Ulllted States Patent
`
`19
`
`11
`
`Patent Number:
`
`5 911 452
`,
`,
`
`
`Yan
`[45] Date of Patent:
`Jun. 15, 1999
`
`U5005911452A
`
`[54] APPARATUS AND METHOD FOR
`MOUNTING A STENT ONTO A CATHETER
`
`EP 0 697 226
`159065
`WO 98/14120
`
`2/1996 European Pat. Off.
`2/1921 United Kingdom ~
`4/1998 WIPO .
`
`.
`
`[75]
`
`Inventor:
`
`John Y. Yan, Sunnyvale, Calif.
`
`WO 98/19633
`
`5/1998 WIPO ~
`
`[73] Assignee: Advanced Cardiovascular Systems,
`Inc., Santa Clara, Calif.
`
`[21] Appl. No.2 08/795,335
`.
`Feb. 4, 1997
`Filed:
`[22]
`Int. Cl.6 .............................. B231) 11/00, B2313 19/04
`[51]
`[52] US. Cl.
`................................. 29/516; 623/1; 606/194;
`606/108; 606/1; 29/282; 425/392
`29/516 407 08
`[58] Field of Search
`29/282, 280, 715, 606/108; 425/318, 391,
`392
`
`56
`
`[
`
`]
`
`C't d
`R f
`l e
`e erences
`U.S. PATENT DOCUMENTS
`
`696,289
`4,468,224
`4,576,142
`4,644,936
`
`.
`.
`3/1902 Williams.
`8/1984 Enzmann et al.
`....................... 604/247
`
`3/1986 Schiff ...............
`128/1
`2/1987 Schiff .......
`128/1
`
`
`-
`7/1987 Cho. et a1~
`476817092
`293319333 13/1333 3°31:
`4’907’336
`41990 Gciarliturci.)"""""""""""""""""""""
`5,132,066
`7/1992 Charlesworth et al
`5,133,732
`7/1992 Wiktor .
`5,183,085
`2/1993 Timmermans .
`5,189,786
`3/1993 Ishikawa et a1.
`5,437,083
`8/1995 Williams et al.
`.................... 29/407.08
`5,546,646
`8/1996 Williams et al.
`5,626,604
`5/1997 Cottone, Jr.
`............................. 606/198
`576307830
`5/1997 Verbeek.
`............................... 604/96
`5,653,691
`8/1997 Rupp et al.
`5738 674
`4/1998 Williams et al.
`606/1
`5,746,764
`5/1998 Green et al
`606/194
`5,783,227
`7/1998 Dunham
`425/318
`5,785,715
`7/1998 Schatz ..................................... 606/108
`FOREIGN PATENT DOCUMENTS
`
`128/1
`32/]
`/
`
`i
`
`.
`
`.
`.
`
`
`
`OTHER PUBLICATIONS
`
`US. Patent Application Serial No. 08/795,335 filed Feb. 4,
`1997~
`U.S. PatentA lication Serial No. 08/837,771 filedA r. 22,
`1997.
`pp
`p
`UHS Patent Application Serial NO 08/089,936 filed Jul. 15,
`1997.
`
`.
`.
`.
`US. Patent Application Serial No. 08/962,632 filed Nov. 3,
`1997'
`The eXTraordinary Stent, C.R. Bard Brochure (Undated).
`
`Primary Examiner—S. Thomas Hughes
`Assistant Examiner—John Preta
`
`Attorney, Agent, or Firm—Fulwider Patton Lee & Utecht,
`LLP
`[57]
`
`ABSTRACT
`
`Asystem for loading a stent onto a catheter is disclosed. The
`system includes a housing having an internal chamber With
`a flexible tube extending therethrough. A stent is positioned
`at about a mid portion of the flexible tube, and the balloon
`portion of the catheter is inserted into the flexible tube and
`positioned Within the stent. Pressurized fluid is injected into
`the internal Chamber thereby circumferentially compressing
`the flexible tube and in turn compressing the stent and
`crimping it onto the balloon portion of the catheter. A
`balloon folding attachment can be mounted onto an end of
`the housing. The inner lumen of the attachment has pro-
`~
`1
`~
`t.
`1 h
`th tf ld th fl
`t
`gresswe y varymg.cross'sec Iona S apes.
`.a 0
`e .a '
`tened balloon portion of the catheter as it is advanced into
`the attachment. The folded balloon portion is continually
`adVaHCCd into the attachment into the flexible tube until it is
`aligned Within the stent.
`
`EP 0 630 623
`
`12/1994 European Pat. Off.
`
`.
`
`17 Claims, 2 Drawing Sheets
`
`76 5A
`
`5B 50
`
`30
`
`
`JE 5F
`
`
`
`
`
`5A
`
`38
`
`30
`
`50
`
`JE 5F
`
`Edwards Lifesciences V. Boston Scientific
`
`IPR2017-00444 EX. 2039
`
`US. Patent No. 6,915,560
`
`Page 1 of 9
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`Page 1 of 9
`
`

`

`US. Patent
`
`Jun.15,1999
`
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`

`US. Patent
`
`Jun.15,1999
`
`Sheetz 0f2
`
`5,911,452
`
`
`
`.48mmQM,mm,mm,inE N6E
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`Page 3 of 9
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`Page 3 of 9
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`

`

`5,911,452
`
`1
`APPARATUS AND METHOD FOR
`MOUNTING A STENT ONTO A CATHETER
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to an apparatus for loading
`a tubular graft, such as a stent, onto a catheter assembly.
`Such a catheter assembly can be, for example, of the kind
`used in typical percutaneous transluminal coronary angio-
`plasty (PTCA) 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 predeter-
`mined 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,
`thereby
`dilating 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 pro-
`cedure is typical, it is not the only method used in angio-
`plasty.
`In angioplasty procedures of the kind referenced above,
`restenosis may occur in the artery, which may require
`another angioplasty procedure, a surgical bypass operation,
`or some other method of repairing or strengthening the area.
`To reduce the likelihood of restenosis and to strengthen the
`area, an intravascular stent is implanted for maintaining
`vascular patency. The stent is typically transported through
`the patient’s vasculature where it has a small delivery
`diameter, and then is expanded to a larger diameter, often by
`the balloon portion of the catheter. The stent also may be of
`the self-expanding type.
`Since the catheter and stent will be traveling 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 of the catheter until it is implanted in the artery.
`In conventional 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 a patient’s vasculature. Non-uniform
`crimping can result in sharp edges being formed along the
`now uneven surface of the crimped stent. Furthermore,
`non-uniform stent crimping may not achieve the desired
`minimal profile for the stent and catheter assembly. Where
`the stent is not reliably crimped onto the catheter, the stent
`may slide off the catheter and into the patient’s vasculature
`prematurely as a loose foreign body, possibly causing blood
`clots in the vasculature, including thrombosis. Thus, it is
`important to ensure the proper crimping of a stent onto a
`catheter in a uniform and reliable manner.
`
`5
`
`10
`
`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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`40
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`45
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`2
`This crimping is often done by hand, which can be
`unsatisfactory due to the uneven application of force, again
`resulting in non-uniform crimps. In addition, it is difficult to
`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 crimping the stent properly.
`Hence, there is a need in the art for a device for reliably
`crimping a stent onto a catheter.
`There have been mechanisms devised for loading a stent
`on to a catheter. For example, US. Pat. No. 5,437,083 to
`Williams et al. discloses a stent-loading mechanism for
`loading a stent onto a balloon delivery catheter of the kind
`typically used in PTCAprocedures. The device comprises an
`arrangement of plates having substantially flat and parallel
`surfaces that move in rectilinear fashion with respect to each
`other. A stent carrying catheter can be crimped between the
`flat surfaces to affix the stent onto the outside of the catheter
`
`by relative motion between the plates. The plates have
`multiple degrees of freedom and may have force-indicating
`transducers to measure and indicate the force applied to the
`catheter during affixation of the stent.
`Williams et al. also discloses a stent-loading device
`comprising an elongated tubular member having an open
`end and a sealed off end. The tubular member houses an
`
`elastic bladder which extends longitudinally along the inside
`of the tubular member. The tubular member and bladder are
`
`designed to hold a stent that is to be loaded onto a balloon
`catheter assembly. Upon placement of the stent over the
`balloon portion of the catheter, a valve in the loading device
`is activated to inflate the bladder. The bladder compresses
`the stent radially inward onto the balloon portion of the
`catheter to a reduced diameter to thus achieve a snug fit.
`Although the above-described methods by which stents
`are crimped are simple, there is a potential for not crimping
`the stent sufficiently tight to prevent it from loosening in the
`tortuous anatomy of the coronary arteries. Because the
`amount of compression needed to be applied by the fingers
`will vary with the (a) strength of the operator, (b) day-to-day
`operation,
`(c) catheter and balloon material and
`configuration, (d) experience of the operator in crimping,
`and (e) other factors,
`the tightness in which the stent is
`crimped onto a balloon catheter may vary considerably.
`Indeed, because of these factors, the tightness follows a
`normal or Chi square distribution. At the lower tail end of the
`distribution,
`the stents will be loose and susceptible to
`movement on the balloon during insertion. At the higher tail
`end, the stent will be too tight and will affect the expansion
`characteristics (i.e., a dog bone effect) of the balloon.
`In view of the foregoing,
`there is a need for a stent
`crimping device that reliably and uniformly crimps stents
`onto the balloon portion of a catheter.
`SUMMARY OF THE INVENTION
`
`The present invention is directed to a stent loading system
`and method for crimping a stent onto a catheter, and pref-
`erably onto a balloon catheter. The system comprises a
`housing having opposite ends forming an internal chamber,
`a port disposed on the housing in fluid communication with
`the internal chamber, and a flexible tube extending through
`the internal chamber and passing through the opposite ends
`of the housing, wherein the flexible tube includes a hollow
`interior and open ends, and wherein the stent is disposed
`within the hollow interior.
`
`A pressurized fluid is injected through the port into the
`chamber. As this fluid fills the internal chamber, the flexible
`
`Page 4 of 9
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`Page 4 of 9
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`

`

`5,911,452
`
`3
`tube undergoes radial compression. When the balloon por-
`tion of the catheter is inserted into the open end of the
`flexible tube and into the stent, the pressurized fluid com-
`presses the flexible tube reducing its diameter and thereby
`compressing the stent onto the balloon portion of the cath-
`eter.
`
`In one embodiment of the present invention, a balloon
`folding attachment
`is connected to the housing end. In
`particular, the balloon folding attachment has a body with an
`interior passage therethrough that has progressively chang-
`ing cross-sectional shapes and which is in communication
`with one opening of the flexible tube, and wherein the
`balloon portion of the catheter is inserted through the
`interior passage and is progressively folded into a desired
`shape.
`Furthermore, the housing may include an optional second
`port having a hydrophobic filter, which filter allows air or
`gases to pass, but not liquids. While the internal chamber is
`filled with a fluid,
`the ambient gas within the internal
`chamber bleeds out through the filter.
`Accordingly, the present invention provides a mechanism
`for uniformly crimping a stent onto a balloon portion of a
`catheter wherein the applied radial force on the stent is
`consistent and precise. The tightness of which the stent is
`crimped onto the balloon catheter can therefore be carefully
`controlled.
`
`Another advantage of the present invention is that the
`housing and other parts can be readily made from a dispos-
`able material. In this embodiment, the stent can be preloaded
`inside the flexible tube and packaged and sterilized. The
`package is then ready for use by the cath lab physician when
`a stent needs to be mounted on a catheter of the physician’s
`choice.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`Alternatively, the stent can be loaded onto the balloon
`portion of the catheter and slightly crimped. Thereafter, the
`combination of the stent and balloon catheter are inserted
`
`35
`
`into the flexible tube where the final crimping step takes
`place. Furthermore, the ports in the housing can be a Luer
`type, to be adaptable to the equipment already available to
`the physician.
`In another embodiment, the housing is made from a shape
`memory alloy material. The housing wraps around the
`flexible tube that houses the stent. When a catalyst such as
`heat is applied to the shape memory alloy housing,
`the
`housing shrinks in size and compresses the flexible tube
`thereunder. In turn, the compressed flexible tube crimps the
`stent onto a balloon catheter inserted therein. Removing the
`heat from the shape memory alloy material of the housing
`causes the housing to restore to its initial size and shape, thus
`permitting withdrawal of the crimped stent and catheter
`combination.
`
`These and other advantages of the 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 of a preferred embodi-
`ment of the present
`invention shown in a cross-section
`depicting the housing, flexible tube, stent, and catheter with
`a balloon portion, just prior to insertion.
`FIG. 2 is a side elevational view showing the present
`invention with a balloon folding attachment connected
`thereto.
`FIG. 3 is a series of cross-sectional views in which FIG.
`
`3A through FIG. 3F are cross-sectional views taken along
`lines A—A through F—F of FIG. 2.
`
`40
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`45
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`50
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`55
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`60
`
`65
`
`4
`FIG. 4 is a cross-sectional view depicting an alternative
`embodiment of the invention wherein the housing is formed
`of a shaped memory alloy capable of contracting and
`crimping the stent onto a catheter.
`FIG. 5 is a cross-sectional view depicting an alternative
`embodiment wherein the length of the housing is adjustable.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`The present invention is directed to a stent loading system
`for mounting a stent onto a balloon portion of a catheter.
`Beneficially,
`the present
`invention system facilitates
`controlled, repeatable, crimping pressure to be applied to a
`stent when the latter is loaded onto a balloon portion of a
`catheter. While the invention is described in detail as applied
`to the coronary arteries, those skilled in the art will appre-
`ciate that it can be applied to devices for use in other body
`lumens as well, such as peripheral arteries and veins. Also,
`although the invention is described with respect to mounting
`a stent on the balloon portion of a catheter, the invention is
`not so limited and includes mounting stents or grafts on any
`type of catheter used to deliver and implant such stents.
`Where different embodiments have like elements, like ref-
`erence numbers have been used.
`
`FIG. 1 provides a side elevational view of a preferred
`embodiment of the present invention stent loading system
`wherein the device is shown in a cross-section to depict the
`interior construction. As seen in this figure, housing 1 has a
`preferably long, cylindrical shape and includes internal
`chamber 2. The opposite ends of housing 1 are sealed to
`completely enclose internal chamber 2. To seal the opposite
`ends, in the preferred embodiment, housing 1 is enclosed by
`press fit seals 3,4.
`A flexible tube 5 is stretched across internal chamber 2,
`and inner lumen 6 of flexible tube 5 is in communication
`
`with openings 7, 8 formed in press fit seals 3, 4. An
`uncrimped stent 9 is positioned at about the midsection of
`flexible tube 5 within inner lumen 6. The inner surface of
`
`inner lumen 6 is close to and perhaps in loose fitting contact
`with the outer surface of uncrimped stent 9.
`In a preferred embodiment, uncrimped stent 9 is inserted
`into inner lumen 6 of flexible tube 5 and is expanded slightly
`to enlarge its inside diameter. In this manner, the slightly
`enlarged inside diameter of stent 9 allows easy clearance of
`catheter 10 to be inserted therein. Furthermore,
`the pre-
`expansion step stretches flexible tube 5, thereby securing
`stent 9 within tube 5. This condition is shown in FIG. 1.
`
`invention system is
`the present
`As mentioned above,
`adapted for use with a PTCA balloon catheter 10 having
`balloon portion 11 at the distal end. Of course, the present
`invention can be used with a balloon catheter of any con-
`ventional design known in the art as well as any catheter
`without a balloon.
`
`In the preferred embodiment, an adapter with a male-
`threaded Luer fitting (not shown) is used as an inflation port.
`A syringe, an inflation/deflation device commonly referred
`to as an “indeflator,” a compressed fluid source, or any
`pressurized source known in the art, is attached to inflation
`port 12. This serves as the inlet for the pressurized fluid that
`fills internal chamber 2.
`
`inflation port 12 can
`In an alternative embodiment,
`include a three-way stopcock (not shown) that is connected
`to the Luer fitting. Thus, a saline filled syringe or indeflator
`is connected to the inlet of the stopcock. Fluid is injected by
`the syringe into internal chamber 2 and air within the
`internal chamber 2 is purged through an extra side port on
`the three-way stockcock.
`
`Page 5 of 9
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`Page 5 of 9
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`

`5,911,452
`
`5
`It is possible to have more than one port connected to
`internal chamber 2 of housing 1. One of these optional ports
`13 can be connected to hydrophobic filter 14. This filter 14
`permits a gas such as air to pass, but seals in liquids such as
`saline. Therefore, while internal chamber 2 is filled with
`saline, air bleeds out through hydrophobic filter 14. This
`mechanism aids the user in purging air from the system.
`Yet another port (not shown) can be used for monitoring
`internal pressures. Still another port can be used for fluid
`input or output. As mentioned earlier,
`the ports in the
`housing can be a Luer type, straight tubes, threaded tubes,
`etc.
`
`Internal chamber 2 can be pressurized with different fluids
`as well as gases. The fluid is preferably saline. The gases can
`be, for example, compressed air, nitrogen, argon, or helium.
`As disclosed, housing 1 includes inflation port 12 for
`funneling a pressurized fluid into internal chamber 2 to
`compress flexible tube 5. Internal chamber 2 is otherwise
`sealed from the ambient atmosphere, while inner lumen 6 of
`flexible tube 5 is open to the ambient atmosphere by virtue
`of openings 7, 8. Since flexible tube 5 has openings 7, 8, it
`is uniformly compressed by the pressurized fluid.
`Furthermore, because neither end of flexible tube 5 is
`exposed to the fluid, uncrimped stent 9 placed within flexible
`tube 5 does not experience an axial pressure which would
`otherwise distort the tubular shape of stent 9 during the
`crimping process.
`The novel stent crimping method is described in the
`following manner. In the preferred method, inflation port 12
`includes a Luer fitting, and as described above, the outlet of
`a three-way stopcock is connected to the Luer fitting. A
`saline-filled syringe or indeflator is connected to the inlet of
`the stopcock. Using the syringe, fluid can be injected into
`internal chamber 2 and air within internal chamber 2 will be
`
`purged therefrom through an extra side port on the three-way
`stopcock.
`In keeping with the preferred method, any lubricant or
`lubricious coatings are removed from the exterior surface of
`catheter balloon 11 with a cleaning fluid such as isopropyl
`alcohol. Stent 9 is preloaded into flexible tube 5 prior to
`crimping. Stent 9 can optionally be slightly expanded by any
`conventional methods to ensure clearance with the outside
`diameter of balloon 11 of catheter 10.
`Catheter 10 is inserted into inner lumen 6 and advanced
`
`toward the midsection of flexible tube 5 through opening 8
`in the direction of the arrow shown in FIG. 1. Ideally,
`catheter 10 is inserted so that balloon 11 is centered directly
`within stent 9. As explained in greater detail below, align-
`ment of balloon portion 11 to stent 9 is accomplished
`visually.
`With balloon portion 11 in position within stent 9, fluid is
`injected into internal chamber 2. Because the internal pres-
`sure is evenly distributed over chamber wall 22 and outer
`surface 15, flexible tube 5 is compressed radially inwardly
`against stent 9. Further, because of open ends 7, 8 in flexible
`tube 5, no fluid pressure is exerted on the ends of flexible
`tube 5 and there are no axial forces applied to stent 9 during
`the crimping step.
`In fact, stent 9 experiences fairly
`homogeneous, radial pressures tending to uniformly crimp
`stent 9 onto balloon portion 11. In a preferred embodiment
`of the present invention, the required amount of pressure
`inside internal chamber 2 is expected to exceed ten atmo-
`spheres. Once the crimping process is complete, the inflation
`fluid can be withdrawn from inside internal chamber 2 by
`use of the syringe or by drainage through one of the ports.
`Housing 1 is preferably made from a transparent material
`so that the alignment of stent 9 relative to balloon portion 11
`
`10
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`can be observed continuously. Materials such as
`polycarbonate, PVC, polysulfone, metals, metal alloys,
`ceramic, or the like can be used as well. Obviously with
`opaque materials, a window can be formed in housing 1.
`Without an observation window or transparent housing, it is
`still possible to gage the relative position of the balloon to
`the stent by using depth indicators or markers on the
`catheter.
`
`In the preferred embodiment, balloon portion 11 is folded
`into a cylindrical shape so that it can be inserted into inner
`lumen 6 of flexible tube 5 without hanging or binding. The
`folding of balloon portion 11 can be achieved through any
`process known in the art.
`In an alternative embodiment, the present invention pro-
`vides balloon folding attachment 16, shown in FIG. 2,
`mounted on housing 1. A deflated balloon portion 11 is
`inserted into balloon folding attachment 16 and advanced
`therealong to fold the flat, outer expanse of the balloon into
`a tightly wrapped cylinder, just prior to inserting the balloon
`within stent 9 for subsequent crimping. To do this, balloon
`folding attachment 16 has a unique internal
`lumen 17
`configuration, shown in progressive cross-sections A
`through F of FIG. 3. The cross-sections of internal lumen 17
`show progressively changing cross-sectional shapes that
`guide a relatively flattened balloon portion 11 inserted
`therein, as it is advanced through lumen 17, to wrap around
`itself to form a cylinder. This is apparent from the drawings
`of sections 3A—A through 3F—F.
`To use balloon folding attachment 16, balloon portion 11
`of catheter 10 is flattened on its outer periphery. The
`flattened balloon 11 is inserted through inner lumen 17 of
`attachment 16. As balloon portion 11 is advanced into inner
`lumen 17, the interior walls of inner lumen 17 guide and
`twist the outer periphery of flattened balloon portion 11.
`When the process begins, flattened balloon portion 11 has a
`cross-sectional shape that resembles a propeller. As the
`balloon portion 11 travels through the varying cross-
`sections,
`the outstretched propeller blades are wrapped
`around a central axis, conceptually speaking. This type of
`folding pattern allows for even expansion of balloon portion
`11 when it is inflated, and is necessary for uniformity of the
`stent expansion when it
`is deployed. Of course, other
`patterns may be possible depending on the internal lumen
`configuration of balloon folding attachment 16.
`Once folded balloon portion 11 passes through attachment
`16, it enters inner lumen 6 of flexible tube 5. The process of
`crimping stent 9 on to folded balloon portion 11 then
`proceeds as described earlier. The crimped stent tends to
`hold the now tightly folded balloon 11 in its low-profile
`configuration for intraluminal delivery.
`Balloon folding attachment 16 can be made from plastics,
`metals, ceramics, or other materials. It can be made by
`molding, machining, or other methods known in the art. It is
`attached to housing 1 through mechanical attachments,
`threads, adhesives, or can be formed into the housing.
`Flexible tube 5 can be sealed into housing 1 by different
`means. The preferred method is to press flexible tube 5
`against the two press fit seals 3, 4. Press fit seals 3, 4, in turn,
`can be joined to housing 1 mechanically through friction,
`threads, or by solvent welding, adhesives, ultrasonic
`welding, or the like.
`In the preferred embodiment, the uncrimped but slightly
`expanded stent 9 is pre-assembled within flexible tube 5 and
`the entire combination is packaged together. The stent and
`housing combination thus packaged can be sterilized and
`shipped together to the end user. After the stent is crimped
`
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`5,911,452
`
`7
`onto the catheter of choice, the flexible tube package is
`discarded. All tools needed to use the present invention are
`commonly found in a cath lab or a hospital. Lastly, no
`special skills are needed to use the present invention to load
`a stent onto a balloon catheter.
`
`In an alternative embodiment, the present invention sys-
`tem provides a housing, internal chamber, and flexible tube
`as before. On the other hand,
`there is no stent
`that
`is
`preloaded into the flexible tube. Rather, the stent is loaded
`manually onto the balloon catheter. Through means known
`in the art, such as by hand crimping, the stent is slightly
`crimped onto the balloon catheter. In this alternative process,
`the stent that is preloaded onto the catheter is then inserted
`into the inner lumen of the flexible tube. Fluid is injected
`into the internal chamber, as described, to further crimp the
`stent onto the balloon portion of the catheter.
`In another alternative embodiment, shown in FIG. 4, there
`is a flexible tube 18 with preloaded stent 19 positioned at
`about a midportion thereof. Wrapped along the exterior of
`flexible tube 18 is housing 20 which is in the form of a coil,
`tube, roll, or similar shape. In this alternative embodiment,
`housing 20 is made from a shape memory alloy material
`such as Nitinol. When this alloy is subjected to temperatures
`at or above the alloy’s transitional temperature, housing 20
`shrinks, thereby compressing flexible tube 18 and in turn
`crimping stent 19 onto the balloon catheter, which has been
`inserted into inner lumen 21.
`
`FIG. 5 provides a cross-sectional view of yet another
`alternative embodiment of the present
`invention. A key
`feature is the adjustable length of housing 1, which is split
`into housing sections 1a and 1b. Sections 1a and 1b are
`assembled coaxially and telescopically. Optional seal or
`O-ring 23 is positioned in between the overlapping sections
`1a and 1b to provide a smooth telescoping action, and to
`minimize leakage of any fluid from internal chamber 2.
`This embodiment permits adjustment of the axial length
`of the housing. One benefit derived from this construction is
`that variations in length of stent 9 can be accommodated.
`Also, during the crimping process, additional pressure
`exerted on stent 9 can be created by forcing section 1b into
`section 1a, thereby reducing the internal volume occupied
`by the fluid. The fluid, depending on its compressibility,
`exerts a reactive force on flexible tube 5 which, in turn,
`exerts a crimping force on stent 9.
`Once the heat source is removed from housing 20, the
`housing restores to its original size and shape, permitting
`removal of the stent and balloon catheter combination
`
`therefrom. If a coiled housing configuration were used, and
`because the metal material of the housing 20 is highly
`elastic, it can be uncoiled rather easily so that tube 18 can be
`removed to release the balloon catheter with the crimped
`stent thereon.
`
`Other modifications can be made to the present invention
`without departing from the scope thereof. The specific
`dimensions and materials of construction are provided as
`examples, and substitutes are readily contemplated which do
`not depart from the invention.
`What is claimed is:
`
`1. A stent loading system for mounting a stent on a
`catheter, comprising:
`a housing having opposite ends forming an internal cham-
`ber;
`a port associated with the housing in fluid communication
`with the internal chamber;
`a flexible tube extending through the internal chamber and
`passing through the opposite ends of the housing,
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`wherein the flexible tube includes a hollow interior and
`
`into the
`
`open ends, and wherein the stent is disposed within the
`hollow interior;
`a pressurized fluid injected through the port
`chamber;
`a balloon folding attachment connected to the housing
`end,
`the attachment having a body with an interior
`passage therethrough that has progressively changing
`cross-sectional shapes and is in communication with
`one opening of the flexible tube, and wherein a balloon
`portion of the catheter is inserted through the interior
`passage and is progressively folded into a desired
`configuration; and
`wherein the catheter is inserted through the balloon fold-
`ing attachment and into the open end of the flexible
`tube and into the stent, and the pressurized fluid com-
`presses the flexible tube radially inwardly thereby
`compressing the stent on to the catheter.
`2. The stent loading system according to claim 1, wherein
`the catheter has a balloon associated with the balloon portion
`so that the stent is mounted on the balloon.
`
`3. The stent loading system according to claim 1, wherein
`the progressively changing cross-sectional shapes include a
`circle with radially extending legs, a circle with radially
`extending curved legs, and a circle with curved legs that
`tangentially intersect the circle.
`4. The stent loading system according to claim 1, wherein
`the progressively changing cross-sectional shapes include a
`silhouette of a twin opposed propeller blades on a circular
`rotor wherein the blades progressively twist around the
`rotor.
`
`5. The stent loading system according to claim 1, wherein
`the port includes a Luer type valve.
`6. The stent loading system according to claim 1, wherein
`the housing includes a second port in communication with
`the internal chamber, the second port having a hydrophobic
`filter.
`
`7. The stent loading system according to claim 6, wherein
`the internal chamber includes a gas that is expelled through
`the hydrophobic filter.
`8. The stent loading system according to claim 1, wherein
`the housing and flexible tube are at least partially formed
`from a transparent material.
`9. The stent loading system according to claim 1, wherein
`the flexible tube further comprises a mid-section having an
`enlarged diameter to hold the stent therein.
`10. A stent loading system for mounting a stent onto a
`balloon portion of a catheter comprising:
`a housing having an internal chamber;
`a flexible tube passing at
`least partially through the
`housing and the internal chamber, wherein the stent is
`disposed inside the flexible tube;
`a port in fluid communication with the internal chamber;
`a fluid injected through the port into the internal chamber
`to compress the flexible tube and the stent;
`a balloon folding attachment connected to the housing
`wherein the folding attachment
`includes an interior
`passage in communication with the flexible tube, the
`interior passage having progressively varying cross-
`sectional shapes that sequentially twist
`the balloon
`portion into a folded cylindrical shape when inserted
`therein; and
`wherein the balloon portion of t