the
`initial fabrication length Llf are preferably equal
`to the
`intended use diameter and the intended use length of the
`stent 20.
`
`It will be appreciated that the stent 20 preferably has a
`tubular shape and is constructed to have a predetermined
`flexibility and a predetermined radial reinforcement
`strength. Radial reinforcement strength and flexibility are
`determinable physical characteristics that are dependent
`upon the structural design of the stent 20. The stent 20 is
`preferably made from a biocompatible material having elas-
`ticity characteristics that allow the stent 20 to be expanded
`and collapsed. The material must be sufficiently deformable
`to permit the stent to retain its expanded and collapsed
`orientations. Suitable materials for fabrication of the stent
`
`tantalum, stainless steel, gold,
`would include silver,
`titanium, Nitinol or any suitable plastic material.
`It will be appreciated that the stent 20 could be con-
`structed from a plurality of overlapping/intertwined wire
`members configured to form an elongated tube, the wire
`members being interconnected at the points at which the
`wire members overlap one another. Alternatively, the stent
`20 could comprise a tube having a pattern cut therein via a
`conventionally known cutting process. Exemplary cutting
`processes include stamping, electromechanical cutting, laser
`cutting, and chemical etching. An exemplary chemical etch-
`ing process suitable for manufacturing a stent having an
`initial fabrication diameter equal to the intended use/final
`expanded diameter of the stent is described later in the
`specification with respect to FIG. 6.
`FIGS. IC and 1d show the stent 20 in the initial fabrication
`orientation with a conventional balloon catheter 22 inserted
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`therein. The balloon catheter 22 includes distal and proximal
`retaining structures 24 and 26 for retaining the stent 20 on
`the catheter 22. The catheter 22 also includes a balloon 28
`
`50
`
`for expanding the stent 20.
`FIGS. 16 and 1f illustrate the stent 20 in a collapsed
`orientation. The stent 20 is shown collapsed radially inward
`upon the catheter 22. In the collapsed orientation, the stent
`20 has a collapsed diameter DC that is sufficiently small to
`allow the stent 20 and the catheter 22 to be inserted within
`
`a desired body passageway. Additionally, it will be appre-
`ciated that as stent 20 is collapsed radially inward, the stent
`20 elongates to a collapsed length LC that is longer than the
`initial fabrication length Lif. However,
`in certain
`embodiments, the length LC may be equal to the length Llf.
`As collapsed, the stent 20 is firmly retained on the catheter
`22, or within a sleeve on the catheter 22, thereby allowing
`the stent 20 to be safely inserted within a body.
`It will be appreciated that the stent 20 can be collapsed by
`a variety of techniques. Specific exemplary collapsing tech-
`
`55
`
`60
`
`65
`
`6
`niques are described later in the specification. However,
`generally, the stent 20 is collapsed by exerting centripetally
`directed forces uniformly about the circumference of the
`stent 20. The forces cause the stent
`to deform radially
`inward. The forces are preferably great enough to cause at
`least portions of the stent 20 to deform beyond their elastic
`limits. By deforming portions of the stent 20 beyond their
`elastic limits, the stent 20 will retain its collapsed orientation
`even after the collapsing forces are no longer applied to the
`stent 20.
`
`the specification, references are made to
`Throughout
`deforming portions of the stent beyond their elastic limits.
`Such references are intended to mean that the portions of the
`stent are sufficiently deformed so as to demonstrate plastic/
`inelastic characteristics such that
`the stent substantially
`maintains the deformed position.
`FIGS. 1g and 1h illustrate the stent 20 in a deployed
`orientation. The stent 20 is shown implanted within an
`exemplary body passageway 30. In the deployed orientation
`the stent 20 has a diameter Dd that is substantially equal to
`the initial fabrication diameter Dif. Also, when the stent 20
`is in the deployed orientation, the stent 20 has a deployment
`length Ld that is substantially equal to the initial fabrication
`length Llf. Consequently, when the stent 20 is in the
`deployed orientation, the stent 20 has substantially the same
`structural configuration as when it was initially fabricated
`and there is very little twisting between the individual
`members that form the stent 20. It will be appreciated that
`the stent 20 as implanted within the body 30 demonstrates
`similar physical characteristics such as reinforcement
`strength and flexibility as the stent at the initial fabrication
`stage.
`The stent 20 is deployed within the body passageway 30
`by positioning the stent 20 at a desired location within the
`body passageway 30 via the catheter 22. Once the stent 20
`is at the desired location within the body passageway 30, the
`catheter balloon 28 is inflated causing a controlled radial
`expansion of the stent 20. The balloon 28 preferably exerts
`sufficient force against the stent 20 to cause portions of the
`stent 20 to deform beyond their elastic limits. Because
`portions of the stent 20 are expanded beyond their elastic
`limits, the stent 20 will maintain its expanded state within
`the body vessel 30. Once the stent 20 is expanded,
`the
`catheter 22 can be removed from the body passageway 30.
`FIGS. 2a—2c illustrate one method for collapsing the stent
`20. The method involves forcing the stent 20 longitudinally
`through a tube 32 having a tapered inner diameter. The tube
`32 has an inlet end 34 having an enlarged inlet diameter and
`an outlet end 36 having a constricted outlet diameter. To
`collapse the stent 20, one end of the stent 20 is inserted into
`the inlet end 34 of the tube 32. The stent 20 is then forced
`
`through the tube 32 toward the outlet end 36. As the stent 20
`is forced through the tube 32, the tapering inner diameter of
`the tube 32 compresses the stent 20 (as best shown in FIG.
`2b). The compression of the stent 20 by the inner diameter
`of the tube 32 causes at least portions of the stent 20 to
`deform beyond their elastic limits. Once the entire stent 20
`is forced through the tube 32, the entire stent 20 has an outer
`diameter approximately equal to the constricted inner diam-
`eter of the outlet end 36 of the tube 32.
`
`FIGS. 3a and 3b illustrate another method for collapsing
`the stent 20. The method utilizes an inflatable cuff 38
`
`selectively in fluid communication with a source of com-
`pressed fluid 40 (liquid or gas). The cuff 38 is generally
`cylindrical and defines an inner opening 42 extending lon-
`gitudinally through the cuff 38. To compress the stent 20, the
`
`Page150f17
`
`Page 15 of 17
`
`

`

`5,911,752
`
`7
`inflatable cuff 38 is first deflated such that the inner opening
`42 enlarges. The stent 20 is then inserted within the enlarged
`inner opening 42 of the inflatable cuff 38. Once the stent 20
`is inserted within the cuff 38, the cuff 38 is inflated via the
`source of compressed air 40. As the cuff 38 inflates, the inner
`opening 42 of the cuff 38 constricts such that the cuff 38
`exerts centripetally directed radial forces about the circum-
`ference of the stent 20. The forces cause the stent 20 to
`deform radially inward such that portions of the stent 20 are
`deformed beyond their elastic limits. Because portions of the
`stent 20 are deformed beyond their elastic limits, the stent 20
`will maintain its collapsed orientation even after the cuff 38
`has been removed from the exterior of the stent 20. The cuff
`is removed from the exterior of the stent 20 by deflating the
`cuff 38 such that the inner opening 42 enlarges to provide
`clearance for removing the stent 20 therefrom.
`FIGS. 4a and 4b illustrate another method for collapsing
`the stent 20. The method employs a mechanical compression
`sleeve 50 comprising a substantially flat member that is
`rolled upon itself to form a generally cylindrical tube. It will
`be appreciated that the longitudinal ends of the flat member
`are overlapped such that the sleeve 50 defines an inner
`longitudinal opening sized to receive the stent 20. To col-
`lapse the stent 20, the stent 20 is first placed in the sleeve 50
`as shown in FIG. 4a. Next, the sleeve 50 is rolled further
`upon itself causing greater overlap between the ends of the
`flat member such that the inner diameter of the sleeve 50
`constricts as shown in FIG. 4b. As the inner diameter of the
`sleeve 50 constricts, the stent 20 is deformed radially inward
`from the expanded orientation to the collapsed orientation.
`It will be appreciated that a variety of tensioning means
`can be utilized to roll the sleeve 50 upon itself. For example,
`a belt equipped with a ratchet mechanism can be wrapped
`around the exterior of the sleeve for compressing the sleeve
`50. Alternatively, a structure similar to a hose clamp can be
`wrapped around the exterior of the sleeve 50 and tensioned
`to constrict the sleeve. A conventional hose clamp structure
`typically comprises a strap member that has overlapping
`ends. The strap member has a plurality of transverse slots. A
`threaded member is rotatably mounted at one of the ends of
`the strap member. The threaded member is longitudinally
`aligned with the strap member and the threads of the
`threaded member cooperate with the slots in the strap
`member. By rotating the threaded member, the diameter of
`the loop formed by the strap member is varied.
`FIGS. 5a—5d illustrate another method for collapsing the
`stent 20. The method utilizes a split collet mechanism 60.
`The split collet mechanism 60 includes a cylindrical outer
`sleeve 62 having a tapered inner diameter. An inner sleeve
`structure 63 including a plurality of collet members 64 is
`reciprocally mounted within the outer sleeve 62. The collet
`members 64 have radially curved inner surfaces 66 that
`cooperate to form a cylindrical inner opening of the inner
`sleeve 63. The collet members 64 also have radially curved
`outer surfaces 68 that cooperate to define a tapered outer
`boundary of the inner sleeve 63. The outer taper of the inner
`sleeve 63 matches the inner taper of the outer sleeve 62.
`When the inner sleeve 63 is pulled longitudinally outward
`from the outer sleeve 62,
`radial spaces are generated
`between the individual collet members 62 such that the inner
`
`opening of the inner sleeve 63 expands. By contrast, when
`the inner sleeve 63 is pushed longitudinally into the outer
`sleeve 62,
`the collet members 64 are pushed radially
`together such that
`the radial spaces between the collet
`members 64 are closed and the inner opening of the inner
`sleeve 63 constricts.
`
`To collapse the stent 20 using the collet mechanism 60,
`the stent 20 is placed in the inner opening of the inner sleeve
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`
`63 while the inner sleeve 63 is expanded (as shown in FIGS.
`5a and 5b). Once the stent 20 is within the expanded inner
`sleeve 63, the inner sleeve 63 is pushed longitudinally into
`the outer sleeve 64 causing the stent 20 to be radially
`compressed and collapsed within the inner opening of the
`inner sleeve 63 (as shown in FIGS. Sc and 5d).
`It will be appreciated that the stent 20 can be collapsed by
`techniques other than those specifically disclosed. For
`example, the stent 20 can be collapsed by applying opposing
`longitudinal forces to opposite ends of the stent 20 such that
`the stent 20 is stretched. Alternatively, the stent 20 can be
`collapsed by applying torque to the stent 20 such that the
`stent 20 is twisted into a collapsed state. Also, it will be
`appreciated that any of the aforementioned stent collapsing
`structures can be sold in a kit that includes one or more stents
`
`configured to be collapsed by the corresponding collapsing
`structure. Furthermore,
`the type of collapsing technique
`utilized will depend upon the inherent structure of the stent
`being collapsed. Consequently, particular collapsing tech-
`niques will be tailored to particular stent designs.
`It will be appreciated that
`the stent 20 need not be
`collapsed upon the catheter 22 at the time the stent 20 is
`manufactured. Instead, the stent 20 could be shipped and
`sold while in the initial fabricated orientation.
`In this
`
`manner, the stent 20 could be provided to physicians in the
`initial fabricated orientation. By providing physicians with
`such a stent 20, the physician’s ability to select a stent of the
`appropriate size for a desired use is enhanced. This is
`because the initially fabricated diameter and length are
`substantially the same as the deployed diameter and length.
`Furthermore, because the stent 20 would be shipped in the
`initial fabrication orientation, the physician can insert his or
`her own catheter balloon 28 within the stent