[19]
`United States Patent
`5,920,975
`[11] Patent Number:
`[45] Date of Patent: Jul. 13, 1999
`Morales
`
`
`
`US005920975A
`
`[54]
`
`STENT CRIMPING TOOL AND METHOD OF
`USE
`
`[75]
`
`Inventor: Stephen A. Morales, Mountain View,
`Calif.
`
`[73] Assignee: Advanced Cardiovascular Systems,
`Inc., Santa Clara, Calif.
`
`[21] Appl. No.: 08/962,632
`
`[22]
`
`Filed:
`
`Nov. 3, 1997
`
`Int. Cl.6 ...................................................... B23P 11/00
`[51]
`[52] US. Cl.
`................................. 29/282; 29/151; 29/516;
`606/1; 606/108; 606/198; 623/1
`[58] Field of Search ................................. 29/516, 407.08,
`29/282, 280, 715, 423, 517, 234, 235, 283,
`269, 270; 606/108, 198, 1; 623/1
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,738,674
`5,746,764
`5,783,227
`5,785,715
`5,810,838
`
`.
`
`4/1998 Williams et a1.
`5/1998 Green et a1.
`.
`7/1998 Dunham .
`7/1998 Schatz .
`9/1998 Solar ....................................... 606/108
`
`FOREIGN PATENT DOCUMENTS
`
`WO 98/14120
`WO 98/19633
`
`4/1998 WIPO.
`5/1998 WIPO.
`
`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.
`
`US. Patent Application Serial No. 08/893,936 filed Jul. 15,
`1997.
`
`Primary Examiner—Joseph M. Gorski
`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 catheter. The stent crimping tool is constructed
`from a base having two vertically extending spaced apart
`supports and a coiled tension spring affixed at one end to a
`shaft and at the opposite end to one of the vertical supports.
`When a stent is loaded onto the balloon portion of a catheter,
`and the stent-catheter assembly is inserted into an axial
`space within the coiled spring, the user can rotate the shaft
`to twist the coiled spring thereby constricting it, and in turn
`the constriction of the coiled spring uniformly crimps the
`stent onto the balloon catheter.
`
`23 Claims, 3 Drawing Sheets
`
`.
`
`.
`
`8/1984 Enzmann et a1.
`4,468,224
`3/1986 Schiff.
`4,576,142
`2/1987 Schiff.
`4,644,936
`7/1987 Cho et a1.
`4,681,092
`10/1987 Schiff .
`4,697,573
`2/1990 Schiff .
`4,901,707
`3/1990 Gianturco .
`4,907,336
`7/1992 Charlesworth et a1.
`5,132,066
`7/1992 Wiktor.
`5,133,732
`2/1993 Timmermans .
`5,183,085
`5,456,667 10/1995 Ham et al.
`.............................. 606/198
`5,476,505
`12/1995 Limon ......................................... 623/1
`5,546,646
`8/1996 Williams et a1.
`.
`5,626,604
`5/1997 Cottone, Jr.
`.
`5,630,830
`5/1997 Verbeek .
`5,653,691
`8/1997 Rupp et a1.
`
`.
`
`.
`
`
`
`Edwards Lifesciences v. Boston Scientific
`
`IPR2017-00444 EX. 2026 Page 1 of 10
`
`US. Patent No. 6,915,560
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`Page 1 of 10
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`US. Patent
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`Jul. 13,1999
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`Sheet 1 013
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`5,920,975
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`US. Patent
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`Jul. 13,1999
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`Sheet 2 0f3
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`5,920,975
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`US. Patent
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`Jul. 13,1999
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`Sheet 3 0f3
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`5,920,975
`
`FIG. 4
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`5,920,975
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`1
`STENT CRIMPING TOOL AND METHOD OF
`USE
`
`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
`vasculature, including thrombosis. Therefore, it is important
`
`10
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`15
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`20
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`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 would be 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
`
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`5,920,975
`
`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 crimping tool for
`crimping a stent onto a catheter comprising a base having a
`first and a second opposed vertical supports separated by a
`predetermined distance, a crank rotatably mounted on the
`second vertical support, wherein the crank includes a shaft
`extending towards the first vertical support and a torque
`transmitting member. The crimping tool further includes a
`cam affixed to the crank in between the first and second
`
`vertical supports, wherein the cam includes an obstruction at
`a circumference thereof. The invention also comprises a
`pawl disposed on the base and biased into engagement with
`the cam obstruction to prevent free rotation of the crank, and
`a coiled filament having an axial space, wherein the coiled
`filament is attached to the first vertical support and the shaft
`of the crank and extends between the first and second
`
`vertical supports, whereby inserting the stent mounted on
`the catheter into the axial space within the coiled filament
`and rotating the crank causes the coiled filament to constrict
`the stent onto the catheter.
`
`the torque transmitting
`In the preferred embodiment,
`member is a handle which is turned by the user to twist the
`coiled filament. Also in the preferred embodiment, the coiled
`filament is a coiled tension spring. The present invention
`crimping tool is designed for a saphenous vein graft, carotid,
`or any other stent product that is released without a delivery
`system. It is an ideal tool for any stent that is introduced to
`market without such a delivery system.
`All of the parts of the present invention are preferably
`made from nylon or a comparable polymer. The present
`invention stent crimping tool is intended to be used in a cath
`lab to accurately and repeatably crimp a stent onto a balloon
`catheter.
`
`The present invention crimping tool operates as follows.
`A catheter with a balloon having a stent mounted thereon is
`inserted into the axial space within the coiled filament. The
`user turns the crank at the opposite end which rotates the
`cam and shaft of the crank. The rotating crank twists the
`coiled filament, which at the opposite end is affixed to the
`immobile first vertical support. Continued twisting of the
`coiled filament constricts the filament onto the stent, which
`stent is in turn compressed onto the balloon.
`In the preferred embodiment,
`the coiled filament is a
`tension spring which when twisted has resilience tending to
`counter-rotate the crank. However, the ratchet mechanism
`formed by an obstruction, which in the preferred embodi-
`ment are unidirectional teeth at the circumference of the cam
`
`engaging the pawl, prevent the resilience in the spring from
`unwinding and counter-rotating the crank.
`When the spring has been manually wound or twisted to
`the point that is has constricted to its minimum diameter, the
`
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`4
`user may force the pawl against its bias to disengage from
`the teeth of the cam. Once the ratchet mechanism is
`
`disengaged, the natural resilience in the spring unconstricts
`and unwinds in the opposite direction thus releasing the
`crimped stent and balloon catheter. As a result of the
`foregoing process, the collapsing or decreasing diameter of
`the constricting spring has thus homogeneously and pre-
`cisely compressed the spring onto the balloon catheter.
`The system is repeatable because the tool resets itself after
`the pawl is disengaged. The number of “clicks” by the
`ratchet can be counted or the number of rotations can be
`
`counted to provide accuracy and precision. Further, the stent
`may not be homogeneously crimped from the proximal to
`the distal end of the stent. A smaller diameter coil can be
`
`used if this is desired. Larger diameter coils would increase
`the force needed to actuate the tool, but would also increase
`uniformity and accuracy of the crimp.
`Therefore, the present invention crimping tool is highly
`useful to cardiologists, for example. Such physicians are
`constantly 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 in that 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 exemplary drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is an elevational view, partially in section, depict-
`ing a stent that has been crimped onto a delivery catheter and
`disposed within a damaged vessel.
`FIG. 2 is a perspective view of a preferred embodiment of
`the present invention stent crimping tool.
`FIG. 3 is a side elevational view of the present invention
`drawn as a simplified schematic showing a stent mounted to
`a balloon catheter prior to being inserted into the axial space
`of the coiled filament.
`
`FIG. 4 is a side elevational view of the present invention
`following the step depicted in FIG. 3, wherein the stent-
`catheter assembly have been inserted into the axial space of
`the coiled filament.
`
`FIG. 5 is a side elevational view of the present invention
`following the step depicted in FIG. 4 showing rotation of the
`crank and constriction of the coiled filament, thus causing
`the stent to be crimped onto the balloon catheter.
`
`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 generally coaxially and interconnected by mem-
`bers 13 disposed between adjacent cylindrical elements 12.
`Delivery catheter 11 has an expandable portion or balloon 14
`for 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, and other like polymers. In order for stent 10 to
`remain in place on balloon 14 during delivery to the site of
`
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`5,920,975
`
`5
`the damage within artery 15, stent 10 is compressed onto
`balloon 14. This compressing step is known as crimping.
`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, delivery sleeve 20
`is retracted to expose stent 10. Depending on the balloon and
`stent assembly, a delivery sleeve may be unnecessary. Bal-
`loon 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 provides a perspective view of a preferred embodi-
`ment stent crimping tool 22. In the preferred embodiment
`shown, stent crimping tool 22 has several major components
`comprising base 24, first vertical support 26, second vertical
`support 28, wherein the two vertical supports 26, 28 are
`spaced apart on base 24. Crank 30 has shaft 32 that rotatably
`passes through an opening in second vertical support 28. A
`cam 34 is affixed on shaft 32 whereby the cam rotates with
`shaft 32.
`
`Cam 34 includes an obstruction which, in the preferred
`embodiment, are teeth 36 located at the circumference of
`cam 34 and are designed to engage pawl 38. Pawl 38 is
`positioned on base 24 and biased into teeth 36. Together,
`cam 34, teeth 36, and pawl 38 form a ratchet mechanism that
`permits rotation in one direction yet prevents rotation of
`shaft 32 in the opposite direction.
`Attached to end 40 of shaft 32 is one end of coiled
`
`filament 42. The opposite end of coiled filament 42 is
`connected to first vertical support 26.
`In the preferred
`embodiment shown in FIG. 2, coiled filament 42 is a coiled
`tension spring with its ends hooked to pins 44, 46.
`the
`In the exemplary embodiment shown in FIG. 2,
`present invention has fairly high extending vertical supports
`26, 28, such that shaft 32 passes through second vertical
`support 28 rather than just resting upon it. Optional bearing
`48 is located inside second vertical support 28 to minimize
`rotational friction between shaft 32 and second vertical
`
`support 28.
`Also, through hole 50 is provided in first vertical support
`26 and is in communication with axial space 52 that is
`defined by the coils of coiled filament 42. Thus, when stent
`
`6
`crimping tool 22 is used, through hole 50 allows the stent-
`catheter assembly to be passed therethrough into axial space
`52 inside coiled filament 42. In the preferred embodiment,
`through hole 50 is aligned with the openining housing
`bearing 48; although it is recognized that through hole 50
`need not be aligned with the rotational axis of bearing 48.
`FIGS. 3—5 are simplified schematic diagrams of a pre-
`ferred embodiment of the present invention. In particular,
`FIG. 3 provides a side elevational view of the present
`invention stent crimping tool 22 just prior to insertion of the
`stent-catheter assembly. As seen in FIG. 3, at the left side of
`the drawing, stent 10 is loaded onto delivery catheter 11 so
`that stent 10 is overlying balloon portion 14 just prior to
`insertion of the assembly into through hole 50 of first
`vertical support 26. Arrow Ashows the direction of insertion
`of the stent-catheter assembly into axial space 52 within
`coiled filament 42.
`
`10
`
`15
`
`As explained above, one end of coiled filament 42 is
`attached to first vertical support 26 and the opposite end is
`anchored to shaft 32 of crank 30. In alternative embodiments
`
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`invention, crank 30 may have a torque
`of the present
`transmitting member such as handle 54 as seen in FIG. 3, or
`textured wheel 56 as seen in FIG. 2. Other torque transmit-
`ting devices known in the art can be used as well.
`FIG. 3 also shows the preferred embodiment ratcheting
`device that prevents counter-rotation of crank 30 during the
`crimping procedure. The preferred embodiment ratcheting
`mechanism of the present
`invention comprises cam 34
`having teeth 36 located at a circumference thereof. Pawl 38
`is biased into engagement with teeth 36 by spring 58 or the
`like. Pawl 38 may be operated by a lever which when turned
`overcomes the bias of spring 58 to disengage pawl 38 from
`teeth 36; conversely, releasing the lever allows the spring
`bias to re-engage pawl 38 to teeth 36.
`In the exemplary embodiment shown in FIG. 2, pawl 38
`can be made from a highly resilient material and shaped into
`a plate that is biased into engagement with teeth 36 of cam
`34. This type of contact engagement permits rotation of shaft
`32 in one direction yet resists rotation in the opposite
`direction due to the obstruction of pawl 38 against one or
`more teeth 36. Other ratcheting mechanisms known in the
`art can be used here as well. For example, in an alternative
`embodiment, the outer circumference of the cam has a rough
`finish and the pawl has an equally high friction finish and
`engages the cam under spring bias.
`In this alternative
`embodiment, friction is used to prevent rotation of the cam
`and shaft. The pawl would then serve as a brake against the
`rotating cam.
`In yet another alternative embodiment, the circumference
`of the cam can include a detent to catch the pawl, which is
`biased into the cam. The profile of the detent can have an
`asymmetric saw-tooth shape to permit the cam to continue
`rotating in one direction by allowing the pawl to slide over
`the detent yet solidly engage the pawl if the cam rotates in
`the opposite direction.
`FIG. 4 is a side elevational view of the present invention
`wherein the stent-catheter assembly has been inserted into
`axial space 52 within coiled filament 42. With pawl 38
`disengaged from teeth 36, shaft 32 of crank 30 is free to
`rotate in either the clockwise or counterclockwise direction.
`
`As mentioned above, optional bearing 48 is used to lower
`the rotational friction between shaft 32 and second vertical
`
`support 28. Lubricants or a low friction sleeve can be used
`here as well.
`
`65
`
`When crank 30 is rotated in the direction of arrow B, shaft
`32 rotates and begins to twist coiled filament 42, which at the
`
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`

`5,920,975
`
`7
`opposite end is anchored to first vertical support 26. As
`coiled filament 42 is twisted, it constricts the stent-catheter
`assembly contained inside aXial space 52. FIG. 5 shows this
`process continuing. As the user continuously turns crank 30,
`the constriction proceeds and the diameter of coiled filament
`42 decreases steadily, thereby uniformly compressing stent
`10 onto balloon portion 14 of delivery catheter 11. As shown
`in FIGS. 3—5, an optional sleeve or sheath 20 overlies stent
`10 before and during crimping for several reasons. The
`sheath protects the stent until the stent is mounted over the
`balloon. Further, as the coiled filament compresses and
`reduces its diameter, the compression forces are evenly and
`uniformly applied over the sheath and onto the stent. After
`crimping, optional sheath 20 can be removed or left in place
`to protect the stent during intravascular delivery.
`Any resilience in coiled filament 42 urging shaft 32 to
`counter-rotate in a direction opposite to arrow B is resisted
`by the ratchet mechanism. Specifically, pawl 38 in FIG. 5 is
`engaging teeth 36 to prevent the counter-rotation. Of course,
`the ratchet mechanism can be eliminated and the counter-
`
`rotation can be resisted manually by the user using force
`against crank 30.
`Torque is applied in the direction of arrow B through
`crank 30 until the desired amount of crimping is achieved.
`The crimping process can be repeated by retracting pawl 38
`from contact with teeth 36 and allowing free counter-
`rotation of shaft 32 to unwind coiled filament 42. At any time
`after coiled filament 42 has begun to unwind, crank 30 can
`be turned in the direction of arrow B to once again constrict
`coiled filament 42 onto the stent-catheter combination. This
`
`process can be repeated over and over as needed until the
`desired crimp is achieved. Moreover, the amount of torque
`applied to crank 30 can slowly increase, decrease, or remain
`steady in magnitude.
`It is optional to keep pawl 38 fully engaged into teeth 36
`during the foregoing crimping process to resist the resilience
`induced counter-rotation of shaft. Pawl 38 need only be
`disengaged from teeth 36 to permit the counter-rotation in
`order to release the crimped stent-catheter assembly or to
`restart the crimping cycle. Indeed, the crimping cycle can be
`repeated over and over without engagement of pawl 38
`against teeth 36 insofar as the user maintains some level of
`torque on crank 30.
`In the preferred embodiment, all parts of the present
`invention are made from nylon or a comparable polymer
`known in the art. The device is sterilized and intended to be
`
`used in the cath lab by a trained technician or cardiologist.
`Coiled filament 42 can be a metal tension spring, a resilient
`polymer ribbon (e.g. mylar) formed into a coil, or the like
`made from a resilient material. Preferably, the coiled fila-
`ment is a coiled spring having either a flat or a round
`cross-section. The filament can vary in thickness or diameter
`as the particular application warrants.
`the
`As will be appreciated by those skilled in the art,
`present invention crimping tool 22 is designed both for
`single use applications in a cath lab by a physician, or for
`multiple use applications in a sterile environment in a high
`volume manufacturing facility.
`In such a manufacturing
`facility where sterile conditions eXist, stent crimping tool 22
`can be used to repeatedly crimp stents onto balloons until the
`mechanism wears out. Thus, repeated uses of the present
`invention are contemplated for controlled, sterile
`environments, although single use applications are required
`when used by cath lab personnel.
`Furthermore, the present invention crimping tool can be
`used with any stent
`that
`is released without a delivery
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`system. The crimping tool may also be sold alone because its
`design is robust enough to undergo many uses.
`What is claimed is:
`
`1. A tool for crimping a stent onto a catheter, the tool
`comprising:
`a base having a first support and a second support defining
`a space therebetween;
`a crank rotatably disposed on the second support and
`extending toward the first support;
`the coiled
`a coiled filament
`located within the space,
`filament having a plurality of turns defining an aXial
`space and having a diameter, the coiled filament ter-
`minating in a first end attached to the first support and
`a second end attached to the crank,
`wherein the aXial space is unobstructed along its central
`aXis from the first end to the second end, such that when
`a stent and catheter are inserted into the aXial space and
`the crank is rotated, the diameter of the aXial space
`becomes reduced whereby the stent becomes crimped
`onto the catheter.
`
`2. The crimping tool according to claim 1, wherein the
`crimping tool further comprises a cam affixed to the crank
`having an obstruction at a circumference; and
`a pawl disposed on the base and biased into engagement
`with the cam obstruction to prevent free rotation of the
`crank.
`
`3. The crimping tool according to claim 2, wherein the
`obstruction includes a detent formed in the cam.
`
`4. The crimping tool according to claim 2, wherein the
`obstruction includes a tooth.
`
`5. The crimping tool according to claim 2, wherein the
`obstruction includes a frictional surface at the circumference
`of the cam.
`
`6. The crimping tool according to claim 1, wherein the
`coiled filament includes a coiled spring.
`7. The crimping tool according to claim 6, wherein the
`coiled spring has either a flat or a round cross-section.
`8. The crimping tool according to claim 1, wherein the
`first support includes an opening through which the stent and
`catheter pass when being inserted into the aXial space of the
`coiled filament.
`
`9. The crimping tool according to claim 1, wherein the
`base includes a polymer material.
`10. The crimping tool according to claim 1, wherein the
`coiled filament includes a flat cross-sectional shape.
`11. The crimping tool according to claim 1, wherein the
`coiled filament includes a circular cross-sectional shape.
`12. The crimping tool according to claim 1, wherein the
`stent is covered by a sheath so that the crimping forces of the
`coiled filament are evenly distributed along the stent.
`13. A tool for crimping a stent on to a catheter, compris-
`ing:
`a base having a first and a second opposed vertical
`supports separated by a predetermined distance;
`a crank rotatably mounted on the second vertical support,
`wherein the crank includes a shaft extending toward the
`first vertical support and a torque transmitting member;
`a cam affixed to the crank in between the first and second
`
`vertical supports, wherein the cam includes an obstruc-
`tion at a circumference thereof;
`a pawl disposed on the base and biased into engagement
`with the cam obstruction to prevent free rotation of the
`crank; and
`a coiled filament having an aXial space, wherein the coiled
`filament is attached to the first vertical support and the
`
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`5,920,975
`
`9
`shaft of the crank and extends between the first and
`
`second vertical supports;
`whereby inserting the stent mounted on the catheter into
`the axial space within the coiled filament and rotating
`the crank causes the coiled filament to crimp the stent
`on to the catheter.
`
`14. The crimping tool according to claim 13, wherein the
`torque transmitting member includes a handle.
`15. The crimping tool accord