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`Edwards Lifesciences v. Boston Scientific
`U.S. Patent No. 6,915,560
`IPR2017-00444 EX. 2025
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`US. Patent
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`Nov. 17, 1998
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`Sheet 1 0f 4
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`5,836,952
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`US. Patent
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`Nov. 17, 1998
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`Sheet 2 0f 4
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`5,836,952
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`US. Patent
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`Nov. 17,1998
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`Sheet 3 0f4
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`5,836,952
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`US. Patent
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`Nov. 17,1998
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`Sheet 4 0f4
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`5,836,952
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`ME?!I
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`5,836,952
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`1
`HAND-HELD STENT CRIMPER
`
`FIELD OF THE INVENTION
`
`The invention generally relates to crimpers and crimping
`procedures that provide consistent and uniform crimping of
`balloon-deployable devices onto catheter balloons by elimi-
`nating subjective factors during crimping. In particular, the
`invention is related to hand-held crimping devices which can
`be disposable and are used to load a stent or other balloon-
`deployable device onto the distal end of a balloon dilation
`catheter assembly. Additionally, the hand-held crimpers are
`very versatile in handling a wide range of diameter and
`length sizes of stents or the like such as those small enough
`to be suitable for coronary uses and those large enough for
`peripheral uses.
`
`BACKGROUND OF THE INVENTION
`
`A stent is an intravascular prosthesis that is generally
`introduced percutaneously, transported transluminally and
`positioned at a desired location within a patient. A stent
`typically is implanted during or closely after angioplasty in
`order to reduce the chance of restenosis and/or strengthen
`the vessel location undergoing angioplasty or other treat-
`ment. When it is of the balloon-launched type, the stent is
`transported to the treatment location by a balloon catheter
`and is implanted by expansion of the balloon when the
`balloon and stent are at the desired location. Expansion of
`the balloon portion of the catheter can simultaneously com-
`press plaque at that location and expand the stent to its
`proper implantation size. The balloon portion of the catheter
`is then deflated and the catheter withdrawn, leaving the stent
`implanted. Alternative procedures are also possible and are
`known to those skilled in the art. Self-expanding stents can
`also be used in percutaneous transluminal angioplasty (PTA)
`and percutaneous transluminal coronary angioplasty
`(PTCA) procedures. Examples of stents useful in the PTA or
`PTCA procedures are described in US. Pat. No. 4,655,771
`to Wallsten, US. Pat. No. 4,739,762 to Palmaz and US. Pat.
`No. 5,019,090 to Pinchuk. Other balloon-deployed devices
`are known. These include filters, catchers and the like.
`In practicing stenting, stents of various diameters and
`lengths are used from procedure to procedure, the diameter
`and length of the stent being selected to correspond to the
`dimensions of the vessel
`location undergoing repair or
`treatment. Delivering the stent to the location undergoing
`repair or treatment requires the stent to have a low profile
`and to have been secured to the balloon catheter so that it
`
`does not slide off the catheter as it is being inserted and
`transported to the desired location within the patient. Similar
`needs exist
`for other balloon-deployed devices.
`Consequently, the stent or the like is typically crimped or
`otherwise secured about a catheter, such as over the balloon
`of a balloon catheter, before being inserted into the patient.
`Once at
`the treatment
`location,
`the stent or the like is
`expanded in a direction which generally reverses the crimp-
`ing procedure, typically expanding even more than when at
`its pre-crimped configuration.
`the
`Crimped stents may be either pre-crimped about
`catheter by the supplier or may be crimped on-site in sterile
`field by medical personnel. If stents pre-crimped about a
`catheter are used, generally a large stock of stent-bearing
`angioplasty catheters must be maintained in order to insure
`that one properly sized stent/catheter unit is available when
`it is needed. Maintaining such an inventory can be expen-
`sive. The inventory expense can be reduced by stocking
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`separate catheters and stents, and having the surgical per-
`sonnel crimp the desired stent about a selected catheter prior
`to a procedure. However, the proper crimping of a stent
`about a balloon catheter is a technique acquired only through
`practice and can be affected by a variety of subjective
`conditions. For example, stents can be crimped using sterile
`pliers. Excessive and/or cylindrically non-uniform force
`applied during crimping, such as when pliers are used, can
`damage the stent and/or the catheter. Crimping problems are
`also caused by the small size of the stents, which are
`typically about 3—4 millimeters (mm) in diameter before
`crimping and 1—10 centimeters (cm) in length or longer.
`Examples of the problems encountered are non-uniform
`crimping, the inability to judge when a reliable and uniform
`crimp has been achieved, and damage to the stent or catheter
`during crimping.
`US. Pat. No. 5,437,083 describes a device for placing a
`stent about a balloon catheter. The device has a series of
`plates which have substantially flat and parallel surfaces that
`move in a rectilinear fashion with respect to each other. A
`stent carrying catheter can be disposed between these sur-
`faces to affix the stent onto the outside of the catheter by
`relative motion between the plates. Force indicating trans-
`ducers are used in conjunction with the plates to indicate the
`force being applied during affixation of the stent. This patent
`also describes an embodiment whereby a fluid filled bladder
`is used to crimp a stent about a balloon catheter. Although
`the device of this patent seems useful in a commercial
`setting, its use in a surgical theater is believed to impose
`some problems, particularly with regard to maintaining
`sterility.
`With regard to the crimping of stents or the like onto
`catheters, there is a need for a simple device, preferably
`disposable, which would eliminate subjective factors during
`crimping, eliminate the handling of the stents themselves in
`the surgical theater, and solve the inventory problem. The
`present invention addresses these objectives by providing
`hand-held crimpers which are loaded with a stent or the like
`and which are structured to receive a catheter therewithin
`
`the like. An
`and in axial alignment with the stent or
`elongated wrapping member or belt exerts a generally
`cylindrical internally compressive force on the stent or the
`like in order to crimp it onto the desired location along the
`catheter. This crimping action is carried out by the simple
`unidirectional rotation of a knob.
`
`It is accordingly a general object of the present invention
`to provide an improved device and procedure for crimping
`a device onto a catheter.
`
`Another object of the present invention is to provide an
`improved crimping device and method which exerts a uni-
`form radially compressive force onto the outer surface of
`any one of a variety of stents or the like having a wide range
`of diameters.
`
`Another object of this invention is to provide an improved
`crimper and method which incorporates a rolling motion to
`allow the force to be distributed evenly to a generally
`cylindrical stent or similar device.
`Another object of the present invention is to provide an
`improved stent crimper and method for packaging stents
`within a disposable device that also crimps the stent onto the
`balloon of an angioplasty catheter or the like.
`Another object of the present invention is to provide an
`improved stent delivery device and procedure which accom-
`modates angioplasty balloon catheters of all sizes.
`Another object of this invention is to provide an improved
`crimper and procedure which requires minimal effort by the
`operator to crimp a stent or similar device onto a balloon
`catheter.
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`5,836,952
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`3
`Another object of the present invention is to provide an
`improved stent crimping device and method in which a
`balloon catheter and a stent spin in the same direction, thus
`folding the balloon during the operation and allowing a
`uniform radial compressive force to be distributed evenly
`around the entire surface area of the stent.
`
`Another object of the present invention is to provide a
`crimper and method by which the physician or medical
`professional neither touches nor is exposed to the stent or
`other device which is being crimped, such as when the
`device is radioactive or is coated with a medication, a
`protective coating or the like.
`Another object of this invention is to provide an improved
`crimper and method which performs a crimping operation in
`one pass, during which the crimping sequence/user interface
`moves from a neutral action to a tensioned crimping action
`and back to a neutral action which indicates that the crimp-
`ing has been completed, all while rotating a drive wheel in
`a single direction.
`These and other objects, features and advantages of the
`present invention will be apparent from and clearly under-
`stood through a consideration of the following detailed
`description.
`
`SUMMARY OF THE INVENTION
`
`The invention is directed to devices for loading a stent or
`other balloon-deployable device onto a balloon catheter and
`crimping same in place about the catheter in a surgical
`theater while avoiding any contact of the stent or other
`device itself by the medical personnel. Reference herein will
`at times be made to a stent or to stents, and it should be
`understood that these terms also encompass other balloon-
`deployable devices which need to be crimped, for example
`filters such as vena cava filters and the like. The invention
`
`eliminates the subjective factors presently involved in stent
`crimping and eliminates the need for tools such as pliers
`which might damage the stent during the crimping opera-
`tion.
`
`The devices of the invention also preferably are
`disposable, eliminating the concerns associated with reus-
`able devices including sterility and improper loading.
`Crimpers according to the invention also safely encase stents
`at the manufacturer level until the stents are conveniently
`inserted over and crimped onto the balloon catheter selected
`by medical personnel prior to delivery.
`A hand-held crimping device according to the invention
`has a longitudinal feed axis which generally defines the
`operational orientation of the device and the longitudinal
`pathway along which the catheter is inserted to receive the
`stent. Generally positioned along this feed axis are a catheter
`guide, a stent holder or sheath, and a stent therewithin. An
`elongated wrapping member or belt having a width which
`extends for at least approximately the length of the stent to
`be crimped wraps substantially around the stent holder or
`sheath. A suitable moving and guiding mechanism tightens
`the wrapping member in order to cylindrically compress the
`sheath and the stent therewithin so as to effect the desired
`
`stent crimping in response to hand-applied digital forces
`imparted to the moving and driving mechanism by the
`person assembling the stent onto the catheter. Afterward, the
`catheter/stent assembly is easily removed from the crimping
`device leaving the stent only on the catheter so that the stent
`is ready for delivery into the patient by means of the catheter.
`Alternatively, the sheath could emerge from the crimping
`device together with the stent, particularly when the sheath
`plasticly deforms, thereby providing stress and strain relief,
`more uniform crimping and stent protection.
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`the moving and guiding
`In a preferred embodiment,
`mechanism of the present invention includes a drive shaft
`and knob unit to which one end of the wrapping member is
`secured, and the wrapping member moves over a pair of
`closely spaced pinch rollers generally adjacent and parallel
`to the sheath and offset from and generally parallel to the
`feed axis. In operation, the user rotates the knob which pulls
`the wrapping member through a guided pathway in order to
`exert the cylindrical compressive force on the sheath and
`thus on the stent
`therewithin. This pathway includes a
`compression site or compressive loop by which the wrap-
`ping member rides over one of the pinch rollers, then the
`sheath, and then the other of the pinch rollers so as to pass
`over the sheath and between the pinch rollers. Because the
`pinch rollers are stationary in the sense that each remains at
`its designated location within the device,
`tension in the
`wrapping member, which exerts a cylindrically compressive
`force on the sheath, collapses the sheath and the stent within
`it. In a typical arrangement, development of this tension is
`enhanced by a drag-imparting means which engages the
`wrapping member or belt at a location downstream of the
`pinch rollers, which is opposite to the drive shaft and knob
`unit along the wrapping member.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective view of a preferred hand-held stent
`crimper according to the invention;
`FIG. 2 is a cut-away perspective view of the device
`illustrated in FIG. 1 and from which a housing component
`of the outer sleeve has been removed;
`FIG. 3 is an exploded perspective view of the stent
`crimper illustrated in FIG. 1;
`FIG. 4 is a cross-sectional view along the line 4—4 of
`FIG. 1;
`FIG. 5 is a detail, cross-sectional view taken from FIG. 4
`which illustrates this portion of the device prior to crimping;
`FIG. 6 is a detail, cross-sectional view corresponding to
`FIG. 5, shown after crimping has taken place;
`FIG. 7 is a perspective, cut-away view of an alternative
`embodiment of a gripping assembly at the catheter-insertion
`end of the device;
`FIG. 8 is a cross-sectional view along the line 8—8 of
`FIG. 7;
`FIG. 9 is an exploded perspective view illustrating an
`anti-reversing feature;
`FIG. 10 is a perspective, cut-away view of a further
`embodiment of another catheter gripping assembly;
`FIG. 11 is an end view of the embodiment of FIG. 10,
`shown in its gripping orientation;
`FIG. 12 is a cross-sectional view along the line 12—12 of
`FIG. 11; and
`FIG. 13 is a view similar to FIG. 12 and illustrates the
`
`non-gripping orientation of this embodiment.
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`A crimper, generally designated at 21 in FIG. 1, includes
`an outer case 22 having a longitudinal feed axis 23 entering
`same as indicated. On an external level, crimping is accom-
`plished by inserting a catheter 24 (FIG. 3) into the crimper
`21 along the longitudinal feed axis 23 to a desired extent, as
`discussed more fully herein, followed by unidirectional
`rotation of a crimper knob 25. Crimping completion is
`indicated when the tension which develops during rotation
`of the crimper knob ceases.
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`5,836,952
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`5
`With more particular reference to the internal operational
`details of the crimper illustrated in FIG. 1 through FIG. 6, an
`important operational component in this regard is the elon-
`gated wrapping member or belt 26. It is operated by means
`of a moving and guiding assembly which includes the
`crimper knob 25. The crimper knob is an extension of a drive
`shaft 27 which can conveniently be rotatably mounted
`between a base member 28 and a cap member 29, for
`example through openings 31, 32, respectively. It will be
`appreciated that the drive shaft 27 will rotate when the user
`rotates the crimper knob or drive wheel 25, the drive shaft
`rotating within the openings 31 and 32.
`Afurther component of the moving and guiding assembly
`is the pair of closely spaced rollers 33 and 34, which operate
`in the nature of pinch rollers as described in greater detail
`herein. Pinch rollers 33 and 34 are mounted in a stationary
`manner by which each remains at its respective designated
`location within the device. Such stationary mounting allows
`for rotation of the pinch rollers 33 and 34, such as within the
`mounting ferrules 35 and 36. As evident from FIG. 4, the
`elongated wrapping member or belt 26 affixes to the drive
`shaft 27 and is threaded over the pinch rollers 33 and 34,
`forming a looped path portion between the closely spaced
`pinch rollers 33 and 34. Thus, when the belt is wrapped
`around the drive shaft 27, such as in the direction of the
`arrow shown in FIG. 4, the belt winds onto the drive shaft
`and is pulled over the pinch rollers 33 and 34 and through
`a looped path portion 37 which generally defines a com-
`pression site or compressive loop.
`It is typically desired to impart extra drag to the belt when
`it is upstream of the pinch roller 34. This ensures that the
`looped path portion 37 will reduce in radial size and thereby
`effect crimping in accordance with the present invention. In
`the illustrated embodiment,
`this drag enhancement
`is
`achieved by a plurality of axles 41, 42 and 43 which are
`generally closely spaced to each other as illustrated. Belt 26
`is fed between these stationary axles in an alternating
`fashion such as that shown in FIG. 4. This threading, in
`combination with the wrapping angles, imparts added fric-
`tion against the belt 26. The resultant added drag nicely
`initiates and carries out the crimping as described herein.
`Furthermore, once the crimping has been completed, which
`means that
`the items being crimped no longer will be
`reduced radially by the action of the belt,
`the belt will
`continue to pass through the looped path portion 37 until the
`free end 38 of the belt clears some or all of the axles or
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`rollers, at which time the crimper knob 25 moves freely,
`approximating a neutral drive condition.
`With more particular reference to the components which
`lie along the longitudinal feed axis 23, a guide member or
`short guidewire 44 lies directly along the feed axis 23. This
`guide member 44 runs substantially the entire length of the
`crimper from the entry end to the base member 28. Sub-
`stantially coaxial with the guide member 44 is a holding
`member or sheath 45. This sheath is externally supported at
`one or both of its ends so as to maintain its general coaxial
`relationship with the longitudinal feed axis 23 and the guide
`member 44. Sheath 45 may, for example, fit within opening
`46 of the cap member 29 and/or a similar opening in the boss
`47 of the base member 28. This holding or mounting of the
`sheath 45 allows for radially inwardly directed movement of
`the sheath in response to forces imparted by the belt 26
`during rotation of the crimper knob 25.
`A stent 48 (FIGS. 5 and 6) is shown located within and
`supported by the holding member or sheath 45. When the
`catheter 24 is inserted into the crimper 21, the orientation is
`such that the illustrated stent 48 overlies a balloon 49 (FIGS.
`
`6
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`3, 5 and 6) of the catheter 24. Also shown in FIGS. 5 and 6
`is a catheter tube 51. It will be noted that the catheter tube
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`generally closely overlies the guide member 44, thereby
`facilitating proper axial placement of the catheter within the
`crimper 21 and coaxial with the feed axis.
`In the illustrated embodiment, the outer case 22 of the
`crimper is composed of two components, a left housing 52
`and right housing 53. It is important that the catheter 24 be
`inserted into the crimper for a proper distance so that the
`balloon 49 is in proper registry with the stent 48 or other
`device. Means for accomplishing this are discussed herein.
`Once the proper positioning is thus achieved, it is useful to
`provide a gripping arrangement in order to hold the catheter
`in place prior to and during the crimping operation that is
`performed by the crimper. The gripping mechanism illus-
`trated in FIG. 3 is substantially that of a generally known
`compression valve, generally designated at 54. This valve
`includes a gripper 55, which is a compressible elongated-
`width washer. A gripper knob 56 engages the gripper 55 and
`applies a squeezing force thereto when the gripper knob is
`screwed on a threaded member 57 of the crimper. Such
`threading causes the internal surface 58 of the gripper 55 to
`move inwardly and thus grip an external portion of the
`catheter 24.
`
`An alternative gripping arrangement is illustrated in FIG.
`7 and FIG. 8. An entry end housing portion 61 incorporates
`a spring clamp member 62 which passes through a slot 63 of
`this housing portion. When the spring clamp member is in its
`raised orientation as shown, an internal gripper portion 64
`will engage and hold a catheter (not shown) which has been
`slid over the guide member 44. When the spring clamp
`member is depressed, such as by pressing on knurled surface
`65, the spring clamp member moves generally downwardly
`in order to remove its grip on the catheter, thereby providing
`for its easy entry and removal as desired. In the illustrated
`example, the spring action is achieved by a living hinge or
`joint 66 by which the spring clamp member 62 is mounted.
`FIGS. 10, 11, 12 and 13 show another gripping arrange-
`ment. This entry end housing portion 81 incorporates a
`slidable clamp member 82 which passes through a slot 83 of
`this housing portion. When the slidable clamp member 82 is
`in its raised orientation as shown in FIGS. 10, 11 and 12, an
`internal gripping opening 84 will engage and hold a catheter
`(not shown) which has been slid over the guide member 44.
`When the slidable clamp member 82 is depressed as shown
`in FIG. 13, such as by pressing on knurled surface 85, the
`slidable clamp member is moved inwardly,
`the internal
`gripping opening 84 moves into general axial alignment
`with orifice 86 of the housing portion 81 in order to relieve
`the gripping action of the opening 84 on the catheter shaft.
`This latter orientation provides for easy entry and removal of
`the catheter from the crimping device. In this embodiment,
`the slidable clamp member 82 is biased in the gripping
`orientation by a finger 86 which is under tension as shown
`in FIG. 13 to return to its orientation shown in FIGS. 10, 11
`and 12.
`
`Whatever gripping assembly is used, the force provided
`by the gripping assembly should not be so tight as to prevent
`catheter rotation when crimping is proceeding. This ensures
`that the catheter will not be subjected to torsion forces that
`could twist it along its length and thus potentially deform or
`damage the catheter.
`Discussing now the alignment approaches which can be
`used in order to ensure proper placement of the stent onto the
`balloon of the catheter, the diameter and length of the stent
`48 contained within the crimper 21 may be marked on the
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`5,836,952
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`7
`device itself, the packaging or wrapping for the device, or on
`both. Additionally or alternatively, the outer case 22 could
`include external markings, for example arrowheads 71, to
`indicate the position of the stent with respect to the crimper
`21. One manner of using these markings is as follows. The
`user positions the balloon of the catheter on the external
`surface of the outer case 22 such that the balloon is centered
`with respect to the arrowheads 71. Then, note is made of the
`location at which the shaft of the catheter lines up with entry
`edge 72 of the crimper. In this manner, the user determines
`how far the catheter must be inserted into the crimper in
`order for the balloon to be properly positioned within the
`stent, and the user then inserts the catheter for that distance.
`The catheter is then held in place by a suitable gripping
`arrangement as previously discussed.
`A variation on this positioning approach is to provide a
`guide slot 73 (FIG. 2), which is an added element
`to
`facilitate determining the depth to which the catheter must
`be inserted into the device in order to properly position the
`balloon with respect to the stent. Markings 74 within this
`guide slot designate the location of the stent. In a manner
`somewhat similar to use of the arrowheads 71, the user will
`position the catheter such that
`its balloon is generally
`centered with respect to these markings 74, and appropriate
`steps will be taken to note the location on the catheter shaft
`which lines up with the entry edge 72 of the crimper.
`When the catheters are of a known type, such as those
`having a marker band at a particular location on the catheter,
`this marker band can be positioned so that same is flush with
`the entry edge 72, for example, of the crimper. When these
`features are present, the balloon and stent will be properly
`aligned by simply inserting the catheter as far as possible
`into the crimper.
`With respect to materials out of which various compo-
`nents can be made, preferably the materials will be relatively
`inexpensive and safely disposable. Materials of particular
`interest are those out of which the elongated wrapping
`member or belt 26 and the stent holding member or sheath
`45 are made. It is generally preferred that the sleeve be
`somewhat softer than the belt. Sleeve and belt typically will
`be of approximately the same thickness, generally between
`about 0.002 inch and about 0.005 inch (from about 0.05 mm
`to about 0.13 mm). Materials used for the belt and the sheath
`should be biocompatible and sterilizable. An especially
`suitable belt material has been found to be polyethylene
`terephthalate. While the sheath may be made of any such
`suitable material,
`including various polymers and
`composites, shrink tubings having been found to be espe-
`cially suitable. A useful material in this regard is polytet-
`rafluoroethylene. This particular material provides stress and
`strain relief so that
`the stent will not be damaged. For
`example, after crimping, witness marks corresponding to the
`shape of the stent are visible on the sheath. Such sheath
`tubing will wrinkle or buckle or crumple when crimping is
`carried out, and it is soft enough so that it will not damage
`the stent within which it
`is in engagement during the
`crimping operation. Generally, the sheath tubing material
`will be more compliant than the belt material. The body or
`housing of the crimper is typically made of a polymer.
`When, for example, the stent or the like is radioactive, a
`more protective material, such as lead or a leaded material
`can be used.
`
`Concerning the length of the holding member or sheath 45
`and the width of the elongated wrapping member or belt 26,
`both should be longer than the length of the stent 48. For
`example, at a minimum, the belt should extend longer than
`the stent on both ends, such as by at least two or three
`
`8
`millimeters at each end. This helps to assure uniform appli-
`cation of cylindrical forces along the entire length of the
`stent. Generally the belt width will be at least as great,
`preferably greater.
`The crimping action in accordance with the present inven-
`tion transforms a torsional load generated by digital twisting
`action by the user into a uniformly radially compressive
`force which is applied to substantially the entirety of the
`outer surface of the stent. This is illustrated in FIG. 5 and
`
`FIG. 6. When the user rotates the crimper knob 25, the belt
`26 moves in the direction of the arrowhead of FIG. 5.
`
`Because of the drag along the trailing or downstream portion
`of the belt, tension, is developed along the belt. That tension
`is present along the looped path portion 37 of the belt. This
`exerts a force on the sheath 45 in a direction that is generally
`radial and toward the longitudinal feed axis 23. The illus-
`trated stent 45 includes a plurality of open areas 50. It will
`be appreciated that, in this type of stent, these open areas
`will open even wider during deployment of the stent within
`the body vessel. In addition, they will generally close up
`during crimping. This closed-up condition of the stent 48 is
`illustrated in FIG. 6. It will also be noted that, in FIG. 6, the
`circumference of the sheath 45 has been reduced. Also
`reduced has been the outer circumference of the balloon 49
`of the catheter.
`
`As noted above, the crimper knob 25 and belt 26 move in
`the direction of the arrowhead of FIG. 5. Preferably, mem-
`bers are provided to prevent rotation in the opposite direc-
`tion. Such an arrangement is shown in FIG. 9. Base member
`28 includes a plurality of clutch teeth 76. Knob 25 incor-
`porates clutch springs 77 which deflect as the knob is rotated
`and the clutch teeth alternatively engage and disengage
`when the knob is rotated in the designated direction. A
`“clicking” action and sound will be apparent. Ramps 78 are
`provided to permit knob rotation in only this one direction.
`Attempted rotation in the opposite direction will be pre-
`vented by engagement between the unramped ends 79
`engaging an opposing face of one or more of the base
`member clutch teeth 76.
`
`In the preferred operation of the crimper, the stent and the
`balloon generally rotate with the belt as it rides over them
`through the sheath. All spin in the same angular direction.
`This allows the balloon of the catheter to be folded over
`
`while the stent is being compressed and plasticly deformed
`onto the balloon. This provides a desirable folding of the
`balloon onto the catheter. Such is desirable because it
`
`achieves a more controlled opening of the balloon and the
`stent during deployment
`in vivo in the body vessel. In
`addition, the profile or outer diameter of the system com-
`prising the stent and the balloon is reduced. The invention
`achieves a particularly uniform roll-up of the balloon and
`stent combination.
`
`thus applies the
`the belt
`It will be appreciated that
`inwardly radially directed force on a large circumferential
`(and cylindrical) portion of the stent surface. It will further
`be appreciated that this belt arrangement can accommodate
`catheters, stents and sheaths which have a variety of sizes
`both before and after crimping. It is particularly to be noted
`that the belting arrangement has virtually no lower stent
`circumference limit inasmuch as the closure effect generated
`by this approach is limited only by the thickness of the
`assembly being crimped.
`In connection with method and procedure aspects of the
`invention, the following is a preferred manner of assembling
`the stent into the sheath 45. First, the stent 48 is pre-crimped
`onto a mandrel. Then, the sheath is positioned over it, care
`
`5
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`10
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`15
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`20
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`25
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`30
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`35
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`45
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`5,836,952
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`9
`being taken to ensure that the sheath extends beyond this
`stent on both ends. The sizing is such that the outside surface
`of the stent engages the inside surface of the sheath. Then the
`mandrel is removed. The result is along the lines of a stent
`within a straw. This assembly is then ready to be positioned
`within the case 22 of the crimper as previously discussed.
`Most notably, the leading end portion of this stent and sheath
`assembly can be inserted within an appropriate cylindrical
`opening of the base member 28. In this way, the stent and
`sheath assembly is supported externally, and the stent is
`positioned longitudinally in order to coincide with a prede-
`termined position, such as between the arrowheads 71 or the
`markings 74. It is also desired that the sheath be secured at
`the cap member 29 so that it will remain within the case 22
`of the crimper after crimping is completed and when the
`catheter is removed from the crimper. In this way, the stent
`which has been crimped onto the balloon of the catheter
`slides right out of the thus held sheath after crimping has
`been completed.
`The crimper allows the physician to crimp the stent
`therewithin onto an appropriate angioplasty balloon catheter
`as selected by the physician. This is done through very
`simple operations and without jeopardizing the safety or
`effectiveness of the crimper. It will be understood that the
`crimping onto the balloon is by compressing the stent at a
`theoretically infinite number of contact points with a uni-
`form radial force by rotating the stent and the catheter
`balloon with the belt looped around the sheath and stationary
`rollers.
`
`In use, the appropriate guide means located on the outside
`of the crimper, such as within a designated slot therefor, is
`utilized to determine the depth of penetration of the catheter
`into the device which is required to center the balloon within
`and with respect to the stent. Next, without applying the grip
`pressure afforded by the gripping mechanism, such as by
`depressing the spring clamp member 62, or the slidable
`clamp member 82,
`the angioplasty balloon catheter is
`inserted to the required depth. This insertion is by passing
`the internal lumen of the catheter over the guide member 44,
`which typically will have a diameter of between about 0.010
`and about 0.035 inch (about 0.25 mm to about 0.9 mm).
`Then, the gripping mechanism is activated, by either releas-
`ing the spring clamp member 62 or the slidable clamp
`member 82 or by threading the gripper knob 56. This locks
`the angioplasty balloon catheter in place within the stent that
`is within the crimper.
`While grasping the outer case 22 of the crimper,