United States Patent [19]
`Brown et al.
`
`[54]
`
`[75]
`
`[73]
`
`STENT CRIMPING TOOL AND METHOD OF
`USE
`
`Inventors: Daniel G. Brown, Temecula; Stephen
`A. Morales, Santa Clara, both of Calif.
`Assignee: Advanced Cardiovascular Systems,
`Inc., Santa Clara, Calif.
`
`Appl. No.: 09/196,534
`Filed:
`Nov. 20, 1998
`Int. Cl." …...... B210 39/04; B23P 11/00
`U.S. Cl. ................................... 29/516; 29/282; 72/90;
`606/1
`Field of Search .................................... 72/88, 90,94;
`29/516, 517, 270, 282, 283.5; 606/1
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`696,289 3/1902 Williams .
`2,964,088 12/1960 Erath ........................................... 72/90
`4,455,854 6/1984 Ermolovich ................................. 72/90
`4,468,224 8/1984 Enzmann et al. .
`4,576,142 3/1986 Schiff .
`4,644,936
`2/1987 Schiff .
`4,681,092 7/1987 Cho et al. .
`4,697,573 10/1987 Schiff .
`4,901,707 2/1990 Schiff .
`4,907,336 3/1990 Gianturco .................................. 29/515
`5,132,066
`7/1992 Charlesworth et al. .
`5,133,732 7/1992 Wiktor ........................................ 606/1
`5,183,085
`2/1993 Timmermans ....
`... 140/89
`5,189,786 3/1993 Ishikawa et al. .
`... 29/283
`5,437,083 8/1995 Williams et al. .
`.... 606/1
`5,546,646 8/1996 Williams et al. .
`... 29/516
`5,626,604 5/1997 Cottone, Jr. ...
`.... 606/108
`5,630,830 5/1997 Verbeek ........
`... 606/108
`5,653,691
`8/1997 Rupp et al. ............................. 606/194
`5,672,169 9/1997 Verbeek ...................................... 606/1
`5,725,519 3/1998 Penner et al. .
`5,738,674 4/1998 Williams et al. ........................... 606/1
`5,746,764 5/1998 Green et al. ............................ 606/108
`5,759,474 6/1998 Rupp et al. .
`
`
`
`US006125523A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,125,523
`Oct. 3, 2000
`
`5,783,227 7/1998 Dunham .
`5,785,715 7/1998 Schatz ......................................... 606/1
`5,787,572 8/1998 Toms ....
`29/282
`5,810,873 9/1998 Morales ...................................... 606/1
`5,836,952 11/1998 Davis et al. ............................ 606/108
`5,920,975 7/1999 Morales .................................... 29/282
`FOREIGN PATENT DOCUMENTS
`630 623 A2 12/1994 European Pat. Off. .
`826 346 A1 3/1998 European Pat. Off. .
`0 873 731 A1 10/1998 European Pat. Off. .
`0.938877A2 9/1999 European Pat. Off. .
`464004 8/1928 Germany ................................... 72/88
`159065 1/1921 United Kingdom .
`WO 98/14120 4/1998 WIPO .
`WO 98/19633 5/1998 WIPO .
`
`OTHER PUBLICATIONS
`The eXTraordinary Stent, C.R. Bard Brochure (undated).
`Primary Examiner—Daniel C. Crane
`Attorney, Agent, or Firm—Fulwider Patton Lee & Utecht,
`LLP
`ABSTRACT
`[57]
`A hand held tool for crimping a stent onto a balloon of a
`catheter is disclosed. The stent crimping tool is operated in
`one hand by squeezing two plates together while simulta
`neously displacing the plates linearly to crimp and roll the
`stent held between the plates. Specifically, the crimping tool
`includes a base plate with two bosses through which respec
`tive pins pass linking the base plate to a compression plate.
`The compression plate has elongated diameter openings at
`opposite sides thereof to receive the pins. With the elongated
`diameter openings, the compression plate can pivot at the
`pins and translate linearly relative to those pins thus
`enabling the rolling action during the crimping process. A
`compression profile pad and a tapered profile pad are
`attached to the crimping areas of the plates to grip and
`together apply pressure to the uncrimped stent held therebe
`tween. The pads may include specific contours in order to
`impart a desired profile to the crimped stent.
`
`23 Claims, 4 Drawing Sheets
`
`Page 1 of 10
`
`EDWARDS LIFESCIENCES EX. 1121
`Edwards Lifesciences v. Boston Scientific Scimed
`U.S. Patent No. 6,915,560
`
`

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`U.S. Patent
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`Oct. 3, 2000
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`Sheet 1 of4
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`6,125,523
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`U.S. Patent
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`Oct. 3, 2000
`Oct. 3, 2000
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`Sheet 2 of 4
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`U.S. Patent
`U.S. Patent
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`Oct. 3, 2000
`Oct. 3, 2000
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`Sheet 3 of 4
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`U.S. Patent
`U.S. Patent
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`Oct. 3, 2000
`Oct. 3, 2000
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`Sheet 4 of 4
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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, on rare occasions it is possible
`that 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.
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`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 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.
`Another stent loading tool design is comprised of a
`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,
`U.S. 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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`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.
`In a preferred embodiment, the present invention is
`directed to a tool for crimping a stent onto a balloon portion
`of a catheter, comprising a base plate having a press area and
`at least one boss; a compression plate having a press area,
`and an elongated opening; a pivot linking the boss and the
`elongated diameter opening so that the compression plate
`moves linearly and rotatably relative to a longitudinal axis of
`the pivot; and a tapered profile pad having ridges disposed
`on the press area of the base plate; whereby the stent is
`mounted on the balloon portion and aligned with the ridges
`of the tapered profile pad, and the compression plate is
`closed thereon to crimp the stent onto the balloon portion of
`the catheter.
`In the preferred embodiment, the tool further comprises at
`least two bosses at opposite edges of the base plate, wherein
`each boss includes a circular hole; at least two cylindrical
`pins disposed in each boss and extending toward each other
`on a common axis; and at least two elongated diameter
`openings on opposite sides of the compression plate, receiv
`ing the two cylindrical pins so that the compression plate
`rotates and translates linearly relative to the common axis.
`With such a construction, the present invention crimping
`tool is capable of imparting a crimping pressure radially by
`closing the compression plate onto the base plate thus
`pinching the stent-catheter assembly therebetween, and
`simultaneously rolling the stent-catheter assembly therebe
`tween by translating or sliding the compression plate lin
`early relative to the base plate or a boss defining the common
`axis. The rolling action evenly distributes the crimping
`pressure to obtain a homogeneous and uniform crimp along
`the circumference of the stent.
`In a preferred embodiment, the present invention crimp
`ing tool includes a compression profile pad having a raised
`surface disposed on the press area of the compression plate.
`It along with the tapered profile pad also having ridges
`disposed on the press area of the press plate impress the
`desired profile on the crimped stent. This is accomplished by
`first forming the desired profile into the special durometer
`polymer pads that engage the uncrimped stent-catheter
`assembly therebetween. When crimping pressure is applied
`and with the rolling of the stent by linear translation of the
`compression plate, the stent is slowly deformed according to
`the contours and profiles of the pads.
`Beneficially, the contours of the pads grip the stent firmly
`and do not allow any damage to either the stent or the
`balloon catheter. Furthermore, the ridges on the tapered
`profile pad and the raised surface of the compression profile
`pad insure proper alignment of the stent on the balloon
`catheter and exact placement of the stent-catheter assembly
`inside the crimping tool.
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`During the crimping process, the compression plate is
`closed on the base plate under finger pressure thereby
`translating the finger squeeze pressure to radial crimping
`pressure. Also, the compression plate is translated linearly
`relative to the base plate to roll the stent-catheter assembly
`therebetween to evenly distribute the radial crimping pres
`sure. These operations slowly reduce the diameter of the
`stent until it crimps tightly onto the balloon catheter.
`As the stent nears its minimum diameter, the present
`invention contemplates applying a strong closing force
`while continuing to roll the stent between the plates.
`Typically, after three to five cycles of the foregoing
`operations, the crimping process is complete. The plates are
`opened and the stent-catheter assembly is removed and is
`ready for use.
`During the process, some adjustment might be necessary
`to make sure the stent is crimped in the appropriate position
`on the balloon. By observing the stent-catheter assembly
`through the gap between the compression plate and the base
`plate, or by swinging the compression plate away from the
`base plate, the user or cardiologist can carefully monitor the
`progress of the crimping operation and assure proper align
`ment of the component parts.
`Important to the movement of the compression plate is the
`presence of an elongated diameter opening. In the preferred
`embodiment, the elongated diameter opening includes a
`rectangular shape opening with opposed semi-circular edges
`into which a pin is inserted to interconnect the compression
`plate to the base plate. The elongated diameter opening,
`similar to a slot, allows the compression plate to translate
`linearly relative to the base plate as well as to pivot about an
`axis coinciding with the pin. Such a pivot may take many
`forms insofar as its construction enables both linear and
`rotational movement by the compression plate relative to the
`base plate.
`Again, in the preferred embodiment, the exteriors of the
`compression plate and base plate may include finger grooves
`for easy gripping by the user or cardiologist. Using the finger
`grooves, the present invention crimping tool is preferably
`held in one hand between the thumb and index, middle, and
`third fingers. The uncrimped stent is mounted on the balloon
`portion of the catheter and then placed equally between the
`tapered ridges on the tapered profile pad. Finger pressure is
`then applied to the crimping tool as described above to crimp
`the stent.
`The present invention tool can be used to crimp mounted
`or unmounted stents. The tool may further be used for
`production crimping of self-expanding stent designs. The
`present invention tool is intended for single-hand use, and it
`is of an ambidextrous design. Naturally, the overall size and
`shape of the tool may change to suit ergonomic, cosmetic,
`and manufacturing considerations.
`The present invention crimping tool is thus 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 fol
`lowing detailed description thereof when taken in conjunc
`tion 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 delivery
`catheter and disposed within a damaged vessel.
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`FIG. 2 is an exploded, perspective view of a preferred
`embodiment of the present invention stent crimping tool.
`FIGS. 3A, 3B, 3C, and 3D are bottom and top plan views,
`and front and side elevational views of a preferred embodi
`ment base plate in accordance with the present invention.
`FIGS. 4A, 4B, 4C, and 4D are top and bottom plan views,
`and side and front elevational views of a preferred embodi
`ment compression plate constructed in accordance with the
`present invention.
`FIGS. 5A, 5B, and 5C are plan views of the present
`invention tool during the crimping process including closing
`the compression plate onto the base plate with the stent
`catheter assembly therebetween as seen in FIG. 5A, and
`linearly translating the compression plate relative to the base
`plate to roll the stent-catheter assembly as seen in FIGS. 5B
`and 5C.
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`FIG. 2 is an exploded, perspective view of a preferred
`embodiment stent crimping tool 22. Stent crimping tool 22
`includes a tapered or trapezoidal shape base plate 24 which
`optionally includes two bosses 26, 28 spaced apart at an
`edge, preferably back edge, of base plate 24. Base plate 24
`further includes optional recessed work area 30 having
`disposed at a central location thereon raised press area 32.
`Raised press area 32, which functions as a platform, has
`ridges 34 that are spaced apart to approximate the length of
`a crimped stent. Disposed on top of press area 32 is tapered
`profile pad 36, also having ridges 38 overlying ridges 34 of
`press area 32. Because tapered profile pad 36 is made from
`a material that is somewhat resilient, its ridges 38 are
`supported from underneath by the more rigid ridges 34 of
`press area 32.
`FIG. 2 also shows a perspective view of compression
`profile plate 40 which is pivotably attached to two lugs or
`bosses 26,28 by use of cylindrical pins 42, 44. Compression
`profile plate 40 includes an underside with press area 46 to
`which is attached compression profile pad 48. Compression
`profile pad 48 has resilience and functions as the counterpart
`to tapered profile pad 36, the two pads pinching the stent
`catheter assembly therebetween during the crimping opera
`tion.
`As indicated by the arrows, pins 42, 44 are inserted into
`the respective apertures or openings 52 in bosses 26, 28 to
`pivotably link base plate 24 to compression profile plate 40.
`The arrows in FIG. 2 also indicate that compression profile
`pad 48 is attached to and overlies press area 46 while tapered
`profile pad 36 is attached to and overlies raised press area 32.
`To illustrate a crimping tool component in greater detail,
`FIGS. 3A-3D provide bottom and top plan views and front
`and side elevational views, respectively, of a preferred
`embodiment of base plate 24 shown in FIG. 2. Most promi
`ment of the features of base plate 24 are vertically extending
`bosses 26, 28, as best seen in FIGS. 3C and 3D, and finger
`grooves 50 along the underside of base plate 24 as shown in
`FIG. 3A. Raised press area 32 has ridges 34 that are best
`seen in the front and side elevational views of FIGS. 3C and
`3D, respectively. In the side elevational view of FIG. 3D,
`boss 28 includes opening 52 to receive cylindrical pin 44.
`Bosses 26,28 thus function as lugs to connect base plate 24
`to compression profile plate 40. In addition, there are
`preferably two bosses 26, 28 in order to minimize torque and
`resultant shifting of compression plate 40 relative to base
`plate 24, which would cause imprecision in the crimping
`operation.
`To show another crimping tool component in detail,
`FIGS. 4A-4D provide top and bottom plan views and side
`and front elevational views, respectively, of compression
`profile plate 40. In the top plan view of FIG. 4A, the top
`surface of compression profile plate 40 is exposed showing
`optional finger grooves 54. The underside of compression
`profile plate 40 includes press area 46 used for application
`of pressure to the uncrimped stent.
`As best seen in the side elevational view of FIG. 4C,
`compression profile plate 40 features an elongated diameter
`opening 56 intended to receive cylindrical pins 40, 44
`therethrough. Thus, back section 58 is narrow and fits
`between bosses 26, 28 of base plate 24 to allow compression
`profile plate 40 to rotate and slide linearly relative to an
`imaginary centerline or axis of cylindrical pins 42, 44. Front
`section 60 is designed to be wide to accommodate a user’s
`hand, and the spaced apart finger grooves 54 improve grip
`and pressure control by the user’s fingers or thumb.
`As best seen in the exploded perspective view of FIG. 2,
`tapered profile pad 36 engages uncrimped stent 10 and its
`ridges 38 help align stent 10 within crimping tool 22 during
`the crimping process. Similarly, compression profile pad 48
`includes raised surface 62 that engages uncrimped stent 10
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`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
`20
`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 assaphenous 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
`known in the art and is essentially the same as a conven
`tional balloon dilatation catheter for angioplasty procedures.
`Balloon 14 may be formed of suitable materials such as
`polyethylene teraphalate, polyethylene, nylon, polyvinyl
`chloride, and other like polymers. 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. 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 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 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.
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`during the crimping process. Specific contours or profiles
`may be formed into raised surface 62 or the area between
`ridges 38 on tapered profile pad 36 in order to impart that
`profile to uncrimped stent 10. Moreover, compression pro
`file pad 48 and tapered profile pad 36 may be replaced with
`materials of varying durometers and proportions to accom
`modate stents of varying dimensions and hoop strengths.
`Thus, the present invention has replaceable pads 36, 38 that
`can be used to accommodate a large variety of stent designs.
`FIGS. 5A-5C provide plan views of the present invention
`stent crimping tool 22 during a stent crimping operation.
`FIG. 5A illustrates when compression profile plate 40 is
`closed onto the stent-catheter assembly as indicated by the
`curved arrow. FIGS. 5B and 5C illustrate the rolling of the
`stent-catheter assembly by linearly translating compression
`profile plate 40 relative to base plate 24, as suggested by the
`al?TOWS.
`In particular, FIG. 5A shows in plan view the open
`position of compression profile plate 40. As depicted here,
`stent 10 is laid across tapered profile pad 36 so that the distal
`and proximal ends of stent 10 are aligned with ridges 38.
`Catheter 11 then preferably extends out one side of crimping
`tool 22. Pins 42 and 44 pivotably link compression profile
`plate 40 to base plate 24 via bosses 26, 28.
`As compression profile plate 40 is slowly closed onto
`stent 10, raised surface 62 of compression profile pad 48
`engages the outer circumference of 10 uncrimped stent 10.
`This action is indicated by the bowed arrow in FIG. 5A.
`In the plan view of FIG. 5B, compression profile plate 40
`has assumed the closed position and is applying radial
`pressure to uncrimped stent 10 that is pinched between it and
`base plate 24. In the condition shown in FIG. 5B, compres
`sion profile plate 40 is in its farthest back position, while in
`the plan view of FIG. 5C, compression profile plate 40 is in
`the farthest forward position as indicated by the up and own
`arrows, respectively. This linear translation is possible due
`to the presence of elongated diameter openings 56 on either
`side of back section 58, which openings 56 permit linear
`translation as well as pivotal motion of compression plate 40
`about the imaginary centerline of cylindrical pins 42, 44.
`Accordingly, FIGS. 5A-5C provide a simplified view of the
`present invention crimping process of closing compression
`profile plate 40 onto uncrimped stent 10 and applying radial
`pressure thereto, and the rolling operation achieved by
`linearly translating compression profile plate 40 relative to
`base plate 24.
`Crimping tool 22 is gripped preferably in one hand and is
`designed for ambidextrous use. Finger grooves 50, 54 on the
`outer surfaces of compression profile plate 40 and base plate
`24 permit the user or cardiologist to exert precise radial
`pressure and control the rolling action. This in turn results in
`homogeneous, precise, and repeatable crimps. Moreover,
`compression profile pad 48 and tapered profile pad 36 are
`carefully contoured to complement each other to prevent
`over-crimping of stent 10 onto balloon 15. Indeed, ridges 34
`of tapered profile 36 may optionally be designed to engage
`raised surface 62 thereby setting a gap distance between
`compression profile plate 40 in its closed position against
`base plate 24. This gap therefore defines the finished or
`crimped outside diameter of stent 10.
`In various alternative embodiments (not shown) the com
`ponents enabling compression profile plate 40 to pivot and
`60
`translate linearly relative to base plate 24 can be modified.
`For example, it may be possible to use a single boss on the
`base plate with a single pin engaging an elongated diameter
`opening in the side of the compression profile plate. In
`another alternative embodiment, cylindrical pins 42, 44 may
`be omitted in favor of ears or tabs extending out the sides of
`the compression profile plate at the back section thereof and
`engaging the openings in the bosses of the base plate.
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`In still another alternative embodiment, cylindrical pins
`42, 44 are again omitted. To achieve the pivoting function,
`the interior, opposed faces of the bosses may be modified
`with bumps, cone shape projections, and the like, that extend
`into and engage elongated diameter openings 56 on either
`side of back section 58 thereby pivotably and slideably
`linking the compression profile plate to the base plate.
`Of course, pins 42, 44 may be replaced with a single rod
`that extends through openings 52 of bosses 26, 28 and also
`passes through elongated diameter opening 56 which is now
`a through-hole to link the compression profile plate to the
`base plate. In yet another alternative embodiment, the bosses
`may have open tops that allow pins extendi