Abstract:
A catheter comprising an inflatable balloon having a proximal end, a distal end, and an inflation cavity therebetween, a catheter shaft having the inflatable balloon affixed proximate a distal end thereof, the catheter shaft having an inflation lumen fluidly connected to the balloon inflation cavity. A guidewire lumen extends through the balloon cavity within a tubular member which is affixed to the inflatable balloon proximate the distal end. A reinforcing sleeve, having a proximal portion and a distal portion with a lumen extending therethrough, wherein the distal portion of the sleeve extends into the inflation cavity with at least a portion of the tubular member slidably disposed through the lumen thereof and the proximal portion is fixed relative to the catheter shaft and disposed in the catheter shaft inflation lumen.

Description:
FIELD OF INVENTION  
       [0001]     This invention relates generally to medical devices including balloon catheters. More specifically, the present invention relates to an improved shaft design for an angioplasty or stent delivery catheter.  
       BACKGROUND OF THE INVENTION  
       [0002]     In angioplasty, a balloon catheter is generally inserted into a patient&#39;s vasculature percutaneously, usually into a femoral or radial artery. The balloon is then advanced until it reaches the treatment site, at which there is usually a stenosis or other occlusion, and expanded to compress or displace the stenosis and improve the flow of blood. In some procedures, the expandable balloon can carry a stent to be expanded at the occlusion site.  
         [0003]     To efficiently and accurately advance a balloon catheter to a treatment site, guide catheters and guidewires are often positioned first. A balloon catheter may then be advanced over a guidewire and through a guide catheter. Consequently, a typical balloon catheter is constructed in the following manner. There is an inner tubular member having a lumen for a guidewire. This tubular member has an opening at the distal end of the balloon catheter for the introduction of the guidewire, and a more proximal opening for the egress of the guidewire. Disposed over this inner tubular member is an outer tubular member; the annular space between the first tubular member and the outer tubular member forms an inflation lumen for the balloon. A distal end of the balloon is sealed to the first tubular member and a proximal end is sealed to the outer tubular member.  
         [0004]     The inner tubular member typically has a distal portion, often approximately the length of the balloon, that extends beyond the distal end of the outer tubular member. Thus, the distal portion of the balloon catheter may include only the distal portion of the inner tubular member and the balloon. This may make the distal end of the balloon catheter more flexible than may be desired. Also, when the balloon catheter is advanced through a patient&#39;s vasculature, much of the force resisting the advance of the balloon catheter is acting on this distal portion of the inner tubular member. This may cause the inner tubular member and the balloon to prolapse within the outer tubular member.  
         [0005]     U.S. Pat. No. 5,425,712 to Goodin, entitled “Dilation Catheter Having Soft Bumper Tip”, herein incorporated by reference, alleviates some of these issues. It discloses a catheter including the features described above. Goodin also discloses bonding the inner tubular member to a distal portion of the outer tubular member adjacent to the proximal neck portion of the balloon. This provides additional support for the distal end of the balloon catheter.  
         [0006]     However, this also creates a balloon catheter in which both the proximal and distal ends of the balloon are fixed to the inner tubular member. It has been found that balloons grow longitudinally during inflation at least 2% and sometimes up to 10%. If the inner tubular member is not attached at the proximal end of the balloon, the entire length of the inner tubular member can accommodate this growth, resulting in a low strain that is under the elastic limit of many materials common to this application. However, if the inner tubular member is attached at the proximal end the balloon, as is the case, for example, in Goodin, only the distal section of the inner tubular member, which is a much shorter segment, is free to accommodate this growth. This results in a significantly higher strain over this distal section, and this strain may be over the elastic limit of many of the materials used in this application.  
         [0007]     U.S. Pat. No. 6,066,157 to Barbere entitled “Anchor Joint for Coaxial Balloon Dilation Catheter” attempts to address this problem by its balloon catheter. Barbere proposes a balloon catheter having a distal balloon, an outer catheter and an inner catheter, with the inner catheter defining a guidewire lumen, and the inner and the outer catheters defining an inflation lumen. The outer tubular member tapers distally and ends near an abutment member disposed on the inner tube in the balloon. This allows the inner catheter to move distally during expansion and prevents the abutment member, and consequently the inner member, from moving proximally. The abutment member creates an area of increased stiffness in the balloon portion.  
         [0008]     It would be desirable to provide a balloon catheter which can provide additional distal support, yet avoid higher strain on a portion of the balloon catheter.  
       SUMMARY OF THE INVENTION  
       [0009]     One example embodiment pertains to a single-operator-exchange balloon catheter. The distal portion of the device has an inner tubular member, an outer tubular member and a balloon. The inner tube extends through the balloon. The distal end of the balloon is sealed to the inner tubular member, and the proximal end of the balloon is sealed to the outer tubular member. A reinforcing sleeve is slidably disposed over the inner tubular member and is attached to the outer tubular member at a distal connection point. The attachment may include a tie material. In one preferred embodiment, the reinforcing sleeve extends proximally to the distal connection point and distally into the balloon inflation cavity. Alternatively, the reinforcing sleeve may extend to near the distal end of the balloon, and may extend further proximally. In another alternative embodiment, the reinforcing sleeve extends to the balloon tip. A single bond area including the inner shaft, reinforcing sleeve and distal balloon waist can then be utilized to improve pushability and column strength.  
         [0010]     Another example embodiment pertains to an over-the-wire balloon catheter. The distal portion of the device has an inner tubular member, an outer tubular member and a balloon wherein the inner tubular member extends through the balloon. A reinforcing tubular member is attached to the outer tubular member and slidably disposed over the inner tubular member, and may extend distally to the distal balloon cone.  
         [0011]     The above summary of some embodiments is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures, and Detailed Description which follow, more particularly exemplify these embodiments. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:  
         [0013]      FIG. 1  is a partial plan view with cross-sections of an example single-operator-exchange balloon catheter;  
         [0014]      FIG. 2  is a cross-sectional view of the catheter of FIG. I taken along line  2 - 2 ;  
         [0015]      FIG. 3  is a partial cross-sectional view of an example over-the-wire catheter;  
         [0016]      FIG. 4  is a partial cross-sectional view of an example cutting balloon catheter; and  
         [0017]      FIG. 5  is a partial cross-sectional view of an alternative single-operator exchange catheter. 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0018]     The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The drawings, which are not necessarily to scale, depict illustrative embodiments of the claimed invention.  
         [0019]      FIG. 1  is a partial plan view with portions in cross-section of an example single-operator-exchange balloon catheter  10  having a proximal end  12  with an outer tubular lo member  14  and a proximal hub assembly  16 . Balloon catheter  10  may be used for an angioplasty procedure, a stent delivery procedure, or other therapeutic technique. An inner tubular member  18  is introduced through a wall of outer tubular member  14  and extends distally past a balloon  20 . Outer tubular member  14  may terminate distally proximate the proximal end of balloon  20 , and the proximal end of balloon  20  may be sealed to outer tubular member  14 . The distal end of balloon  20  may be sealed to inner tubular member  18 . A lumen  22  of inner tubular member  18  may be a guidewire lumen. Of course, while tubular member  14  is called an outer tubular member, and tubular member  18  is called an inner tubular member, these terms are not meant to imply that tubular member  14  must be the outermost tube and tubular member  18  must be the innermost tube. While this configuration is contemplated and described herein, other configurations with one or more tubular members outside tubular member  14  or inside tubular member  18  are also contemplated. Slidably disposed on inner tubular member  18  is a reinforcing sheath  24 . Reinforcing sheath  24  may extend from a point proximate the distal end of the outer tubular member  14  distally into the balloon  20  inflation cavity  21  or into a distal cone  23  of balloon  20  or other desired location. For example, reinforcing sheath  24  may extend halfway into the balloon  20  inflation cavity, may extend to the distal balloon cone, or may extend into the balloon cone. Reinforcing sheath  24  and inner tubular member  18  may be axially aligned with the center of the lumen of outer tubular member  14  or may be offset toward one wall, if desired.  
         [0020]     In one preferred embodiment, reinforcing sheath  24  is attached to outer tubular member  14  at an attachment point  26 .  FIG. 2  is a cross-sectional view of balloon catheter  10  at attachment point  26 . In this embodiment, an adhesive  28  is provided between outer tubular member  14  and reinforcing sheath  24  at attachment point  26 . Adhesive  28  may occupy part of the annular lumen between reinforcing sheath  24  and outer tubular member  14  to provide stability to the bond between the sheath and the tubular member, and may also leave the substantial part of the lumen free for rapid inflation and deflation. In this way, the size of the inflation lumen may be optimized. Alternatively, a heat bond could be utilized.  
         [0021]     Attachment point  26  may be at any point distal the proximal end of inner tubular member  18  and proximal the distal end of outer tubular member  14 . It may, for example, be proximate the distal end of outer tubular member  14  as shown in  FIG. 1 . Reinforcing sheath  24  may terminate proximally at or near attachment point  26  or may continue proximally past attachment point  26  to alter the flexibility and stiffness of balloon catheter  10 . For example, referring to  FIG. 2 , reinforcing sheath  24  may extend 20-25 cm into outer tubular member  114 , or other suitable distance.  
         [0022]     The term “slidably” is herein defined to mean both a loose fit between the inner tubular member and the reinforcing sheath where the diameter of the inner surface of reinforcing sheath  24  is as large or larger than the diameter of the outer surface of inner tubular member  18  and also certain configurations where the diameter of the inner surface of reinforcing sheath  24  is smaller than the diameter of the outer surface of inner tubular member  18  provided that the tubular member may slide within the reinforcing sheath prior to reaching plastic deformation and return to an unstrained position when the balloon is deflated. There may, of course, also be a gap between reinforcing sheath  24  and tubular member  18 , if desired.  
         [0023]      FIG. 3  is a cross-sectional view of an example over-the-wire balloon catheter  110 . Balloon catheter  110  has an inner tubular member  118  extending proximally within outer tubular member  114  to proximal end  112  in an over-the-wire fashion, but is otherwise similar to balloon catheter  10  except for differences herein pointed out. In balloon catheter  110 , reinforcing sheath  124  is bonded to outer tubular member  114  at attachment point  126 . This bonding may be done by laser welding or other suitable method. This bonding may require reinforcing sheath  124  and inner tubular member  118  to be axially offset with respect to the center of the lumen of outer tubular member  114  at the attachment point  126 . The diameter of the inner surface of reinforcing member  124  may be slightly larger than the diameter of the outer surface of inner tubular member  118 . Reinforcing member  124  may extend distally into the distal cone of balloon  120  and may extend to the distal joint between balloon  120  and inner member  118 . Reinforcing member  124  may have a distally tapering distal end  134 .  
         [0024]      FIG. 4  is a partial cross-sectional view of the distal portion of an example cutting balloon catheter  2 l 0 . Cutting balloon catheter  210  includes outer tubular member  214 , inner tubular member  218  and cutting balloon  220  with cutting surfaces  230 . Slidably disposed over inner tubular member  218  and extending distally into balloon  220  cavity is reinforcing member  224 . Reinforcing member  224  is fixed to outer tubular member  214  by adhesive  228 . Radiopaque markers  232  may be disposed on reinforcing member  224  or at other desired locations.  
         [0025]      FIG. 5  is a partial cross-sectional view of the distal portion of another example single-operator-exchange balloon catheter  310 . Balloon catheter  310  has an outer tubular member  314 , an inner tubular member  318  and a balloon  320 . A reinforcing member  324  is disposed over inner tubular member  318  and extends distally to proximate the distal end of balloon  320  and proximally past attachment point  326 . Reinforcing sheath may extend proximally past attachment point  326  1-25 cm, 1-20 cm, 1-10 cm, or 1-5 cm.  
         [0026]     The balloon may be made from typical angioplasty balloon materials including polymers such as polyethylene terephthalate (PET), polyetherimide (PEI), polyethylene (PE), etc. Some other examples of suitable polymers, including lubricious polymers, may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM), polybutylene terephthalate (PBT), polyether block ester, polyurethane, polypropylene (PP), polyvinylchloride (PVC), polyether-ester (for example, a polyether-ester elastomer such as ARNITEL® available from DSM Engineering Plastics), polyester (for example, a polyester elastomer such as HYTREL® available from DuPont), polyamide (for example, DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA, for example, available under the trade name PEBAX®), silicones, Marlex high-density polyethylene, Marlex low-density polyethylene, linear low density polyethylene (for example, REXELL®), polyetheretherketone (PEEK), polyimide (PI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polysulfone, nylon, perfluoro(propyl vinyl ether) (PFA), other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like. In some embodiments, it may be desirable to use high modulus or generally stiffer materials so as to reduce balloon elongation. The above list of materials includes some examples of higher modulus materials. Some other examples of stiffer materials include polymers blended with liquid crystal polymer (LCP) as well as the materials listed above. For example, the mixture can contain up to about 5% LCP.  
         [0027]     The inner and outer tubular members may be manufactured from a number of different materials. For example, the tubular members may be made of metals, metal alloys, polymers, metal-polymer composites or any other suitable materials. Some examples of suitable metals and metal alloys include stainless steel, such as 300 series stainless steel (including 304V, 304L, and 316L; 400 series martensitic stainless steel; tool steel; nickel-titanium alloy such as linear-elastic or super-elastic Nitinol, nickel-chromium alloy, nickel-chromium-iron alloy, cobalt alloy, tungsten or tungsten alloys, MP35-N (having a composition of about 35% Ni, 35% Co, 20% Cr, 9.75% Mo, a maximum 1% Fe, a maximum 1% Ti, a maximum 0.25% C, a maximum 0.15% Mn, and a maximum 0.15% Si), hastelloy, monel 400, inconel 825, or the like; or other suitable materials. Some examples of suitable polymers include those described above in relation to balloon  16 . Of course, any other polymer or other suitable materials including ceramics may be used without departing from the spirit of the invention. The materials used to manufacture inner tubular member  18  may be the same as or be different from the materials used to manufacture outer tubular member  14 . Of course, a tubular member may incorporate layers or blends of certain polymers to get certain properties. For example, the inner tubular member may have a high density polyethylene inner layer, a polyether block amide polymer outer layer, and a linear low density polyethylene tie layer between the inner layer and the outer layer.  
         [0028]     The reinforcing sheath may be made from any of the materials described above to with respect to the tubular members, or it may be made from other materials. In preferred embodiments, the reinforcing sleeve is elastic (recovers all or almost all the imposed strain up to about 10%). The material of construction is preferably an elastomer or elastomer-based material. An example of an elastomer is Kraton G1657, a relatively stiff styrene-butadiene polymer from Kraton Polymers or, alternatively, PEBAX® 7233 or 7033. An elastomer-based material can include a composite of a brittle polymer and softer elastomer. The reinforcing sheath may be extruded separately and assembled onto the inner tubular member or may be coextruded with the inner tubular member.  
         [0029]     It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the invention. The invention&#39;s scope is, of course, defined in the language in which the appended claims are expressed.