United States Patent £19]
`Ariola et al.
`
`Ill
`
`1111~11111111 ~11111111111~ 11111111111
`US005697906A
`5,697,906
`[llJ Patent Number:
`[45] Date of Patent:
`Dec. 16, 1997
`
`[54]
`
`INTRA-AORTIC BALLOON CATHETER
`
`[75]
`
`Inventors: John Ariola, Norton; Kevin R. Heath.
`Weston, both of Mass.
`
`[73] Assignee: Boston Sciendfic Corporation, Natick,
`Mass.
`
`[21] Appl. No.: 816,200
`
`[22] Filed:
`
`Mar. 18, 1997
`
`Related U.S. Application Data
`
`[63] Continuation of Ser. No. 556,533, Nov. 13, 1995, aban-
`doned.
`Int. Cl.6
`.................................................... A61M 25100
`[51]
`[52] U.S. CI. ................................................................ 604/96
`[58] Field of Search ................................ 604/53. 96, 194,
`604/282; 606/194; 128/658, 772
`
`[56]
`
`References Cited
`
`5,243,996
`5,308,319
`5,341,818
`5,346,505
`5,397,306
`5,411,476
`5,439,443
`5,441,489
`5,449,343
`5,456,665
`5,460,607
`5,480,383
`5,505,699
`5,507,766
`
`9/1993 Hall ......................................... 1281772
`5/1994 Ide et al .................................... 600/18
`8/1994 Abrams et al .......................... 128/772
`9/1994 Leopold .................................. 606/194
`3/1995 Nobuyoshi et al ....................... 604196
`5/1995 Abrams et al ............................ 604195
`. ........................... 604196
`8/1995 Miyata et al.
`8/1995 Utsumi et al ........................... 6041180
`9/1995 Samson et al ............................ 604/96
`10/1995 Postell et al .............................. 604196
`............................ 604196
`l0/1995 Miyata et al.
`1/1996 Bagaaisan et al. ....................... 604196
`411996 Forman et al ............................ 604196
`411996 Kugo et al .............................. 606/194
`
`FOREIGN PJITENT DOCUMENTS
`
`340 304 A1 1111989 European Pat. Off ..
`WO 93/17750
`9/1993 WIPO .
`WO 95/24236
`9/1995 WIPO.
`
`Primary EXaminer-Manuel Mendez
`Attome)i Agen~ or Finn-Nawrock:i, Rooney & Sivertson,
`P.A.
`
`U.S. PATENT DOCUMENTS
`
`[57]
`
`ABSTRACT
`
`5/1982 Hanson et al ........................... 128/1 D
`4,327,709
`4,362,150 12/1982 Lombardi, Jr. et al. ................ 128/1 D
`2/1986 Schiff et al. ............................ 128/1 D
`4,569,332
`3/1987 Neuman et al ......................... 128/1 D
`4,646,719
`9/1990 Taylor et al. ........................... 128/657
`4,955,384
`4,994,018
`2/1991 Saper ........................................ 600/18
`2/1992 Montafis et al ........................... 604196
`5,090,957
`5/1992 Milder et al .............................. 600118
`5,116,305
`
`An improved intra-aortic balloon catheter having an outer
`tube of a polymeric material and an inner tube of superelas(cid:173)
`tic metal material with varying flexibility. The inner tube has
`a proximal end and a distal end The inner tube is more
`flexible proximate the distal end than the proximal end.
`
`14 Claims, 2 Drawing Sheets
`
`24
`
`12
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`U.S. Patent
`
`Dec. 16, 1997
`
`Sheet 1 of 2
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`5,697,906
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`U.S. Patent
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`Dec. 16, 1997
`
`Sheet 2 of 2
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`5,697,906
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`

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`5,697,906
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`1
`INTRA-AORTIC BALLOON CATHETER
`
`This application is a continuation of U.S. Ser. No.
`08/556,533, filed Nov. 13, 1995, now abandoned entitled
`''Intra-Aortic Balloon Catheter".
`
`FIELD OF THE INVENTION
`The present invention generally relates to the field of
`intravascular medicine, and more particularly to the field of
`catheters such as intra-aortic balloon catheters used for
`assisting the pumping action of the heart.
`
`2
`Metallic inner tubes have also been utilized. For example,
`stainless steel inner tubes are relatively less :flexible than
`plastic tubes, but due to the rigidity of stainless steel tubes,
`they do not as easily track a guidewire. In addition, stainless
`5 steel inner tubes are susceptlble to kinking at a relatively
`large kink radius. Superelastic metal alloy inner tubes can
`also be utilized to provide the finished catheter with a
`somewhat higher :flexibility or steerability than stainless
`steel versions. Superelastic metal alloy tubes can also have
`10 greater pushability than plastic inner tubes having the same
`wall thickness.
`One example of an intra-aortic balloon catheter having a
`superelastic metal alloy inner tube is disclosed in U.S. Pat.
`No. 5,456,665 to Postell et al., the disclosure of which is
`incorporated herein by reference. This catheter comprises a
`metal alloy inner tube which bas uniform longitudinal
`:flexibility. The metal alloy inner tube can be comprised of
`nitinol, which allows the inner tube to be more kink-resistant
`than those made from stainless steel, and thinner than those
`formed from plastic or metal ribbon wrapped plastic.
`The inner tube construction of Postell et al. does not
`provide a tube having varying :flexibility along its length.
`Consequently, the proximal end of the inner tube will be as
`:flexible as the distal end of the tube. It is preferable,
`however. that the proximal end of the inner tube be more
`rigid than the extreme distal end of the inner tube. Such a
`variation in :flexibility would provide high pushability along
`the majority of the length of the catheter, and high flexibility
`or steerability at the distal end of the catheter which must
`negotiate the vasculature tracking the guidewire.
`
`SUMMARY OF THE INVENTION
`
`BACKGROUND OF THE INVENTION
`The use of balloon catheters for treatment in the vascular
`system of the body is well known in the field of medicine. 15
`Intra-aortic balloon catheters are used in applications where
`a patient's heart requires assistance to circulate blood
`through such patient's vasculature.
`Over-the-wire intra-aortic balloon catheters have become
`a widely used type of intra-aortic balloon catheter. Over- 20
`the-wire balloon catheters are generally dual-lumen balloon
`catheters, including a shaft having an inner tube extending
`longitudinally from the proximal to the distal end of the
`catheter. The inner tube defines a guidewire lumen also
`extending longitudinally from the proximal to the distal end 25
`of the catheter to facilitate movement of the catheter over a
`guidewire. An in:flatablelde:flatable balloon is positioned
`such that its distal end is sealably attached to the distal end
`of the inner tube. The shaft of the intra-aortic balloon
`catheter also includes an outer tube extending longitudinally 30
`from the proximal end of the catheter to the proXima.I end of
`the balloon where it is sealably attached. The inner tube is
`generally coaxially disposed within the outer tube to define
`a :fluid :flow lumen or gas lumen therebetween from the
`The present invention relates to an improved intra-aortic
`proximal end of the catheter to the interior of the balloon. A 35 balloon catheter having an outer tube and an inner tube. The
`hub assembly is sealably attached to the proximal end of the
`inner tube is constructed utilizing kink-resistant superelastic
`metal material having varying :flexibility of the length
`shaft to provide means for supplying fluid pressure to the
`balloon through the gas lumen from an external pump.
`thereof and a high degree of pusbability. The inner tube is
`Generally, intra-aortic balloon catheters are constructed of
`most :flexible nearest its distal tip. The :flexible tip improves
`polymeric materials, such as a polyurethane balloon and 40 the steerability of the catheter and reduces the likelihood of
`outer tube, and a polymeric, stainless steel, or metal alloy
`vessel trauma during placement The flexibility of the tip end
`of the improved intra-aortic balloon catheter inner tube can
`inner tube.
`In operation, the intra-aortic balloon catheter is usually
`be designed to approach that of prior plastic inner tubes,
`introduced percutaneously into the femoral artery over a
`while the proximal end can have the pushability of prior
`guidewire, and advanced through the vasculature until the 45 catheters having metallic inner tubes.
`Although reference throughout this specification may be
`distal tip of the balloon is positioned just below or distal to
`the left subclavian artery. Care must be taken during inser-
`specifically made to intra-aortic balloon catheters, these
`tion to avoid any trauma or perforation, particularly when
`references are applicable to other catheter types such as
`the balloon is passing the branches, arteries or curves of the
`guide catheters, diagnostic catheters, coronary, neuro, gen-
`vasculature. Once in position, a balloon pump can be 50 eral periphery, and vascular type catheters.
`operated synchronously with the patient's heart beat In
`The present invention provides a dual-lumen intra-aortic
`particular, the balloon can be inflated and deflated to assist
`balloon catheter design which includes a shaft having an
`blood circulation from the heart by causing inflation to occur
`inner tube extending longitudinally from the proximal to the
`as the aortic valve is closing, and causing deflation to occur
`distal end of the catheter. The inner tube defines a guidewire
`ss lumen designed to accommodate a guidewire to facilitate
`just prior to the onset of systole.
`It is often difficult to advance a balloon assembly over a
`placement of the catheter. The inner tube is formed of a
`highly elastic, kink-resistant metal material such as nitinol
`guidewire for any great distance. Prior art designs which
`utilized plastic inner tubes are very fleXIble, but have poor
`having varying :flexibility and a high degree of pushability.
`circumferential rigidity. Typically, thick plastic walls were
`The inner tube is more flexible nearest its tip.
`required to provide adequate compressive strength to obtain 60
`An inflatable/de:flatable balloon is positioned such that the
`distal end of the balloon is sealably attached to the inner tube
`sufficient pushability. However, using thick-walled inner
`tubes results in a reduction in the gas lumen cross-sectional
`proximate its distal end. The shaft of the intra-aortic balloon
`area for an outer tube of a given inside diameter. The
`catheter of the present invention also includes an outer tube
`extending longitudinally from the proximal end of the
`reduction in cross-sectional area undesirably slowed defla-
`tion and inflation of the balloon. Metal ribbon wrapped 65 catheter to the proximal end of the balloon where it is
`sealably attached. The outer tube and balloon can preferably
`plastic inner lumens can also be used, but the added thick-
`ness of the metal wrap reduces the available gas lumen area
`be constructed of a polyurethane.
`
`

`
`5,697,906
`
`3
`The inner tube is coaxially disposed within the outer tube
`defining a :O.uid :How or gas lumen therebetween. A hub
`assembly is sealably attached to the proximal end of the
`shaft to provide means for supplying fluid pressure to the
`balloon through the gas lumen.
`In a preferred embodiment. the inner tube is comprised of
`three regions of flexibility over its longitudinal length. a high
`flexibility region distal, a transition region intermediate, and
`a low flexibility region proximal. The inner tube is prefer(cid:173)
`ably formed of a kink-resistant. superelastic metal material
`such as nitinol.
`A method of forming the three regions of flexibility of the
`inner tube is also provided. According to this method, the
`inner tube is manufactured from nitinol and the three regions
`of flexibility are formed by selective heat treatment of the
`inner tube in a high temperature salt bath. The method
`includes the steps of providing a nitinol tube having a
`predetermined austenite finish temperature as a starting
`material. A salt bath is then heated to a desired temperature.
`The nitinol tube is then dipped in the salt bath such that two
`of the three regions are submerged. The process of heating
`the nitinol tube raises its austenite finish temperature. and
`through a physical change in its material properties, the
`flexibility of the nitinol tube is increased. Since the third
`region is not submerged it will retain its original austenite
`finish temperature. The tube is then extracted slowly at a
`predetermined rate from the salt bath until only one region
`is submerged. After continued heat treatment of this single
`region to a desired austenite finish temperature, the nitinol
`tube is then removed from the salt bath.
`In an alternative version of the method of the present
`invention, the entire nitinol tube is initially submerged in the
`salt bath to achieve an overall desired austenite finish
`temperature. The tube is then removed, then reinserted and
`extracted slowly from the salt bath following the process
`described above until only the third region is submerged. In
`yet another alternative version of the method of the present
`invention, the entire nitinol tube is alternately held. then
`extracted at desired rates from the salt bath to create any
`desired number of austenite finish temperature transition
`regions and constant temperature regions along the length of
`the inner tube.
`
`BRIEF DESCRIPTION OF TilE DRAWINGS
`
`FIG. 1 is a schematic elevational view of the intra-aortic
`balloon catheter assembly of the present invention;
`FIG. 2 is a simplified partial cross-sectional view of the
`intra-aortic balloon catheter assembly of FIG. 1 showing the
`balloon assembly;
`FIG. 3 is a simplified partial cross-sectional view of the
`intra-aortic balloon catheter assembly of FIG. 1 showing the
`hub assembly; and
`FIG. 4 is an elevational view of the inner tube of the
`intra-aortic balloon catheter assembly of FIG. 1 having
`varying flexibility zones depicted thereon.
`
`35
`
`10
`
`4
`14 has a proximal end 15 and a distal end 19.Agas input and
`output tube 18 includes a proximal end 20 configured for
`connection to a balloon in:Oationlde:Oation pump and a distal
`end 22 connected to hub U. Catheter 10 has a proximal end
`5 24 and a distal end including a distal tip member 26.
`Proximal end 24 includes a fixture defining the proximal end
`of an inner tube 38 having guidewire lumen 28 (shown in
`FIGS. 2 and 3). Guidewire lumen 28 extends longitudinally
`through catheter 10.
`Catheter 10 can include a repositioning shield 30 having
`a proximal end 32 connected to hub U and a distal end 34
`configured to be connected to a proximal end of a catheter
`introducer (not shown). As generally known and understood
`in the art, the repositioning shield is easily axially com-
`15 pressible to allow balloon 14 and shaft 16 to be moved
`longitudinally relative to the catheter introducer.
`FIG. 2 is a longitudinal cross-sectional view of balloon 14
`of catheter 10 of FIG. 1. As shown in FIG. 2, shaft 16
`includes an outer tube 36 and an inner tube 38, generally
`20 concentrically disposed through outer tube 36. Inner tube 38
`includes a distal end 39. Outer tube 36 includes a distal end
`40. which is sealably connected to the proximal end 15 of
`balloon 14. Inner tube 38 extends distally through outer tube
`16 and balloon 14 to distal tip member 26. Inner tube 38 is
`25 preferably formed from a superelastic metal alloy. such as
`nitinol.
`A gas lumen 42, in fluid communication with the inside of
`the balloon 14, is defined between outer tube 36 and inner
`30 tube 38. Inner tube 38 defines guidewire lumen 28 there(cid:173)
`through to distal tip member 26. Tip member 26 defines the
`remaining distal portion of guidewire lumen 28. The distal
`end 19 of balloon 14 is adhered to distal tip member 26
`proximally. A strain relief 44 can be placed around inner
`tube 38, where tube 38 extends from distal tip member 26.
`Distal tip member 26 can include a marker band 46 to assist
`the physician in locating the distal tip of catheter 10 by
`radiological means.
`FIG. 3 is a partial cross-sectional view of catheter 10
`40 taken where shaft 16 and repositioning shield 30 are con(cid:173)
`nected to hub U. As shown in FIG. 3, outer tube 36 includes
`a proximal end 48 connected to hub 12 and extending
`distally therefrom. Inner tube 38 also includes a proximal
`end 50 connected to hub 12 and extending distally therefrom
`45 through outer tube 36. A typical guidewire 52 extends
`through guidewire lumen 28. Inner tube 38 defines most of
`guidewire lumen 28, however, the portion of guidewire
`lumen 28 extending between proximal end 50 of tube 38 and
`proximal end24 of catheter 10 is defined by hub 12. Hub 12
`50 also defines a portion of gas lumen 42 fluidly connecting that
`portion of gas lumen 42 defined by outer tube 36 and inner
`tube 38 with a lumen extending through gas tube 18. For
`clarity, strain relief 17 is not shown in FIG. 3.
`The balloon 14 and outer tube 36 are preferably formed
`55 from polyurethane, and are preferably formed in one con(cid:173)
`tinuous piece having no adhesive joint at the proximal end
`of balloon 14. As well known in the art of balloon
`catheterization, numerous other materials may be used to
`form outer tube 38 and/or balloon 14. Also, balloon 14 need
`60 not be formed in one piece with outer tube 38. Distal tip
`member 26 is preferably formed from polyurethane. but may
`be formed from any other suitably biocompatible flexible
`material.
`FIG. 4 is a partial elevational view of the intra-aortic
`balloon catheter 10 of FIG. 1, showing the inner tube 38. The
`inner tube 38 includes three regions, a high flexibility region
`A. a transition region B. and a low flexibility region C. The
`
`DEfAaED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`Referring now to the drawings. wherein like reference
`numerals refer to like elements throughout the several
`views, FIG. 1 shows an elevational view of the intra-aortic
`balloon catheter 10 in accordance with the present invention.
`Catheter 10 includes a hub U, a balloon 14 and a shaft 16 65
`extending therebetween. A strain relief 17 can provide a
`transition in flexibility between hub 12 and shaft 16. Balloon
`
`

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`5,697,906
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`15
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`20
`
`5
`three zones of flexibility of inner tube 38 result in a high
`degree of pushability, while maintaining a more flexible tip.
`In a preferred embodiment, the inner tube 38 is formed of
`nitinol, and the three regions of flexibility are defined by
`treatment of inner tube 38 in a high temperature salt bath. A 5
`nitinol tube having an austenite finish temperature of
`19°-20° C. as starting material is first provided. A salt bath
`is then heated to a temperature in the range of 450° C. to
`550° C. The nitinol tube is then immersed in the salt bath
`such that region A and B are submerged. The process of
`heating the nitinol tube raises its austenite finish
`temperature, and through a physical change in its material
`properties, the flexibility of the nitinol tube is increased.
`Since region C is not submerged it will retain its original
`austenite finish temperature of 19°-20° C. The tube is then
`extracted slowly at a selected rate from the salt bath until
`only region A remains submerged. This extraction time is
`typically in the range of 15-45 minutes. The nitinol tube is
`then removed from the salt bath after section A has achieved
`a selected austenite finish temperature. Although a molten
`salt bath is preferred, other means of heating the nitinol tube
`can be utilized.
`There is an inverse relationship between the necessary
`extraction time and the temperature of the salt bath. A higher
`temperature salt bath, for example, will require a shorter
`extraction time to reach the target austenite finish tempera(cid:173)
`ture. In this preferred embodiment, the final austenite finish
`temperature of region A is 30° C. Region C will have a
`constant austenite finish temperature of 20° C. Region B will
`have an austenite finish temperature that varies from zoo C.
`at the interface to region C, to 30° C. at the interface to
`region A. In this preferred embodiment, it is desirable that
`region A have a length that is approximately two inches, and
`that region B have a length of approximately Z inches. In
`operation, balloon 14 preferably has a length of between
`6-12 inches. It is understood. however, that regions A and B
`and balloon 14 can be varied.
`In an alternative method of treatment, the entire nitinol
`tube is initially submerged in the salt bath to achieve a
`desired austenite finish temperature for region C. The tube is
`then removed, then reinserted and extracted slowly from the
`salt bath following the process described in the preferred 40
`embodiment above until only region A is submerged. The
`extraction time is determined by the desired austenite finish
`temperature for region A. The nitinol tube is then removed
`from the salt bath. It is understood in the alternative embodi(cid:173)
`ment that the austenite finish temperature of region C, 45
`transition region B, or region A can be of any desired value
`as long as the austenite finish temperature of region A is
`greater than the austenite finish temperature of region C.
`In another alternative method of treatment, the nitinol
`tube is extracted at a desired nonconstant rate in order to 50
`create a nonlinear transition region B. In this embodiment,
`transition region B will have a nonlinear variation in aus(cid:173)
`tenite finish temperature as a function of tube length.
`In yet another alternative method, the nitinol tube is
`alternately held, then partially extracted at desired rates, thus
`creating any desired number of austenite finish temperature
`transition regions and constant temperature regions.
`Numerous characteristics and advantages of the invention
`covered by this document have been set forth in the fore(cid:173)
`going description. It will be understood, however, that this
`disclosure is, in many respects, only illustrative. Changes
`may be made in details, particularly in matters of shape, size,
`and arrangement of parts without exceeding the scope of the
`invention. The invention's scope is, of course, defined in the
`language in which the appended claims are expressed.
`What is claimed is:
`l. In a catheter including a shaft having a proximal end,
`a distal end, and a balloon disposed proximate the distal end
`
`6
`of the shaft, wherein the shaft includes an outer tube and
`inner tube disposed therethrough the improvement charac(cid:173)
`terized by:
`the inner tube comprising a nitinol tube having at least a
`first region of flexibility and a second region of flex(cid:173)
`ibility along the longitudinal length thereof wherein the
`first region has a greater flexibility and a higher aus(cid:173)
`tenite finish temperature than the second region.
`2. The catheter in accordance with claim 1, wherein the
`10 austenite finish temperature of the first region is at least
`about 33° C.
`3. The catheter in accordance with claim l, wherein the
`austenite finish temperature of the second region is at most
`about 20° C.
`4. The catheter in accordance with claim l, wherein the
`first region is distal of the second region.
`5. The catheter in accordance with claim 4, wherein the
`inner tube further comprises a third region of flexibility
`disposed longitudinally between the first and second regions
`of flexibility.
`6. The catheter in accordance with claim 5, wherein the
`flexibility of the third region of flexibility has a distal end
`proximate the first region of flexibility and a proximal end
`proximate the second region of flexibility and the flexibility
`of the third region varies between the first and second
`25 regions of flexibility, the third region being most flexible
`proximate the distal end and least flexible proximate the
`proximal end.
`7. The catheter in accordance with claim 6, wherein the
`austenite finish temperature of the third region varies
`30 between at least about 30° C. proximate the distal end to at
`most about 20° C. proximate the proximal end.
`8. An intra-aortic balloon catheter, comprising:
`a shaft having a proximal end and a distal end, the shaft
`including an outer tube and a nitinol tube disposed
`within the outer tube, wherein the nitinol tube defines
`a guidewire lumen therethrough and the inner and outer
`tube define an inflation lumen therebetween;
`a balloon disposed at the distal end of the shaft, wherein
`the inflation lumen is in fluid communication with the
`interior of the balloon; and
`the nitinol tube having at least a first region of flexibility
`and a second region of flexibility wherein the first
`region has a greater flexibility and a higher austenite
`finish temperature than the second region.
`9. The catheter in accordance with claim 8, wherein the
`finish temperature of the first region is at least about 33° C.
`10. The catheter in accordance with claim 8, wherein the
`austenite finish temperature of the second region is at most
`about zoo C.
`11. The catheter in accordance with claim 8, wherein the
`first region is distal of the second region.
`12. The catheter in accordance with claim 11, wherein the
`inner tube further comprises a third region of flexibility
`disposed between the first and second regions of flexibility.
`13. The catheter in accordance with claim 12, wherein the
`55 flexibility of the third region of flexibility has a distal end
`proximate the first region of flexibility and a proximal end
`proximate the second region of flexibility and the flexibility
`of the third region varies between the first and second
`regions of flexibility, the third region being most flexible
`60 proximate the distal end and least flexible proximate the
`proximal end.
`14. The catheter in accordance with claim 13, wherein the
`austenite finish temperature of the third region varies
`between at least about 30° C. proximate the distal end to at
`65 most about 20° C. proximate the proximal end.
`
`35
`
`* * * * *