_
`
`United States Patent [191
`Bagaoisan et al.
`’
`
`US005415635A
`
`5,415,635
`[11] Patent Number:
`[45] Date of Patent: May 16, 1995
`
`[54] BALLOON ASSEMBLY WITH SEPARATELY
`INFLATABLE SECHONS
`[75] Inventors: Celso J. Bagaoisan, Newark; Kenn
`P. Muni, San Jose, both of Calif.
`[73] Assignee: Advanced Cardiovascular Systems,
`Inc" Santa Clara’ Cam"
`[21] Appl, No_; 917,812
`.
`Jul‘ 21’ 1992
`[22] F?ed’
`[51] Int. Cl.6 ........................................... .. A61M 29/00 _
`[52] US. Cl. .................................... .. 604/96; 604/101;
`'
`606/ 194
`[58] Field of Search ................................ .. 604/ 96-103;
`606/ 191-197
`
`5,071,406 12/1991 Jang .................................... .. 604/96
`Primary Examiner-John D. Yasko
`Attorney, Agent, or‘Firm—Crosby, Heafey, Roach &
`May
`ABSTRACT
`’
`[57]
`A dilatation or other similar catheter for intraluminal
`use which has an elongated shaft and an in?atable mem
`her or section on the distal extremity of the catheter
`shaft which has multiple working sections, a ?rst work
`ing section which elastically expands upon inflation to a
`?rst pressure within a ?rst pressure range and a second
`working section which elastically expands upon in?a
`tion to a second pressure within a second pressure range
`which is at least in part higher than the ?rst pressure
`vrange. The ?rst working section may be in?ated to
`secure the catheter within the body lumen and then the
`References QM
`second working section may be in?ated to dilatate the
`US. PATENT DOCUMENTS
`4,911,163 3/1990 Fina .............................. .. 606/192 x b°dy 19mm
`
`[56]
`
`4,990,139 2/1991 Jang . . . . . . . .
`
`. . . . . . .. 604/101
`
`5,019,042 5/1991 Sahota ............................... .. 604/101
`
`29 Claims, 3 Drawing Sheets
`
`Page 1 of 11
`
`Edwards Lifesciences v. Boston Scientific Scimed
`IPR2017-01294, U.S. Patent 6,371,962
`Exhibit 2004
`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 1 of 3
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`5,415,635
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`Page 2 of 11
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`May 16, 1995
`
`- Sheet 2 of 3
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`USS. Patent
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`5,415,635
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`Page 3 of 11
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`Page 3 of 11
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`

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`US. Patent
`
`May 16, 1995
`
`Sheet 3 of 3
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`5,415,635
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`Page 4 of 11
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`

`

`1
`
`SEPARATELY
`BALLOON ASSEMBLY
`INFLATABLE SECTIONS
`
`5
`
`20
`
`25
`
`30
`
`BACKGROUND OF THE INVENTION
`The present invention is directed to a balloon assem
`bly for catheters which are suitable for intraluminal
`procedures such a percutaneous transluminal coronary
`angioplasty (PTCA).
`PTCA is a widely used procedure for the treatment
`of coronary heart disease. In this procedure, a balloon
`dilatation catheter is advanced into the patient’s coro
`nary artery and the balloon on the catheter is in?ated
`within the steno?c region of the patient’s artery to open
`up the arterial passageway and increase the blood ?ow
`through the artery. To facilitate the advancement of the '
`dilatation catheter into the patient’s coronary artery, a
`guiding catheter having a preshaped distal tip is ?rst
`percutaneously introduced into the cardiovascular sys
`tem of a patient by the Seldinger technique through the
`brachial or femoral arteries. The catheter is advanced
`therein until the preshaped distal tip of the guiding
`catheter is disposed within the aorta adjacent the ostium
`of the desired coronary artery. The guiding catheter is
`twisted or torqued from the proximal end, which ex
`tends out of the patient, to guide the distal tip of the
`guiding catheter into the ostium. A balloon dilatation
`catheter may then be advanced through the guiding
`catheter into the patient’s coronary artery until the
`balloon on the catheter is disposed within the stenotic
`‘ region of the patient’s artery. The balloon is in?ated to
`open up the arterial passageway.
`. One type of catheter frequently used in PTCA proce
`dures is an over-the-wire type balloon dilatation cathe
`ter. Commercially available over-the-wire type dilata
`tion catheters include the SIMPSON ULTRA-LOW
`PROFILE ®, the HARTZLER ACX ®, the HART
`ZLER ACX IITM, the PINKERTON 0.018TM and
`the ACS TEN TM balloon dilatation catheters sold by
`the assignee of the present invention, Advanced Cardio
`40
`vascular Systems, Inc. (ACS). Over-the-wire type dila
`tation catheters are described and claimed in US. Pat.
`No. 4,323,071 (Simpson-Robert).
`When using an over-the-wire dilatation catheter, a
`guidewire is usually inserted into an inner lumen of the
`dilatation catheter before it is introduced into the pa
`tient’s vascular system and then both are introduced
`into, and advanced through, the guiding catheter to its
`distal tip which is seated within the ostium. The guide
`wire is ?rst advanced out the seated distal tip of the
`guiding catheter into the desired coronary artery until
`the distal end of the guidewire extends beyond the le
`sion to be dilatated. The dilatation catheter is then ad
`vanced out of the distal tip of the guiding catheter into
`the patient’s coronary artery, over the previously ad
`vanced guidewire, until the balloon on the distal ex
`tremity of the dilatation catheter is properly positioned
`across the lesion to be dilatated. Once properly posi
`tioned across the stenosis, the balloon is in?ated one or
`more times to a predetermined size with radiopaque
`liquid at relatively high pressures (e.g., generally 4-12
`atmospheres) to dilate the stenosed region of a diseased
`artery. After the in?ations, the ‘balloon is ?nally de
`?ated so that the dilatation catheter can be removed
`from the dilatated stenosis to resume blood ?ow.
`65
`Fixed-wire type dilatation catheter systems are also
`utilized very frequently in PI‘CA procedures. This type
`of dilatation catheter has a guidewire or guiding mem
`
`5,415,635
`2
`bet secured within the catheter and it provides low
`pro?les, i.e. small transverse dimensions, because there
`is no iJmer tubular member which is characteristic of
`commercially available over-the-wire dilatation cathe
`ters. Commercially available ?xed-wire dilatation cath
`eters include the HARTZLER EXCEL ®, the HART
`ZLER LPS ® and the SLALOM TM dilatation cathe
`ters sold by ACS. Fixed~wire dilatation catheters are
`disclosed and claimed in US. Pat. No. Re. 33,166 which
`is incorporated by reference into this application.
`Another type of dilatation catheter, the rapid ex
`change type catheter, was introduced by ACS under
`the trademark ACS RX ® Coronary Dilatation Cathe
`ter. It is described and claimed in US. Pat. No.
`5,040,548 (Yock), US. Pat. No. 5,061,273 (Yock) and
`US. Pat. No. 4,748,982 (Horzewski, et al.). This dilata
`tion catheter has a short guidewire receiving sleeve or
`inner lumen extending through a distal portion of the
`catheter. The sleeve or inner lumen extends proximally
`from a ?rst guidewire port in the distal end of the cathe
`ter to a second guidewire port in the catheter spaced
`proximally from the in?atable member of the catheter.
`A slit may be provided in the wall of the catheter body
`which extends distally from the second guidewire port,
`preferably to a location proximal to the proximal end of
`the in?atable balloon. The structure of the catheter
`allows for the rapid exchange of the catheter without
`the need for an exchange wire or adding a guidewire
`extension to the proximal end of the guidewire. This
`catheter has been widely praised by the medical profes
`sion, and it has met with much success in the market
`place because of the advantages of its unique design.
`The perfusion type dilatation catheter was another
`type of dilatation catheter ?rst introduced into the mar
`ketplace by ACS. This catheter, which can take the
`form of an over-the-wire, ?xed-wire or a rapid ex
`change type catheter, has one or more perfusion ports .
`proximal to the dilatation balloon in ?uid communica
`tion with. the guidewire receiving inner lumen extend
`ing to the distal end of the catheter. A plurality of perfu
`sion ports are preferably provided in the catheter distal
`to the balloon which are also in ?uid communication
`with the inner lumen extending to the distal end of the
`catheter. When the balloon of this dilatation catheter is
`in?ated to dilatate a stenosis, oxygenated blood in the
`artery or the aorta, or both, depending upon the loca
`tion of the dilatation catheter within the coronary anat
`omy, is forced to pass through the proximal perfusion
`ports, through the inner lumen of the catheter, and out
`the distal perfusion ports. The catheter provides oxy
`genated blood downstream from the in?ated balloon to
`thereby prevent or
`ischemic conditions in
`tissue distal to the balloon. The perfusion of blood distal
`to the in?ated balloon allows for long term dilatations,
`e.g. 30 minutes or even several hours or more. This
`catheter has likewise been highly praised by the medical
`profession and has met with much commercial success.
`Commercially available perfusion type dilatation cathe
`ters include the STACK PERFUSION ® and the ACS
`RX PERFUSION TM dilatation catheters which are
`sold by ACS.
`It is not uncommon with all types of dilatation cathe
`ters to have some dif?culty in properly positioning the
`in?atable member or balloon on the distal ends of these
`catheters within the stenotic region of a patient’s artery
`or other body lumen or, if properly positioned within
`the stenosis, to have dif?culty in maintaining the posi
`
`50
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`55
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`25
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`30
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`5,415,635
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`4
`tion of the in?atable member or balloon within the
`working sections at a ?rst pressure level to expand the
`stenosis during balloon in?ation. What is needed and
`?rst in?atable working section to a diameter which
`has been previously unavailable is an in?atable member
`secures the ?rst working section within the artery. The
`which can be preferentially in?ated at different sections
`pressure is increased to a second higher pressure level,
`to better control the position of the in?atable member
`which causes the second in?atable working section to
`and to provide a more uniform pressure against the
`expand to a diameter which dilatates the stenosis. Pref
`stenosis during the dilatation. The present invention
`erably, the ?rst working section is expanded substan
`tially before any signi?cant expansion of the second
`satis?es these and other needs.
`working section occurs and during the dilatation of the
`stenosis, the dilatation catheter is held ?rmly in position
`within the artery by the expanded ?rst working section.
`However, after in?ating the ?rst in?atable working
`section to the ?rst diameter to secure the catheter
`within the artery, further increases in internal pressure
`to in?ate the second in?atable working section to dilate
`the stenosis, do not signi?cantly increase the diameter
`of the ?rst in?atable working section. The elastic expan
`sion of the second in?atable working section within the
`stenosis applies little or no shear stress to the stenosis,
`thereby minimizing the‘ chances for a dissection of the
`stenosis which can interrupt blood ?ow through the
`artery and can hasten restenosis.
`In one presently preferred embodiment of the inven
`tion the ?rst in?atable working section is disposed
`within the artery proximal to stenosis while the second
`in?atable working section is disposed within the steno
`sis. In the second preferred embodiment, the ?rst in?at
`able working section is disposed distal to the stenosis
`while the second in?atable working section is disposed
`within the stenosis. The ?rst and second preferred em
`bodiments may be utilized in essentially the same man
`ner.
`Use of the third embodiment provides for a ?rm ?x of
`the in?atable section of the catheter on both sides of the
`stenosis by the in?ation of the ?rst and third working
`sections prior to the expansion of the second working
`section to dilate the stenosis.
`The working sections of the balloon of the invention
`can be formed in a variety of ways to provide the desir
`able differential expansion. One presently preferred
`method is to extrude a tubular member of one or more
`polyolefmic ionomers, such as the sodium, lithium and
`zinc ionomers sold by El. dupont, deNemours & Co.
`under the trademark Surlyn ®, and then to irradiate at
`least the portion of the extruded tubular member which
`is to be the in?atable portion to cross-link the polymer.
`Blends with other polymers such as polyethylene with
`the ionomers may also be employed. The portion of the
`tubular member which is to be formed into the second
`working section is given a heat treatment after the ex
`trusion thereof within 50° C. of the crystalline melting
`point, whereas the portion of the tubular member which
`is to be formed into the ?rst working section is given
`essentially the same heat treatment after the extrusion
`thereof but is also in?ated to expand this portion of the
`balloon within the thermal treatment range. A tight
`?tting sheath or other suitable device is placed around
`the portion which forms the second working section of
`the in?atable section to prevent its expansion during the
`in?ation of the ?rst working section. After the expan
`sion of the ?rst working section, it is cooled and the
`expanded portion is heated to heat shrink the expanded
`section.
`Other means can be employed to provide the separate
`expansion of the ?rst and second working sections of
`the balloon. For example, the portion of the balloon
`which forms the first working section can formed from
`a portion of the tubular member which has a thinner
`
`SUMMARY OF THE INVENTION
`The present invention is directed to an improved
`in?atable assembly for intraluminal catheters such as
`are employed in PTCA and peripheral angioplasty.
`The in?atable catheter portion of the present inven
`tion has at least two separately in?atable working sec
`tions, a ?rst working section which upon in?ation to a
`?rst pressure within a ?rst pressure range expands sub
`stantially in an elastic mode and a second working sec
`tion which upon in?ation to a second pressure, higher
`than the ?rst pressure within a second pressure range
`expands substantially in an elastic mode. The individual
`working sections of the in?atable member are consider
`ably less compliant at pressures greater than the ?rst
`and second pressure ranges respectively and exhibit
`much less expansion at pressures above the respective
`pressure ranges. Upon de?ation, the working sections
`of the in?atable member preferably contract substan
`tially by means of elastic recoil to provide very low
`de?ated pro?les. Preferably, the elastic expansion of the
`?rst working section is substantially complete before
`any signi?cant amount of elastic expansion of the sec
`ond working section occurs to allow the ?rst working
`section to ?rmly secure the catheter within a body
`lumen before the second working section is in?ated to
`any signi?cant extent. In other embodiments, the com
`plete in?ation of the ?rst working section before the
`initiation of in?ating the second working section allows
`the ?rst working section to predilate a stenosis so that
`the second working section can be advanced within the
`stenosis and then be in?ated to a pressure within the
`second pressure range to complete the dilatation.
`In one presently preferred embodiment, the ?rst
`working section of the in?atable catheter section is
`proximal to the second working section, whereas, in
`another presently preferred embodiment the ?rst work
`ing section is distal to the second working section. In a
`third embodiment, a variant of the ?rst embodiment, a
`‘third working section, preferably having essentially the
`same characteristics as the ?rst working section, may be
`provided distal to the second working section.
`A dilatation catheter having a in?atable balloon as
`sembly in accordance with the present invention gener
`ally has an elongated shaft with an inner lumen extend
`ing within the shaft which is in ?uid communication
`with the interior of the in?atable working sections. The
`55
`use of a single in?ation lumen for delivery of in?ation
`?uid to multiple in?atable members reduces considera
`bly the pro?le of the catheter shaft.
`A dilatation catheter having ?rst and second in?at
`able members or sections of the invention may be ad
`vanced within a patient’s arterial system in a conven
`tional manner such as described in the BACK
`GROUND OF THE INVENTION until the second
`in?atable working section extends into the stenosis and
`the ?rst in?atable working section of the balloon is
`disposed proximally adjacent to the stenosis. In?ation
`?uid is directed through the inner lumen of the catheter
`shaft into the interior of the ?rst and second in?atable
`
`35
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`Page 6 of 11
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`15
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`30
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`40
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`5,415,635
`6
`5
`tubular member 15 disposed concentrically about the
`wall than the portion which forms the second working
`inner tubular member and de?ning with the inner tubu
`section. Upon expansion of the balloon to a ?rst pres
`lar member an annular in?ation lumen 16. The inner
`sure level the ?rst working section with a thinner wall
`will expand to its working diameter before the second
`tubular member 14 has an inner lumen 17 which is
`adapted to slidably receive a guidewire 18.
`working section. The ?rst and second in?atable work- 5
`The in?atable section 12 has a ?rst in?atable working
`ing sections may be made of different materials to pro
`section 20 which has an interior in ?uid communication
`vide the same effects of in?ating at different pressure
`with the annular lumen 16 and which is adapted to
`levels. Providing different levels of irradiation of the
`in?atable sections may also be employed to generate
`in?ate at pressures within a ?rst pressure range and a
`second in?atable working section 21 which is also in
`differentials in material properties of the in?atable
`working sections by varying the cross-linking of the
`?uid communication with the annular lumen 16 and
`polymer material.
`which is adapted to in?ate at pressures within a second
`The in?atable portion of the catheter of the invention
`‘ pressure range which is at least in part greater than the
`with separate expansion of multiple working sections
`?rst pressure range. The in?ated pro?les of the working
`allows the expansion of the ?rst working section to
`sections 20 and 21 are shown in phantom in the draw
`ings. During in?ation the proximal working section 20
`?rmly secure the in?atable member within the artery or
`other body lumen before signi?cant the expansion of the
`elastically expands to a ?rst diameter within the ?rst
`pressure range as shown by 20’. The distal working
`second working section to apply pressure to the artery
`section 21 elastically expands to a second diameter
`or other lumenal wall. Moreover, the second working
`sectionprovides for the uniform application of radial
`within the second pressure range as shown by 21’. The
`expanded proximal working section 20' may expand
`pressure to the artery or body lumen without applying
`signi?cant shear stress to the artery of body lumen wall,
`slightly more when the in?ation pressure is increased to
`in?ate the second section as shown by 20". While the
`which can signi?cantly reduce the risk of dissections
`?nal in?ated diameters of the ?rst and second working
`during dilatations which can impede blood ?ow
`sections 20 and 21 are shown in the drawing to be the
`through the artery. The lower shear stresses can also
`25
`reduce the incidence of restenosis which is common in
`same they need not be the same.
`FIG. 3 depicts an alternative embodiment wherein
`over 30% of arterial dilatations.
`the second working section 30 is proximal to the ?rst
`The various in?atable working sections may also be
`working section 31. It is otherwise the same as the pre
`designed to in?ate to different diameters such as de
`viously discussed embodiment. The utilization is essen
`scribed in U.S. Pat. No. 5,002,532. The most distal
`tially the same except that the ?rst working section
`working section may be provided with a smaller in
`secures the in?atable member distal to the stenosis. The
`?ated diameter and be used to predilate the stenosis at a
`in?ated shapes of the working sections 30 and 31 are
`?rst pressure so that the second working section can be
`shown in phantom by 30’, 31’ and 31".
`subsequently advanced into the stenosis to be in?ated
`and complete the dilatation.
`FIG. 4 illustrates an alternative embodiment which is
`35
`a variant to the embodiment shown in FIGS. 1 and 2
`Other advantages of the invention will become more
`apparent from the following detailed description of the
`wherein a third in?atable working section 40 is pro
`vided distal to the second working section 41. This
`invention when taken in conjunction with the accompa
`nying exemplary drawings.
`construction allows the in?atable section to be secured
`within the lumen on both sides of the stenosis. The
`BRIEF DESCRIPTION OF THE DRAWINGS
`expansion of the third in?atable working section 40
`within the ?rst pressure range is shown in phantom at
`FIG. 1 is an elevational view, partially in section, of
`40’ and within the second higher pressure range is
`a dilatation catheter embodying features of the inven
`shown is phantom at 40". The expansions of the ?rst
`tion,
`expandable working section 42 is essentially the same as
`FIG. 2 is a transverse cross-sectional view of the 45
`for the third working section 40 and is designated 42'
`catheter shown in FIG. 1 taken along the lines 2—2.
`and 4 ".
`FIG. 3 is an elevational view, partially in section, of
`Another alternative embodiment is shown in FIG. 6.
`the distal portion of an alternative embodiment of the
`In this embodiment the ?rst and second in?atable work
`invention.
`4
`ing sections 50 and 51 are separated by an essentially
`FIG. 4 is an elevational view, partially in section, of 50
`nonin?atable portion 53. The other portions of the cath
`the distal portion of another alternative embodiment of
`eter are essentially the same as in the previous embodi
`the invention.
`FIG. 5 is a graphical representation of the relation
`ments and are similarly numbered. In this catheter de
`sign the in?ated diameter of the ?rst working section,
`ship between balloon diameter and in?ation pressure for
`shown in phantom and designated 50', is smaller than
`in?atable working sections of the invention.
`55
`the in?ated diameter of the second working section
`FIG. 6 is an elevational view, partially in section, of
`shown in phantom and designated 51’. The ?rst in?at
`the distal portion of another alternative embodiment of
`able working section 50 may be utilized to predilate a
`the invention.
`stenosis and then the catheter can be advanced within
`the artery until the second in?atable working section 51
`is disposed within the predilated stenosis and in?ated to
`complete the dilation of the stenosis.
`The dimensions of the dilatation catheters of the in
`vention may be conventional. However, the length of
`the in?atable section of the catheter will generally be
`longer than conventional dilatation balloons. The ?rst
`and third in?atable working sections of dilatation cathe
`ters for coronary angioplasty may be about 1 to about 5
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`FIGS. 1 and 2 schematically illustrate a dilatation
`catheter 10 embodying features of the invention which
`would be suitable for PTCA. The catheter 10 includes a
`catheter shaft 11, and in?atable section 12 on a distal
`portion of the catheter shaft and an adapter 13 on the
`proximal end of the catheter shaft. As shown, the cathe
`ter shaft 11 has an inner tubular member 14 and an outer
`
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`10
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`cm in length, whereas the second working section may
`be about 1 to about 3 cm in length, which is about the
`length of conventional dilatation balloons for coronary
`angioplasty. Typical diameters for coronary angio
`plasty may range from about 1 to about 4 mm. Other
`lengths and diameters may be used. For example, for
`prostatic urethral dilatations the in?ated diameter of the
`?rst working section may be in range of about 10 to
`about 30 mm.
`A presently preferred in?atable member of the inven
`tion may be made by ?rst extruding pellets of a zinc
`ole?nic ionomer, identi?ed as F1855 (a low molecular
`weight variant of 9020 Surlyn® from dupont, deNe
`mours 8: Co.) at a temperature between about 350° F. to
`about 450° F. into tubular stock. Upon exiting from the
`extrusion die, the tubular stock is quenched in a trough
`of cool water and then stabilized at about 40° C. to 80°
`C., typically about 60° C. for about 2 to about 6 hours,
`typically about 4 hours. The stabilized tubular product
`is then irradiated. The portion of the tubular member
`20
`which is to form the ?rst working section is irradiated at
`about 5 to about 20 Mrads, preferably about 5 to abut 1O
`Mrads, and the portion which is to form the second
`working section is irradiated at about 40 to about 70
`Mrads, preferably about 50 to about 60 Mrads. The
`25
`portions of the tubular product which are to be formed
`into the working sections of the in?atable member are
`then heat treated at ‘a temperature of about 225° F. to
`about 250° F. The portion of the tubular member which
`is to be the ?rst working section is subjected to an inter
`30
`nal pressure of about 50 to about 85 psi, preferably
`about 60 to about 75 psi, at the elevated temperature of
`the heat treatment to expand or blow this heat treated
`portion of the tubular member into a balloon which
`forms the ?rst working section. The balloon is blown
`35
`slightly larger than the desired in?ated size, e.g. up to
`about 3.1 m if an in?ated diameter of 3.0 mm is de
`sired. The balloon is blown within a capture or shaping
`tube to ensure that the desired balloon shape is obtained.
`After cooling, the blown balloon is heated to a tempera
`ture of about 55° C. to about 65° C. for about 10 to about
`30 minutes to heat shrink the balloon to a diameter
`about the same or slightly larger than its original diame
`ter to form the ?rst in?atable working section. The
`unblown heat treated portion of the tubular member
`45
`forms the second in?atable working section Preferably,
`a heat shrinkable sheath is placed about the balloon
`during the heat treatment so as to form the small wings
`generated around the inner member to reduce the pro
`?le. Curve A found in FIG. 5 illustrates the relationship
`between the outer diameter of a in?atable working
`section of a balloon and the internal pressure of the
`in?ation ?uid when a working section has been treated
`as described above. As indicated, the expansion of the ,
`working section is directly related to pressure, i.e. elas
`tic, up to about 9 atmospheres and after about 9 atmo- -
`spheres the rate of expansion, while constant indicating
`elastic expansion, decreases considerably.
`In another example, the same extruded and irradiated
`tubular product described above, which is formed of
`60
`zinc ole?nic ionomer, was treated by heat treating at
`about 225° F. to abut 250° F., but was not in?ated at the
`elevated temperature nor heat shrunk as in the prior
`example. Curve B in FIG. 5 illustrates a typical relation
`ship between the internal ?uid pressure and the outer
`balloon diameter of in?atable members or balloons
`which have been formed in this manner. In this case,
`there is relatively little expansion of the in?atable mem
`
`65
`
`8
`her until the internal pressure exceeds about 7 atmo
`spheres and then there is a substantial increase in the
`rate of expansion until the internal pressure reaches
`about 12 atmospheres. The expansion is elastic within
`this range. At about 12 atmospheres the rate of expan
`sion of the in?atable member is reduced considerably
`over the rate of expansion found between about 7 and
`12 atmospheres.
`While the present invention has been described
`herein in terms of coronary dilatation catheters, those
`skilled in the art will recognize that the catheter of the
`invention can be utilized in a variety of situations such
`as in the dilatation of a prostatic urethra of a male pa
`tient to treat benign hyperplasia. In this latter instance
`the ?rst working section, which in?ates at the lower
`pressure, may be disposed distal to the second working
`section so that it can be in?ated within the patient’s
`bladder to position the catheter within the urethra at the
`?rst pressure and then the second in?atable working
`section is in?ated to a second higher pressure to dilate
`the prostatic urethra.
`A variety of modi?cations can be made to the present
`invention. For example, the in?atable member need not
`be formed from the catheter shaft but may be formed
`separately and be secured to the distal end of the cathe
`ter shaft. The in?atable working sections of the in?at
`able portion of the catheter may likewise be formed as
`separate in?atable members and then subsequently
`joined to the catheter shaft by suitable means such as an
`adhesive. Other modi?cations and improvements can be
`made to the invention without departing from the scope
`thereof.
`~
`What is claimed is:
`1. An in?atable tubular member formed of polymeric
`material having:
`a ?rst in?atable working section which has an interior
`adapted to receive in?ation ?uid, which upon in?a
`tion to a ?rst internal pressure within a ?rst pres
`sure range expands substantially to a ?rst in?ated
`diameter and which is signi?cantly less compliant
`at pressures above the ?rst pressure range than
`pressures within the ?rst pressure range; and
`second in?atable working section longitudinally
`disposed from the ?rst in?atable working section
`which has an interior adapted to receive in?ation
`?uid and in ?uid communication with the interior
`of the ?rst in?atable working section, which does
`not expand signi?cantly upon in?ation to the ?rst
`internal pressure and upon in?ation to a second
`internal pressure within a second pressure range,
`higher than the ?rst internal pressure, expands to a
`second in?ated diameter.
`2. The in?atable member of claim 1 wherein the ?rst
`working section is located proximal to the second work
`ing section.
`3. The in?atable member of claim 1 wherein the ?rst
`working section is located distal to the second working
`section.
`4. The in?atable member of claim 2 wherein a third
`working section is located distal to the second working
`section which upon in?ation within a third pressure
`range, lower at least in part than the second pressure
`range, expands to a third in?ated diameter.
`5. The in?atable balloon of claim 4 wherein the ?rst
`pressure and the third pressure are essentially the same.
`6. The in?atable member of claim 1 wherein an essen
`tially nonin?atable section is disposed between the ?rst
`and second working sections.
`
`Page 8 of 11
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`10
`
`15
`
`20
`
`5,415,635
`7. The in?atable member of claim 1 wherein the
`working sections are formed of a polymer containing at
`least 70% of an olefmic ionomer selected from the
`group consisting of sodium, lithium and zinc ionomers
`and blends thereof.
`8. The in?atable member of claim 7 wherein the sec
`ond working section thereof has been given a thermal
`treatment within 50° C. of the crystalline melting point
`of the ionomer for a period of about 5 minutes to about
`60 minutes.
`9. The in?atable member of claim 7 wherein the ?rst
`working section thereof has been formed by thermal
`treating a tubular member of the requisite ole?nic iono
`mer within 50'’ C. of the crystalline melting point of the
`ionomer and subjecting the tubular member at elevated
`temperature to internal ?uid pressure at elevated pres
`sure to expand it.
`10. The in?atable member of claim 9 wherein the
`expanded tubular member is heat shrunk to a diameter
`smaller than the expanded diameter thereof to form the
`?rst working section.
`11. The in?atable member of claim 1 wherein the
`second working section of the balloon exhibits little
`expansion at pressures within the ?rst pressure range
`which expands the ?rst working section.
`12. A method of making a in?atable member having
`?rst and second working sections which in?ate at dif
`ferent pressure levels, comprising:
`a) extruding a tube formed of an ole?nic polymer;
`b) expanding a ?rst section of the tube to a ?rst outer
`diameter by subjecting the ?rst section to an ele
`vated temperature within 50° C. of the crystalline
`melting point thereof and to an elevated internal
`?uid pressure;
`c) heat shrinking the expanded ?rst section of the
`tube to a second outer diameter which is signi?
`cantly less;