`

`US 6,360,577 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`5,630,830 A
`5,672,169 A
`5,700,285 A
`5,725,519 A
`5,738,674 A
`5,746,644 A
`5,746,764 A
`5,749,921 A
`5,766,057 A
`5,766,203 A
`
`5/1997 Verbeek
`9/1997 Verbeek
`12/1997 Myers et al.
`3/1998 Penner et al. .................. 606/1
`4/1998 Williams et al.
`5/1998 Cheetham
`5/1998 Green et al.
`5/1998 Lenker et al.
`6/1998 Maack
`6/1998 Imran et al.
`
`5,792,415 A
`5,807,520 A
`5,810,871 A
`5,810,873 A
`5,836,952 A
`5,836,965 A
`5,860,966 A
`5,893,852 A
`5,893,867 A
`5,911,752 A
`* cited by examiner
`
`8/1998 Hijlkema .................... 264/530
`9/1998 Wang et al.
`................ 264/520
`9/1998 Tuckey et al.
`9/1998 Morales ...................... 606/198
`11/1998 Davis et al.
`11/1998 J endersee et al.
`1/1999 Tower
`4/1999 Morales
`4/1999 Bagaoisan et al.
`6/1999 Dustrude et al. .............. 623/1
`
`Page 2 of 23
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`

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`U.S. Patent
`
`
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`US 6,360,577 B2
`US 6,360,577 B2
`
`Mar.26,2002
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`Sheet 1 of 15
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`Page 3 of 23
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`U.S. Patent
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`Mar. 26, 2002
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`Sheet 3 of 15
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`US 6,360,577 B2
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`110
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`111
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`166
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`FIG. 3a
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`FIG. 3b
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`106
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`FIG. 3c
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`Page 5 of 23
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`U.S. Patent
`US. Patent
`
`Mar. 26, 2002
`Mar. 26, 2002
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`Sheet 4 0f 15
`Sheet 4 of 15
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`US 6,360,577 B2
`US 6,360,577 B2
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`138
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`FIG. 4A
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`US 6,360,577 B2
`
`1
`APPARATUS FOR CONTRACTING, OR
`CRIMPING STENTS
`
`BACKGROUND OF THE INVENTION
`
`2
`with three equally spaced rollers with mating inverse
`V-shaped profiles to provide precise rotatable support to the
`cam plate. Depending on the direction of rotation, the linear
`slides which each carry a radially disposed crimping blade,
`5 are either moved inwards to apply a crimping force to the
`stent, or outwards to release the stent. Also when crimping,
`depending on the degree of rotation of the cam plate, a
`specific radial crimping displacement may be obtained to
`match the diametral reduction required for any particular
`10 stent.
`All US patents and applications and all other published
`documents mentioned anywhere in this application are
`incorporated herein by reference in their entirety.
`
`This invention relates to an apparatus and a method for
`reducing in size a medical device such as a stent, stent-graft,
`graft, or vena cava filter. The apparatus may be used in
`particular for fastening a medical device onto a catheter.
`Medical devices such as stents, stent-grafts, grafts, or
`vena cava filters and catheters for their delivery are utilized
`in a number of medical procedures and situations, and as
`such their structure and function are well known.
`A stent, for example, is a generally cylindrical prosthesis
`introduced via a catheter into a lumen of a body vessel in a 15
`configuration having a generally reduced diameter and then
`expanded to the diameter of the vessel. In its expanded
`configuration, the stent supports and reinforces the vessel
`walls while maintaining the vessel in an open, unobstructed
`condition.
`Stents are typically inflation expandable or self(cid:173)
`expanding. Self expanding stents which are constrained by
`a sheath or other restraining means, must be provided in a
`reduced diameter.
`An example of a stent described in PCT Application No.
`960 3092 Al, published Feb. 8, 1996.
`In advancing a stent through a body vessel to the deploy(cid:173)
`ment site, the stent must be able to securely maintain its axial
`position on the delivery catheter, without translocating
`proximally or distally, and especially without becoming
`separated from the catheter. Stents that are not properly
`secured or retained to the catheter may slip and either be lost
`or be deployed in the wrong location. The stent must be
`crimped in such a way as to minimize or prevent altogether
`distortion of the stent and to thereby prevent abrasion and/or
`reduce trauma of the vessel walls.
`In the past, this crimping or size reduction has been done
`by hand often resulting in the application of undesired
`uneven forces to the stent. Such a stent must either be 40
`discarded or re-crimped. Stents which have been crimped or
`otherwise reduced in size multiple times can suffer from
`fatigue and may be scored or otherwise marked which can
`cause thrombosis. A poorly crimped stent can also damage
`the underlying balloon.
`Recently, stent crimping devices have been disclosed in
`U.S. Pat. No. 5,546,646 to Williams et al, U.S. Pat. No.
`5,183,085 to Timmermans et al., U.S. Pat. No. 5,626,604 to
`Cottone, Jr., U.S. Pat. Nos. 5,725,519, 5,810,873 to Morales,
`WO 97/20593 and WO 98/19633.
`A cam actuated stent crimper, shown in FIG. 1, employs
`a plurality of arc-shaped or curved slots with semi-circular
`ends, disposed such that each slot or cam engages a cam
`follower bearing 22. The arc-shaped or curved surfaces of
`the slots are inclined to be non-concentric relative to the axis
`of rotation 26, and therefore rotation of the cam plate 28
`transmits equal radial displacements to the cam follower
`bearings 22, to simultaneously actuate a like number of
`linear bearings 24, which have their corresponding linear
`tracks or rails mounted on a fixed plate. As shown in FIG. 60
`1 the cam plate rotary drive 29 comprises a pneumatic
`cylinder mounted on a pivot or trunnion, arranged with the
`cylinder rod connected rotatably to a short arm fixed rigidly
`to the cam plate. Accordingly, linear motion produced by the
`pneumatic cylinder translates into controllable arcs of 65
`motion of the circular cam plate, which has a projecting
`V-shaped profile on its outer edge in rolling engagement
`
`20
`
`30
`
`35
`
`BRIEF SUMMARY OF THE INVENTION
`It would be desirable to produce a device capable of
`crimping a stent uniformly while minimizing the distortion
`of and scoring and marking of the stent due to the crimping.
`The present invention is directed to that end.
`The present invention is particularly concerned with the
`crimping and otherwise reducing in size of inflation expand(cid:173)
`able stents, self-expanding stents and other expandable
`medical devices. For the purpose of this disclosure, it is
`understood that the term 'sten' includes stents, stent-grafts,
`25 grafts and vena cava filters. It is also understood that the
`term 'crimping' refers to a reduction in size or profile of a
`stent.
`In the description that follows it is understood that the
`invention contemplates crimping a medical device either
`directly to a catheter tube or to a catheter balloon which is
`disposed about a catheter tube. When reference is made to
`crimping a medical device to a catheter, a balloon may be
`situated between the medical device and the catheter tube or
`the medical device may be crimped to a region of a catheter
`tube directly. The invention also contemplates crimping a
`stent in the absence of a catheter to reduce the stent in size.
`The present invention is directed, in one embodiment, to
`an apparatus for reducing a medical device in size.
`Desirably, the medical device is a stent, a stent-graft, a graft
`or a vena cava filter, whether self-expandable, balloon
`expandable or otherwise expandable, although the inventive
`apparatus may also be employed with any other suitable,
`generally tubular medical device which must be reduced in
`45 size.
`The inventive apparatus comprises at least three coupled
`movable blades disposed about a reference circle to form an
`aperture whose size may be varied. Each blade is in com(cid:173)
`munication with an actuation device which is capable of
`50 moving the blade to alter the size of the aperture. Each blade
`includes a single radial point on the surface of the blade
`which a) lies on the circumference of the reference circle
`prior to movement of the blade, and b) may be moved only
`along a radius of the reference circle on movement of the
`55 blade.
`The apparatus further includes an actuation device which
`comprises a cam and a plurality of linear slide devices. Each
`linear slide device is in communication with a blade. Each
`of the linear slide devices is also in mechanical communi(cid:173)
`cation with the cam. Rotation of the cam results in linear
`translation of the slide device and blade, such that the slide
`device moves along an axis parallel to the radius on which
`the radial point of the blade lies or along the radius itself.
`The invention is also directed to an apparatus similar to
`that described above, with blades disposed about a reference
`tube to form a tubular aperture whose size may be varied.
`Each blade is in communication with an actuation device
`
`Page 18 of 23
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`

`

`US 6,360,577 B2
`
`4
`FIG. 6 is a schematic, perspective view of an embodiment
`of the inventive apparatus;
`FIG. 7 shows a partial view of the embodiment of FIG. 6;
`FIGS. Sa and Sb are partial side elevational views of an
`5 embodiment of the inventive apparatus taken along a radial
`plane during the size reduction process;
`FIG. Sc is a partial side elevational view of an embodi(cid:173)
`ment of the inventive apparatus taken along a radial plane
`following crimping of a stent to a catheter;
`FIG. 9 is a diagrammatic side elevational view of an
`embodiment of the inventive apparatus;
`FIG. 10 is a partial side elevational view of an embodi(cid:173)
`ment of the inventive apparatus taken along a radial plane of
`15 an embodiment of the invention consisting of three indi(cid:173)
`vidual apparatuses arranged sequentially;
`FIG. 11 is a schematic showing a stent being reduced in
`size and loaded into a sheath;
`FIG. 12 is a partial side elevational view of an embodi(cid:173)
`ment of the inventive apparatus taken along a radial plane
`showing a balloon that has been molded with the inventive
`device; and
`FIG. 13 is a partial side elevational view taken along a
`radial plane showing a stepped balloon that has been molded
`25 with the inventive device.
`
`20
`
`3
`which is capable of moving the blade to alter the size of the
`tubular aperture. Each blade includes a single line which a)
`lies on the surface of the reference tube prior to movement
`of the blade, and b) may be moved only along a radial plane
`of the reference tube on movement of the blade.
`The inventive apparatus finds particular utility in crimp(cid:173)
`ing a medical device such as those mentioned above to a
`catheter or to a balloon disposed about a catheter.
`The inventive apparatus also finds utility in reducing the
`diameter of a medical device such as those mentioned above 10
`prior to crimping.
`The invention is also directed to a method of manipulating
`a medical device which comprises the steps of providing the
`medical device and providing at least three blades capable of
`applying a radial inward force. The blades are disposed
`about a reference circle to form a shrinkable aperture. A
`medical device such as a stent is placed into the shrinkable
`aperture and the blades simultaneously moved inward to
`apply a radial inward force to the medical device. The blades
`are constructed and arranged such that each blade has a
`single point which a) lies on the circumference of the
`reference circle prior to movement of the blade, and b) is
`moved along a radius of the reference circle on movement
`of the blade.
`The inventive apparatus may also be used as a variable
`size balloon mold. To that end, the invention is further
`directed to a method of molding a medical balloon. In the
`practice of the method, a balloon preform prepared through
`any suitable technique known in the art is provided. The 30
`preform is placed in an apparatus which has a shrinkable
`tubular aperture formed by at least three movable blades
`disposed about a reference tube. The blades are constructed
`and arranged such that each blade has a single line which a)
`lies on the surface of the reference tube prior to movement 35
`of the blade, and b) is moved along a radial plane of the
`reference tube on movement of the blade. The aperture may
`be set to a predetermined size prior to placement of the
`preform therein or after placement of the preform therein.
`An inflation fluid is supplied to the balloon preform to 40
`expand the balloon preform until it contacts the blades. The
`preform may optionally be heated prior to, during or after
`the blowing step. The thus formed balloon is then pressure
`relieved and removed from the apparatus.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`While this invention may be embodied in many different
`forms, there are described in detail herein specific preferred
`embodiments of the invention. This description is an exem(cid:173)
`plification of the principles of the invention and is not
`intended to limit the invention to the particular embodiments
`illustrated.
`As shown generally at 100 in FIGS. 2a and 2b, the
`inventive apparatus comprises eight coupled blades 106
`disposed about a reference circle 114 to form an aperture 118
`whose size may be varied. The apparatus may comprise as
`few as three blades and as many as sixteen or more blades.
`Desirably, the apparatus will have four or more blades and
`more desirably, eight or more blades. The maximum number
`of blades is limited only by how many blades can physically
`be coupled together under the relevant size constraints. As
`45 the number of blades is increased, the profile of the aperture
`and hence of the medical device following reduction in size,
`becomes smoother. FIG. 2b shows the apparatus of FIG. 2a
`after the stent has been reduced in size.
`Blades 106 as shown in FIG. 3a have an inner end 108
`50 which is desirably beveled 111 so as to mesh with adjacent
`blades and an outer end 110 which is displaced from aperture
`118. Aperture 118 is polygonal. Blades 106 may also be
`shaped with a curved end 112, as shown in FIGS. 3b and 3c
`so as to form a substantially circular shaped aperture, when
`55 the aperture is fully closed.
`Each blade 106 includes a single radial point 122 which
`lies on a radial line 126 of reference circle 114 prior to
`movement of blade 106 and which may be moved only along
`the radius 126 of reference circle 114 on movement of blade
`60 106. Desirably, the single radial point 122 will be disposed
`at the tip of the blade adjacent to beveled end 111.
`In the embodiment shown in FIG. 4a, radial point 122 lies
`at the tip of blade 106. Each blade 106 has a connecting link
`130 extending from second end 110. Connecting link 130
`65 ends in mounting means 134, typically a mounting flange
`adapted for attachment to a linear bearing block, for inter(cid:173)
`facing with an actuation device, shown generally at 138.
`
`BRIEF DESCRIPTION OF THE SEVERAL
`VIEWS OF THE DRAWING(S)
`
`FIG. 1 shows a perspective view of a stent crimper;
`FIG. 2a is a schematic front view of an embodiment of the
`inventive apparatus;
`FIG. 2b is a schematic front view of the embodiment of
`FIG. 2a after the stent has been reduced in size;
`FIGS. 3a and 3b are schematics of blades;
`FIG. 3c is a partial schematic front view of an embodi(cid:173)
`ment of the inventive apparatus employing the curved blades
`of FIG. 3b;
`FIG. 4a is a partial front view of an embodiment of the
`inventive apparatus;
`FIG. 4b is a partial front view of an embodiment of the
`inventive apparatus;
`FIG. 4c shows a side view of the embodiment of FIG. 4b
`taken along lines 4c--4c;
`FIG. Sa shows a partial front view of another embodiment
`of the inventive apparatus;
`FIG. Sb shows a link connected to a blade;
`
`Page 19 of 23
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`

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`US 6,360,577 B2
`
`5
`Actuation device 138 is capable of simultaneously moving
`blades 106 to alter the size of aperture 118.
`Actuation device 138 includes actuation plate 142 which
`is coaxial with reference circle 114. Actuation plate 142 has
`eight equi-spaced radial slots 146. More generally, for every 5
`blade there will be a corresponding radial slot on actuation
`plate 142. Each radial slot 146 overlaps a mounting means
`134 for a linear bearing block at the end of a connecting link
`130. Each blade 106 is engaged to actuation plate 142 via a
`cam follower bearing 150 disposed in radial slot 146 and 10
`attached to mounting means in slotted end 134.
`Each bearing 150 extends from a linear slide 154. Linear
`slide 154 is mounted on a non-rotating plate 156 (shown in
`FIG. 8). Linear slide 154 is constructed and arranged to slide
`along a line 158 which is parallel to the radius 126 on which 15
`radial point 122 of blade 106 lies.
`For the purposes of this disclosure, the term 'cam follower
`bearing' includes cam follower bearings, low friction rollers,
`roller bearings, needle roller bearings and a slipper block
`pivot mounted on a bearing and stub shaft. FIG. 4b is a 20
`partial front view of an embodiment in which a slipper block
`is used. A side view of the embodiment of FIG. 4b taken
`along lines 4c--4c is shown in FIG. 4c. Slipper block 150
`resides in slot 146 of actuation plate 142. Slipper block 150
`is mounted on stub shaft 151 which extends from connecting 25
`link 130. Desirably, bearings 153 will be present between
`shaft 151 and slipper block 150. Connecting link 130, in
`turn, is fastened to linear bearing block 212 via fasteners
`214. Bearing block 212 is linearly mounted on linear slide
`which is mounted on fixed plate 156. Linear motion is 30
`facilitated by the presence of bearings 216.
`Cam follower bearing 150 may be replaced by any other
`suitable connecting member which can connect the slide and
`the link.
`In use, as actuation plate 142 is rotated in a clockwise
`direction, the clockwise motion of the actuation plate is
`translated into linear motion of each of linear slide 154 and
`blade 106 via bearing 150. Each blade 106 moves outward
`in a direction parallel to the radius 126 on which the radial 40
`point 122 of the blade 106 lies, resulting in the opening of
`aperture 118. As actuation plate 142 is rotated in a counter(cid:173)
`clockwise direction, each blade 106 moves inward in a
`direction parallel to the radius 126 on which the radial point
`122 of the blade 106 lies, resulting in the closing of aperture
`118. As aperture 118 closes, a radially inward force is
`applied to a medical device disposed in the aperture. The
`actuation plate is rotated until the desired size reduction of
`the aperture and medical device has been achieved. Follow(cid:173)
`ing the reduction, the actuation plate is rotated in the 50
`opposite direction to allow for removal of the medical
`device from the aperture.
`The apparatus may be used to reduce the diameter of a
`suitable medical device such as those disclosed above or
`may be used to crimp a medical device to a catheter.
`Another embodiment of the invention is shown in FIG.
`Sa. Each blade 106, as shown in FIG. Sa, has a connecting
`link 130 extending therefrom. Connecting link 130 is rigidly
`attached to blade 106. Connecting link 130 ends in an angled
`end 134 for interfacing with an actuation device, shown
`generally at 138. Actuation device 138 is capable of simul(cid:173)
`taneously moving blades 106 to alter the size of aperture
`118.
`Actuation device 138 includes a rotatable actuation plate
`142 which is co-axial with reference circle 114. Rotatable 65
`actuation plate includes cam slots 146 which are not con(cid:173)
`centric with the axis of rotation, arcing inward. Each con-
`
`6
`necting link 130 is engaged to actuation plate 146 via a cam
`follower bearing 150 disposed in slot 146 and attached to
`both angled end 134 of connecting link 130 and to a linear
`slide 154. Linear slide 154 is mounted on a non-rotating
`plate similar to that shown in FIG. 8. Linear slide 154 is
`constructed and arranged to slide along a radial line 158 on
`which radial point 122 of blade 106 lies.
`Connecting link 130 may be bonded adhesively, welded,
`joined with a fastener or otherwise joined to blade 106. As
`shown in FIG. Sa, a single screw 131 is used to connect link
`130 to blade 106. FIG. Sb shows a connecting link 130
`including a right angle portion which is fastened to a blade
`106 using two screws 131. Connecting link 130 and blade
`106 may optionally be formed of a single piece of material.
`Regardless of how the connecting member is joined to the
`blade, no movement of the blade relative to the connecting
`link is permitted.
`In use, as actuation plate 142 is rotated in a clockwise
`direction, the clockwise motion of the actuation plate is
`translated into a linear outward motion of each of linear
`slides 154 and blades 106 via bearings 150 resulting in the
`opening of aperture 118. The outward motion results from
`the radially outward arcing of cam slot 146. As actuation
`plate 142 is rotated in a counterclockwise direction, each
`blade 106, because of the radially inward arc of cam slots
`146, moves inward in a direction parallel to the radius 126
`on which the radial point 122 of the blade 106 lies, resulting
`in the closing of aperture 118. As discussed above, as the
`aperture is decreased in size, a radial inward force is brought
`to bear against a medical device disposed in the aperture,
`thereby reducing the size of the medical device.
`The embodiment of FIG. Sa differs from the embodiment
`of FIG. 4a in that in the embodiment of FIG. Sa, the slide
`moves along the radial line on which the radial point of the
`35 attached blade lies whereas in FIG. 4a the slide moves
`parallel to the radial line. In both of the embodiments, each
`of the blades is constrained with two degrees of freedom to
`satisfy the condition that the movement of the tip be radial
`in accordance with the invention.
`In the embodiments of FIGS. 4a and Sa, the slots in the
`actuation plate are constructed and arranged to allow for a
`sufficient reduction in size of the aperture so that a medical
`device can be reduced in size to a desired diameter. Those of
`45 ordinary skill in the art will recognize other suitable actua(cid:173)
`tion devices that may be used in the practice of this inven-
`tion.
`Desirably, in the above embodiments, the blades will be
`as long as or longer than the medical device disposed within
`so that the medical device is uniformly reduced in size along
`its entire length.
`This is illustrated in the embodiment of FIGS. 6 and 7 and
`further in FIGS. 3a and 3b in which blades 106 are disposed
`about a reference tube 160 to form a tubular aperture 162
`55 whose size may be varied. Reference circle 114 is seen to lie
`along reference tube 160. Each blade 106 is in communi(cid:173)
`cation with an actuation device such as that shown in FIGS.
`4 or 5. The actuation device is capable of moving blades 106
`to alter the size of tubular aperture 162. Each blade 106
`60 includes a single line 166 which a) lies on a radial plane 170
`of the reference tube 160 prior to movement of blade 106,
`and b) may be moved only along a radial plane 170 of
`reference tube 160 on movement of blade 106. Desirably,
`reference tube 160 is cylindrical and exceeds the length of
`the medical device to be reduced in size.
`Another embodiment of the invention is illustrated in
`FIGS. Sa and Sb. In the embodiment of FIGS. Sa and Sb, two
`
`Page 20 of 23
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`

`

`US 6,360,577 B2
`
`10
`
`7
`non-rotating plates 156 are present, one at each end of the
`apparatus. Each blade 106 is connected at first end 174 to a
`linear slide 154a via a connecting link 130a and at second
`end 178 to a linear slide 154b a via a connecting link 130b.
`Linear slide 154a is mounted on non-rotating plate 156a and
`linear slide 154b is mounted on non-rotating plate 156b. The
`presence of the second non-rotating plate 156b, linear slide
`154b and connecting link 130b is optional but contributes to
`providing a rigid frame upon which the connecting links and
`associated blades may slide without misalignment relative to
`the reference circle.
`FIGS. Sa and Sb illustrate the use of the inventive
`apparatus in various stages of the size reduction process. In
`FIG. Sa, stent 180 has been placed in tubular aperture 162
`which is characterized by a diameter d1 . In FIG. Sb, the
`device has been actuated by rotating actuation plate 142 so
`as to move blades 106 inward. Aperture 162, as shown in
`FIG. Sb is characterized by a diameter d2 which is reduced
`relative to diameter d1 . Stent 180 is seen to be of reduced
`diameter relative to its previous diameter as shown in FIG.
`Sa.
`FIG. Sc differs from FIG. Sb, only in that stent 180 has
`been crimped onto catheter 184 in FIG. Sc.
`Blades 106 may be made of any suitable, hard material
`including hardened steel. Desirably, the blades will be made
`of a material such as zirconia ceramic. Blades made of
`zirconia ceramic may be used without lubrication.
`Furthermore, because of their low thermal conductivity, they
`may be used to create a highly insulated chamber suitable for
`cryogenic processing of martensite in nitinol stents.
`Such an embodiment is shown in FIG. 9. Stent 180 is
`disposed between blades 106 which can move inward in the
`direction of the arrows. Blades 106 are cooled by a first
`source of cooling fluid 184 located at first end 174 of blades
`106. Although not shown, a second source of cooling fluid
`may be provided at second end 178 of blades 106 as well.
`The cooling fluid may be a liquid cryogenic. Exemplary
`cryogenics include liquid nitrogen, argon or carbon dioxide
`although other cryogens may also be used. The cooling fluid 40
`may also be a chilled gas such as air. The cooling fluid may
`also be a cooled inert gas such as nitrogen, argon or other
`inert gasses.
`The aperture formed by the blades is a highly insulated
`chamber which is suitable for cryogenic processing of 45
`martensite in nitinol stents. The chamber is maintained at
`-80° C. and a nitinol stent inserted therein. Upon equilibra(cid:173)
`tion of the temperature of the stent, the blades are moved
`inward to reduce the diameter of the stent. The stent is thus
`reduced in diameter while being maintained in the marten(cid:173)
`sitic state.
`The embodiment of FIG. 9 further has a loading plunger
`188 for loading a stent or other suitable medical device into
`the aperture. A sheath housing 192 which houses sheath 196
`is provided at second end 178 of blades 106. Plunger 188
`may be further used to transfer the stent after it has been
`reduced in diameter or size to sheath 196. Desirably, sheath
`196 will have a slightly larger diameter than stent 180
`following reduction in size of the stent. More desirably, the
`fit of the stent within the sheath will be within about 1132 11 and
`even more desirably, within about 1/64 11
`Where lengthy stents or other medical devices are to be
`reduced in size, the invention contemplates using one of the
`above described apparatuses with long blades to accommo(cid:173)
`date the stent. As an alternative, the invention also contem(cid:173)
`plates disposing two or more of such apparatuses sequen(cid:173)
`tially to form one long aperture. The two or more apertures
`
`8
`may then be reduced in size simultaneously or consecu(cid:173)
`tively. The arrangement of FIG. 10 shows an embodiment
`with three devices lOOa-c arranged sequentially. A stepped
`reduction in size may be achieved by placing a stent 180 or
`5 similar medical device in the apparatus and independently
`reducing each aperture 118a-c to a desired size. To that end,
`the invention may provide particular utility in manipulating
`bifurcated stents or other stents whose diameter varies along
`its length. The embodiment of FIG. 10 shows the end
`portions of the stent being reduced in size prior to the middle
`portion of the stent. The device may also be operated so as
`to reduce the middle portion in size prior to the end portions
`or in any other sequence.
`The invention contemplates yet another approach to
`15 reducing the diameter of lengthy stents or similar medical
`devices, namely walling the stent through the apparatus.
`This may be accomplished by either moving the stent
`relative to the apparatus or moving the apparatus relative to
`the stent as shown schematically in FIG. 11. To that end,
`stent 180 is inserted in device 100. Aperture 118a is reduced
`in size with blades 106a in turn reducing portion 180a of
`stent 180 in size. Aperture 118a is then opened and aperture
`118b reduced in size thereby reducing portion 180b of stent
`180. Simultaneously, or shortly thereafter, sheath 196 is
`25 pushed by plunger 188 over the portion of the stent that has
`been reduced in size. Aperture 118b is opened and the stent
`advanced in the apparatus. The process is repeated until the
`entire length, or the desired portion of the stent or medical
`device is reduced in size.
`The reduction in size of the stent or other medical device
`may occur as part of a precrimping step or it may occur as
`part of crimping a stent onto a catheter and desirably, onto
`a balloon disposed about a catheter. In a general sense, it
`may be used for manipulating a medical device and
`35 specifically, for applying a radial inward force to a medical
`device.
`In another embodiment, the invention is directed to a
`method of manipulating a medical device. As part of the
`method, a medical device such as those disclosed above is
`provided. The device has at least three blades capable of
`applying a radial inward force. The blades are disposed
`about a reference circle to form a shrinkable aperture. The
`blades are constructed and arranged such that each blade has
`only a single point which a) lies on the circumference of the
`reference circle prior to movement of the blade, and b) is
`moved along a radius of the reference circle on movement
`of the blade. The medical device is placed into the shrinkable
`aperture and the blades simultaneously moved inward to
`apply a radial inward force to the medical device and thereby
`50 reduce the medical device in size, and desirably, in diameter.
`Following reduction in size of the medical device, the blades
`are simultaneously moved outward and the medical device
`removed from the aperture.
`The inventive apparatus may also be incorporated into a
`55 blow molding tool to provide a variable size balloon mold as
`shown generally at 100 in FIG. 12. The various parts of the
`apparatus of FIG. 12 have been discussed in conjunction
`with FIGS. Sa-c and, with exception of balloon 181 and
`mold cavity ends 193, the reference numerals used in FIG.
`60 12 correspond to those used for FIGS. Sa-c. Mold cavity
`ends 193 may be provided in a variety of sizes and lengths
`to contain the balloon at each end. Desirably, the end molds
`will be adjustably mounted to a portion of the apparatus such
`as fixed plates 156 to provide for an adjustable length
`65 balloon mold.
`The invention is also directed to a method for molding a
`medical balloon using the inventive apparatus described
`
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`Page 21 of 23
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`US 6,360,577 B2
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`9
`above. A balloon preform prepared through any standard
`method is provided. The inventive mold, shown generally at
`100 is also provided. Balloon 181 is inserted into aperture
`162. Aperture 162 is optionally reduced to a predetermined
`size and the preform expanded using standard techniques. 5
`An inflation fluid, for example, may be supplied to the
`preform and the preform expanded and heated. The balloon
`in its expanded state is shown in FIG. 12.
`More generally, the invention may be practiced by pro(cid:173)
`viding at least three movable blades disposed about a 10
`reference tube to form a shrinkable tubular aperture. The
`blades are constructed and arranged such that each blade has
`a single line which a) lies on the surface of the reference tube
`prior to movement of the blade, and b) is moved along a
`radial plane of the reference tube on movement of the blade.
`A balloon preform is placed into the shrinkable aperture. The 15
`aperture may be set at a predetermined size prior to or
`following insertion of the balloon therein. An inflation fluid
`is provided and the balloon preform inflated so that the
`preform expands to the size of the aperture. The preform
`may be heated during this inflation/blowing step. The infla- 20
`tion fluid is then removed from the thus formed balloon and
`the balloon removed from the apparatus.
`The balloon may be also be molded in accordance with
`the method described in U.S. Pat. No. 5,163,989, or in
`accordance with other methods as are known to those of
`ordinary skill in the art, substituting the instant apparatus for
`the standard balloon mold. Other patents which discuss
`balloon molding include U.S. Pat. No. 5,807,520. Other
`references illustrating the materials and methods of making
`catheter balloons include: U.S. Pat. Nos. 4,413,989 and 30
`4,456,000 to Schjeldahl et al, U.S. Pat. No. 4,490,421, U.S.
`Pat. No. Re. 32,983 and U.S. Pat. No. Re. 33,561 to Levy,
`and U.