United States Patent
`
`[19]
`
`[11] Patent Number:
`
`6,092,273
`
`Villareal
`[45] Date of Patent: Jul. 25, 2000
`
`
`
`USOO6092273A
`
`[54] METHOD AND APPARATUS FOR A STENT
`CRIMPING DEVICE
`
`L .S. Patent Application Serial No. 09/072,925 filed May 5,
`1998.
`
`L .S. Patent Application Serial No. 09/169,270 filed Oct. 9,
`1998.
`
`The eXTraordinary Stent, C.R. Bard Brochure (Undated).
`L .S. Patent Application Serial No. 08/795,335 filed Feb. 4,
`1997.
`
`L .S. Patent Application Serial No. 08/837,771 filed Apr. 22,
`1997.
`
`L .S. Patent Application Serial No. 08/893,936 filed Jul. 15,
`1997.
`
`L .S. Patent Application Serial No. 08/962,632 filed Nov. 3,
`1997.
`
`L .S. Patent Application Serial No. 09/024,910 filed Feb. 17,
`1998.
`
`
`
`[75]
`
`Inventor: Plaridel K. Villareal, San Jose, Calif.
`
`[73] Assignee: Advanced Cardiovascular Systems,
`Inc., Santa Clara, Calif.
`
`[21] Appl. No.: 09/123,844
`
`[22]
`
`Filed:
`
`Jul. 28, 1998
`
`Int. Cl.7 ..................................................... B21D 39/00
`[51]
`[52] US. Cl.
`................................. 29/516; 29/282; 29/515;
`606/1; 606/108
`[58] Field of Search .................................... 29/282, 283.5,
`29/515, 516, 517, 715; 606/1, 108, 198;
`623/1
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`696,289
`4,468,224
`4,546,646
`4,576,142
`4,644,936
`4,681,092
`4,697,573
`
`3/1902 Williams .
`8/1984 Enzmann et a1.
`10/1985 Williams et a1.
`3/1986 Schiff.
`2/1987 Schiff.
`7/1987 Cho etal..
`10/1987 Schiff.
`
`.
`
`.
`
`(List continued on next page.)
`FOREIGN PATENT DOCUMENTS
`
`159065
`WO 98/14120
`WO 98/19633
`
`2/1921 United Kingdom .
`4/1998 WIPO .
`5/1998 WIPO .
`
`OTHER PUBLICATIONS
`
`US. Patent Application Serial No. 09/063,905 filed Apr. 21,
`1998.
`
`US. Patent Application Serial No. 09/063,587 filed Apr. 21,
`1998.
`
`US. Patent Application Serial No. 09/069,010 filed Apr. 28,
`1998.
`
`US. Patent Application Serial No. 09/069,011 filed Apr. 28,
`1998.
`
`L .S. Patent Application Serial No. 09/030,261 filed Feb. 25,
`1998.
`
`Primary Examiner—David P. Bryant
`Assistant Examiner—Essama Omgba
`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 stationary
`plate and a sliding platform connected to the stationary plate
`and slidable linearly relative thereto. A closing plate is
`hinged to the sliding platform so that it at least partially
`overlies the stationary plate in a down position, and swings
`away from the stationary plate to an up position, whereby
`the stent already having been hand crimped onto the balloon
`catheter is placed on the stationary plate from a lateral
`position, and the closing plate is moved to the down position
`to hold the stent between the closing plate and the stationary
`plate so that an external force on the closing plate as well as
`translational motion of the closing plate together crimp the
`stent onto the balloon catheter. The surfaces engaging the
`stent may be covered by elastomeric pads having ridges
`corresponding in location to respective rings or cylindrical
`elements of the stent.
`
`20 Claims, 2 Drawing Sheets
`
`
`
`Edwards Lifesciences V.
`
`Boston Scientific
`
`US. Patent N0. 6,915,560
`IPR2017-00444 EX. 2051
`
`Page 1 of 9
`
`Page 1 of 9
`
`

`

`6,092,273
`
`Page 2
`
`US. PATENT DOCUMENTS
`
`5,783,227
`
`7/1998 Dunham .
`
`4 901 707
`4,907,336
`5:189:786
`5,437,083
`5,626,604
`5,653,691
`5,672,169
`5,693,066
`5,738,674
`5,746,764
`5,782,855
`5,782,903
`
`.
`.
`
`2/1990 Schiff
`3/1990 Gianturco .
`3/1993 Ishikawa et al.
`8/1995 Williams et al.
`5/1997 Cottone, Jr.
`.
`8/1997 Rupp 6t 8.1.
`9/1997 Verbeek .
`............................. 606/198
`12/1997 Rupp et 61.
`4/1998 Williams et a1.
`.
`5/1998 Green et a1”
`
`
`7/1998 Lau et al.
`................................ 606/194
`
`7/1998
`
`.
`
`7/1998 Schatz .
`5,785,715
`9/1998 Solar ....................................... 606/108
`5,810,838
`9/1998 Tuclfey et al.
`.......................... 606/198
`5,810,871
`578369952 “/1998 Dam .et al'
`~
`..................... 606/198
`5,893,867
`4/1999 Bagaorsan et al.
`5,920,975
`7/1999 Morales .................................... 29/282
`5,931,851
`8/1999 Morales .................................. 606/194
`8/1999 Green et a1
`- 606/194
`5944735
`
`. 606/198
`5,947,993
`9/1999 Morales
`5,948,191
`9/1999 Solovay
`156/86
`
`9/1999 Tuckey et al.
`.......................... 606/108
`5,951,569
`6,024,737
`2/2000 Morales ...................................... 606/1
`
`Page 2 of 9
`
`Page 2 of 9
`
`

`

`US. Patent
`
`Jul. 25,2000
`
`Sheet 1 0f2
`
`6,092,273
`
`5:“ ~35" —
`
`_ izizia
`
`Page 3 of 9
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`Page 3 of 9
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`US. Patent
`
`6,092,273
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`6,092,273
`
`1
`METHOD AND APPARATUS FOR A STENT
`CRIMPING DEVICE
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to a method and 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
`percutaneous transluminal coronary angioplasty (PTCA) or
`percutaneous 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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`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, some suffer from problems such as
`non-uniform crimping forces,
`resulting in non-uniform
`crimps. Consequently, there is a need for improved stent
`crimping tools for use by physicians in a cath lab who desire
`to consistently crimp stents onto balloon catheters.
`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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`6,092,273
`
`3
`coronary arteries. In approximately 35 to 40 percent 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 make certain 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. Specifically, the present invention is directed to a
`stent crimping tool for crimping a stent onto a balloon
`catheter. In a preferred embodiment, the stent crimping tool
`comprises a stationary plate, a sliding platform connected to
`the stationary plate which is slidable linearly relative
`thereto, a closing plate that is hinged to the sliding platform
`so that
`the closing plate at
`least partially overlies the
`stationary plate in a down position, and swings away from
`the stationary plate to an up position, whereby the stent
`having been loaded onto the balloon catheter is placed on the
`stationary plate from a lateral position, and the closing plate
`is moved to the down position to hold the stent between the
`closing plate and the stationary plate so that an external force
`on the closing plate and translational motion of the closing
`plate crimp the stent onto the balloon catheter.
`In this
`manner, the pinching pressure of the stationary plate against
`the closing plate generates a radially inward force on the
`stent; the translational motion of the sliding platform effec-
`tively rolls the stent-catheter assembly to evenly distribute
`the crimping force for a homogeneous crimp.
`In an exemplary embodiment, the closing plate and the
`stationary plate have facing surfaces that include contoured
`pads that help grip the stent. Furthermore, the pads have
`optional ridges, channels, or other contours that correspond
`with specific locations on the stent. So for example in an
`ACS Multi-LinkTM stent, ridges in the pads can be situated
`to coincide with the locations of the proximal and distal
`rings of the stent. A ridge may be provided on the pads to
`grip a mid-length ring as well. These pinch points help
`insure uniform reduction in the diameter of the stent during
`the crimping procedure. The pinch or grip points also help
`stabilize the stent-catheter assembly during the crimping
`operation. Of course, the number, location, and shape of
`each grip point can be varied as needed.
`In a preferred embodiment, a spacer having a cylindrical
`shape is positioned on the stationary plate to set a predeter-
`mined gap between the stationary plate and the closing plate
`in the down position. That gap therefore corresponds with
`the diameter of the spacer. Such spacers work as gap
`controllers to obtain repeatable and consistent diameters on
`the crimped stents. Furthermore, the spacers prevent over-
`crimping, which may potentially produce pin holes in the
`balloon catheter.
`
`In alternative embodiments, a mandrel can be inserted
`into the balloon catheter to provide some level of internal
`support during the crimping process. Moreover, it is recom-
`mended that the surface directly in contact with the stent
`during the crimping procedure be slightly softer than the
`material used on the stent to allow for yield. Elastomer type
`materials with higher durometers may be considered.
`When the stent is inserted into the stationary plate from a
`lateral position, a stop or riser formed into the stationary
`
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`4
`plate maintains proper alignment of the stent-catheter
`assembly relative to the crimping tool. The stent abuts
`against the stop so that the stent-catheter assembly is not
`inserted too far or not far enough into the tool.
`Accordingly,
`the present
`invention is very simple to
`operate. With few moving parts and use of a spacer to set the
`gap between the stationary plate and closing plate,
`it is
`possible to consistently and repeatably crimp stents onto
`balloon catheters. Loading and unloading the stent-catheter
`assembly into and out of the present invention crimping tool
`is quick because the closing plate swings out of the way.
`The present invention crimping tool is highly useful to
`cardiologists, for example. Such physicians are often con-
`cerned 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 per-
`formed fairly efficiently and quickly. These and other advan-
`tages of the present invention will become apparent from the
`following detailed description thereof when taken in con-
`junction with the accompanying exemplary 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 balloon
`portion of a delivery catheter and disposed within a vessel.
`FIG. 2 is a perspective view of a preferred embodiment of
`the present invention showing a stent crimping tool wherein
`the closing plate is in an up position and the stent-catheter
`assembly is shown in dashed lines.
`FIGS. 3A and 3B are perspective views showing alterna-
`tive embodiments of a pad having ridges and a pad having
`channels that are helpful in gripping the stent.
`FIG. 4 is a perspective view of a slide having a dove tail
`to which a closing plate is attached.
`FIG. 5 is a perspective view of a preferred embodiment
`platform showing a channel designed to receive the dove tail
`of the slide shown in FIG. 4.
`
`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 rings or cylindrical elements
`12 disposed coaxially and interconnected by members 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, 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
`
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`6,092,273
`
`5
`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. In this mounting step, stent 10 is crimped down
`onto balloon 14 to create a low profile. The present invention
`addresses this crimping procedure.
`The stent-catheter 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
`stent-catheter 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.
`The present invention is directed to a stent crimping tool
`that crimps a stent onto a balloon catheter. This is preferably
`accomplished through tangential forces exerted by the tool
`on the outside surface of the stent to slowly reduce its
`diameter. The diameter of the stent is continuously reduced
`until it is stabilized on the balloon catheter.
`
`FIG. 2 provides a perspective view of a preferred embodi-
`ment of the present invention stent crimping tool 22. Stent
`crimping tool 22 is comprised of base plate 24 to which is
`mounted stationary plate 26 at one end and platform 28 at an
`opposite end. In the preferred embodiment shown, stationary
`plate 26 and platform 28 are spaced apart from each other.
`They are formed from or firmly mounted to base plate 24
`with adhesives or fasteners to prevent relative motion ther-
`ebetween.
`
`FIG. 5 provides a perspective view of platform 28 isolated
`from the other parts of stent crimping tool 22. As seen in
`FIG. 5, platform 28 preferably includes a channel 30 formed
`along a length thereof having twin parallel grooves 32 at the
`base of channel 30.
`Slide 34 is shown both in FIG. 2 and in isolation in the
`
`perspective view of FIG. 4. Slide 34 includes dove tail 72
`that
`is designed to slidably engage grooves 32 and to
`slidably move within channel 30 of platform 28 in FIG. 5.
`With preferably tight tolerances in the parts, it is possible to
`have very precise linear movement of slide 34 within
`channel 30 of platform 28 with very little lateral play or slop.
`This minimizes the chance for inconsistent crimps due to
`unwanted play in the component parts of crimping tool 22.
`Closing plate 36 is preferably attached to the top of slide
`34 by use of hinge 38, as best seen in FIG. 2. Hinge 38
`permits closing plate 36 to swing about
`two positions;
`namely, the up position as shown in solid lines, or the down
`position as shown in dashed lines. Hinge 38 may be loaded
`with an optional torsion spring, for example, to bias closing
`plate 36 toward the up position or the down position as
`needed.
`
`In an alternative embodiment (not shown), the hinge can
`be made of a bar of spring steel attached at opposite ends to
`
`6
`the slide and the closing plate. When the closing plate
`swings open or closed, it does so by flexing the bar. Thus, the
`spring steel bar can be made to resist or to forward bias the
`closing plate toward either the up or the down positions. The
`bar may, of course, be made from any resilient material
`known in the art.
`
`Returning to FIG. 2, when closing plate 36 is in the down
`position, the underside of closing plate 36 faces the top side
`of stationary plate 26. These opposing surfaces are covered
`with optional pads 40 and 42. Pad 40 includes two raised
`ridges 44, 46 while pad 42 has a single ridge 48. Ridges 44,
`46, 48 are preferably aligned along the longitudinal direction
`as indicated by arrow A. ArrowA also indicates the direction
`of translation of slide 34 relative to platform 28 and station-
`ary plate 26, thereby moving closing plate 36 in its down
`position to an overlying alignment above stationary plate 26.
`Ridges 44, 46, 48 are intended to engage the rings or
`cylindrical elements 12 of stent 10. Indeed, stent 10, after
`being optionally hand crimped to balloon 14,
`is inserted
`laterally in a direction generally perpendicular to the direc-
`tion indicated by arrowAinto crimping tool 22. Ideally, each
`ridge 44, 46, 48 engages a corresponding cylindrical element
`12 of stent 10. For example, ridges 44, 46, 48 can be situated
`to specifically engage the distal, proximal, and middle
`cylindrical elements 12 of stent 10. To be sure, it has been
`observed that engagement of the ridges 44, 46, 48 against
`cylindrical elements 12 of stent 10 helps grip the stent 10
`during the crimping process.
`In order to control the amount of crimp on stent 10,
`optional cylindrical spacers 50 are positioned as shown on
`stationary plate 26 in FIG. 2. The diameter of each spacer 50
`controls the distance of gap 52, which defines the distance
`between the opposing pads 40, 42 of stationary plate 26 and
`closing plate 36,
`respectively. Controlling gap 52 thus
`controls the amount of crimp received by stent 10. Also, use
`of spacers 50 to define the size of gap 52 improves the
`chances for a precise and repeatable crimp.
`Force vector F in the general direction as shown in FIG.
`2 is applied to closing plate 36 while it is in the down
`position. While force F is applied, closing plate 36 and slide
`34 translate linearly and reciprocate along direction A to
`perform the crimping process.
`is clear that a theory of
`Based on the foregoing,
`it
`operation of the present
`invention crimping tool 22 is
`essentially two plates 26, 36 sliding against one another. One
`of the plates 26 can be stationary while the other plate 36 is
`mounted on a sliding mechanism. The pinching action due
`to force F reduces the diameter of stent 10 while the sliding
`motion rolls the stent-catheter assembly as represented by
`arrow R to distribute the forces.
`
`As mentioned earlier, use of optional spacers 50 controls
`the size of gap 52. In an alternative embodiment, a mandrel
`(not shown) can be inserted into delivery catheter 11 to
`provide a level of internal resistance in the radial direction
`to prevent over-crimping of stent 10 onto balloon 14.
`Furthermore, use of an optional mandrel positioned within
`the balloon 14 of catheter 11 during the crimping process
`ensures repeatability and a precise crimp of stent 10.
`To use the present invention stent crimping tool 22, the
`cardiologist
`lays a slightly hand-crimped stent-catheter
`assembly onto pad 42 as represented by the dashed lines of
`FIG. 2. Closing plate 36 is moved from its up position to the
`down position overlying stationary plate 26. Applying force
`F, which has been observed to be in the range of two to six
`pounds, while reciprocating and translating slide 34 along
`direction A cause the stent-catheter assembly to roll along
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`direction R. As the rolling action continues, force F slowly
`reduces the diameter of stent 10 thus crimping it on to
`balloon 14 of catheter 11.
`
`FIGS. 3A and 3B provide perspective views of alternative
`embodiment pads 54, 56. In pad 54 of FIG. 3A, there are
`three ridges 58 corresponding to specific cylindrical ele-
`ments 12 of stent 10. As mentioned earlier, these ridges or
`contours provide grip points on the stent
`that
`improve
`stability during the crimping process.
`Astop or riser 60 having vertical surface 62 against which
`the distal end of stent 10 abuts helps with alignment of stent
`10 within tool 22. Assuming pad 54 is substituted on closing
`plate 36 or stationary plate 26 in place of pads 40, 42, pad
`54 is oriented such that ridges 58 are parallel to ridge 48 as
`shown in FIG. 2. When the stent-catheter assembly is
`positioned on pad 54, the distal end of stent 10 abuts vertical
`surface 62 thus aligning stent 10 lengthwise within the force
`transmitting surface area of pad 54. Riser 60 thus acts as a
`stop for stent 10. The height of riser 60 is low enough to
`clear catheter 11 and guide wire 18 yet still abut stent 10.
`Likewise, in the alternative embodiment shown in FIG.
`3B, pad 56 includes channels 64 that create raised areas 66
`intended to engage corresponding cylindrical elements 12 of
`stent 10. Pad 56 also includes optional riser 68 having
`vertical surface 70.
`
`Needless to say, the profiles of ridges 58 or channels 64
`can have various shapes and dimensions. For example, the
`ridges may be pointed as in a cone, angled as in a saw-tooth,
`or be rounded. The ridges may also be a collection of round
`pegs closely bunched to hold the stent. Other conventional
`geometric shapes are contemplated.
`It is preferable that the surface directly in contact with
`stent 10 during the crimping process be slightly softer than
`the material used on the stent to allow for yield. Elastomer-
`type materials with high durometers known in the art can be
`used for the pads, for example. More precisely, the con-
`toured pads can be made from materials such as Mylar,
`silicone, rubber, or polycarbonate. The entire crimping tool
`or parts thereof can be made from stainless steel, aluminum,
`Delrin, polycarbonate, or the like.
`The present invention tool is preferably sterilized and
`intended to be used in a cath lab by a trained technician or
`cardiologist. As will be appreciated by those skilled in the
`art, the present invention crimping tool 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, the present invention
`stent crimping tool can be used repeatedly to crimp stents
`onto balloons until the mechanism wears out. Thus, repeated
`uses of the present
`invention are contemplated for
`controlled, sterile environments, as are single use applica-
`tions when operated by cath lab personnel.
`Furthermore, the present invention crimping tool can be
`used with any stent
`that
`is released without a delivery
`system. The crimping tool may also be sold alone, because
`its design is robust enough to undergo many uses.
`Other modifications can be made to the present invention
`without departing from the scope thereof. The specific
`dimensions, procedural steps, and materials of construction
`are provided as examples, and substitutes are readily con-
`templated which do not depart from the invention.
`What is claimed is:
`
`1. A stent crimping tool for crimping a stent on to a
`balloon catheter, comprising:
`a stationary plate;
`a sliding platform, connected to the stationary plate and
`slidable linearly relative thereto;
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`a closing plate hinged to the sliding platform so that the
`closing plate at least partially overlies the stationary
`plate in a down position, and swings away from the
`stationary plate to an up position;
`whereby the stent having been loaded on to the balloon
`catheter is placed on the stationary plate from a lateral
`position, and the closing plate is moved to the down
`position to hold the stent between the closing plate and
`the stationary plate, so that an external force on the
`closing plate and translational motion of the closing
`plate crimp the stent on to the balloon catheter.
`2. The stent crimping tool of claim 1, wherein the closing
`plate and the stationary plate having facing surfaces that
`include pads for gripping the stent.
`3. The stent crimping tool of claim 1, wherein stationary
`plate includes at least one spacer to control a gap between
`the stationary plate and the closing plate in the down
`position.
`4. The stent crimping tool of claim 1, wherein the closing
`plate and the stationary plate having facing surfaces that
`include opposed contoured pads.
`5. The stent crimping tool of claim 4, wherein the con-
`toured pads include longitudinally oriented ridges.
`6. The stent crimping tool of claim 4, wherein at least one
`contoured pad includes a material selected from the group
`consisting of polyethylene terephthalate, silicone, rubber, or
`polycarbonate.
`7. The stent crimping tool of claim 1, wherein the tool
`includes a material selected from the group consisting of
`stainless steel, aluminum, acetal, or polycarbonate.
`8. A stent crimping tool for crimping a stent on to a
`balloon catheter, comprising:
`a base plate having opposed first and second ends;
`a stationary plate disposed on the first end of the base
`plate;
`a platform disposed on the second end of the base plate,
`wherein the platform includes a channel;
`a s