5,974,652
`[11] Patent Number:
`[19]
`United States Patent
`
`Kimes et al.
`[45] Date of Patent:
`*Nov. 2, 1999
`
`US005974652A
`
`[54] METHOD AND APPARATUS FOR
`UNIFORMLY CRIMPING A STENT ONTO A
`CATHETER
`
`[75]
`
`Inventors: Richard M. Kimes, Carlsbad; Michael
`S. Mirizzi, San Jose, both 0f Calif.
`
`wo 98/19633
`
`5/1998 wuno.
`
`OTHER PUBLICATIONS
`US. Patent Application Serial No. 08/795,335 filed Feb. 4,
`1997.
`US. Patent Application Serial No. 08/837,771 filed Apr. 22,
`1997.
`
`[73] Assignee: Advanced Cardiovascular Systems,
`Inc., Santa Clara, Calif.
`.
`.
`.
`.
`.
`This patent is subject to a terminal dis-
`claimer.
`
`.
`[*] Notice:
`
`US. Patent Application Serial No. 08/089,936 filed Jul. 15,
`1997.
`US. Patent Application Serial No. 08/962,632 filed Nov. 3,
`1997.
`The eXTraordinary Stent, C.R. Bard Brochure (Undated).
`
`[22]
`[51]
`
`[21] Appl No . 09/072 925
`.
`N
`’
`Filed:
`May 5, 1998
`Int. Cl.6 ........................... A61M 29/00; B23P 11/00;
`B23P 19/02
`................................. 29/516; 606/1; 606/108;
`606/192. 606/198' 623/1. 29/282
`’
`29/516 ’ 407 08
`[58] Field 0f Search
`29/282, 280, 715’ 423’ 517’ 234’ 235’ 283,
`269, 270; 606/108, 198, 1; 623/1
`
`[52] US. Cl.
`
`[56]
`
`References Cited
`US. PATENT DOCUMENTS
`
`696’289
`4,468,224
`4,576,142
`4,644,936
`4,681,092
`4,697,573
`4,786,271
`498389264
`479017707
`4,907,336
`5,132,066
`5,133,732
`5 183 085
`5,189,786
`
`.
`
`.
`
`.
`
`3/1902 Williams ’
`8/1984 Enzmann et a1.
`3/1986 Schiff .
`2/1987 Schiff .
`7/1987 Cho et a1.
`10/1987 Schiff .
`11/1988 Menn .
`6/1989 Bremef 6t al~ -
`2/1990 SChifl -
`3/1990 Gianturco .
`7/1992 Charlesworth et a1.
`7/1992 Wiktor.
`2/1993 Timmermans
`3/1993 Ishikawa et a1...
`.
`.
`(LlSt continued on next page.)
`FOREIGN PATENT DOCUMENTS
`
`Primary Examiner—David P. Bryant
`Assistant Examiner—John Preta
`Attorney, Agent, or Firm—Fulwider Patton Lee & Utecht,
`LLP
`[57]
`
`ABSTRACT
`
`A stent crimping tool for firmly and uniformly crimping a
`stent onto a balloon catheter is constructed from a crimping
`section holding the stent and the balloon catheter therein,
`wherein the crimping is actuated by a shaft haVing an input
`.
`.
`.
`.
`end and an output end, engaging the crimping section at the
`output end. The shaft has a detent formed into the input end.
`A gripping member has an internal cavity to receive the
`P
`P
`in ut end, and includes a hole
`roximate to the shaft,
`wherein a ball bearing and a compression spring are located
`within the hole to bias the ball bearing toward the shaft and
`to. engage the detent. When. a torque is applied to the
`gripping member, it is transmitted through the ball bearing
`to the shaft;
`if the torque exceeds a predetermined
`magnitude, it overcomes the force of the spring on the ball
`bearing causing the bearing to slide out of the detent thereby
`disconnecting the applied torque from the shaft. The crimp-
`ing section can be a rubber tube having a lumen holding the
`stent and catheter. When the shaft compresses the rubber
`tube as it advances, the lumen collapses and crimps the stent
`onto the catheter.
`In another embodiment,
`the crimping
`section is a coiled filament suspended at both ends and
`having an aXial space holding the stent and catheter. Rotat-
`ing the shaft twists the filament which in turn constricts and
`crimps the stent onto the catheter.
`
`WO 98/14120
`
`4/1998 WIPO .
`
`11 Claims, 3 Drawing Sheets
`
`22
`
`36
`
`Edwards
`Lifesciences v.
`
`
`'VIIII'IIIA'I.—‘-\;\\
` -» iii];
`
`
`
`
`gar—9 W4
`
`34
`
`40
`
`Boston Scientific
`
`US. Patent N o.
`
`6,915,560
`IPR2017-00444
`
`EX. 2050
`
`Page 1 of 12
`
`Page 1 of 12
`
`

`

`5,974,652
`Page 2
`
`US. PATENT DOCUMENTS
`
`5,263,969
`5,352,197
`5,437,083
`5,465,716
`5,546,646
`5,626,474
`5,626,604
`
`11/1993
`10/1994
`8/1995
`11/1995
`8/1996
`5/1997
`5/1997
`
`.
`
`Phillips .
`Hammersmark et al.
`Williams et al.
`.
`AVitall .
`Williams et al.
`Kuka et al.
`.
`Cottone, Jr.
`
`.
`
`.
`
`5,630,830
`5,653,691
`5,738,674
`5,746,764
`5,783,227
`5,785,715
`5,836,952
`
`5/1997
`8/1997
`4/1998
`5/1998
`7/1998
`7/1998
`11/1998
`
`Verbeek .
`
`.
`
`.
`Rupp et al.
`Williams et al.
`Green et al.
`.
`Dunham .
`Schatz .
`DaVis et al.
`
`.
`
`Page 2 of 12
`
`Page 2 of 12
`
`

`

`US. Patent
`
`N0V.2, 1999
`
`Sheet 1 0f3
`
`5,974,652
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`Page 3 of 12
`
`Page 3 of 12
`
`

`

`US. Patent
`
`N0V.2, 1999
`
`Sheet 2 0f3
`
`5,974,652
`
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`Page 4 of 12
`
`Page 4 of 12
`
`

`

`US. Patent
`
`N0V.2, 1999
`
`Sheet 3 0f3
`
`5,974,652
`
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`36
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`Page 5 of 12
`
`Page 5 of 12
`
`

`

`5,974,652
`
`1
`METHOD AND APPARATUS FOR
`UNIFORMLY CRIMPING A STENT ONTO A
`CATHETER
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to an apparatus for loading
`a tubular graft, such as a stent, onto the distal end of a
`catheter assembly of the kind used, for example, in percu-
`taneous transluminal coronary angioplasty (PTCA) or per-
`cutaneous transluminal angioplasty (PTA) procedures.
`In typical PTCA procedures, a guiding catheter is percu-
`taneously introduced into the cardiovascular system of a
`patient through the brachial or femoral arteries and advanced
`through the vasculature until the distal end of the guiding
`catheter is in the ostium. A guide wire and a dilatation
`catheter having a balloon on the distal end are introduced
`through the guiding catheter with the guide wire sliding
`within the dilatation catheter. The guide wire is first
`advanced out of the guiding catheter into the patient’s
`coronary vasculature and the dilatation catheter is advanced
`over the previously advanced guide wire until the dilatation
`balloon is properly positioned across the arterial
`lesion.
`Once in position across the lesion, a flexible and expandable
`balloon is inflated to a predetermined size with a radiopaque
`liquid at relatively high pressures to radially compress the
`atherosclerotic plaque of the lesion against the inside of the
`artery wall and thereby dilate the lumen of the artery. The
`balloon is then deflated to a small profile so that
`the
`dilatation catheter can be withdrawn from the patient’s
`vasculature and the blood flow resumed through the dilated
`artery. As should be appreciated by those skilled in the art,
`while the above-described procedure is typical, it is not the
`only method used in angioplasty.
`In angioplasty procedures of the kind referenced above,
`restenosis of the artery may develop over time, which may
`require another angioplasty procedure, a surgical bypass
`operation, or some other method of repairing or strengthen-
`ing the area. To reduce the likelihood of the development of
`restenosis and to strengthen the area, a physician can implant
`an intravascular prosthesis for maintaining vascular patency,
`commonly known as a stent, inside the artery at the lesion.
`The stent is crimped tightly onto the balloon portion of the
`catheter and transported in its delivery diameter through the
`patient’s vasculature. At the deployment site, the stent is
`expanded to a larger diameter, often by inflating the balloon
`portion of the catheter. The stent also may be of the
`self-expanding type.
`Since the catheter and stent travel through the patient’s
`vasculature, and probably through the coronary arteries, the
`stent must have a small delivery diameter and must be firmly
`attached to the catheter until
`the physician is ready to
`implant it. Thus, the stent must be loaded onto the catheter
`so that it does not interfere with delivery, and it must not
`come off the catheter until it is implanted.
`In procedures where the stent is placed over the balloon
`portion of the catheter, it is necessary to crimp the stent onto
`the balloon portion to reduce its diameter and to prevent it
`from sliding off the catheter when the catheter is advanced
`through the patient’s vasculature. Non-uniform crimping
`can result in sharp edges being formed along the now uneven
`surface of the crimped stent. Furthermore, non-uniform stent
`crimping may not achieve the desired minimal profile for the
`stent and catheter assembly. Where the stent is not reliably
`crimped onto the catheter, the stent may slide off the catheter
`and into the patient’s vasculature prematurely as a loose
`foreign body, possibly causing blood clots in the
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`vasculature, including thrombosis. Therefore, it is important
`to ensure the proper crimping of a stent onto a catheter in a
`uniform and reliable manner.
`
`This crimping is often done by hand, which can be
`unsatisfactory due to the uneven application of force result-
`ing in non-uniform crimps. In addition,
`it
`is difficult
`to
`visually judge when a uniform and reliable crimp has been
`applied.
`Some self-expanding stents are difficult to load by hand
`onto a delivery device such as a catheter. Furthermore, the
`more the stent is handled the higher the likelihood of human
`error, which is antithetical
`to a properly crimped stent.
`Accordingly, there is a need in the art for a device for
`reliably crimping a stent onto a catheter.
`There have been attempts at devising a tool for crimping
`a stent onto a balloon delivery catheter. An example of such
`a tool comprises a series of plates having substantially flat
`and parallel surfaces that move in a rectilinear fashion with
`respect to each other. A stent carrying catheter is disposed
`between these surfaces, which surfaces crimp the stent onto
`the outside of the catheter by their relative motion and
`applied pressure. The plates have multiple degrees of free-
`dom and may have force-indicating transducers to measure
`and indicate the force applied to the catheter during crimp-
`ing of the stent.
`loading tool design is comprised of a
`Another stent
`tubular member housing a bladder. The tubular member and
`bladder are constructed to hold a stent that is to be crimped
`onto a balloon catheter assembly. Upon placement of the
`stent over the balloon portion of the catheter, a valve in the
`loading tool is activated to inflate the bladder. The bladder
`compresses the stent radially inward to a reduced diameter
`onto the balloon portion of the catheter to achieve a snug fit.
`In this way, the stent is crimped onto the distal end of a
`balloon catheter with a minimum of human handling. The
`foregoing stent crimping tools are disclosed in, for example,
`US. Pat. Nos. 5,437,083 and 5,546,646 to Williams et al.
`Yet another stent crimping tool is known in the art as the
`BARD XT, which is actually a stent loader. It is constructed
`from a rigid, tubular body with a ball at one end connected
`to a plurality of long, thin strips passing through the tubular
`body. An uncrimped stent is placed over the plurality of
`long, thin strips, which hold the stent in an expanded state.
`The balloon portion of a catheter is inserted into the cylin-
`drical space formed by the plurality of strips. When the user
`pulls the ball while holding the tubular body against the
`stent, the strips are slid from beneath the stent and the stent
`is transferred onto the balloon portion.
`Still another conventional stent crimping tool is manu-
`factured by JOHNSON & JOHNSON and appears similar to
`a hinged nutcracker. Specifically, the tool is comprised of
`two hand operated levers hinged at one end and gripped in
`the palm of the hand at the opposite end. A cylindrical
`opening holding a crimping tube is provided through the
`mid-portion of the tool to receive therein a stent loaded onto
`a balloon catheter. The crimping operation is performed by
`the user squeezing the handle thereby pressing the crimping
`tube which in turn pinches the stent onto the balloon
`catheter.
`
`While the prior art devices are suitable for crimping stents
`onto balloon catheters, they suffer from problems such as
`non-uniform crimping forces,
`resulting in non-uniform
`crimps. Consequently, they are unsuitable for use by phy-
`sicians in a cath lab who desire to crimp the stent onto the
`balloon catheter.
`
`SUMMARY OF THE INVENTION
`
`Both PTCA and PTA procedures have become common-
`place in treating stenoses or lesions in blood vessels and
`
`Page 6 of 12
`
`Page 6 of 12
`
`

`

`5,974,652
`
`3
`coronary arteries. In approximately 35% to 40% of the
`procedures,
`restenosis may develop requiring a further
`angioplasty, atherectomy or bypass procedure to return the
`patency of the vessel. Intravascular stents are now being
`deployed after PTCA and PTA procedures, and after
`atherectomies, in order to help prevent the development of
`restenosis. Importantly, such stents, mounted on the balloon
`portion of a catheter, must be tightly crimped to provide a
`low profile delivery diameter, and to ensure that the stent
`stays on the balloon until the balloon is expanded and the
`stent is implanted in the vessel. The present invention is
`directed to a crimping tool that can repeatedly provide a
`uniform and tight crimp to ensure the low profile diameter
`of the stent on the balloon portion of the catheter, and to
`ensure that
`the stent remains firmly attached until
`it
`is
`implanted in the vessel by expanding the balloon.
`The present invention is directed to a method and appa-
`ratus to obtain consistent crimping of a stent on a balloon
`catheter independent of the balloon profile. This is accom-
`plished by limiting the amount of force that is applied to
`crimp the stent by using a clutch that disconnects the applied
`torque at a predetermined level.
`In particular, the present invention is directed to a tool for
`crimping a stent onto a balloon catheter, comprising a
`crimping section holding the stent and the balloon catheter
`therein; a shaft having an input end and an output end,
`engaging the crimping section at the output end, which shaft
`when rotated actuates the crimping section to crimp the
`stent; a detent formed into the input end of the shaft; a
`gripping member having an internal cavity to receive the
`input end of the shaft, wherein the cavity includes a hole
`proximate to the shaft; a stop member; a biasing member
`disposed in the hole and biasing the stop member into
`engagement with the detent; whereby applying a torque to
`the gripping member beyond a predetermined level over-
`comes the force of the biasing member and slides the stop
`member out of the detent to disengage the applied torque
`from the shaft.
`
`Rotation of the shaft halts, and the magnitude of the
`crimping force encountered by the stent levels off or drops
`off due to resilience or backlash in the system. Damage to
`the stent from excessive crimping force is avoided.
`In one exemplary embodiment,
`the crimping section
`comprises a housing having an internal chamber with an
`enclosed first end, and an open second end having threads,
`wherein the output end of the shaft is partially disposed
`within the internal chamber through the open second end of
`the housing, and wherein the input end of the shaft includes
`threads that engage the threads of the internal chamber; and
`an elastic tubing having a lumen, wherein the tubing is
`disposed within the internal chamber adjacent the enclosed
`first end, and the output end of the shaft is disposed adjacent
`the tubing. Accordingly, the stent and balloon catheter are
`positioned within the lumen and rotation of the shaft
`advances the shaft into the tubing, compressing the tubing,
`and crimping the stent.
`In another exemplary embodiment, the crimping section
`comprises a rigid chassis having a hollow interior enclosed
`by a closed back end and leading to an open front end,
`wherein the back end includes a threaded opening; an end
`cap enclosing the open front end, the end cap including a
`central opening; an elastic tube disposed within the hollow
`interior adjacent to the front end and having a length less
`than a length of the hollow interior to define a chamber
`adjacent to the back end; a piston slidably disposed within
`the chamber; wherein the shaft passes through the closed
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
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`
`60
`
`65
`
`4
`back end of the chassis and the shaft
`
`includes threads
`
`engaging the threads of the back end, and the output end of
`the shaft engages the piston so that the shaft when rotated
`displaces the piston to compress the elastic tube; whereby
`the stent is loaded onto the catheter and is inserted through
`the central opening into the elastic tube, and the compressed
`elastic tube squeezes the stent radially onto the catheter.
`In yet another exemplary embodiment, the crimping sec-
`tion comprises a base having at least first and second spaced
`apart supports, wherein the shaft is rotatably disposed on the
`second support with the output end of the shaft extending
`toward the first support; a coiled filament having an axial
`space and being attached to the first support and the output
`end of the shaft and extending between the first and second
`supports; whereby inserting the stent and catheter into the
`axial space of the coiled filament and rotating the shaft
`reduces the diameter of the axial space thereby crimping the
`stent onto the catheter.
`
`In conclusion, it is clear that the present invention tool can
`be adapted to a variety of stent crimping sections that are
`operated by application of torque. The clutch of the present
`invention ensures that the amount of force applied during the
`crimping process is controlled. This is achieved by discon-
`necting the gripping member from the shaft at a predeter-
`mined level of torque. Doing so disrupts the transfer of
`torque to the crimping section of the tool, which in turn
`levels the amount of crimping force exerted on the stent.
`With precise control of applied crimping forces,
`the
`present invention tool is capable of homogeneously crimp-
`ing a stent onto a balloon catheter. Such a crimping tool is
`highly useful to cardiologists, for example. Such physicians
`are often concerned with proper deployment of the stent
`within the patient that it is desirable to have a consistently
`and reliably crimped stent. The present invention tool is
`further a time saver, because the stent crimping procedure
`can be performed fairly efficiently and quickly. These and
`other advantages of the present
`invention will become
`apparent from the following detailed description thereof
`when taken in conjunction with the accompanying exem-
`plary drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a side elevational view, partially in section,
`depicting a stent that has been crimped onto a delivery
`catheter and disposed within a vessel.
`FIG. 2 is a sectional view of a preferred embodiment of
`the present invention, showing the clutch mechanism and
`the crimping section of the tool.
`FIG. 3 is a cross-sectional view of an alternative embodi-
`
`ment of the present invention tool shown in FIG. 2.
`FIG. 4 is a perspective view of an exemplary embodiment
`tool wherein the crimping section includes a coiled filament
`used to crimp the stent.
`FIGS. 5 and 6 are simplified schematic diagrams depict-
`ing a stent crimping operation performed by the present
`invention tool.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`FIG. 1 illustrates intravascular stent 10 which is mounted
`
`onto delivery catheter 11. Stent 10 generally comprises a
`plurality of radially expandable cylindrical elements 12
`disposed coaxially and interconnected by members 13 dis-
`posed between adjacent cylindrical elements 12. Delivery
`catheter 11 has an expandable portion or balloon 14 for
`
`Page 7 of 12
`
`Page 7 of 12
`
`

`

`5,974,652
`
`5
`expanding stent 10 within coronary artery 15 or other vessel
`such as saphenous veins, carotid arteries, arteries, and veins.
`Artery 15, as shown in FIG. 1, has dissected lining 16 which
`has occluded a portion of the arterial passageway.
`Delivery catheter 11 onto which stent 10 is mounted is
`essentially the same as a conventional balloon dilatation
`catheter for angioplasty procedures. Balloon 14 may be
`formed of suitable materials such as polyethylene, polyvinyl
`chloride, polyethylene terephthalate and other like poly-
`mers. In order for stent 10 to remain in place on balloon 14
`during delivery to the site of the damage within artery 15,
`stent 10 is compressed onto balloon 14.
`An optional retractable protective delivery sleeve 20 may
`be provided to further ensure that stent 10 stays in place on
`balloon 14 of delivery catheter 11 and to prevent abrasion of
`the body lumen by the open surface of stent 10 during
`delivery to the desired arterial location. Other means for
`securing stent 10 onto balloon 14 may also be used, such as
`providing collars or ridges on the ends of the working
`portion, i.e., the cylindrical portion of balloon 14.
`In order to implant stent 10,
`it is first mounted onto
`inflation balloon 14 on the distal extremity of delivery
`catheter 11. Stent 10 is crimped down onto balloon 14 to
`ensure a low profile. The present invention addresses this
`crimping procedure.
`The catheter-stent assembly can be introduced into the
`patient’s vasculature through processes known in the art.
`Briefly, guide wire 18 is disposed across the arterial section
`where an angioplasty or atherectomy has been performed
`requiring a follow-up stenting procedure. In some cases, the
`arterial wall lining may be detached so that guide wire 18 is
`advanced past detached or dissected lining 16 and the
`catheter-stent assembly is advanced over guide wire 18
`within artery 15 until stent 10 is directly under detached
`lining 16. Prior to inflation of balloon 14, optional delivery
`sleeve 20 is retracted to expose stent 10. Depending on the
`balloon and stent assembly, a delivery sleeve may be unnec-
`essary. Balloon 14 of delivery catheter 11 is then inflated
`using an inflation fluid. Expansion of balloon 14 in turn
`expands stent 10 against artery 15. Next, balloon 14 is
`deflated and catheter 11 is withdrawn leaving stent 10 to
`support the damaged arterial section. As mentioned above,
`in order to ensure proper seating of stent 10 on balloon 14,
`and to ensure proper deployment of stent 10 at the site of the
`damage within artery 15, the stent crimping procedure is
`important.
`FIG. 2 is a cross-sectional view of a preferred embodi-
`ment of the present invention stent crimping tool 22. Stent
`crimping tool 22 as shown preferably has crimping section
`24 and actuation section 26. Actuation section 26 is rotated
`
`and torque is transmitted through shaft 28 to crimping
`section 24.
`
`In order to limit the amount of torque transmitted to shaft
`28 and to thus limit the amount of crimping force,
`the
`present invention includes a clutch mechanism. In the pre-
`ferred embodiment, the clutch mechanism includes com-
`pression spring 30, ball bearing 32, and detent 34 located on
`shaft 28. As gripping member 36, which can be a knob,
`crank, knurled spindle, or the like,
`is rotated,
`torque is
`transmitted through a stop member, here ball bearing 32, to
`detent 34. Spring 30 which is positioned within hole 38
`biases ball-bearing 32 into detent 34 with sufficient force to
`maintain the transfer of torque from gripping member 36 to
`shaft 28. If, however, a predetermined amount of torque is
`exceeded,
`the axial
`force of compression spring 30 is
`overcome causing ball bearing 32 to slide out of detent 34
`
`10
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`15
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`20
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`25
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`30
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`
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`
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`
`60
`
`65
`
`6
`and to retract into hole 38. Of course, this predetermined
`amount of torque can be adjusted by modifying the spring
`force, depth of the detent, size of the ball bearing, and other
`parameters known in the art.
`At that instant, the linkage between gripping member 36
`and shaft 28 is broken because ball bearing 32 is free to
`rotate and slide along the outer circumference of shaft 28.
`The clutch mechanism thus limits the torque delivery
`through shaft 28 into crimping section 24.
`In the exemplary embodiment shown in FIG. 2, detent 34
`is a semi-spherical cut-out formed in the input end 40 of
`shaft 28. Input end 40 is also received within cavity 42 of
`gripping member 36. Gripping member 36 may be formed
`in a cylindrical shape for easy gripping as shown, or may
`take other grippable shapes known in the art. Furthermore,
`a resilient piece of material may be used to replace spring 30
`to bias ball bearing into shaft 28. For example, a sponge-like
`material can be used that has compliance and a level of
`resilience needed to urge ball bearing 32 into detent 34 in
`order to transfer torque between gripping member 36 and
`shaft 28.
`
`At the opposite end of shaft 28 is output end 44 which is
`preferably located adjacent resilient
`tubing 46. Shaft 28
`further includes external threads 48 meant to engage internal
`threads 50 formed inside housing 52 of crimping section 24.
`Resilient tubing 46 fits within hollow interior 54 of housing
`52, wherein the latter is sufficiently rigid to not expand or
`distort under pressure. At the opposite end of housing 52 is
`end cap 56 that encloses the back end.
`Thus, as the user manually rotates shaft 28 through
`application of torque to gripping member 36, shaft 28
`advances into and compresses resilient tubing 46. Within
`resilient tubing 46 is lumen 58 containing uncrimped stent
`10 already loaded onto balloon 14 of catheter 11. End cap 56
`has an optional central opening 60 in communication with
`lumen 58. Hence, delivery catheter 11 can be inserted
`through central opening 60 and advanced into alignment
`with uncrimped stent 10 inside lumen 58. As compression of
`the resilient tubing 46 takes place, the length of resilient
`tubing 46 is shortened thereby causing lumen 58 to collapse
`and simultaneously crimp stent 10 onto delivery catheter 11.
`After the crimping step, shaft 28 is rotated in the opposite
`direction to retract it away from resilient tubing 46, which
`regains its original shape. Thereafter, the crimped stent and
`catheter assembly can be withdrawn through central opening
`60.
`
`In an alternative embodiment, a through hole (not shown)
`can be formed through the length of shaft 28 and through
`gripping member 36. After the crimping step, the crimped
`stent and catheter assembly can be advanced over a guide
`wire (not shown), passing through the through hole, and out
`the opposite end of the tool. Therefore, in this alternative
`embodiment, the crimped stent and catheter assembly can be
`immediately advanced over the guide wire to the patient for
`implantation after the crimping step.
`During the crimping step, if maximum torque is exceeded,
`as explained above, ball bearing 32 slides out of detent 34.
`On the other hand, if gripping member 36 is continuously
`rotated, ball bearing 32 can be reseated within detent 34
`during a subsequent revolution of gripping member 36 about
`input end 40, thereby re-engaging the linkage between shaft
`28 and gripping member 36. At that moment, torque can be
`reapplied by rotating the gripping member 36 in either
`direction to advance or retract shaft 28. By alternately
`advancing and retracting shaft 28, it is possible to repeat the
`crimping step and ensure a firm and consistent crimp of stent
`
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`5,974,652
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`7
`10 on catheter 11. To be sure, it is also possible to rotate
`delivery catheter 11 during each cycle of the crimping step.
`FIG. 3 is an alternative embodiment of the exemplary
`embodiment shown in FIG. 2. More precisely, FIG. 3 is a
`cross-sectional view showing crimping section 62 that is a
`modification of crimping section 24 from FIG. 2. As seen in
`FIG. 3, torque is transferred between gripping member 36
`and crimping section 62 through threaded shaft 64. Crimp-
`ing section 62 is similar to that disclosed in co-pending US.
`patent application entitled “Indeflator-Driven, Rubber-
`Compression Crimping Tool” by Stephen A. Morales,
`(ACS-42071) Ser. No. 09/063,905, filed Apr. 21, 1998,
`whose entire contents are incorporated herein by reference.
`In this embodiment, crimping section 62 is constructed
`from cylindrical shape chassis 66 having open end 68 and
`closed end 70. Open end 68 is sealed closed with optional
`end cap 72 that is bonded to open end 68 using adhesive 74
`of a type known in the art. Optionally, end cap 72 may be
`attached to chassis 66 using threads, snaps, clamps, or other
`mechanical means known in the art.
`
`Within cylindrical shape chassis 66 is hollow interior 76
`that contains elastic tube 78 that is coaxially disposed within
`chassis 66. Notably, elastic tube 78 has a length that is
`shorter than the length of hollow interior 76. Because of this
`difference in length, and because elastic tube 78 is disposed
`adjacent open end 68, chamber 80 is formed adjacent to
`closed end 70. Slidably disposed within chamber 80 is
`movable piston 82. Shaft 64 engages piston 82 as shown in
`FIG. 3.
`
`End cap 72 includes central opening 84 that is aligned and
`in communication with axial space 86 of elastic tube 78.
`Central opening 84 allows the stent-catheter assembly to be
`inserted into crimping section 62 prior to undergoing the
`crimping procedure.
`Leading up to the procedure, a user introduces stent 10
`already loaded onto balloon portion 14 of catheter 11 into
`axial space 86 within elastic tube 78. In the exemplary
`embodiment, the inside diameter of elastic tube 78 is slightly
`greater than the outside diameter of the uncrimped stent 10,
`or uncrimped stent and balloon 10 and 14, respectively.
`As gripping member 36 is rotated, torque is transmitted
`through spring 30 to ball bearing 32 and to the walls of
`detent 34 formed in shaft 64. Shaft 64 once in rotation
`
`advances piston 82 into elastic tube 78 as indicated by the
`arrow. As a result, elastic tube 78 is compressed axially or
`lengthwise. The elastic material of elastic tube 78 must
`maintain a constant volume due to its surface elasticity and
`containment within the confines of hollow interior 76.
`
`Continuous compression of elastic tube 78 by piston 82
`causes the material of elastic tube 78 to displace axially and
`then radially into axial space 86, in effect collapsing that
`space. This decreases the diameter of axial space 86. In turn,
`stent 10 contained inside axial space 86 is compressed
`radially onto balloon portion 14 of catheter 11.
`As in the previously described embodiment, exceeding a
`pre-determined torque on gripping member 36 disengages
`ball bearing 32 from detent 34 to disconnect the application
`of torque to shaft 64. On the other hand, insofar as gripping
`member 36 and shaft 64 are linked through the clutch
`mechanism, it is possible to rotate and counter-rotate shaft
`64 to advance and retract, respectively, piston 82. Indeed, it
`is possible to cycle through the crimping step over and over
`as necessary.
`
`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`8
`In the various exemplary embodiments of the present
`invention crimping tool shown in FIGS. 2 and 3, the housing
`pieces, piston, shafts, gripping member, etc. can be made
`from a rigid, injection molded plastic material. Also, trans-
`lucent and transparent materials can be used so that the task
`at hand can be visually monitored. The present invention
`design is well suited for fabrication from surgical steel, too.
`Resilient tubing 46 and elastic tube 78 of each embodiment
`can be made from rubber or other elastomers known in the
`art.
`
`FIG. 4 is a perspective view of an alternative embodiment
`of the present
`invention tool. In this embodiment, stent
`crimping section 90 contains a filament used to constrict a
`stent onto a balloon catheter inserted within an axial space
`formed by the coiled filament. Torque is still applied through
`gripping member 36, which is connected to shaft 92. As best
`seen in this figure, the surface of gripping member 36 may
`optionally be contoured or knurled by pattern 94 to provide
`a better gripping surface.
`Stent crimping section 90 is similar to that disclosed in
`co-pending US. patent application entitled “Stent Crimping
`Tool and Method of Use” by Stephen A. Morales, (ACS-
`42070) Ser. No. 08/962,632, filed Nov. 3, 1997, the entire
`contents of which are incorporated herein by reference. In
`FIG. 4, stent crimping section 90 includes base 96, first
`vertical support 98, second vertical support 100, wherein the
`two vertical supports 98 and 100 are spaced apart on base 96.
`Shaft 92 rotatably passes through an opening in second
`vertical support 100. Cam 102 is affixed on shaft 92 whereby
`the cam rotates with shaft 92.
`
`Cam 102 optionally includes an obstruction which, in the
`preferred embodiment, are teeth 104 located at the circum-
`ference of cam 102 and are designed to engage pawl 106.
`Pawl 106 is positioned on base 96 and biased into teeth 104.
`Together, cam 102, teeth 104, and pawl 106 form a ratchet
`mechanism that permits rotation in one direction yet pre-
`vents rotation of shaft 92 in the opposite direction.
`Attached to output end 108 of shaft 92 is one end of coiled
`filament 110. The opposite end of coiled filament 110 is
`connected