Patent Publication Number: US-2003236495-A1

Title: Non-buckling balloon catheter

Description:
RELATED APPLICATIONS  
     [0001] This application claims the benefit of U.S. Provisional Application No. 60/381,975, filed May 16, 2002, entitled “Non-Buckling Balloon Catheter”. 
    
    
     
       TECHNICAL FIELD  
       [0002] This invention relates to medical devices, and more particularly to balloon catheters that can be placed within a body lumen and inflated to perform various medical procedures. The invention is especially relevant to balloon catheters with balloons formed of non-elastomeric films or materials, wherein the film that forms the balloon is folded and unfolded during deflation and inflation, respectively, of the balloon.  
       BACKGROUND OF THE INVENTION  
       [0003] Balloon catheters are used to perform various medical procedures wherein the balloon is positioned within a body lumen or canal and subsequently inflated. In some of these medical procedures, such as in an angioplasty procedure, the balloon is inflated so as to expand the interior volume of the body canal. In this type of procedure, the balloon is expanded to apply pressure to the interior surface of the body canal to thereby compress any tissue protruding into the canal and thereby enlarge the interior volume thereof. Once the tissue has been compressed, and the body canal widened, the balloon is deflated and removed.  
       [0004] In other types of medical procedures, such as photodynamic therapy (PDT), a balloon catheter is used to align and stabilize the catheter within the body lumen. For example, the balloon catheter may be inflated under low pressure within a body lumen such as the esophagus. A therapeutic fiber optic device is then inserted into the catheter in the vicinity of the balloon. The therapeutic fiber optic device is then used to emit light waves to treat the surrounding tissue. In this procedure, the balloon is used to both align the catheter in the center of the body lumen, and to prevent the catheter from moving during the PDT procedure. However, the tissue to be treated must not be unduly compressed by the expanded balloon. Thus, the balloon is expanded only enough to lightly contact the interior surface of the lumen and align the catheter.  
       [0005] As will be explained below, conventional balloon catheters have a number of shortcomings that make them inadequate for many of the above-described procedures, and in particular, for PDT procedures.  
       [0006] A typical balloon catheter  100  is shown in FIGS.  5 A- 5 D. As best seen in FIG. 5A, a conventional balloon catheter  100  comprises a balloon  102  that is affixed to a catheter  104 . The balloon  102  is typically manufactured from a non-elastomeric material (e.g., a semi-rigid or non-compliant material), and includes a distal neck or end  106 , a proximal neck or end  108  and a central portion  110 . The balloon  102  is affixed to the catheter  104  by inserting the distal end  112  of the catheter  104  into and through the proximal end  108  of the balloon  102 . The balloon  102  is then slid over the catheter  104  until the distal end  112  of the catheter  104  is inserted into the distal end  106  of the balloon  102 . The distal end  112  of the catheter  104  is then affixed to the distal end  106  of the balloon  102  by an adhesive, ultrasonic welding, or some other method. The proximal end  108  of the balloon  102  is similarly affixed to the outer wall of the catheter  104  so as to anchor and seal the proximal end of the balloon  102 .  
       [0007] The catheter  104  includes an aperture  114  for the introduction of air or some other fluid into the interior volume of the balloon  102 . Although not shown in the drawings, the proximal end of the catheter  104  is typically attached to a device, such as a syringe, that is manipulated to either inflate or deflate the balloon  102  by injecting a fluid into or withdrawing a fluid from, respectively, the interior volume of the balloon  102 .  
       [0008] The conventional balloon catheter  100  has a number of drawbacks for use in many of the above-described procedures, and in particular, for use in PDT procedures. When initially manufactured, the balloon catheter  100  generally assumes a shape and configuration as depicted in FIG. 5A. As can be seen in this drawing, the central portion  110  of the balloon  102  is connected to the distal end  106  and the proximal end  108  by tapered or conical sections  116 . The tapered sections  116  provide a transition between the larger diameter of the central portion  110  of the balloon  102  and the outermost portions of the balloon  102  (i.e., the distal end  106  and the proximal end  108 ) that are connected to the catheter  104 .  
       [0009] At the time of packaging by the manufacturer or at the initiation of the medical procedure, the balloon  102  is typically deflated prior to inserting of the balloon catheter  100  into the body canal. Deflation of the balloon  102  is necessary to reduce the overall cross-section or diameter of the device to permit it to pass through an endoscope and/or to navigate and pass through the body&#39;s internal canals. FIG. 5B depicts the balloon catheter  100  in the deflated state. As can be seen in this drawing, the balloon  102  is forced to compress in length. This is because the overall length of the material that forms the central portion  110  and the tapered portions  116 , as measured along the surface of the balloon  102  in a generally axial direction of the catheter  104  (i.e., from one end of the balloon  102  to the other), is greater than the distance between the distal end  106  and the proximal end  108 . As a result of this compression, transverse creases  118  typically form along the surface of the balloon  102 .  
       [0010] After the balloon catheter  100  is positioned within the body canal (not shown) at the desired location, inflation of the balloon  102  is initiated as shown in FIG. 5C. As depicted in this drawing, the creases  118  in the surface of the material may prevent the balloon  102  from fully expanding to its normal length (i.e., as shown in FIG. 5A). In other words, the balloon  102  tends to act like a spring under tension. As a result, the portion of the catheter  104  that lies between the distal end  106  and the proximal end  108  of the balloon  102  will be forced into compression, and may begin to bow  120  as a result of these compressive forces.  
       [0011] As inflation of the balloon  102  continues, bowing  120  of the catheter  104  may be increased as shown in FIG. 5D. This is the result of transverse or outward expansion of the central portion  110  of the balloon, which tends to pull the distal end  106  and the proximal end  108  towards each other.  
       [0012] Bowing  120  of the catheter  104  may not be eliminated until a sufficiently high inflation pressure is applied to the balloon  102  (see FIG. 5A). However, some bowing  120  of the catheter  104  may nevertheless remain if the initial deflation of the balloon  102  (see FIG. 5B) resulted in the formation of permanent transverse creases  118 . Permanent bowing  120  of the catheter  104  is more likely if the balloon  102  is constructed from a non-elastomeric material.  
       [0013] The formation of transverse creases  118  and the bowing  120  of the catheter  104  can negatively impact the use of the conventional balloon catheter  100  during certain medical procedures. For example, during angioplasty procedures, permanent creases  118  in the surface of the balloon  102  may prevent the complete or uniform compression of the tissue on the interior surface of the body canal against which the balloon  102  is expanded. This may result in a decrease in effectiveness of the angioplasty procedure.  
       [0014] With respect to PDT procedures, any bowing  120  of the catheter  104  can prevent accurate alignment and centering of the catheter  104  within the body lumen or canal to be treated. This is because typical PDT procedures do not allow the expanded balloon  102  to exert excess pressure or heavy contact on the interior surface of the body lumen. Thus, the balloon  102  cannot be inflated with a pressure that is sufficient to eliminate any bowing  120  of the catheter  104 . The catheter  104  may consequently not be properly centered in the body lumen. As a result, effective treatment of the body lumen tissue with the therapeutic fiber optic device, which is positioned inside the catheter  104 , may be inhibited.  
       [0015] In addition, because the distal end  106  and the proximal end  108  of the balloon  102  are both fixed to the catheter  104  at permanent (i.e., non-moveable) locations, the ability to reduce the diameter of the deflated balloon  102  may be limited, particularly if the balloon  102  is manufactured from a non-elastomeric material. In other words, the central portion  110  of the balloon  102  may not compress tightly about the catheter  104  during deflation because of the creases  118  formed in the material of the balloon  102  (see FIG. 5B). Bunching of the balloon material may likewise limit the deflated diameter or cross-section of the balloon  102 . Consequently, the device may be more difficult to maneuver during ingress or egress of the device through the body&#39;s canals. In addition, the resulting “wrinkled” surface of the balloon  102  may cause irritation to body canal tissue during ingress or egress of the device and/or prevent the device from passing through the endoscope channel.  
       [0016] What is needed is an improved balloon catheter that overcomes the disadvantages of the conventional devices. In particular, what is needed is a balloon catheter that can be deflated to a minimal diameter for ingress and egress through the body&#39;s canals and/or an endoscope channel, that resists the formation of transverse creases in the surface of the balloon during deflation, and that resists bowing of the catheter portion located within the balloon upon inflation.  
       SUMMARY OF THE INVENTION  
       [0017] The foregoing problems are solved and a technical advance is achieved by the balloon catheter of the present invention. The balloon catheter includes a rounded or cylindrically shaped balloon that is affixed to a catheter. The balloon includes a distal end, a proximal end and a central portion, and may be formed of a non-elastomeric material. The balloon is attached to the catheter by inserting the distal end of the catheter into and through the proximal end of the balloon until the distal end of the catheter is inserted into a portion of the distal end of the balloon. The proximal end of the balloon is then affixed to the outer wall of the catheter so as to provide an air tight seal between these components.  
       [0018] The distal end of the catheter is  not  affixed to the distal end of the balloon. Instead, a slip joint is formed between these components. The slip joint allows the distal end of the balloon to axially move or translate with respect to the distal end of the catheter.  
       [0019] Alternatively, the catheter may be terminated so as to not contact the distal end of the balloon, thereby eliminating the slip joint altogether. Or the catheter can be segmented so that separate components are connected to each end of the balloon, but are allowed to move relative to each other.  
       [0020] The above-described configurations allow the overall length of the balloon to change during inflation or deflation, the change in length of the balloon not being impeded by the predetermined length of the catheter. In addition, the above-described configurations prevent the relative axial rigidity of the catheter from generating any axial tensile or compressive forces in the balloon. Consequently, transverse creasing of the central portion of the balloon is eliminated or at least minimized. Moreover, the central portion of the balloon can be collapsed into a smaller diameter or cross-section for ingress or egress of the balloon catheter through the body&#39;s canals and/or the endoscope channel.  
       [0021] The slip joint (or the elimination of a continuous catheter connected between both ends of the balloon) also prevents balloon from generating any adverse forces in the catheter during inflation or deflation of the device. In particular, since the distal end of the balloon is not rigidly connected to the distal end of the catheter, any axial contraction or expansion of the balloon will not impart any tensile or compressive forces along the axis of the catheter, and the catheter will not be bowed or stretched as result of the inflation or deflation of the balloon. Consequently, the catheter should remain centered with respect to cross-section of the balloon irrespective of the state of inflation of the balloon.  
       [0022] These and other advantages, as well as the invention itself, will become apparent in the details of construction and operation as more fully described below. Moreover, it should be appreciated that several aspects of the invention can be used with other types of balloon catheters or medical devices. 
     
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS  
     [0023] Several embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:  
     [0024]FIG. 1 is a cross-sectional side view of an illustrative embodiment of a balloon catheter in accordance with the teachings of the present invention;  
     [0025]FIG. 2 is a cross-sectional side view of a second embodiment of a balloon catheter in accordance with the teachings of the present invention;  
     [0026]FIG. 3 is a cross-sectional side view of a third embodiment of a balloon catheter in accordance with the teachings of the present invention;  
     [0027]FIG. 4 is a cross-sectional side view of a fourth embodiment of a balloon catheter in accordance with the teachings of the present invention;  
     [0028] FIGS.  5 A- 5 D depict cross-sectional side views of a conventional balloon catheter in various stages of inflation and deflation;  
     [0029]FIG. 6 is a cross-sectional side view of a fifth embodiment of a balloon catheter in accordance with the teachings of the present invention; and  
     [0030]FIG. 7 is a cross-sectional side view of a sixth embodiment of a balloon catheter in accordance with the teachings of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0031] A first embodiment of a balloon catheter  10  of the present invention is depicted in FIG. 1. The balloon catheter  10  includes a rounded, oval, cylindrical, bullet or other appropriately shaped balloon  12  that is affixed to a catheter  14 . The balloon  12  is typically manufactured from a non-elastomeric material (e.g., a semi-rigid or non-compliant material), and preferably comprises a translucent, transparent or optically clear film. For example, the balloon  12  could be manufactured from a biocompatible polymer such as polyamide, polyurethane, polyester, polyolefin, polyethylene terephthalate and the like.  
     [0032] The balloon  12 , as shown in the drawings, includes a distal end  16 , a proximal end  18  and a central portion  20 . However, different configurations or designs can also be utilized for the balloon  12 . For example, the distal end  16  and the proximal end  18  could both comprise a tubular construction so as to form a neck. The balloon  12  is attached to the catheter  14  by inserting the distal end  22  of the catheter  14  into and through the proximal end  18  of the balloon  12 . The balloon  12  is then slid over the catheter  14  until the distal end  22  of the catheter  14  is inserted into a portion of the distal end  16  of the balloon  12 . The proximal end  18  of the balloon  12  is then affixed to the outer wall of the catheter  14  by an adhesive, ultrasonic welding, or some other method so as to anchor and seal the proximal end of the balloon  12 . In the preferred embodiment shown, the inside diameter of the proximal end  18  is sized to fit tightly or snugly over the catheter  14  so as to improve the integrity of the seal between these two components.  
     [0033] The distal end  22  of the catheter  14  is  not  affixed to the distal end  16  of the balloon  12 . As shown in the drawing, the distal end  22  of the catheter  14  extends partially, but not fully, into the distal end  16  of the balloon  12  so as to form a slip joint  26  between these two components. The slip joint  26  allows the distal end  16  of the balloon  12  to axially move or translate with respect to the distal end  22  of the catheter  14 . This configuration allows the overall axial or longitudinal length of balloon  12  to change during inflation or deflation without transferring tensile or compressive forces to the catheter  14 . For example, when the balloon  12  is deflated, the balloon  12  tends to elongate in the axial direction as the central portion  20  is drawn inwardly towards the catheter  14 , thereby moving the distal end  16  of the balloon  12  distally from or relative to the distal end  22  of the catheter  14 . Since the distal end  16  of the balloon  12  is not prevented from moving axially, transverse creasing of the central portion  20  of the balloon  12  during deflation is eliminated or at least minimized. Moreover, the central portion  20  of the balloon  12  can be collapsed into a smaller diameter or cross-section for ingress or egress of the balloon catheter  10  through the body&#39;s canals and/or the endoscope channel.  
     [0034] The slip joint  26  also prevents the application of adverse forces on the catheter  14  by the balloon  12  during inflation or deflation of the device. In particular, since the distal end  16  of the balloon  12  is not connected to the distal end  22  of the catheter  14 , any axial contraction or expansion of the balloon  12  will not impart any tensile or compressive forces onto the catheter  14 . In other words, the catheter  14  will not be bowed or stretched as result of the inflation or deflation of the balloon  12 . Consequently, the catheter  14  should remain centered with respect to cross-sectional area of the balloon  12  irrespective of the state of inflation of the balloon  12 .  
     [0035] By partially extending the distal end  22  of the catheter  14  into the distal end  16  of the balloon  12 , the distal end  22  of the catheter  14  can provide some lateral or transverse support to the distal end  16  of the balloon  12 . This lateral support can help to guide the device, and prevent the balloon  12  from folding or collapsing, as the device is being inserted into the body&#39;s canals. The length of the distal end  16  of the balloon  12 , and the position of the distal end  22  of the catheter  14  therein, should be sufficient to permit these components to freely translate with respect to each other in response to all stages of inflation and deflation of the device.  
     [0036] The distal end  16  of the balloon  12  is sealed so as to enclose the balloon  12 . In the preferred embodiment shown, the distal end  16  of the balloon  12  is formed by inserting and sealing a small rod into the neck of the balloon  12 . The distal end  16  of the balloon  12  may also be rounded to improve the ingress of the balloon catheter  10  into and through the body&#39;s canals and lumens, as well as through the channel of an endoscope. In addition, the inside diameter of the distal end  16  of the balloon  12  is slightly larger than the outside diameter of the distal end  22  of the catheter  14  so as to permit air or fluid to enter or be removed from the interior volume of the balloon  12  by passing through the distal end  22  of the catheter  14 . Alternatively, an aperture  28  may be provided in the wall of the catheter  14  at a location proximal to the distal end  22 , but within the interior volume of the balloon  12 .  
     [0037] The central portion  20  of the balloon  12  may be provided with longitudinally or axially extending pleats or folds  24 . These folds  24  provide creases along which the surface of the balloon  12  will fold or pleat when deflated. The folds  24  permit the central portion  20  of the balloon  12  to be collapsed to a minimal cross-sectional area or diameter, and prevent the formation of transverse or lateral creases along the same area.  
     [0038] The proximal end  6  of the catheter  14  is typically connected to an inflation device  8 , such as a standard medical syringe. The inflation device  8  is in fluid communication with the interior of the balloon  12  via a lumen extending through the inside of the catheter  14 . The catheter  14  may also comprise additional lumens through which contrast fluids or guide wires (not shown) can be passed.  
     [0039] A second embodiment of a balloon catheter  30  of the present invention is depicted in FIG. 2. The balloon catheter of this embodiment  30  is similar to the embodiment of the balloon catheter  10  shown in FIG. 1, but comprises a two-part catheter  32  having a relatively flexible portion  34  and a relatively rigid portion  36 . The flexible portion  34  extends from approximately the proximal end  38  of the balloon  40  to the proximal end  46  of the catheter  32 . The flexible portion  34  has a similar design and construction as that of the catheter  14  of the first embodiment shown in FIG. 1.  
     [0040] The rigid portion  36  extends from approximately the proximal end  38  of the balloon  40  to the distal end  42  of the catheter  32 . In other words, the rigid portion  36  is that portion of the catheter  32  that is disposed within the balloon  40 . The rigid portion  36  is less likely to sag under its own weight or the weight of the balloon  40 , and may provide increased lateral support to the distal end  44  of the balloon  40 . The increased rigidity of the rigid portion  36  of the catheter  32  may be particularly beneficial for use in PDT procedures, where proper centering and alignment of the therapeutic fiber optic device (not shown) within the catheter  32  is critical.  
     [0041] In the embodiment shown, the flexible portion  34  is connected to the rigid portion  36  at a joint  48  that is preferably located within the proximal end  38  of the balloon  40 . The proximal end  38  provides reinforcement to the joint  48 , as well as improving the integrity of the seal between these components.  
     [0042] With the exception of the two-part catheter  32  described above, the remaining components of the balloon catheter  30  of the second embodiment are the same or similar to the components of the balloon catheter  10  of the first embodiment. A detailed description of these components and their functions will consequently not be repeated here.  
     [0043] A third embodiment of a balloon catheter  50  of the present invention is depicted in FIG. 3. The balloon catheter  50  of this embodiment is similar to the embodiment of the balloon catheter  30  shown in FIG. 2 in that it also comprises a two-part catheter  52  having a flexible portion  54  and a rigid portion  56 . However, the rigid portion  56  does  not  extend to the distal end  64  of the balloon  60 . In other words, the rigid portion  56  only extends from near the proximal end  58  of the balloon  60  to part way into the interior volume of the balloon  60 , and the distal end  62  of the rigid portion  56  does not form a slip joint with the distal end  64  of the balloon  60 .  
     [0044] With the exception of the two-part catheter  52  described above, and the length of the rigid portion  56  thereof, the remaining components of the balloon catheter  50  of the third embodiment are the same or similar to the components of the balloon catheter  30  of the second embodiment. A detailed description of these components and their functions will consequently not be repeated here.  
     [0045] A fourth embodiment of a balloon catheter  70  of the present invention is depicted in FIG. 4. The balloon catheter of this embodiment  70  is similar to the embodiment of the balloon catheter  10  shown in FIG. 1, but comprises a segmented catheter  72  having a flexible portion  74  and a segmented or spaced apart portion  76 . The flexible portion  74  extends from approximately the proximal end  78  of the balloon  80  to the proximal end  86  of the catheter  72 . The flexible portion  74  has a similar design and construction as that of the catheter  14  of the first embodiment shown in FIG. 1. The distal end  92  of the flexible portion  74  is affixed to the proximal end  78  of the balloon  80  by adhesive or some other form of bonding. The segmented portion  76  can be either rigid or flexible, and either hollow or solid. In other words, the segmented portion  76  can be a rod-like length of material as opposed to a catheter-like tube since the segmented portion  76  does not necessarily need to carry fluid between the inflation device (not shown) and the balloon  80 .  
     [0046] The distal end  82  of the segmented portion  76  is affixed to the distal end  84  of the balloon  80 . The segmented portion  76  extends proximally from the distal end  82  and terminates within the proximal end  78  of the balloon  80 . The proximal end  90  of the segmented portion  76  is  not  affixed or bonded to the proximal end  78  of the balloon  80 , but is free to move axially within the proximal end  78 . In other words, a slip joint  94  is formed between the proximal end  90  of the segmented portion  76  and the proximal end  78  of the balloon  80 . A gap  88  is provided between the proximal end  90  of segmented portion  76  and the distal end  92  of the flexible portion  74  within the proximal end  78  of the balloon  80 . This gap  88  provides room for the segmented portion  76  to move longitudinally within the proximal end  78  of the balloon  80  as the balloon  80  longitudinally contracts or elongates during inflation and deflation, as well as allowing fluid from the inflation device (not shown) to pass through the distal end  92  of the flexible portion  74  and into the interior of the balloon  80 . The proximal end  78  of the balloon  80  also provides lateral support to the proximal end  90  of the segmented portion  76 .  
     [0047] This embodiment has the advantage of allowing the balloon  80 , and the segmented portion  76  of the catheter  72 , to flex near the proximal end  78  of the balloon  80 . This may provide increased maneuverability of the balloon catheter  70  during insertion of the device into and through the body&#39;s canals.  
     [0048] Of course, it should be appreciated that the segmented portion  76  could terminate short of the proximal end  78  of the balloon  80 . In other words, the segmented portion  76  could extend only partially into the interior volume of the balloon  80 , thereby eliminating any contact with the proximal end  78  of the balloon  80 .  
     [0049] With the exception of the segmented catheter  72  described above, and the location of the slip joint  94  at the proximal end  78  of the balloon  80 , the remaining components of the balloon catheter  70  of the fourth embodiment are the same or similar to the components of the balloon catheter  10  of the first embodiment. A detailed description of these components and their functions will consequently not be repeated here.  
     [0050] A fifth embodiment of a balloon catheter  120  of the present invention is depicted in FIG. 6. The balloon catheter of this embodiment  120  is similar to the embodiment of the balloon catheter  70  shown in FIG. 4 in that this embodiment comprises a segmented or two-piece catheter  122 . However, the proximal portion  124  of the catheter  122  extends from the proximal end  126  of the catheter, through the proximal end  128  of the balloon  130 , and into the interior volume of the balloon  130  where it terminates near the mid-section of the balloon  130 . The proximal portion  124  of the catheter  122  is affixed to the proximal end  128  of the balloon  130 .  
     [0051] The distal portion  132  of the catheter  122  is affixed to the distal end  134  of the balloon  1   30 , and likewise extends into the interior volume of the balloon  130  where it terminates near the mid-section of the balloon  130 . The proximal end  136  of the distal portion  132  of the catheter  122  overlaps the distal end  138  of the proximal portion  124  of the catheter  122  in a sliding arrangement. In the embodiment shown, the proximal end  136  of the distal portion  132  of the catheter  122  comprises an expanded tubular portion with an interior diameter that is slightly larger than the exterior diameter of the distal end  138  of the proximal portion  124  of the catheter  122  so as to permit relative axial movement between these two catheter components. This type of connection is often referred to as a male-female type of connection.  
     [0052] A sixth embodiment of a balloon catheter  140  of the present invention is depicted in FIG. 7. The balloon catheter of this embodiment  140  is similar to the embodiment of the balloon catheter  120  shown in FIG. 6 in that this embodiment comprises a segmented or two-piece catheter  142 , wherein the proximal portion  144  of the catheter  142  extends from the proximal end  146  of the catheter, through the proximal end  148  of the balloon  150 , and into the interior volume of the balloon  150  where it terminates near the mid-section of the balloon  150 . The proximal portion  144  of the catheter  142  is affixed to the proximal end  148  of the balloon  150 .  
     [0053] The distal portion  152  of the catheter  142  is affixed to the distal end  154  of the balloon  150 , and likewise extends into the interior volume of the balloon  150  where it terminates near the mid-section of the balloon  150 . The proximal end  156  of the distal portion  152  of the catheter  142  overlaps the distal end  158  of the proximal portion  144  of the catheter  142  in a sliding arrangement. In the embodiment shown, the distal portion  152  of the catheter  142  comprises a uniform tubular cross-section with an interior diameter that is slightly larger than the exterior diameter of the distal end  158  of the proximal portion  144  of the catheter  142  so as to permit relative axial movement between these two catheter components.  
     [0054] In the fifth and sixth embodiments (FIGS. 6 and 7), the overlapping portions of the separate catheter segments provide transverse or lateral stability to the balloon without impeding the axial expansion or contraction of the balloon. This is because the balloon is only fixedly connected to a either one of the catheter portions at single location.  
     [0055] Any other undisclosed or incidental details of the construction or composition of the various elements of the disclosed embodiments of the present invention are not considered to be critical to the achievement of the advantages of the present invention, so long as the elements possess the attributes required to perform as disclosed herein. The selection of these and other details of construction are believed to be well within the ability of one of ordinary skill in the relevant art in view of the present disclosure. Illustrative embodiments of the present invention have been described in considerable detail for the purpose of disclosing practical, operative structures whereby the invention may be practiced advantageously. The designs described herein are intended to be exemplary only. The novel characteristics of the invention may be incorporated in other structural forms without departing from the spirit and scope of the invention.