United States Patent
`
`[19]
`
`[11] Patent Number:
`
`5,860,966
`
`
`Tower
`[45] Date of Patent:
`Jan. 19, 1999
`
`U8005860966A
`
`[54] METHOD OF SECURING A STENT ON A
`BALLOON CATHETER
`
`5,217,483
`5,352,199
`5,389,106
`
`6/1993 Tower .
`10/1994 Tower .
`2/1995 Tower .
`
`[75]
`
`Inventor: Allen J. Tower, North Lawrence, NY.
`
`576137981
`5,628,754
`
`3/1997 Boyle.et al~ ~
`5/1997 Shthn et a1.
`
`.......................... 606/108
`
`[73] Assignee: NuMed, Inc., NicholVille, NY.
`
`[21] Appl. No.. 834,430
`[22]
`Filed:
`Apr. 16, 1997
`
`[51]
`Int. Cl.6 ..................................................... A61B 17/00
`
`[52]
`............ 606/1; 606/198
`[58] Field of Search ....................... 606/1, 108, 191—200;
`623/1, 11, 12
`
`[56]
`
`References Cited
`
`4,733,665
`5,161,547
`
`U’S’ PATENT DOCUMENTS
`3/1988 Palmaz.
`11/1992 Tower.
`
`Primary Examiner—Glenn K. Dawson
`Attorney, Agent, or Firm—Wall Marj ama Bilinski & Burr
`[57]
`ABSTRACT
`
`.
`Apparatus for securing a stent upon a balloon catheter. The
`apparatus has a tubular housing that is open at each end for
`containing a balloon catheter in a deflated state upon which
`is mounted a stent. An inflatable cylindrical membrane is
`mounted inside the housing and sealed at both ends to
`provide a fluid tight chamber between the membrane and the
`housing. Apressurized fluid is introduced into the chamber
`to inflate the membrane into pressure contact with the stent
`to urge the stent into gripping engagement with the balloon.
`
`13 Claims, 3 Drawing Sheets
`
`
`
`«77777777777
`
`
`'. 'l I. .' I. I. I. .. .. -
`,a_ ......-
`
`Edwards Lifesciences V. Boston Scientific
`
`IPR2017-00444 EX. 2040
`
`US. Patent No. 6,915,560
`
`Page 1 of 7
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`Page 1 of 7
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`

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`US. Patent
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`Jan. 19, 1999
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`Sheet 1 013
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`5,860,966
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`Page 2 of 7
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`Page 2 of 7
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`US. Patent
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`Jan. 19, 1999
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`Sheet 2 0f 3
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`5,860,966
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`III:Edell.
`‘\...‘‘6
`I’ll!»
`“..\vIIt
`III..
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`Page 3 of 7
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`Page 3 of 7
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`US. Patent
`
`Jan. 19, 1999
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`Sheet 3 0f3
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`5,860,966
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`Page 4 of 7
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`Page 4 of 7
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`5,860,966
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`1
`METHOD OF SECURING A STENT ON A
`BALLOON CATHETER
`
`BACKGROUND OF THE INVENTION
`
`to a
`This invention relates to stents, and in particular,
`method and apparatus for securely mounting a stent on a
`balloon catheter.
`It is well known that a balloon catheter is well suited for
`
`5
`
`use as a delivery and implantation system for an expandable
`stent. Typically, the stent is mounted over a balloon at the
`distal end of the catheter and is carried into a treatment zone
`
`10
`
`through a blood vessel. Once properly positioned in the
`treatment zone, the balloon is inflated to expand the stent
`radially to open an occlude passage in the vessel caused by
`plaque or an aneurism. The catheter, during insertion, must
`oftentimes travel a rather tortuous path before reaching the
`treatment zone. If the stent is not securely mounted upon the
`balloon it can become dislodged or misaligned thus render-
`ing the procedure ineffective. In severe cases, the stent may
`become entirely dislodged from the catheter while it
`is
`inside the patient, thus requiring its recovery through sur-
`gical procedures.
`In an effort to more securely mount a stent upon a balloon
`catheter,
`it
`is common practice to compress the stent
`inwardly using special crimping tools similar to pliers.
`Because the crimping forces are applied repeatedly in dif-
`ferent localized regions about the stent, the holding force
`around the stent
`tends to be non-uniform which can
`
`adversely effect the way the stent expands as the balloon
`inflates, thus leading to less than satisfactory implantation.
`More importantly, because the amount of force applied
`during the crimping operation is generally unregulated, the
`stent can penetrate the balloon rendering it uninflatable. The
`fact the balloon has been punctured by the stent generally is
`not discovered until such time as the stent has been posi-
`tioned in the body. As a result, the catheter and stent must be
`retrieved from inside the patient and the procedure repeated.
`Cylindrical crimping devices have also been devised
`wherein the balloon with a stent mounted thereupon are
`drawn into a cylinder having a predetermined inside diam-
`eter. The inside diameter of the cylinder is selected so that
`ideally the stent is collapsed just enough to apply a non-
`damaging, yet secure gripping force upon the balloon. This
`ideal relationship unfortunately is difficult
`to achieve in
`practice and puncturing of the balloon by the stent is not
`uncommon. Accurately guiding the stent bearing balloon
`into the cylinder can also be difficult and the stent may
`become misaligned or dislodged during this procedure.
`SUMMARY OF THE INVENTION
`
`It is therefore an object of this invention to securely mount
`an expandable stent upon a balloon catheter without harming
`the balloon.
`
`Afurther object of the present invention is to improve the
`safety of stent delivery systems using balloon catheters.
`A still further object of the present invention is to apply
`a uniform collapsing pressure to a stent as it
`is being
`mounted upon a deflated balloon at
`the distal end of a
`catheter.
`
`Another object of the present invention is to protect the
`integrity of a balloon as an unexpanded stent
`is being
`secured thereto.
`
`Yet another object of the present invention is to improve
`the reliability of balloon catheter delivery systems.
`These and other objects of the present
`invention are
`attained by a tubular housing that is open at each end for
`
`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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`50
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`2
`containing a balloon catheter in a deflated condition upon
`which is mounted a stent. An inflatable cylindrical mem-
`brane is mounted in the opening of the housing and is sealed
`against the housing to establish a leak-tight chamber ther-
`ebetween. Apressurized fluid is introduced into the chamber
`to expand the membrane into contact with the stent to apply
`a uniform pressure thereagainst to urge the stent into secure
`gripping contact with the balloon.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`For a better understanding of these and other objects of
`the present invention, reference will be made to the detailed
`description below which is to be read in association with the
`following drawings, wherein:
`FIG. 1 is a side elevation of apparatus embodying the
`teachings of the present invention;
`FIG. 2 is a sectional view taken along lines 2—2 in FIG.
`
`1;
`
`FIG. 3 is an enlarged side elevation with portions broken
`away showing a balloon catheter carrying a stent being
`inserted into the housing of the present apparatus;
`FIG. 4 is a side elevation similar to that illustrated in FIG.
`
`3 showing the stent and the balloon of the catheter centered
`in the housing; and
`FIG. 5 is also a side elevation showing the stent being
`compressed into gripping contact against the balloon.
`DESCRIPTION OF THE INVENTION
`
`Turning now to the drawings, there is shown stent mount-
`ing apparatus, generally referenced 10, for securing an
`expandable stent 12 upon a balloon 13 located at the distal
`end of a catheter 15. As is well known, the elongated body
`of the catheter contains at least one lumen that is adapted to
`carry air or fluid under pressure to the balloon whereby the
`balloon can be inflated to expand an occluded blood vessel
`or the like. The balloon catheter can also serve as a delivery
`vehicle for an expandable stent which is mounted upon the
`balloon and is guided into an occluded area caused by
`plaque, an aneurism or the like. Once the stent is properly
`inserted and its position verified by fluoroscopic means, the
`balloon is inflated to expand the stent into contact with the
`occluded vessel, thus opening the vessel. The stent remains
`in the expanded condition when the balloon is deflated, thus
`supporting the vessel in the expanded state.
`As disclosed in US. Pat. No. 5,217,483, the present stent
`can be formed of a fully annealed platinum wire that is
`shaped into a cylinder that can be easily slipped over the
`deflated balloon of a catheter. As the stent is guided by the
`catheter through a blood vessel,
`it generally must move
`through a rather tortuous path of travel. Unless the stent is
`firmly attached to the balloon, it can become misaligned
`whereby it will not
`inflate properly or it may become
`dislodged entirely from the balloon which, in severe cases,
`may require a surgical recovery. As noted above, the stent is
`typically crimped against the balloon to force the stent into
`gripping contact with the balloon. The prior art method of
`attaching a stent to a balloon generally involved the appli-
`cation of uncontrolled, non-uniform compression forces to
`the stent which can result in the balloon becoming punctured
`when too much force is applied or the stent becoming
`misaligned during insertion when too little force is applied.
`The apparatus of the present
`invention is specifically
`designed to apply a controlled, uniformly distributed crimp-
`ing force to the stent which will provide the maximum
`desired gripping pressure to the balloon without causing
`damage to the balloon.
`
`Page 5 of 7
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`Page 5 of 7
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`5,860,966
`
`3
`The apparatus of the present invention includes a tubular
`housing 20 having an axially disposed cylindrical opening
`passing therethrough. The housing is open at both ends to
`permit
`the distal end of a balloon catheter 15 to pass
`therethrough. Astent 12 is loosely inserted over the deflated
`balloon 13 in a non-expanded condition. An inflatable cylin-
`drical shaped membrane 23 is contained within the housing
`opening and both ends of the membrane are joined to the
`housing using a suitable epoxy or the like to form end seals
`25 and 26, thus creating a fluid-tight chamber 27 between
`the inner wall of the housing and the membrane. The
`membrane can be fabricated from any suitable material,
`however, nylon is preferred.
`The chamber 27 is placed in communication with an air
`line 30 (FIG. 1) by means of a threaded connection 32. The
`other end of the air line is, in turn, connected to a three-way
`valve 35 mounted upon an air compressor unit 36. Although
`not shown,
`the unit contains a small electrically driven
`compressor, the discharge side of which is connected to the
`valve 35. A pressure control valve (not shown) is mounted
`in the unit to regulate the output of the compressor. The
`desired pressure is set by a control knob 38 and registered by
`a gauge 39. Alternately, a compressed air source (not shown)
`or an indeflator (not shown) can be used to supply air or fluid
`under pressure to the membrane.
`As illustrated in FIG. 3,
`the chamber 27 is initially
`deflated by opening valve 35 to atmosphere and the distal
`end of the balloon catheter is passed axially into the housing.
`An adjustable stop generally referenced 40 is mounted on
`the housing that is arranged to intercept the end of the
`catheter when the stent is centered inside the membrane. The
`
`axial length of the membrane is greater than the axial length
`of the stent, the reason for which will become apparent from
`the description below. Alternately,
`the housing and the
`membrane can be made from transparent materials to allow
`a user to visually position the catheter therein.
`Once the stent is centered in the membrane, as shown in
`FIG. 4,
`the valve 35 is closed to atmosphere and the
`compressor brought up to a desired operating pressure.
`Valve 35 is now cycled to allow compressed air under a
`desired pressure to enter the chamber 27 thus inflating the
`membrane.
`
`As illustrated in FIG. 5, the inflated membrane expands
`inwardly to completely embrace the stent about its entire
`outer surface area. Accordingly, the stent is urged inwardly
`at a controlled pressure to firmly grip the balloon. Apressure
`of at least, 300 psi, according to the present embodiment, is
`suitable for deforming the membrane. Because of the ability
`of the stent to hold the position in which it is placed, it will
`remain in gripping contact when the membrane is deflated.
`The membrane is then deflated as described and the catheter
`
`removed from the housing.
`The housing is provided with the above mentioned stop
`40 that can be adjusted to help center the stent inside the
`inflatable membrane. The stop includes a stop plate 91 that
`is suspended at the distal end of a rod 92. The rod, in turn,
`is slidably retained within a block 93 mounted on top of the
`housing. The stop plate is arranged to depend downwardly
`from the rod past the axial center line of the housing so that
`it can intercept
`the distal end of the catheter and thus
`interrupt its forward progress as it is passed through the
`housing. The position of the stop plate is set so that when the
`catheter is intercepted by the plate, the stent and the balloon
`upon which it is mounted are about centered within the
`membrane. Accordingly, when the membrane is inflated, it
`will completely envelope the stent and urge it inwardly
`
`4
`under a controlled pressure to uniformly embrace the bal-
`loon. Once brought
`to a desired position,
`the plate is
`optionally locked in place using a threaded set screw 95. In
`a separate embodiment, not shown, a spiral wound sleeve
`can be used in lieu of the housing and membrane which can
`be disposed or wound in overlaying relationship to the stent
`as placed on the collapsed catheter balloon. The sleeve is
`fixed at one end and can be pulled at its remaining end under
`a controlled pressure to uniformly apply force to the outer
`surface of the stent thereby compressing the stent radially to
`the catheter balloon.
`
`While this invention has been explained with reference to
`the structure disclosed herein, it is not confined to the details
`set forth and this invention is intended to cover any modi-
`fications and changes as may come within the scope of the
`following claims:
`What is claimed is:
`1. Apparatus for securing a stent upon a balloon catheter
`that includes:
`
`a tubular housing that is open at each end and sized for
`receiving a balloon catheter having a stent mounted
`upon a balloon,
`an inflatable membrane mounted in axial alignment
`between the ends of said housing,
`sealing means for sealing respective ends of said mem-
`brane to the housing to provide a fluid tight chamber
`between the membrane and said housing,
`inflation means for introducing a fluid under pressure into
`said chamber to inflate said membrane into pressure
`contact with said stent to uniformly urge the stent into
`clamping engagement with said balloon, and
`positioning means for aligning the stent within the hous-
`mg.
`2. The apparatus of claim 1 wherein the membrane is
`formed of a deformable material capable of being expanded
`to at least 300 psi.
`3. The apparatus of claim 2, wherein the membrane is
`formed of nylon.
`4. The apparatus of claim 1 wherein the axial length of the
`membrane is sized to be greater than that of the balloon
`whereby the membrane completely envelopes the balloon
`when the membrane is inflated.
`5. The apparatus of claim 1, that further includes pressure
`regulator means for controlling the pressure of the fluid
`introduced into the chamber.
`
`6. The apparatus of claim 5 that further includes a relief
`valve for releasing pressurized fluid from said chamber.
`7. The apparatus of claim 1 wherein the chamber is
`inflated with compressed air.
`8. The apparatus of claim 1, wherein the positioning
`means is adjustable.
`9. The aparatus of claim 1 wherein the housing and the
`membrane are formed of a transparent material.
`10. A method of securing an expandable stent upon a
`balloon mounted upon a catheter that includes the steps of:
`providing an elongated tubular housing having an open-
`ing passing therethrough,
`mounting a cylindrical inflatable membrane within the
`housing opening,
`inserting a balloon catheter carrying a stent upon the
`balloon into the housing opening and axially centering
`the stent within the membrane,
`positioning the stent relative to the membrane within the
`housing, and
`introducing a fluid under pressure into the membrane to
`expand the membrane into pressure contact with said
`stent to urge the stent into gripping contact with the
`balloon.
`
`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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`50
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`55
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`60
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`65
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`Page 6 of 7
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`Page 6 of 7
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`5,860,966
`
`5
`11. The method of claim 10 that includes the further step
`of controlling the pressure of fluid introduced into the
`membrane.
`12. The method of claim 10 that includes a further step of
`releasing the fluid from said membrane after the stent has
`been urged into contact With the balloon membrane.
`
`5
`
`6
`13. The method of claim 10 that includes the further step
`of sealing both ends of the membrane to the housing to
`provide a fluid-tight chamber between the inside wall of the
`housing and the membrane.
`
`*
`
`*
`
`*
`
`*
`
`*
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`Page 7 of 7
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`Page 7 of 7
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