Unlted States Patent
`[19]
`[11] Patent Number:
`6,082,990
`
`Jackson et al.
`[45] Date of Patent:
`Jul. 4, 2000
`
`USOO6082990A
`
`[54]
`
`STENT CRIMPING TOOL
`
`[75]
`
`Inventors: Gregg A. Jackson; Stephen A.
`Morales, both of Mountain View, Calif.
`
`5,746,764
`5,783,227
`
`5,785,715
`578367952
`5,860,966
`
`5/1998 Green et al.
`7/1998 Dunham .
`
`.
`
`7/1998 SChiftZ-
`11/1998 DaVlS 6t a1~ ~
`1/1999 Tower
`......................................... 606/1
`
`[73] Assignee: Advanced Cardiovascular Systems,
`Inc, Santa Clara, Calif.
`
`6/1999 Yan ........................................... 29/516
`5,911,452
`FOREIGN PATENT DOCUMENTS
`
`.
`[21] Appl‘ No“ 09/024910
`[22]
`Filed:
`Feb. 17, 1998
`
`Int. Cl.7 ..................................................... B29C 55/22
`[51]
`[52] US. Cl.
`.......................... 425/517; 425/329; 425/392;
`425/DIG. 5; 264/249; 72/189; 72/194; 29/517;
`29/283.5
`[58] Field of Search ............................. 264/249; 425/329,
`425/391, 392, DIG. 5, 517; 606/1, 108;
`29/282, 516, 283.5, 515, 517, 518; 72/189,
`194
`
`[56]
`
`References Cited
`US. PATENT DOCUMENTS
`
`2 088 811
`W0 98/14120
`WO 98/19633
`
`6/1982 United Kingdom .
`4/1998 WIPO .
`5/1998 WIPO .
`
`OTHER PUBLICATIONS
`US. Application No. 08/795,335 filed Feb. 4, 1997.
`US. Application No. 08/837,771 filed Apr. 22, 1997.
`US. Application No. 08/089,936 filed Jul. 15, 1997.
`US. Application No. 08/962,632 filed Nov. 3, 1997.
`.
`.
`.
`Primary Examlfler—Jan H~ Sllbéugh .
`Asststant Exammer—Stefan StalCOVlCl
`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. The stent crimping tool is
`constructed of three orthogonally arranged semi-circular
`shaped cams rotatably mounted on a common base. TWO
`cams are disposed horizontally side-by-side and one cam is
`.
`.
`.
`.
`verticallydlsposed. Rotation of the three cams lssynchro-
`mled by mteraamg mks 0“ “Ch cam A grOOVe 15 formed
`into the outer circumference of each cam and the three cams
`are arranged on the base, which also includes a groove, to
`collectively form an axial space in which a stent-catheter
`assembly is inserted. Rotation of the cams draws the
`uncrimped stent and catheter into the axial space in which
`the stent is crimped onto the balloon catheter by the com-
`.
`EZZSWC forces exerted by the grooves 0f the cams and the
`'
`
`25 Claims, 5 Drawing Sheets
`
`3,439,519
`4,468,224
`4,538,440
`475767142
`4’644’936
`4,681,092
`4 697 573
`4,703,546
`4:901:707
`5,183,085
`5,207,960
`5,546,646
`5,626,604
`gagggaggg
`;
`,
`5,658,181
`5,672,169
`5,715,723
`5,738,674
`
`.
`
`............................... 29/157.1 R
`
`4/1969 Gerding .................................... 72/189
`8/1984 Enzmann et al..
`9/1985 Kottke ....................................... 72/189
`3/1986 SChlfL
`2/1987 SChlfl ‘
`7/1987 Cho et al.
`10/1987 Schiff .
`11/1987 Gilbert
`2/1990 Schiff .
`2/1993 Timmermans ,
`5/1993 Moret De Rocheprise ............ 264/103
`8/1996 Williams et al.
`.
`5/1997 COttOIle; JT-
`-
`3133; Kerbed:
`~1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 606/198
`upp e a .
`.
`8/1997 Brown, 11
`................................. 445/23
`9/1997 Verbeek.
`2/1998 Owens .
`4/1998 Williams et al.
`
`.
`
`IPR2017-00444 EX. 2046
`
`Edwards Lifesciences v. Boston Scientific
`
`US. Patent N0. 6,915,560
`
`Page 1 of 13
`
`Page 1 of 13
`
`

`

`US. Patent
`
`Jul. 4,2000
`
`Sheet 1 0f5
`
`6,082,990
`
`
`
`£325;
`\filial
`
`::S
`
`Page 2 of 13
`
`Page 2 of 13
`
`

`

`US. Patent
`
`Jul. 4, 2000
`
`Sheet 2 0f5
`
`6,082,990
`
`
`L:fiia:
`
`iiiq—{
`
`
`
`
`f 3—
`—C :—
`
`24
`
`Page 3 of 13
`
`Page 3 of 13
`
`

`

`US. Patent
`
`Jul. 4, 2000
`
`Sheet 3 0f5
`
`6,082,990
`
`
`
`Page 4 of 13
`
`Page 4 of 13
`
`

`

`US. Patent
`
`Jul. 4, 2000
`
`Sheet 4 0f5
`
`6,082,990
`
`
`
`Page 5 of 13
`
`Page 5 of 13
`
`

`

`US. Patent
`
`Jul. 4, 2000
`
`Sheet 5 0f5
`
`6,082,990
`
`F/G. 8D
`
`
`
`Page 6 of 13
`
`Page 6 of 13
`
`

`

`6,082,990
`
`1
`STENT CRIMPING TOOL
`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 obstructed arteries, blood
`clots in the vasculature, including thrombosis. Therefore, it
`is important to ensure the proper crimping of a stent onto a
`catheter in a uniform and reliable manner.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`This crimping is often done by hand, which can be
`unsatisfactory due to the uneven application of force result-
`ing in non-uniform crimps or loosely fitted stents which pose
`a critical danger to the patient. 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
`
`Page 7 of 13
`
`Page 7 of 13
`
`

`

`6,082,990
`
`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.
`More precisely, the present invention is directed to a tool
`for crimping a stent onto a balloon catheter comprising a
`base having a central groove, first and second semi-circular
`cams that rotate side-by-side within a common horizontal
`plane, wherein the cams include parallel first and second
`tangents located at a minimum distance between the cams,
`wherein each cam is rotatably supported in an overlying
`position above the base, and wherein each cam has a groove
`at a respective outer circumference. The present invention
`crimping tool further includes a vertically disposed third
`cam contained in a vertical plane intersecting the horizontal
`plane containing the first and second cams, wherein the third
`cam includes a third tangent parallel to the first and second
`tangents located at a minimum distance from the first and
`second cams, and wherein the third cam is rotatably attached
`to and overlying the base, and further engages the first and
`second cams at a circumference. The third cam also includes
`
`a groove at an outer circumference.
`The present invention crimping tool further provides that
`the grooves of the cams and in the base collectively form an
`axial space co-extensive with the parallel first, second, and
`third tangents, whereby the stent loaded onto the balloon
`catheter is inserted into the axial space and rotation of the
`cams collectively crimp the stent onto the catheter.
`In the preferred embodiment, the first and second cams
`each have toothed racks at a circumference on a top surface,
`and the third cam includes toothed racks at a circumference
`on one side and on an obverse side. So that the three cams
`
`move synchronously, the toothed rack of the third cam on
`one side engages the toothed rack of the first cam, and the
`toothed rack on the obverse side engages the toothed rack of
`the second cam.
`
`Accordingly, the coordinated rotation of the cams of the
`present invention crimp the stent onto the balloon catheter as
`it feeds through the respective grooves defining the axial
`space. Two of the side-by-side, horizontal cams are spaced
`apart such that they can optionally be driven by the user’s
`thumb and forefinger. In the alternative, the horizontal cams
`can be driven by finger pressure on the third, vertical cam.
`In other words, the third cam is geared to be driven by the
`first two side-by-side cams, or vice versa.
`The cams are preferably positioned orthogonally to one
`another. Also, the two horizontal cams are preferably moon-
`shaped with semi-circular edges having the grooves
`described above.
`
`The groove or slot at the outer circumference of each cam
`and in the base is preferably a quarter circle in cross-
`sectional shape. Those cross-sections complement each
`other to collectively form a complete circle when the partial
`grooves of the three cams and the base plate are combined
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`at the intersection of the cams and the base. This intersection
`is where the parallel
`tangents of each cam are at
`their
`minimal distances apart; it coincides with the axial space
`where the stent crimping and the final sizing of the stent
`occur.
`
`The present invention is preferably used in the following
`process. An uncrimped stent is placed on the balloon cath-
`eter slightly distal of where it is intended to be crimped. In
`most cases, this is approximately 1 to 1.5 millimeters. A
`mandrel is placed in the balloon catheter before the crimping
`process begins. Next,
`the balloon catheter and stent are
`advanced together toward the axial space created by the
`intersection of the cam grooves and the raised groove of the
`base. The slightest resistance felt by the user’s fingers on the
`cams indicates that the stent has interfaced with the cams
`
`and has begun to deform.
`Next, the user holding the balloon catheter and stent in
`one hand continues to squeeze with the other the outward
`most edges of the cams together causing them to rotate
`further. This rotation advances the balloon catheter and stent
`
`into the axial space, which has a smaller diameter than the
`uncrimped stent. While the stent-catheter assembly is drawn
`into the axial space, the user can see the stent being crimped
`or pinched down onto the balloon catheter as each cam
`exerts radial compressive pressure on the stent.
`The cams are rotated until the balloon catheter and stent
`
`have passed completely through the axial space and can
`move freely. The free movement signals that
`the stent
`surface is no longer in contact with the cam surface, or more
`precisely, the groove surface of the cams. The stent crimping
`process is thus complete.
`Of course, the crimping process can be repeated over and
`over. Each pass of the stent-catheter assembly through the
`axial space ensures homogeneous and consistent crimping of
`the stent. The stent can also be rotated about its longitudinal
`axis while it is pushed and pulled through the axial space.
`In an alternative embodiment, the opposing cams may be
`biased together to continuously apply a crimping force on
`the stent and balloon catheter as the assembly passes through
`the axial space. In this alternative embodiment with a spring
`compliance mechanism, the crimping pressure is continuous
`due to the force from tension or compression springs, torsion
`springs, or elastic bands that bias the opposed cams together.
`So repeated passes through the axial space between the
`pinching cams continuously deform and reduce the diameter
`of the stent to that which is smaller than the radius of the
`
`grooves in the cams. The limit is reached when the radial
`forces encounter the mandrel, which resists further defor-
`mation and resultant decreases in the stent diameter.
`
`The present invention tool is thus capable of homoge-
`neously and precisely crimping a stent onto a balloon
`catheter. Such a crimping tool is highly useful to cardiolo-
`gists and radiologists, 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, because the stent crimping procedure
`can be performed fairly efficiently and quickly. Indeed, these
`and other advantages of the present invention will become
`apparent from the following detailed description thereof
`when taken in conjunction with the accompanying exem-
`plary drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a side elevational view, partially in section,
`depicting a stent that has been crimped onto a delivery
`catheter and disposed within a vessel.
`
`Page 8 of 13
`
`Page 8 of 13
`
`

`

`6,082,990
`
`5
`FIG. 2 is a perspective view of a preferred embodiment of
`the present invention stent crimping tool employing three
`orthogonally arranged cams.
`FIG. 3 is a top plan view omitting the vertical cam to
`reveal the operation of the two side-by-side, opposed cams
`just prior to the crimping of a stent.
`FIGS. 4A, 4B, and 4C are plan views showing the stent
`loaded onto a balloon catheter and passing the stent-catheter
`assembly through the axial space formed by the grooves.
`FIGS. 5A and 5B are a side elevational and a plan view,
`respectively, of a preferred embodiment cam, and FIG. 5C
`further provides an enlarged detail view of a preferred
`embodiment groove.
`FIG. 6 is a side elevational view of a preferred embodi-
`ment base showing the raised groove.
`FIG. 7 is a plan view of the base shown in FIG. 6.
`FIGS. 8A, 8B, 8C, and 8D illustrate an alternative
`embodiment for the present invention stent crimping tool.
`FIGS. 9A and 9B are partial sectional views of alternative
`embodiment cam grooves having a tapered cross-section and
`a mottled cross-section.
`
`10
`
`15
`
`20
`
`6
`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 is a perspective view of a preferred embodiment of
`the present invention stent crimping tool 22. As recognized
`in this perspective view, the present invention stent crimping
`tool 22 is characterized by three cams arranged orthogonally
`on a flat base plate. In particular, stent crimping tool 22
`comprises first and second horizontal cams 24, 26 and third
`vertical cam 28, all arranged in an overlying relationship
`above base 30. The arrangement enables rotation of cams 24,
`26, 28 in unison by use of interacting surfaces described
`below.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`FIGS. 5A and 5B provide a side elevational and a plan
`view, respectively, of a preferred embodiment first horizon-
`tal cam 24. First horizontal cam 24 and second horizontal
`
`25
`
`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, polyethylene terephthalate, nylon 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 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
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`cam 26 are preferably identical. As seen in FIG. 2, both cams
`24, 26 lie in a common horizontal plane.
`As best seen in FIGS. 5A and 5B, first horizontal cam has
`a generally semi-circular shape with optional semi-circular
`edges 32. In fact, semi-circular edge 32 can be chamfered or
`beveled in alternative embodiments. Coinciding with edge
`32 at an outer first circumference is groove 34, which is
`depicted in the enlarged detail view of FIG. 5C. Groove 34
`preferably has a quarter-circle profile that is meant to engage
`the outside diameter of an uncrimped stent.
`On one side of first horizontal cam 24 is rack 36. Rack 36
`
`is located at a second circumference having a shorter radius.
`Rack 36 is optionally made from gear teeth 19 for engage-
`ment with another rack of like design. The specific con-
`struction of gear
`teeth 19 is known in the art.
`In an
`alternative embodiment (not shown), gear teeth 19 can be
`replaced with a roughened surface for frictional engagement
`with the roughened surface of a rack on an opposing cam.
`Preferably at a center point or focus of first horizontal cam
`24 is through hole 38, used for mounting cam 24 to base 30.
`As seen in FIG. 2, each horizontal cam 24, 26 is mounted to
`base 30 by passing upright posts 40, 42 through holes 38, 44.
`FIG. 6 provides a front elevational view of base 30 showing
`upright posts 40, 42. Connected to upright post 40, 42 is
`crossbar 46. Naturally, crossbar 46 and upright posts 40, 42
`can be either manufactured in one piece or in separate pieces
`that are assembled as shown.
`
`Crossbar 46 is used to support optional third vertical cam
`28 as shown in FIG. 2. Third vertical cam 28 has a
`construction similar to first horizontal cam 24, shown in
`FIGS. 5A and 5B. To be sure, third vertical cam 28 has hole
`48 through which crossbar 46 passes. Third vertical cam 28
`also has a preferably semi-circular shape and further
`includes groove 50 at an outer circumference having a
`quarter circle profile, similar to the detail view of FIG. 5C.
`A feature distinguishing third vertical cam 28 from hori-
`zontal cams 24, 26 is the presence of racks 52, 54. All three
`cams 24, 26, 28 are rotatably mounted to their respective
`supports and are free to turn. On the other hand, racks 52, 54
`of third vertical cam 28 engage rack 36 and rack 56 of first
`horizontal cam 24 and second horizontal cam 26, respec-
`
`Page 9 of 13
`
`Page 9 of 13
`
`

`

`6,082,990
`
`7
`tively. Through this mechanical engagement, the motion of
`all three cams 24, 26, 28 are synchronized so that rotation of
`one cam causes rotation of the other two cams. All three
`
`cams 24, 26, 28 are mounted to base 30 by use of the support
`structure shown in FIG. 6.
`
`FIG. 7 is a simplified plan view of base 30 shown in FIG.
`6. Crossbar 46 has been omitted for clarity. In this plan view,
`curved lines 58, 60, 62, and 64 coincide with the possible
`locations of outer edge 32 of first horizontal cam 24 and
`outer edge 66 of second horizontal cam 26, shown in FIG.
`2, depending on the radius of each cam. Therefore, in the
`plan view of FIG. 7, curved lines 58, 60, 62, 64 provide an
`indication of the possible gap between the two side-by-side
`mounted first and second horizontal cams 24, 26.
`In the preferred embodiment, tangent line 68 coincides
`with the tangents of first and second horizontal cams 24, 26
`at a minimal distance between the cams. This minimal
`
`distance or gap between horizontal cams 24, 26 that is
`coextensive with tangent line 68 can be adjusted by moving
`posts 40, 42 or changing the radius of the respective cams.
`FIG. 6 also depicts raised portion 70 having groove 72
`extending thereon. Accordingly, as seen in FIG. 2, cams 24,
`26, and 28 are oriented along groove 72, which coincides
`with tangent line 68. As mentioned earlier, a groove is
`formed into the outer edge or circumference of each cam 24,
`26, 28, which grooves with groove 72 collectively form
`axial space 76 that spans a minimum distance among the
`three cams. Axial space 76 is also the imaginary intersection
`of the three cams 24, 26, 28. Each groove has preferably a
`quarter circle cross-sectional shape thereby forming a com-
`plete circle at the axial space.
`FIGS. 9A and 9B are exemplary embodiments of various
`other cross-sectional shapes of the groove of each cam.
`Specifically, FIG. 9A shows a tapered groove while FIG. 9B
`shows a mottled groove. The mottled groove has raised
`contours or bumps. Because the grooves are used to pinch
`uncrimped stent 10 onto balloon catheter 11, the surface
`texture or shape such as that shown in FIGS. 9A and 9B can
`be imparted into stent 10 during the crimping process.
`Profiles and shapes other than that shown in FIGS. 9A and
`9B are possible and are contemplated. Furthermore, the arc
`defined by the curvature of the groove can range from, for
`example, a 60 degree arc for a six-cam arrangement to a 180
`degree arc for a two-cam arrangement. Also, the groove of
`each cam can be coated or lined with an elastomeric material
`such as rubber.
`
`FIG. 3 and FIGS. 4A, 4B and 4C illustrate the preferred
`crimping process for applying the present invention crimp-
`ing tool 22. FIG. 3 is a plan view of the present invention
`crimping tool 22 wherein crossbar 46 and third vertical cam
`28 have been omitted for clarity of illustration. In this plan
`view, stent crimping tool 22 is operated by user’s fingers 74
`pushing on first and second horizontal cams 24, 26. As
`mentioned earlier, the motion of horizontal cams 24, 26 is
`controlled through racks 36, 56 and their engagement with
`racks 52, 54 of vertical cam 28 so that all three cams rotate
`in unison. Groove 72 of base 30 is shown coinciding with
`tangent 68 shown in FIG. 7. Groove 72 passes through axial
`space 76. The user mounts uncrimped stent 10 onto delivery
`catheter 11 and slowly advances the stent-balloon assembly
`forward toward axial space 76, denoted in FIG. 3 by a circle.
`FIG. 4A is a partial plan view depicting the stent-catheter
`assembly just prior to engagement with the outer circum-
`ference of horizontal cams 24, 26. Actually, it is the groove
`of each respective cam that engages stent 10. The grooves,
`however, have been omitted from the figures for clarity.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`FIG. 4B shows the crimping process as the stent-catheter
`assembly passes into axial space 76, which has a smaller
`diameter than the uncrimped stent. As a result, first and
`second horizontal cams 24, 26 pinch crimp 10 onto balloon
`14 in the horizontal plane.
`Importantly, a mandrel (not shown) should be placed in
`the guide wire lumen (not shown) within balloon 14 before
`the crimping process to support crimped stent 10 from
`underneath. The finished diameter of crimped stent 10 is
`determined by the amount of pressure exerted by horizontal
`cams 24, 26 and the diameter of the internal mandrel.
`FIG. 4C shows the crimping procedure continuing
`wherein first and second horizontal cams 24, 26 have
`crimped the entire length of intravascular stent 10; indeed,
`the stent-catheter assembly has passed almost entirely
`through axial space 76. The arrows in FIGS. 4A, 4B and 4C
`indicate the direction of rotation of first and second hori-
`
`zontal cams 24, 26 in order to pass the stent-catheter
`assembly through axial space 76.
`By counter-rotating cams 24, 26 while the stent-catheter
`assembly is in the position shown in 4C, the stent-catheter
`assembly can be withdrawn through axial space 76 in the
`opposite direction. Thus, stent 10 can be crimped onto
`balloon 14 in either direction. Furthermore,
`to ensure an
`even circumferential crimp, the stent-catheter assembly can
`be manually rotated about its longitudinal axis by the user as
`the assembly is crimped in the axial space 76.
`In the exemplary embodiment shown in FIG. 2, first and
`second horizontal cams 24, 26 apply pressure to stent 10 at
`the 0° and 180° positions while third vertical cam 28 and
`raised portion 70 with groove 72 apply pressure in the 90°
`and 270° positions. The application of radial forces at the
`various angular positions are only exemplary. It is contem-
`plated that the cams be relocated or more cams added to
`provide radial forces from different or addition angular
`positions.
`FIGS. 8A, 8B, 8C, and 8D are simplified schematic
`diagrams of an alternative embodiment of the present inven-
`tion. In FIG. 8A, opposed first and second horizontal cams
`24, 26 are biased by linear springs 78, 80, torsion springs,
`elastic bands or the like, toward each other as seen in this
`plan view. When the stent-catheter assembly is inserted into
`axial space 76, rotation of cams 24, 26 as well as the
`expansion force from springs 78, 80 push cams 24, 26 into
`stent 10, consequently crimping stent 10 onto balloon 14.
`This action is seen in the front elevational view of FIG. 8B.
`
`FIG. 8C provides a front elevational view of an alternative
`embodiment wherein third vertical cam 28 is shown along
`with counteracting fourth vertical cam 82. Cams 28, 82 act
`in unison to apply radial forces from the 90° and 270°
`positions around stent 10 while cams 24, 26 apply compres-
`sive forces from the 0° and 180° positions around stent 10.
`Importantl