United States Patent [19]
`Penner et al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,725,519
`Mar. 10, 1998
`
`[541 STENT LOADING DEVICE FOR A BALLOON Primary Examiner—Glenn K. Dawson
`CATHETER
`Attorney, Agent, or Firm-Levisohn. Lerner. Berger &
`Langsam
`
`[75] Inventors: Abraham Penner. Tel-Aviv; Ofer
`Nativ. Rishon Lezion. both of Israel
`
`[73] Assign?c: Medtronic Instent Israel Ltd" Helen‘
`Israel
`
`[21] APPl- N05 724,543
`-
`.
`Sep' 30’ 1996
`[22] Filed‘
`[51] Int. Cl.6 ................................................... .. A61B 19/00
`[52] us. Cl.
`................................... .. 606/1; 606/198
`[58] Field of Search .......................... .. 606/1. 108. 190.2;
`29/234_ 235_ 232_ 233
`
`[56]
`
`References Cited
`
`Us‘ PATENF DOCUMENTS
`8/1995 Williams et a], ......................... .. 606/1
`5,437,033
`5/1997 Cottone .......... ..
`606/108
`5,626,604
`5,628,754 5/1997 Shevlin et a1.
`606/108
`5,630,830 5/1997 Verbeek ................................ .. 606/108
`
`24
`
`ABSTRACT
`[57]
`A device for loading a medical stent on a balloon catheter.
`Atube. preferable pre-installed with a stent. is secured to one
`component having a pulling knob. The tube with stent
`extends into the bore of a second component. also having a
`pulling lmob. The bore of the second component is conical
`and reduces down in the direction of the ?rst component. For
`intended use. the preselected balloon catheter is inserted
`within the con?nes of the lumen of the tube (which places
`it within the center of the stent) Then. the two knobs are
`Pulled apart The force of the Pull causes the tube with the
`stent around the catheter within it. to pass through the
`decreasing bore. thereby loading and compressing the stent
`onto the balloon catheter. The tube serves as the vehicle to
`carry the balloon catheter and stent through the bore for
`loading the stent onto the balloon catheter. The tube can be
`T??o? coated to facilitate thc Pulling and stent loading 0r
`alternatively‘ the tube can be elastic and/or plastic.
`
`21 Claims, 6 Drawing Sheets
`
`Page 1 of 12
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`

`

`US. Patent
`US. Patent
`
`Mar. 10, 1998
`Mar. 10, 1998
`
`Sheet 1 of 6
`Sheet 1 of 6
`
`5,725,519
`5,725,519
`
`FIG.1
`
`FIG. 1
`
`Page 2 of 12
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`Page 2 of 12
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`

`

`US. Patent
`US. Patent
`
`Mar. 10, 1998
`Mar. 10, 1998
`
`Sheet 2 of 6
`Sheet 2 0f 6
`
`5,725,519
`5,725,519
`
`FIG.2
`
`FIG. 2
`
`Ua
`
`:
`
`Page 3 of 12
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`Page 3 of 12
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`

`

`US. Patent
`US. Patent
`
`Mar. 10, 1998
`Mar. 10, 1998
`
`Sheet 3 of 6
`Sheet 3 of 6
`
`5,725,519
`5,725,519
`
`E
`
`
`
`m.9“.
`
`Page 4 of 12
`
`Ivil
`
`
`
` 5‘';l
`I;
`
`
`
`(If
`
`I’ll/‘IHWJInlllllIll/Iv
`
`
`E!|h.mlhmhuflhlllll/{LIIJ
`
` )4
`
`Page 4 of 12
`
`
`
`

`

`US. Patent
`US. Patent
`
`Mar. 10, 1998
`Mar. 10, 1998
`
`Sheet 4 of 6
`Sheet 4 0f 6
`
`5,725,519
`5,725,519
`
`FIG.4
`
`FIG. 4
`
`Page 5 of 12
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`Page 5 of 12
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`

`

`US. Patent
`U.S. Patent
`
`Mar. 10, 1998
`Mar. 10, 1998
`
`Sheet 5 of 6
`Sheet 5 of 6
`
`5,725,519
`5,725,519
`
`FIG.5
`
`FIG. 5
`
`Page 6 of 12
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`Page 6 of 12
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`

`

`US. Patent
`US. Patent
`
`Mar. 10, 1998
`Mar. 10, 1998
`
`Sheet 6 of 6
`Sheet 6 of 6
`
`5,725,519
`5,725,519
`
`FIG.7B
`
`Page 7 of 12
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`Page 7 of 12
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`

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`5,725,519
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`1
`STENT LOADING DEVICE FOR A BALLOON
`CATHETER
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to a device for loading a
`medical stent on a balloon catheter for use in a medical
`procedure. Stents are currently a very acceptable mechanism
`for treating a variety of medical conditions. but. in general.
`they are used at the site of a collapsed blood vessel to reopen
`the same and thereby permit normal blood ?ow. One current
`method of ?rst locating and then releasing the stent at the
`site of need is by use of a balloon catheter which is threaded
`with the stent to the site. Then. the physician releases the
`stent from the catheter (by a mechanical release mechanism
`or by in?ation of the balloon). in?ates the balloon for stent
`deployment and the stent expands. The present invention
`relates to a device which enables the physician to load and
`secure the stent to the end of the balloon catheter with
`uniformity of application force. geometry. and ease. Use of
`the device allows the physician to locate the stent on the
`balloon catheter in an easily repeatable. structurally secure.
`tight and uniform manner. The device of the present inven
`tion results in the uniform crimping of the stent on the end
`of the balloon catheter. The device maintains the balloon’s
`integrity. ensures that the stent is positively located at the
`desired position on the end of the balloon catheter and with
`the proper amount of holding force so that the stent will
`travel along with the catheter to the site of deployment and.
`yet. when and where so located. the stent can be easily
`released and in?ated for its intended purpose. The device of
`the present invention reduces human errors and vagaries in
`the conventions human-hand crimping procedure.
`According to the present invention. the loading of the
`stent onto the balloon catheter occurs by applying a uniform
`radially inward force on the stent which causes it to become
`crimped onto the distal end of the balloon catheter. The stent
`is loaded or secured to the catheter by use of a tube. The user
`pulls the catheter and stent. in the tube. through a conical
`ori?ce. In this manner the stent is uniformly. radially com
`pressed around the catheter as it passes through the ori?ce.
`The cone-like or radial decreasing diameter of the ori?ce
`applies the radially compressive force to the stent. resulting
`in the stent becoming crimped onto the catheter.
`
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`DESCRIPTION OF THE PRIOR ART
`The stent loading device of the present invention is related
`to the medical products ?eld. Stents are currently used by
`physicians for the treatment of atherosclerotic stenones in
`blood vessels. In such a treatment procedure. a catheter is
`?rst introduced into the patient’s blood vessel. Through this
`catheter. a guide wire is inserted for opening of the lesion.
`This is followed by a balloon catheter being inserted to the
`lesion region. The balloon end of the catheter is then in?ated
`to increase the opening in the blood vessel's lumen. To
`maintain the opening in the lumen of the blood vessel. a stent
`is then inserted at the site. The stent is intended to keep the
`blood vessel open and to decrease the possibility of rest‘
`enosis.
`The stent is an intravascular prosthesis which is usually
`delivered to the lesion zone by attaching it to the tip of a
`balloon catheter. Prior to threading of the stent and balloon
`catheter through the blood vessel. followed by location of
`the balloon catheter and stent at the site. the stent is ?rst
`“loaded” or secured to the end of the balloon catheter. The
`balloon catheter serves as the mechanism for locating the
`stent at the site of the lesion and. in addition. the balloon
`
`2
`catheter serves as the mechanism for deployment. i.e..
`activation of the stent. More speci?cally. the stent is neces
`sarily of reduced diameter while being threaded through the
`blood vessels of the patient until it reaches the site of
`deployment. After location is con?rmed at the site of the
`lesion. the balloon catheter is in?ated and the stent is
`released for residing at the site. In?ation of the balloon
`catheter causes the reduced diameter stent to revert or
`convert to a stent of relative increased diameter according to
`the balloon diameter and degree of in?ation provided The
`outside of the stent pushes against the inside wall of the
`otherwise collapsed blood vessel and. in this manner. the
`stent serves to maintain the lumen in a more open condition
`to allow for blood ?ow. The in?ation of the balloon catheter
`causes the stent to expand to its open or enlarged condition!
`form. while pushing against the vessel wall and strengthen
`ing it. The balloon catheter is then de?ated and removed
`from within the center of the stent. leaving the stent in place.
`The balloon catheter is then removed from the patient
`Today. there are several ways for loading or securing the
`stent on the end of the balloon catheter. The most common
`is by hand-crimping of the stent. The physician ?rst selects
`the particular stent for use in the patient (taking into con
`sideration diameter. length. and intended location). The
`physician also selects the desired and appropriate balloon
`catheter. conventionally. the physician has manually
`crimped the stent to the end of the catheter and over the
`balloon tip by using his ?ngers. The result then is a crimped
`stent. surrounding the balloon end of the catheter. The
`manual manner of crimping. however. results in loaded
`stents. even with the same physician. which will vary in their
`uniformity. loading quality. and geometry. from loaded stent
`to stent. The holding force. reduced diameter. and uniformity
`of pro?le varies then. from stent crimp to stent crimp. Large
`variations exist. too. from one physician to another.
`There is a need. therefore. for a mechanism which will
`facilitate the crimping and loading of a stent on a balloon
`catheter. The device should result in a stent loaded on the
`end of a balloon catheter which is uniform in its size.
`diameter. pro?le. strength of securement. etc. The present
`invention accomplishes these objectives.
`In the current marketplace. i.e.. before the present
`invention. there are several stent crimping devices.
`Basically. these are modi?ed pliers. The instruments are not
`completely satisfactory in that there is still a wide diver
`gence between application force. pro?le and stent diameter
`from stent application to another. even with the same phy
`sician doing the loading. Another device that was available
`before the present invention is a pre-crimped stent on a
`balloon catheter. This pre-loaded device has uniformity of
`securement of the stent to the balloon catheter but is prob
`lematic because of the large number of possible combina
`tions between stents and balloon catheters. Each stent type.
`diameter. length. and anatomic location would have to be
`pre-loaded and available for each of the various balloon
`catheters. Obviously. this is a potentially large inventory for
`a physician to store.
`Thus. standardized crimping of stents on balloon catheters
`exists and yet. the physician would be required to warehouse
`a wide variety of pre-crimped stents on catheters. Clearly. it
`is far preferable for the physician to be provided with a
`device which will allow the physician to select the balloon
`catheter appropriate for the patient. then. separately. select
`the stent for the patient. and then. using the present
`invention. allow the physician to uniformly and securely
`crimp that stent on the selected catheter.
`SUMMARY OF THE PRESENT INVENTION
`The present invention is a simple mechanical device
`which allows a physician to load. i.e.. position and crimp a
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`5.725.519
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`3
`stent onto a balloon catheter. The proposed device is a
`mechanical implement which is manipulated by hand for
`loading the stent on the distal end of a balloon catheter. A
`?rst embodiment of the present invention contemplates the
`provision of a stent located or pre-installed within a plastic
`(such as Te?on) tube. Thus. consistent with the present
`invention. the stents are stored for future selection by the
`physician within the bore of a tube. the tube being held by
`one end of a separable pair of opposed gripping knobs. The
`physician will insert the desired balloon catheter into the
`open end of the device. The device can be provided with a
`wire which can be threaded down the longitudinal axis of the
`catheter to ensure that the lumen of the catheter is protected
`from collapsing during the procedure. With the balloon
`catheter located within the stent. with the stent located
`within the tube. the two knobs of the device are slowly
`pulled apart. This draws the tube (connected securely to the
`distal knob) through a reduced or conical bored section. As
`the knobs are pulled apart. the tube is uniformly reduced in
`diameter by it coming into contact with the reduced diameter
`side walls of the bore of the proximal component of the
`device. As this happens. the tube pulls the stent and balloon
`catheter along with it. This. in turn. causes the stent. con
`tained within the tube to reduce in diameter and become
`secured to the balloon catheter. The thin guide wire passing
`down the longitudinal axis of the device. ensures that the
`lumen of the catheter does not collapse or become damaged
`during the process. Then. after the proximal end of the tube
`is fully passed through the reduced diameter bore of the
`proximal component of the device. the catheter. with the
`stent secured thereto. can be easily removed ?rst from the
`tube and then threaded back through the distal end of the
`proximal component of the device. A uniformly loaded stent
`on a balloon catheter is the result. In one embodiment of the
`invention. the bore of the proximal component of the device
`is provided with a reverse or inverted conical bore portion.
`to facilitate the reverse passage of the balloon with loaded
`stent through the device.
`To summarize. then. the present invention is the provision
`of a plastic hand-held device having. in the preferred
`embodiment. a stent pre-loaded within a tube. This elimi
`nates the physician holding by hand the small and fragile
`stent. Actually. the stent is housed within a plastic or
`Te?on-coated tube (to ease passage through the bore) which
`itself is initially within the bore of a proximal component of
`the device. The other end of the tube is secured to the distal
`component. Both the proximal and the distal components of
`the device are provided with drawing knobs to facilitate
`pulling the components apart. Before pulling on the knobs.
`the selected catheter is threaded into the proximal
`component. such that its balloon end is within the center of
`the stent. The transparency of the device allows the physi
`cian to visually ensure proper location. Then. when so
`located. the knobs are pulled apart such that the distal
`component. securing one end of the tube (the other end
`extending into the bore of the proximal component and
`housing the stent. encircling the balloon tip of the catheter)
`is separated from the proximal component. Pulling the two
`components apart causes the tube. attached to the distal
`component. to pass through a cone-shaped bore of the
`proximal component. This reduces the diameter of the tube.
`which. in turn. by transfer of the compressive force. reduces
`the diameter of the stent. thereby collapsing and securing it
`around the balloon catheter. In this manner. the device
`operates in a fashion similar to metal rod swaging through
`a die. Since there is no relative movement between the stent.
`the balloon catheter and the plastic tube. the stent and
`
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`4
`balloon are pulled through the reducing bore of the proximal
`component. The reducing bore of the proximal component
`causes a uniform radially inward force to compress the stent
`onto the balloon tip. In this manner. the stent is crimped onto
`the balloon.
`After the two components are fully separated. the balloon
`catheter. with stent secured to its tip. is ?rst removed from
`the tube. Then. the balloon catheter and stent are removed
`from the proximal component. This is accomplished.
`according to the preferred embodiment. by reverse passing
`of the tip of the balloon catheter through the proximal
`component. This movement is facilitated by the provision of
`an inverted cone shaped bore-portion of the reducing bore of
`the proximal component. This facilitates the removal of the
`balloon catheter and stent from the bore of the device.
`The mechanism and procedure results in a uniform.
`repeatable and tight loading of the stent that substantially
`preserves the stent’s original con?guration. albeit in a
`reduced diameter. By utilization of the stent loading device.
`the physician can select the appropriate balloon catheter for
`the speci?c patient and treatment. without the need to
`manually hold a large inventory of possible pro-loaded
`combinations of stents and balloon catheters. As mentioned.
`in the preferred embodiment. the stent is pre-installed in the
`stent loading device. within the plastic tube. This eliminates
`the need to hold the small and fragile stent.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a perspective view of the preferred embodiment
`of the invention. showing the stent loading device before it
`has been used. In this embodiment. the stent is pro-installed
`within a Te?on-coated or other plastic-like tube. A metal
`wire is provided. passing through the longitudinal center of
`the tube and the stent. This FIGURE shows the device before
`the insertion of a balloon catheter. upon which the stent is
`intended to be loaded.
`FIG. 2 is another perspective view of the present
`invention. after the balloon catheter has been inserted such
`that its balloon tip is located within the stent (pre-installed
`in the plastic tube). The device is shown just before the two
`components. the proximal and the distal components. are to
`be pulled apart for stent loading. The physician’s hands are
`visible as they would be in contact with the knobs of the two
`components. The metal wire is shown threaded down the
`axis of the balloon catheter and proteds against the collapse
`of the lumen of the balloon catheter during stent loading.
`FIG. 3 is a reduced. cross-sectional view of the device.
`shown at the middle of the stent loading or mid-crimping
`stage.
`FIG. 4 is another perspective view of the device. after the
`proximal and distal components have been pulled apart. This
`FIGURE shows the relative location of the plastic coated or
`Te?on tube after the proximal and distal components have
`been separated. The metal wire. extending through the
`reducing-diameter bore or ori?ce of the proximal component
`is also shown. The stent and balloon catheter have been
`pulled through the bore of the proximal component by the
`gripping action of the Te?on or plastic tube as it passes
`through the bore.
`FIG. 5 is a perspective. explosed view of both the proxi
`mal (bottom-most) and distal (top-most) components. after
`the stent and balloon catheter have passed through the
`diameter-reducing bore or ori?ce of the proximal compo
`nent. As can be seen. the stent is now crimped or loaded onto
`the balloon tip of the catheter. The distal component with the
`attached tube and the metal wire have been removed from
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`the balloon catheter and stent. thereby exposing the stent and
`the balloon tip. The FIGURE shows the loaded stent on the
`balloon catheter after the Te?on tube and the metal wire
`have been pulled through the bore.
`FIG. 6 is a side elevational view of the crimped stent on
`the balloon catheter. after it has been pulled backwardly
`through the reducing-diameter bore or ori?ce. thereby
`removing the proximal component of the crimping or load
`ing device from the stent-loaded catheter.
`FIG. 7 is a perspective view. similar to FIG. 1. showing
`an alternate embodiment of the plastic/Te?on tube.
`DETAILED DESCRIPTION OF THE FIGURES
`AND THE PREFERRED EMBODIlvIENT
`The stent loading device 10 is shown in FIG. 1. It
`represents the preferred embodiment of the present inven
`tion. In this con?guration. the stent 12 is supplied as a
`pre-installed component. Providing the stent 12 as a pre
`installed component eliminates the need for the physician to
`manually touch the stent during the loading procedure. This
`is desirable since the stent is small and fragile. Pre-installing
`the stent 12 reduces the possibility of dropping or inappro
`priately handling the stent before the medical insertion
`procedure. The device 10 is preferably made from a clear.
`rigid plastic so that the physician can see the location of the
`pre-installed stent 12. prior to the insertion of the balloon
`catheter. and during the stent loading procedure. The device
`10 comprises a proximal component 14 and a distal com
`ponent 16. Proximal component 14 has a reducing-diameter
`bore or ori?ce 20 passing through and along the longitudinal
`axis of the proximal component. The ori?ce 20 extends from
`the proximal end 22 of the knob 24 to the distal end 26 of
`the proximal component 14. The ori?ce. in the preferred
`embodiment. comprises a uniform. relatively large diameter
`section. commencing at the proximal end 22 of the knob 24.
`and necks down into a conical portion 30 which terminates
`at the distal end 26 of the proximal component. The diameter
`of the ori?ce at the proximal end. adjacent the knob 24. is
`suf?ciently large such that a balloon catheter BC can be
`easily inserted and threaded therein. The diameter of the
`ori?ce 20 at the distal end 26 of the proximal component 14
`is signi?cantly smaller than the diameter of the ori?ce 20 at
`the proximal end 22. and yet allows the tube and central wire
`(described hereinafter). the balloon catheter BC and the stent
`12 to pass therethrough. albeit with a manual pulling force
`since the inside wall of the conical portion 30 swages i.e..
`reduces in diameter. the stent 12. onto the tip of the balloon
`catheter BC. The diameter of the stent 12 is reduced and
`secured to the tip of the balloon catheter BC as the tube.
`wire. stent 12 and balloon catheter BC are pulled through the
`ori?ce 20. The transfer of the pulling force into a radial
`compressive force is facilitated by the relative low frictional
`resistance provided by the tube 64.
`In the preferred embodiment of the present invention. the
`proximal component 14 is molded from a single piece of
`clear. rigid plastic and the knob 24 has a smooth curved
`outer wall which gently merges into the cylindrical outer
`wall 32. A ?at. circular end 34 is provided at the proximal
`end 22 of the proximal component 14. de?ning one end of
`the knob 24. and a ?at. circular end 36. of smaller relative
`diameter to that of ?at end 34. is located at the distal end 26
`of the proximal component 14. In the preferred embodiment
`of the present invention. the ori?ce 20 also includes a
`downstream. reduced and uniform diameter section 40.
`extending between the conical portion 30 and the ?at end 36.
`In the preferred embodiment of the present invention. a
`portion of the downstream. reduced and uniform diameter
`
`6
`section 40. adjacent to the ?at end 36. is an inverted conical
`section 42 (see FIG. 3). with its wider mouth being located
`at the ?at end 36 and its smaller opening upstream. i.e.. more
`proxirnally located. This. as will be more fully explained
`hereinafter. facilitates the easy and uneventful removal of
`the proximal component from the balloon catheter with
`loaded stent.
`The distal component 16 is also made from rigid. trans
`parent plastic and comprises a knob 50 extending and
`gradually merging into a cylindrical portion 52. One end 54
`(the distal end) of the distal component 16 constitutes a flat.
`circular disk 56. which de?nes the end of the knob 50. The
`other or proximal end 58 of the distal component 16. i.e.. the
`end which opposes and mates with the distal end 26 or the
`?at end 36 of the proximal component 14. is also a ?at disk
`60 of relative reduced diameter in comparison to the diam
`eter of the disk 56. The diameter of disk 56 of the distal
`component 16 is about the same as that of the ?at. circular
`end 34 of proximal component 14. Similarly. the ?at end 36
`of proximal component 14 is about the same size as the ?at
`end 58 of distal component 16. Extending between disk 56.
`at the distal end 54 of the distal component 16 and the disk
`60 of proximal end 58 of the distal component is a constant
`diameter bore 62. A Te?on coated or plastic tube 64 is
`secured within bore 62 and extends beyond the proximal end
`58 of the distal component. The tube 64 extends into the
`ori?ce 20 of the proximal component 14. at least before
`pulling the components apart for stent loading. According to
`the preferred embodiment of the invention. the tube 64
`extends beyond ?at end 34 of the proximal component 14
`(see FIG. 1). The Teflon-coated tube is squeezable. i.e.. it
`will reduce in diameter as it passes through the small
`diameter of conical portion 30. In its original shape. tube 64
`is of a constant diameter throughout the bore 62 of the distal
`component 16. Originally. i.e.. before the two knobs are
`pulled apart. the end of the tube 64 which extends into the
`ori?ce 20 is of a larger diameter. In the preferred embodi
`ment of the present invention. the tube 64 extends upstream
`and beyond the knob 24 of the proximal component (see
`FIG. 1 ). at least it extends there when the proximal end 58
`of the distal component is closely adjacent and ?ush with the
`distal end 26 of the proximal component 14. In the preferred
`embodiment of the invention. the tube 64 is of a larger
`relative diameter for that portion originally located within
`the ori?ce yet upstream. i.e.. proximally. of the conical
`portion 30 of the ori?ce 20. A smooth walled neck portion
`66 connects the enlarged diameter portion 68 of the tube 64
`(within the ori?ce 20) to the reduced diameter portion 70 of
`tube 64. located at or about the upstream end of the conical
`portion 30 of ori?ce 20. The outside diameter of the reduced
`diameter portion 70 is about that of the inside diameter of the
`bore 62 so that a snug ?t is achieved. Pulling on the distal
`component 16. pulls the tube 64 along with it. In one
`embodiment. a commercial adhesive or bonding can be used
`to ensure a tight fit between the tube 64 and the distal
`component 16 so that they move in tandem.
`A wire 80 is also secured to the distal component 16.
`axially located within the bore 62 and the tube 64. The wire
`80 is of relative small diameter and extends from the distal
`component. through the distal end 26 of the proximal
`component. through the reduced diameter section 40 of the
`ori?ce 20. through and beyond the proximal end 22 of the
`proximal component 14. FIG. 1 shows the wire 80 in its
`original position. i.e.. extending out of the tube 64. beyond
`the knob 24 of the proximal component. The wire 80 extends
`beyond the end of the tube 64. The ?xed end of the wire is
`secured to the distal component 16 so that the distal
`component. the wire and the tube all move in unison.
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`7
`The diameter of the ori?ce 20 of the device 10. at the
`distal end 26. is preferably the diameter desired for the stent
`to be crimped and secured to the balloon catheter. The
`diameter is about 0.3 mm less than the sum of the original
`(pre-loaded) outer diameter of the stent 12 and the wall
`thickness of the Te?on tube 64. The decrease in the ori?ce’s
`inner diameter. to the dimension at the location of the distal
`end 26. is at least initially gradual. to minimize the force
`needed for smooth and easy crimping. The Te?on tube 64 is
`preferably 1.7 mm inside diameter. having about a 2.1 mm
`10
`outside diameter. The metal wire 80 is preferably stainless
`steel and is about 0.3 3 mm in diameter. The wire 80 extends
`down the center line of the tube 64. through the ori?ce 20.
`As mentioned. it. too. is secured to the distal component 16.
`The purpose of the wire 80 is to protect the lumen of the
`balloon catheter. as the stent is crimped onto the tip of the
`same. More speci?cally. the wire provides a support surface
`to the interior of the balloon catheter during the crimping of
`the stent to the balloon catheter.
`In operation. a device 10 with the correct size and type
`stent is selected from the physician’s inventory. Then the
`appropriate balloon catheter BC is selected The physician
`then inserts the wire 80 into the lumen of the balloon
`catheter as the tip of the balloon catheter is slid or threaded
`into the tube 64. The balloon catheter is pushed into the tube
`64 until the physician sees that the tip of the balloon catheter
`is slightly beyond the distal end of the pre-installed stent 12.
`Since the device is visually transparent. the physician can
`easily locate the balloon at the desired location relative to the
`stent. This is depicted in FIG. 2.
`The next step is for the physician to start pulling the knob
`24 away and apart from knob 50. thereby separating proxi
`mal component 14 from that of distal component 16. This is
`shown in FIG. 3. Pulling the knobs apart causes the Te?on
`tube 64. connected to distal component 16. to travel along
`the longitudinal axis of the device. i.e.. down the ori?ce 20
`of the proximal component. The balloon catheter BC and the
`stent 12. within the tube 64. similar move through the ori?ce
`20. within the tube 64. since there is no relative movement
`between the elements. The tube 64 grips and carries the
`balloon catheter and stent along with it. through the conical
`portion 30 of ori?ce 20. The gradual decrease in the diameter
`of the ori?ce 20. along conical portion 30. applies a radial
`compressive force on the Te?on tube 64. The Te?on tube 64.
`in turn. transfers this compressive force onto the stent. The
`radial compressive force is uniform and causes the stent to
`reduce in diameter as it passes through the conical portion 32
`of the ori?ce 20. This results in the stent becoming crimped
`onto the balloon catheter. This results in the desired loading
`of the stent 12 onto the balloon catheter BC. Continuing the
`pulling apart of the knobs ultimately results in the tube 64
`clearing out of the distal end 26 of the proximal component.
`This results. of course. in the clearance. too. of the stent 12
`and the tip of the balloon catheter BC beyond the distal end
`26. This is shown in FIG. 4. Here. it can be seen. that the
`stent is loaded onto the tip of the balloon catheter. Next. the
`Te?on tube 64 and the metal wire 80 are pulled 01? of the
`stent and from the balloon catheter. This is done by holding
`the catheter and pulling the distal component 16 with its tube
`64 off of the stent-loaded catheter. The result is shown in
`FIG. 5. The proximal component 14 must then be removed.
`too. This is accomplished by pulling the balloon catheter.
`loaded with the now-compressed stent 12. back through the
`ori?ce 20 of the proximal component. Since the Te?on tube
`64 has already been removed. this step is relatively elfort
`less. An inverted conical section 42 (see FIG. 3). at the distal
`end 26 of the proximal component 14. facilitates the thread
`
`55
`
`65
`
`30
`
`35
`
`45
`
`5.725.519
`
`8
`ing of the stent and tip of the balloon catheter. as the same
`is removed from the proximal component. The inverted
`conical section 42 minimizes the impedance provided to the
`balloon-stent. as they pass back through the ori?ce 20. The
`end product is a crimped stent on the tip of the balloon
`catheter BC. This is shown in FIG. 6.
`Another embodiment of the present invention comprises
`the use of an interchangeable or variable ori?ce so that the
`same loading device 10 may be used for several diiferent
`pro?le/sizelshaped balloons. The ori?ce diameter can be
`changed in many ways. A typical example for performing
`this function would be to use a hole in a cone made of a
`semi-rigid material (such as Te?on or PEEK) as the orifice.
`Then. by pressing the cone against the conic hole with
`angles diiferent from those of the cone. the hole in the cone
`tends to reduce its diameter. The ?nal ori?ce diameter
`depends on the force applied on the cone.
`Yet another embodiment of the present invention includes
`the use of an ori?ce made from a ?exible material. such as
`Nylon. When a low pro?le balloon catheter is used. the force
`applied by the ori?ce and on it is relatively small. However.
`when a high pro?le balloon catheter is to be used. the
`crimping force is necessarily larger. which causes the ori?ce
`to increase its diameter. The result is that such an ori?ce
`applies an almost constant force onto the stent. Such a
`loading device is suitable for a wide variety of balloon
`catheter pro?les.
`Another embodiment of the present invention contem
`plates the use of a constant ori?ce. However. instead of using
`a Te?on-coated tube. a more ?exible tube such as Nylon or
`silicon is used. When pulling the tube. stent and balloon
`catheter. through the ori?ce. the tube elongates according to
`the pro?le of the ori?ce and the impedance provided by the
`ori?ce. When using a low pro?le balloon. the impedance is
`small and the tube wall thickness remains almost
`unchanged. When a high pro?le or diameter balloon catheter
`is to be used. a high impedance on the passage of the tube
`through the ori?ce results. Thus.