Abstract:
An inflatable medical balloon for multiple procedures, including angioplasty procedures, procedures for delivering medical devices, such as stents, and a method of making the catheter systems. The catheter system employs a balloon having a plurality of flexible portions and a combination of hard and soft portions.

Description:
FIELD OF THE INVENTION 
     This invention relates to catheters used for multiple procedures, including angioplasty procedures, procedures for delivering medical devices, such as stents, and a method of making the catheter systems. The catheter system employs a balloon having a plurality of flexible portions and a combination of hard and soft portions. 
     BACKGROUND OF THE INVENTION 
     Catheters are used for many medical purposes. The present invention is not directed to a specific type of catheter, but rather types of balloons and methods of making said balloons. The balloons may be used for a variety procedures, such as, but not limited to, plain old balloon angioplasty (POBA), stent delivery, peripheral catheter procedures. 
     Examples of catheters and procedures are addressed below for the sake of background. 
     In typical PTA or PTCA procedures, a guiding catheter is percutaneously introduced into the cardiovascular system of a patient and advanced through the aorta until the distal end is in the desired (coronary) artery. Using fluoroscopy, a guide wire is then advanced through the guiding catheter and across the site to be treated in the coronary artery. An over the wire (OTW) balloon catheter is advanced over the guide wire to the treatment site. The balloon is then expanded to reopen the artery. The OTW catheter may have a guide wire lumen which is as long as the catheter or it may be a rapid exchange catheter wherein the guide wire lumen is substantially shorter than the catheter. Alternatively, a fixed wire balloon may be used. This device features a guide wire which is affixed to the catheter and cannot be removed. 
     To help prevent arterial closure, repair dissection, or prevent restenosis, a physician can implant an intravascular prosthesis, or a stent, for maintaining vascular patency inside an artery or other vessel at the lesion. 
     Stents are also used for a variety of other purposes including maintaining the patency of any physiological conduit including arteries, veins, vessels, the biliary tree, the urinary tract, the alimentary tract, the tracheobronchial tree, the genitourinary system, and the cerebral aqueduct. 
     The stent may either be self-expanding or balloon expandable. For the latter type, the stent is often delivered on a balloon and the balloon is used to expand the stent. The self-expanding stents may be made of shape memory materials such as nitinol or constructed of conventional metals but of a design which exhibits self expansion characteristics. 
     A balloon may be used to widen a vessel into which the catheter is inserted by dilating the blocked vessel, such as in an angioplasty procedure. The catheter may also be used to deliver a medical device, such as a stent, into a body lumen. Some examples of stent delivery balloons are disclosed in U.S. Pat. Nos. 5,702,418, 5,968,069 and 5,797,877, the entire contents of these patents are hereby incorporated by reference. 
     In these and other medical device delivery applications, radial expansion of a balloon may be used to expand or inflate a stent at a desired positioned within the body. Using a balloon equipped catheter to deliver a stent often requires precise positioning of the balloon and stent as well as a balloon with accurate and predictable expansion properties. The present invention aids in positioning the balloon and stent in the targeted areas with enhanced precision. 
     Currently, a specific concern physicians have with regard to the difficulty in delivering a stent to the targeted site is vessel straitening. This phenomenon is a result of rigidness built up due to the overlapping of the stent, balloon and typically the inner shaft. To reduce this rigidness, flexible stents have been produced. The present invention, in one aspect, seeks to provide balloons which address this problem, among others. 
     All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety. 
     Without limiting the scope of the invention a brief summary of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below. 
     A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is directed generally to medical balloon designs which have increased longitudinal flexibility in both the wrapped, collapsed state, while maintaining control of radial expansion. The flexibility is enhanced by creating a plurality of hinge points in the balloon material. These hinge points may be created in a number of ways. The hinge points may be changes in the thickness in the balloon, interruptions in the continuity of the balloon material and/or changes in the physical properties of portions of the balloon. These differing embodiments are discussed in the Detailed Description of the present disclosure. 
     The balloon designs utilize surface finishing and structure of a balloon body to obtain improved flexibility. The designs work by interrupting the usual straight rigid wall of a standard balloon. In addition, certain aspects of the invention have the potential for improved stent retention due to higher friction between the balloon and stent and a more receptive contour on the surface of the balloon for receiving the stent. 
     In some aspects, the present invention improves flexibility and also provides for low compliance. Discussions of compliance characteristics may be found in U.S. Pat. Nos. 6,146,356 and 5,980,532. 
     The invention also contemplates balloons utilizing two materials with different modulus of elasticity. The materials are combined on a balloon in a way as to provide flexibility in the longitudinal direction and stiffness or non-compliance in the radial direction. 
     A further aspect of the invention contemplates the aid the present designs provide in re-wrap of the balloon. Balloons on catheters may be inflated and deflated by applying internal pressure. To minimize the profile of the catheter, balloons are typically “folded”. After the balloon is inflated during use, it is subsequently deflated. It is desired that the balloon be constructed to “re-wrap” into its original configuration upon deflation to maintain the catheter&#39;s low profile during withdrawal of the catheter. This re-wrap may be achieved my incorporating a “memory” within the balloon such that when the internal pressure is removed, the balloon tends to return to its original configuration. The present novel designs aid in this re-wrap phenomenon. 
     Additional details and/or embodiments of the invention are discussed below. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A detailed description of the invention is hereinafter described with specific reference being made to the drawings in which: 
         FIG. 1  is a cross-sectional view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 2  is a side view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 3  is a partial cross-sectional view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 4  is a side view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 5  is a partial cross-sectional view of the embodiment shown in  FIG. 4 ; 
         FIG. 6  is a side view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 7  is a partial cross-sectional view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 8  is a side view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 9  is a cross-sectional view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 10  is a cross-sectional view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 11  is a cross-sectional view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 12  is a side view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 13  is a partial cross-sectional view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; 
         FIG. 14  is a cross-sectional view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon; and 
         FIG. 15  is a partial cross-sectional view of the distal end of a balloon catheter illustrating a particular embodiment of the inventive balloon. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention may be embodied in many different forms, there are described in detail herein specific preferred embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
     For the purposes of this disclosure, unless otherwise indicated, identical reference numerals used in different figures refer to the same component. 
     The balloons shown in the figures are partially expanded to illustrate the inventive aspects. 
     For the purposes of this disclosure, the term stent refers to stents, stent-grafts, grafts and other endoluminal prostheses whether self-expanding, balloon expandable, self-expanding and balloon expandable or otherwise expandable as are known in the art. 
     In addition to the over-the-wire embodiments (example also found in U.S. Pat. No. 5,980,533) shown in  FIGS. 1-4 , the inventive catheter system may also be provided in a rapid-exchange configuration. Examples of rapid-exchange catheters may be found in U.S. Pat. Nos. 5,534,007 and 5,833,706. The inventive stent delivery systems may also be made in fixed wire form. Examples of fixed-wire catheters may be found in U.S. Pat. No. 5,702,364. 
     The system may be adapted for use with a medical device such as a stent, for example, a self-expanding, balloon expandable or combination self-expanding and balloon expandable stent. The system may also be used for delivery of other medical devices for use in the body as well including, but not limited to, ultrasonic devices, laser devices, vena cava filters, implantable drug delivery devices and the like. 
     The inventive medical systems disclosed herein may also be provided with any of the features disclosed in U.S. Pat. Nos. 6,096,056, 6,068,634, 6,036,697, 6,007,543, 5,968,069, 5,957,930, 5,944,726 , 5,653,691 and 5,534,007. 
     The stent delivery system may also comprise various coatings as are known in the art, including lubricious coatings to facilitate movement of the various parts of the system, as well as collagen-type coatings. More information concerning suitable coatings may be found in U.S. Pat. No. 5,443,907, and U.S. application Ser. Nos. 08/382478, 09/306939 and 09/316502. 
     The invention is also directed to medical device delivery systems and catheters produced using the inventive methods. 
     For the purposes of the detailed description of the invention, Figures of a portion of the distal end of a typical balloon catheter will be used. It should be understood, as mentioned above, that the present invention is applicable to other medical devices which include an expandable balloon. It should also be understood that the materials used may be any of those materials known in the art where applicable. 
     The illustrative figures show differing embodiments of the invention. Each balloon has proximal  12  and distal  14  waists, proximal  16  and distal  18  cone portions and a body  20  separating said waists and cones. In the cut away figures, an inner shaft  22  (guide wire shaft), marker bands  24 , distal tip  26 , outer shaft  28 , guide catheter  30  and a guide wire  31  may be seen. These elements are well known in the art and serve as a framework to illustrate the balloon embodiments. The balloons may be considered deflated or partially inflated to illustrate the unique features of the balloon embodiments. 
     Balloons of the disclosed embodiments may be made of any suitable balloon material including compliant and non-compliant materials and combinations thereof. Compliant materials include low pressure, relatively soft or flexible polymeric materials, such as thermoplastic polymers, thermoplastic elastomers, polyethylene (high density, low density, intermediate density, linear low density), various co-polymers and blends of polyethylene, ionomers, polyesters, polyurethanes, polycarbonates, polyamides, poly-vinyl chloride, acrylonitrile-butadiene-styrene copolymers, polyether-polyester copolymers, and polyetherpolyamide copolymers. Suitable materials include a copolymer polyolefin material available from E. I. DuPont de Nemours and Co. (Wilmington, Del.), under the trade name Surlyn™ Ionomer and a polyether block amide available under the trade name PEBAX™. Non-compliant materials include relatively rigid of stiff high pressure polymeric materials, such as thermoplastic polymers and thermoset polymeric materials, poly(ethylene terephthalate) (commonly referred to as PET), polyimide, thermoplastic polyamide, polyamides, polyesters, polycarbonates, polyphenylene sulfides, polypropylene and rigid polyurethane. Further examples of balloon material may be found in U.S. Pat. No. 6,146,356. It should be understood that the specific materials disclosed below for the individual embodiments does not limit the embodiment to those materials. 
       FIG. 1  shows balloon  10  having a body  20  which has a wavy configuration. A stent  21  is mounted on the balloon. Although the remaining figures do not show a stent, it should be understood that each embodiment may similarly have a stent mounted thereon. The wavy body  20  has a plurality of peaks  32  and troughs  34  which form the hinge points, as discussed above, to provide longitudinal flexibility in the balloon. In this particular embodiment, the entire body  20  wall is wavy, forming peaks and troughs from the outside of the balloon as well as from the inside of the balloon. The favored compliance of the balloon is also not distinctly altered. 
     The embodiments of the present invention improves flexibility and also provides for low compliance. Suitably, the balloons are semi-compliant or less. 
     The wavy nature of the balloon  10  also aids in stent  21  retention. The peaks  32  provide for an nonuniform surface which complements the nonuniform surface of a typical stent, therefore providing for greater friction and a more secure seat for the stent. The increased retention limits the axial movement of the stent during delivery and deployment. 
     It should also be understood that the embodiment is not limited to the full body  20  of the balloon being “wavy”. Specific portions of the body  20  may comprise waves while the remaining portions of the balloon remain unchanged. For example, a portion in the middle of the body  20  may be wavy or a proximal and/or distal portion of the body  20  may be wavy, or combinations thereof. The body  20  may be tailored to the user&#39;s desires. 
       FIG. 2  shows balloon  36  having a body  20  which has a wrinkled configuration. The wrinkled body  20  has a plurality of wrinkles  38  which form the hinge points, as discussed above, to provide longitudinal flexibility in the balloon. In this particular embodiment, the entire body  20  wall is wrinkled, forming a multitude of wrinkles  38  from the outside of the balloon as well as from the inside of the balloon. The favored compliance of the balloon is also not distinctly altered. 
     The wrinkled nature of the balloon  36  also aids in stent (not shown) retention. The wrinkles  38  provide for an nonuniform surface which complements the nonuniform surface of a typical stent, therefore providing for greater friction and a more secure seat for the stent. The increased retention limits the axial movement of the stent during delivery and deployment. 
     It should also be understood that the embodiment is not limited to the full body  20  of the balloon being “wrinkled”. Specific portions of the body  20  may comprise wrinkles while the remaining portions of the balloon remain unchanged. For example, a portion in the middle of the body  20  may be wrinkled or a proximal and/or distal portion of the body  20  may be wrinkled, or combinations thereof. The body  20  may be tailored to the user&#39;s desires. 
     In one aspect, the “wrinkling” can be implemented as a process after molding the balloon. It can be compressed and expanded longitudinally multiple times to create the wrinkles. The wrinkle pattern can also be put into the balloon mold so that the molded pattern takes on the wrinkled pattern. 
       FIG. 3  shows balloon  40  having a body  20  which has two circumferential channels  42 . A cross section of the balloon is shown to illustrate the balloon wall. The body  20  may have one or more channels  42  which form the hinge points, as discussed above, to provide longitudinal flexibility in the balloon. In this particular embodiment, the body  20  wall forms the channel such that the surface on the inside of the balloons forms an inward bulge  44 . The favored compliance of the balloon is also not distinctly altered. 
     The channels  42  of the balloon  40  also aid in stent (not shown) retention. The channels  42  provide for an nonuniform surface which complements the nonuniform surface of a typical stent, therefore providing for greater friction and a more secure seat for the stent. The increased retention limits the axial movement of the stent during delivery and deployment. 
     It should also be understood that the embodiment is not limited to a specific number of channels  42 . Specific portions of the body  20  may have channels while the remaining portions of the balloon remain unchanged. For example, a portion in the middle of the body  20  may have a channel or a proximal and/or distal portion of the body  20  may have channels, or combinations thereof. The body  20  may be tailored to the user&#39;s desires. 
       FIG. 4  shows balloon  46  having a body  20  with ground rings. The body  20  has a plurality of ground rings  48  which form the hinge points, as discussed above, to provide longitudinal flexibility in the balloon. In this particular embodiment, the material of the body  20  wall is selectively ground to form rings. The resulting body wall  20  has less material in the ground ring  48  area, leaving the inside surface  50  of the balloon unchanged. This can be seen in  FIG. 5  where a cross-section of the balloon  46  is revealed. The favored compliance of the balloon is also not distinctly altered. 
     Grinding, in this and any of the other embodiments requiring grinding, may be accomplished via conventional means, which include, but are not limited to, mechanical grinding or laser grinding. Examples of grinding may be seen in U.S. Pat. No. 6,193,738. 
     The ground nature of the balloon  46  also aids in stent (not shown) retention. The ground rings  48  provide for an nonuniform surface which complements the nonuniform surface of a typical stent, therefore providing for greater friction and a more secure seat for the stent. The increased retention limits the axial movement of the stent during delivery and deployment. 
     It should also be understood that the embodiment is not limited to the number or positioning of the ground rings  48 . Specific portions of the body  20  may comprise ground rings  48  while the remaining portions of the balloon remain unchanged. For example, there may be a ring or rings in the middle or on the proximal and/or distal portion of the body  20 , or combinations thereof. The body  20  may be tailored to the user&#39;s desires. 
     The embodiment may be made using any conventional methods. Suitable methods may include centerless grinding of a balloon blank and laser cutting of a molded balloon. 
       FIG. 6  illustrates a balloon  52  which is a modification of the embodiment of  FIGS. 4-5 , wherein the ground rings  48  are in a spiral configuration. The rings  48  may take the form of one continuous spiral or separate rings  48  which are slanted relative to the axis of the catheter. 
       FIG. 7  shows balloon  54  having a body  20  with ground rings  48 , as discussed above. However, in this embodiment, the body  20  wall is a co-extrusion. Co-extrusions are well-known in the art. The body  20  wall comprises a first layer  56  on the outside of the balloon body  20  and a second layer  58  on the inside of the balloon body  20 . 
     As can be seen, the body  20  has a plurality of ground rings  48  which form the hinge points, as discussed above, to provide longitudinal flexibility in the balloon. In this particular embodiment, the material of the body  20  wall is selectively ground to form rings. The resulting body wall  20  has less material in the ground ring  48  area, leaving the inside surface  60  of the balloon unchanged. This can be seen in  FIG. 7  where a cross-section of the balloon  46  is revealed. The favored compliance of the balloon is also not distinctly altered. 
     The embodiment of  FIG. 7  allows for a deeper grind since there are two layers. This allows for greater longitudinal flexibility in the balloon wall. The depth of the grind can be dictated by the needs of the user, limited only by the thickness of the two layer body wall  20 . Combination of grinding patterns may be employed. In  FIG. 7 , the ground ring extend through the first layer  56 , but does not penetrate the second layer  58 . 
     The two layers may comprise the same or different materials. Different materials allow the designer to alternate between hard and soft polymers to achieve better flexibility with low compliance. Suitable materials include, but are not limited to, thermoplastic elastomers, such as PEBAX, polyester-polyether block copolymers such as ARNITEL and HYTREL and polyurethane. Suitable combinations include, but are not limited to, PEBAX with Nylon (suitably nylon 12), ARNITEL with PBT or PET and Polyurethane with a polymer having a higher hardness or an aromatic polymer. 
     The ground nature of the balloon  46  also aids in stent (not shown) retention. The ground rings  48  provide for an nonuniform surface which complements the nonuniform surface of a typical stent, therefore providing for greater friction and a more secure seat for the stent. The increased retention limits the axial movement of the stent during delivery and deployment. 
     It should also be understood that the embodiment is not limited to the number or positioning of the ground rings  48 . Specific portions of the body  20  may comprise ground rings  48  while the remaining portions of the balloon remain unchanged. For example, there may be a ring or rings in the middle or on the proximal and/or distal portion of the body  20 , or combinations thereof. As with  FIG. 6 , the ground rings  48  may be in a spiral configuration. The rings  48  may take the form of one continuous spiral or separate rings  48  which are slanted relative to the axis of the catheter. The body  20  may be tailored to the user&#39;s desires. 
     It should be understood that the co-extrusion element of this embodiment may be incorporated into any of the other embodiments of the present application. 
       FIG. 8  illustrates a balloon  62  body  20  incorporating a pattern of recesses or grooves  64  in a pattern which are cut or ground into the balloon  62  material. The process involves grinding from different directions.  FIG. 8  illustrates what is commonly referred to as a quilt pattern, although other patterns may be used. The pattern is cut into the balloon material via conventional mechanical or laser methods. The grooves  64  form the hinge points, as discussed above, to provide longitudinal flexibility in the balloon. The favored compliance of the balloon is also not distinctly altered. 
     Patterns can be imparted to the balloons by forming the patterns on the inside of the mold in which the balloons are shaped. When the balloons are blown in the mold, the balloon takes on the pattern on the inside of the balloon. If the balloon mold has a quilted pattern, then a balloon molded in it will have a quilted pattern, etc. 
     The grooves  64  of the balloon  62  also aid in stent (not shown) retention. The grooves  64  provide for an nonuniform surface which complements the nonuniform surface of a typical stent, therefore providing for greater friction and a more secure seat for the stent. The increased retention limits the axial movement of the stent during delivery and deployment. 
     It should also be understood that the embodiment is not limited to a specific pattern of grooves  64 . Specific portions of the body  20  may have grooves  64  while the remaining portions of the balloon remain unchanged. For example, a portion in the middle of the body  20  may have a grooves or a proximal and/or distal portion of the body  20  may have grooves, or combinations thereof. The body  20  may be tailored to the user&#39;s desires. 
       FIG. 9  shows balloon  66  having a body  20  with a plurality of thin portions  67  and a plurality of thick portions  68 . The inside  70  of the body wall  20  has a relatively even contour as apposed to the undulating contour of the outer body wall. The body wall may comprise one hard material. Suitable materials include, but are not limited to, PET, nylon, polyethylene and hard polyurethanes. The cones and waists of the balloon may also have the altered contour. 
     As can be seen, the outside of body  20  has an undulating contour defining a plurality of thin portions  67  which form the hinge points, as discussed above, to provide longitudinal flexibility in the balloon. Suitably, the balloons are formed and then ground or thermo formed with the desired contour. The thin portions are achieved through mechanical or laser grinding of the balloon tube, after which the balloon is formed. The resulting body wall  20  has less material in the thin portions  67 , leaving the inside surface  70  of the balloon unchanged. The thickness of the thin portions can be dictated by the needs of the user, limited only by the thickness of the body wall  20 . The favored compliance of the balloon is also not distinctly altered. 
     The undulating nature of the balloon  66  also aids in stent (not shown) retention. The body  20  provides for an nonuniform surface which complements the nonuniform surface of a typical stent, therefore providing for greater friction and a more secure seat for the stent. The increased retention limits the axial movement of the stent during delivery and deployment. 
     It should also be understood that the embodiment is not limited to the number or positioning of the thin portions  67 . Specific portions of the body  20  may comprise thin portions  67  while the remaining portions of the balloon remain unchanged. For example, there may be thin portions  67  in the middle or on the proximal and/or distal portion of the body  20 , or combinations thereof. The thin portions  67  may be in a spiral configuration. The thin portions  67  may take the form of one continuous spiral or separate rings which are slanted relative to the axis of the catheter. The body  20  may be tailored to the user&#39;s desires. 
     The balloons of the present invention may also comprise plurality of materials to produce the hinge effects. These designs utilize two materials with different modulus of elasticity. The materials can be combined on and/or in a balloon in a way as to provide flexibility in the longitudinal direction and stiffness or non-compliance in the radial direction. For the remaining embodiments, the harder material is relatively non-compliant and the softer material is relatively compliant. Suitable harder materials include, but are not limited to, polyethyleneterephthalate (PET), and polybutylene terephthalate (PBT). Suitable softer materials include, but are not limited to, HYTREL®, which are randomized block co-polymers of polyethers and polyesters, and other thermoplastic elastomers. Other useful balloon materials have been listed above with regard to the previous embodiments, and are further listed below. It should be understood that the specific materials disclosed below for the individual embodiments does not limit the embodiment to those materials. 
     It should be understood that the two materials may be hard and soft, respectively, relative to each other. As such, the balloon may consist of two hard materials or two soft material, as long as one material is harder than the other. 
       FIG. 10  shows balloon  72  having a body  20  with a plurality of rings  76  within the balloon material  74 . In the embodiment shown, the rings  76  are continuous, however, it should be understood that the rings may be discontinuous, but generally forming a ring. Only the continuous rings are shown. These embodiments illustrate the use of at least two materials varying in hardness. Suitably, the difference is at 10 Shore D or larger. The embodiments shown in  FIGS. 10-11  have a plurality of soft rings  76  incorporated within the harder body material  74 . The soft rings  76  which interrupt the harder body material  74  act as hinge points for longitudinal flexibility without sacrificing radial extension. 
     In this particular embodiment, the rings  74  are incorporated within the body wall  20 . The inside and outside surfaces of the body wall  20  are relatively uninterrupted and have relatively smooth contours. However, the rings  76  may protrude from the surface of the body wall  20  either on the inside or the outside, or both. 
     It should also be understood that the embodiment is not limited to the number or positioning of the soft rings  76 . Specific portions of the body  20  may comprise soft rings  76  while the remaining portions of the balloon remain unchanged. For example, there may be soft rings  76  in the middle or on the proximal and/or distal portion of the body  20 , or combinations thereof. The soft rings  76  may be in a spiral configuration as shown in balloon  78  in FIG.  11 . The soft rings  76  may take the form of one continuous spiral or separate rings which are slanted relative to the axis of the catheter. The body  20  may be tailored to the user&#39;s desires. 
       FIG. 12  shows balloon  80  having a body  20  with a plurality of rings  84  within the balloon material  82 . In the embodiment shown, the rings  84  are continuous, however, it should be understood that the rings may be discontinuous, but generally forming a ring. Only the continuous rings are shown. 
     These embodiments also illustrate the use of at least two materials varying in hardness. As above, suitably, the difference is at 10 Shore D or larger. The embodiments shown in  FIG. 12  have a plurality of hard rings  84  incorporated within the softer body material  82 . The softer body material  82  between the hardened rings  84  act as hinge points for longitudinal flexibility without sacrificing radial extension. The hardened rings  84  prevent growth in the radial direction while the softer sections between the hardened rings  84  provide longitudinal flexibility. 
     In this particular embodiment, the rings  84  are incorporated within the body wall  20 . The inside and outside surfaces of the body wall  20  are relatively uninterrupted and have relatively smooth contours. However, the rings  84  may protrude from the surface of the body wall  20  either on the inside or the outside, or both. The rings may also help with stent securement. 
     It should also be understood that the embodiment is not limited to the number or positioning of the hardened rings  84 . Specific portions of the body  20  may comprise hardened rings  84  while the remaining portions of the balloon remain unchanged. For example, there may be hardened rings  84  in the middle or on the proximal and/or distal portion of the body  20 , or combinations thereof. The hardened rings  84  may be in a spiral configuration. The hardened rings  84  may take the form of one continuous spiral or separate rings which are slanted relative to the axis of the catheter. The body  20  may be tailored to the user&#39;s desires. 
       FIGS. 13-15  are variations of the embodiment of FIG.  12 . The figures show varying positions of the hardened rings  84 . Balloon  86  of  FIG. 13  shows the hardened rings  84  embedded within the softer material  82  of the balloon wall  20  such the contour of the outside of the balloon body wall  20  is relatively smooth. The hardened rings  84  do not however extend the width of the body wall  20 . 
     Balloon  88  of  FIG. 14  shows the hardened rings  84  on the surface of the softer material  82  of the balloon wall  20  such that the contour of the outside of the balloon body wall  20  is uneven or bumpy. As discussed above, the uneven contour aids in the retention of a stent. 
     Balloon  90  of  FIG. 15  is a combination of balloons  86  and  88 . Balloon  90  shows the hardened rings  84  embedded within the softer material  82  of the balloon wall  20 . The hardened rings  84  do not however extend the width of the body wall  20 . The hardened rings  84  do however extend above the surface of the softer material  82 , such that the contour of the outside of the balloon body wall  20  is uneven or bumpy. As discussed above, the uneven contour aids in the retention of a stent. 
     Suitable materials include, but are not limited to, thermoplastic elastomers, such as PEBAX, polyester-polyether block copolymers such as ARNITEL and HYTREL and polyurethane. Suitable materials are also included in U.S. Pat. No. 6,146,3356 in addition to materials mentioned above. Suitable combinations include, but are not limited to, PEBAX with Nylon (suitably nylon 12), ARNITEL with PBT or PET and Polyurethane with a polymer having a higher hardness or an aromatic polymer. 
     Based on the above description it should be understood that several different polymers with a wide range of characteristics may be used to form a longitudinal or longitudinal and radial stabilized balloon of the present invention. 
     The above examples and disclosure are intended to be illustrative and not exhaustive. These examples and description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims, where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims. Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each single dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below (e.g. claim  6  may be taken as alternatively dependent from any of claims  2 - 5 , claim  4  may be taken as alternatively dependent from claim  3 ; etc.).