WO1995007667A1

WO1995007667A1 - Polymerizable angioplasty balloon implant device and method

Info

Publication number: WO1995007667A1
Application number: PCT/US1994/009838
Authority: WO
Inventors: Paul J. Buscemi; Andrew W. Buirge; Fertac Bilge
Original assignee: Scimed Life Systems, Inc.
Priority date: 1993-09-17
Filing date: 1994-09-06
Publication date: 1995-03-23
Also published as: US5443495A

Abstract

A balloon (10) for enlarging in situ to fit against a vessel wall and harden in place upon the application of energy. The balloon may have portions of scission material (18) which will degrade upon application of energy, thereby allowing the end portions (16) to detach from the balloon and to adhere to the shaft (12) while the body (14) of the balloon remains in the vessel.

Description

POLYMERIZABLE ANGIOPLASTY BALLOON IMPLANT DEVICE AND METHOD

FIELD OF THE INVENTION This invention relates generally to a polymcrizable balloon for use in balloon angioplasty and other procedures involving balloon catheters. More particularly, this invention relates to a balloon of polymcrizable material, the cylindrical body portion of which, or a sleeve thereon, is caused to harden after inflation of the balloon in a body vessel duct or the like to form a liner or stcnt therein.

BACKGROUND OF THE INVENTION

Development of the balloon angioplasty technique began about fifteen years ago. The purpose of this technique is to open arteries in which the flow of blood has been impeded by build-up of arteriosclerotie plaques on the interior walls of the arteries. This technique consists of inserting a small diameter catheter into a blocked artery, the catheter having a small flexible balloon attached to its distal end. The catheter is moved through the artery until the balloon is placed in the area of the artery in which blood flow is impeded by plaque build-up. The balloon is then inflated in order to shear and disrupt the wall components of the vessel to obtain an enlarged lumen. With respect to arterial arlhroscl erotic lesions, the relatively incompressible plaque remains unaltered, while the more clastic medial and advcntitial layers of the vessel stretch around the plaque, thus opening the artery to permit improved blood flow. The balloon is then deflated and removed leaving plaque flattened against the artery walls.

After a period of several months, however, approximately one- third of the treated arteries sometimes undergo rcstcnosis or a rcclosing of the artery at the treated area, requiring repetition of balloon angioplasty. The rcstcnosis problem has received considerable attention and several proposals have been made to deal with it.

The most promising approach to rcstcnosis prevention has been the placement of a stcnt in a blood vessel which has undergone balloon angioplasty at the position in the vessel where the balloon was inflated. The stcnt is generally implanted inside a body vessel in a procedure immediately following the balloon angioplasty procedure. A stcnt (also referred to as a graft prosthesis, arterial cndoprosthcsis, intraluminal graft or intravascular mechanical support) is typically placed or implanted within the vascular system to reinforce collapsing, partially occluded, weakened or abnormally dilated localized sections of blood vessels or the like. Because stcnts generally have too large a diameter to fit through a prc-angioplasty, uncxpandcd, diseased portion of a vessel, conventional metal stenting procedures implant a stcnt or other intraluminal vascular graft subsequent to the initial balloon angioplasty procedure in which the vessel has been expanded. The simultaneous placement of a stent during the primary dilatation phase of a balloon angioplasty or other procedure would alleviate the rcstcnosis problems and the need for a two-step procedure wherein the angioplasty procedure is performed first, followed by the stcnt placement procedure. Another disadvantage of balloon angioplasty is the tendency of the balloon to adhere to the vessel wall during the dilatation phase of the angioplasty procedure. If a balloon adheres to a vessel wall, the procedure could produce dissection, or a splitting and tearing of the vessel wall layers, wherein the intima or internal surface of the vessel suffers Assuring. This dissection forms a "flap" of underlying tissue which may reduce the blood flow through the lumen, or block the lumen altogether. Typically, the distending intraluminal pressure within the vessel can hold the disrupted layer or flap in place. If the intimal flap created by the balloon dilation procedure is not maintained in place against the expanded intima, the intimal flap can fold down inlo the lumen and close off the lumen or become detached. When the intimal flap closes off the body passageway, immediate surgery is necessary to correct this problem. Thus, the adhesion of the balloon to the vessel wall can cause undesirable defects or irregularities in the wall surface, resulting in thrombosis, and rcstcnotic episodes.

It would be advantageous to be able to provide a liner or a stcnt to cover and reinforce the interior portion of the vessel with a material that would provide a non-thrombogenic protective and supporting surface. Ideally, this protective liner would be provided during the primary dilatation phase of the angioplasty procedure rather than after the initial expansion of the vessel wall as in conventional angioplasty procedures. Thus, it would be extremely advantageous if the balloon itself, or a sleeve encasing the balloon, could be converted into a device capable of overcoming the two previously mentioned disadvantages: rcsentosis and adhesion.

SUMMARY OF THE INVENTION

In one aspect, the present invention is an angioplasty balloon having a cylindrical body portion adapted to harden in an enlarged state witiiin a body vessel after the primary dilatation phase of a balloon angioplasty procedure. In another aspect, the present invention is a balloon sleeve adapted to cylindrically encase a conventional angioplasty balloon, thereby protecting the balloon and giving it a low profile for insertion into and through the diseased portion of a vessel, the sleeve being adapted to enlarge upon inflation of an angioplasty balloon and to harden in an enlarged stale such that the balloon sleeve covers and provides mechanical support to the luminal surface of the vessel after removal of the angioplasty balloon. In short, both aspects of the invention provide a stcnt which can be placed simultaneously with the primary dilatation phase of the angioplasty procedure. The device may also be used to create or sustain openings or vessels in the renal, urinary, hepatic organs or other vessels, ducts and the like.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a portrayal of a balloon in the folded or wrapped conformation. The balloon deflated and stretched slightly to form essentially longitudinal creases in the balloon. The darkened regions (B) of the balloon represent regions of the balloon material which arc chemically altered to degrade under the influence of heat or light, regions A, B, C of the balloon may be of differing chemical compositions to allow either stiffening or degradation of the material.

Fig. 2 shows the balloon of Figure 1 in inflated form to approximately one to 12 atms atmospheres. All portions of the balloon inflate uniformly despite the differing chemical compositions.

Fig. 3 shows the balloon of Figures 1 and 2 after the application of heat or light energy that has activated regions B and C. Region B has disintegrated; region C has become more rigid. The catheter shaft and the attached cones are withdrawn through the placed stcnt.

Fig. 4 shows a chemically alterable stcnt loaded onto a folded balloon for delivery. The stcnt may contain slits or holes or slots which expand when the balloon expands the stent.

Fig. 5 shows the expanded stcnt of Figure 4 on inflated balloon. The slots have increased in open area. The cross sectional area of the stcnt has decreased with the increase in diameter. The stcnt is activated by light or heat to cause an increase in stiffness. Fig. 6 shows a stcnt as in Figure 4a except that in place of slots or slits, the stcnt is comprised of a microporous material, which again increases in cross sectional area as the balloon expands the stcnt.

Fig. 7 shows the balloon of Figure 6 expanded.

Fig. 8 shows a balloon with a resistance heating element. Fig. 9 shows a balloon with a radiation diffusing optical fiber. Fig. 10 is an enlarged portion of Figure 9.

DETAILED DESCRIPTION OF THE DRAWINGS AND THE PREFERRED EMBODIMENTS OF THE INVENTION

One approach according to this invention for the percutaneous repair of cardiovascular anomalies is that the balloon itself may become a stcnt if it is released from the catheter by separation of the central body from the end cones. An extension of this approach is to make a balloon that hardens in the middle and degrades at the ends upon delivery.

Such a device would be delivered to the desired portion of vasculature in the usual manner for a percutaneous dilatation. The actual device would closely resemble a PTCA balloon catheter. After die device was positioned, it would be inflated so that the body of die balloon would come in contact with the vessel wall. At this point, energy would be supplied to die balloon through the catheter, in the form of heat or light, causing die center (cylindrical) portion of the balloon body to harden while the ends would dissolve or degrade away. The ends may also be made to detach from the cylindrical body of the balloon by the degradation of an adhesive or die like holding the cone ends to the balloon body initiated by die delivery of energy. Thirdly, the ends of the balloon may be made to detach by shrinking away from the hardening balloon section and adhering to the shaft of the cad ctcr upon delivery of the energy. The implanted portion of die balloon provides support for the vasculature and/or may be a drug delivering matrix. The implanted section of the balloon may be biodegradable, thus eventually being rcsorbcd into the body.

Another approach comprises a sleeve which encases an ordinary PTCA balloon. The sleeve would be the equivalent of the balloon body described above. After hardening the sleeve, the balloon would be deflated and removed, leaving the sleeve in place.

Figure 1 illustrates an angioplasty balloon of the first preferred embodiment of the present invention. The balloon, shown generally by 10 is incorporated into a conventional angioplasty balloon catheter 12 by being wrapped about the catheter as shown for insertion into the lumen of a vessel. The balloon as seen in Figure 2 in an inflated condition comprises a cylindrical body portion 14 and two end or cone portions 16. In use, the balloon is positioned in the area of a vascular lesion and is thereafter inflated. After inflation, energy is supplied to the balloon, causing the cylindrical body portion 14 of the balloon to harden while simultaneously causing the cone portions 16 of the balloon to dissolve or degrade or otherwise separate from body 14 as seen in Figure 3. The cylindrical body portion 14 of d e balloon, in its enlarged state, lies against the luminal surface of the vessel wall, providing mechanical support thereto. The body portion of die balloon provides the vessel wall with a protective, non-thrombogcnic surface during the primary dilatation phase of the angioplasty procedure, while also acting as a stcnt. The catheter along widi end portions or cones 16 is wididrawn through the cmplaccd stent.

The material comprising the body portion 14 of die balloon 10 is made to undergo a transformation such that it becomes rigid and inelastic upon the application of appropriate energy thereto. Upon transformation, the material comprising the body portion of the balloon remains widiin place in the vessel due to its tight fit. It may also adhere to the luminal surface of the vessel wall. A prcpolymcr is a material containing polymcrizable groups such as aery late or mcthacrylatc. Acrylatcd or mcthacrylatcd materials such as polyethylene glycol (PEG) dimcthacrylatc, isobornyl acrylatc, and ncopcntyl glycol diacrylate arc all prcpolymcrs. These materials, when in the presence of 2-hydroxy-2-mcthyl-l-phenylpropan-l-onc and irradiated widi ultraviolet light, will form a crosslinkcd, insoluble polymer matrix. For example, the hardcnablc balloon material may be a mixture of poly-D-L-lactic acid, (polymer), polyethylene glycol dimethacrylate (prepolymcr, and isobornyl aciylatc, neopentyl glycol diacrylate and/or 2-hydroxy-mcthyl-l-phcnylpropan- 1-onc (initiators). Other initiator materials which arc able to produce free radial bearing fragments upon irradiation may also be used. Such radical compositions arc UV hardenablc. A second balloon material can be formulated from all the above components, with the substitution of poly-DL- lactic acid or polycaprolactonc for poly-L-lactic acid as the polymer. The crosslinking component need not be physically separate from the predominant polymer. It could be attached to the backbone or a sidechain, or die end of the polymer. Non dcgradablc polymers as well as poly anhydrides. Polyphosphazines and odicr aliphatic could be interdeposed to form co- polymers widi the lactidcs and glycolidcs. Copolymcrs may be formed with carbohydrates and other biocompatiblc molecules. Radiation from a UV laser catheter introduced tlirough a lumen of a balloon catheter via an optical fiber may be used to supply the requisite energy to polymerize die material. Odicr prc-polymcr examples:

ethylenc glycol dimethacrylate cyclohexyl mcthacrylate dicthylene glycol diacrylate dicthylenc glycol dimethacrylate neopentyl gylcol diacrylate polyethylene glycol (600) dimethacrylate tripropylcne glycol diacrylate lauryl methacrylate stcaiyl methacrylale cthoxylatcd bisphenol A dimethacrylate cdioxylated bisphenol A diacrylate di-trimethylol propane tctraacrylate (LTX) isodccyl aciylatc dipcrt acrythritol pcntaaciylate isobornyl mcthacrylatc cthoxylatcd trimcthylol propane triacrylatc (LTX) highly cthoxylatcd bispcnol A dimethacrylate propoxylatcd trimcthylol propane triacrylatc dodecyl mcthacrylatc cthoxylatcd pcntaciythritol tctraacrylate caprolactonc aciylatc highly edioxylatcd TMPTA (trimcthylolpropanc triacrylatc) highly propoxylatcd TMPTA highly cthoxylaled TMPTA bobrnyl acrylatc propoxylatcd neopentyl glycol diacrylate glyceiyl propoxy triacrylatc highly propoxylatcd gylccryl triacrylatc aciylated or methacrylatcd metabolic fragments dcrvicd from reduction of Krcbs diacids and subsequent csterification

The material comprising the body portion 14 may contain activating agents which arc incorporated directly into die polymer material. Examples of such activating agents include peroxides, azidcs, and other UV activated or heat activated agents as known in the art. The activating agents arc incorporated into the polymer material and allow the polymer material to rapidly cross-link upon exposure to an activating energy source, such as fiber optic light. The energy will initiate the polymerization and/or cross-linking reaction to occur. The polymerization and or cross-linking causes the sleeve matcrial to form a hardened or rigid material capable of supporting the interior surface of the lumen for an indefinite period of time. The transformation from flexible to rigid and self supporting causes the central balloon portion to stay in place. The polymerization and/or cross-linking of the material of body portion 14 causes an increase in the modulus elasticity of the material from values typical of soft polymers, i.e. , 0.1 GPa (Gigapascal) to that of stiffer molecules with moduli elasticity near 4.0 GPa for example. When the activating agents arc located on the outside surface of the balloon, the polymerization and/or cross-linking reaction takes place on d e surface of the vessel itself. This allows for bonding of the surface agents to bodi the polymer and the vessel wall.

Lower concentrations of polymerization and/or cross-linking agents on the lumen or interior side of the balloon cause that portion to degrade density enhances blood compatibility of the outer layer of die balloon since rapidly degrading materials will prevent a protein, platelet or leukocyte accumulation.

In addition, the polymerization and/or cross-linking agents d at cause the modulus of elasticity to increase within the bulk of d e polymer may not necessarily be the same one or ones that arc preferred on the outside surface of the balloon where actual contact with the vessel is made. Cross- linking agents may be part of die polymer chains or may be incorporated into the bulk of the polymer by exposing preferably the exterior surface to a solution of the agent or agents so that die exterior side develops a higher concentration of agents than the lumen side.

In another preferred embodiment of the present invention highly active cross-linking agents arc encapsulated wid in micelles. When the body 14 of the balloon 10 is stressed, i.e., expanded by inflation of the balloon, the micelles collapse releasing the activating agents. Upon expansion, the stress in thc inflating body portion will be the greatest in the outer layers. If the body portion of the balloon comprises multiple layers, it is thus preferable to concentrate the micelles in the outer layers of body portion. The miccllar encapsulated material may also be released by other suitable forms of stress energy, such as ultrasonic disruption. Thus, after the body portion of d e balloon is inflated, an ultrasonic probe or transducer is inserted dirough a lumen in the catheter into or near the balloon cavity and activated, causing the release of activating agents. An example of such a system would be die incorporation of mcthylcnc diisocyanatcs (MDI) contained within phospholipid micelles composed of sodium dodccysulfatc. the MDI micelles would be incorporated as an oil or oil in water emulsion into die stcnt material, which in this case may contain reactive aminc groups, when it was cast from solution so diat the micelles would not be physically stressed. Upon expansion of die balloon, the walls of die stcnt become thinner in proportion to the expansion of the stent. The shear stress placed on the micelles would cause them to burst or otherwise crack. The MDI would immediately react with the amines to crosslink the polymer comprising the stcnt.

Alternatively the micelles could be comprised of phosphatidylcthanolaminc or any other short chain polymer diat would form micelles or microparticles. If die micelles contained peroxides or other free radical producing agents and if the polymer contained reactive double bonds as acrylates, then upon stressing the micelles, the free radicals would cause crosslinking of the polymer to occur. Alternately, the transducer may be the balloon itself which is then activated lo release the miccllar encapsulated activating agents. To accomplish this, the balloon may be comprised of a piezoelectric material as PVDF (e.g. polyvinylidincfluoridc) that is electrically connected to a power source at the proximal end of the catheter. Upon die application of an alternating voltage, the polymer will vibrate in response to the polarity of the voltage and in accordance to how die material was polled (dipolcs set).

The balloon of the first preferred embodiment of the present invention as shown in Figures 1-3 is incorporated into a catheter device which closely resembles a conventional percutaneous translumial coronary angioplasty ("PCTA") balloon catheter. The balloon is delivered to the desired portion of die vasculature in the usual manner for a percutaneous dilation. After the balloon is properly positioned in the area of the vascular lesion, it is inflated so that the balloon contacts and pushes back the material, generally plaque, which lines the vessel wall. Once die balloon is sufficiently inflated, energy is supplied to the balloon. The energy, preferably in the form of heat or light, causes the center body portion of the balloon to harden. The cones or ends 16 separate as described below and catheter 12 is then removed from die body as shown in Figure 3, leaving the hardened body portion 14 of die balloon inside the vessel lo provide mechanical support and to cover the vessel in order to prevent the formation of thrombus. The result is an in situ formed stent.

Energy may be delivered to die stcnt during its formation in the following manner. If the energy is thermal the inner shaft of the balloon may be coated with a semiconduclive material or wrapped widi a wire resistance heating clement 30 as shown in Figure 8 such that, upon application of a current d rough leads 32 and 34, resistive heating occurs. The energy is conductivcly transferred to the surface of the balloon by the liquid filling the balloon (not shown).

If die material in the stcnt or sleeve is activatiblc by light energy, then the center shaft of the catheter will contain an optic fiber 40 as shown in Figures 9 and 10 for diffusing radiation outwardly tlirough the balloon. The fiber may be made such that it will diffuse light transmitted down die optic fiber to the interior surface of the balloon. This light energy would be absorbed by the reactive species in the stcnt and induce the crosslinking of the polymer comprising die stcnl or the formation of an intcrpenctrating network. Alternatively, vibrational energy, delivered by a piczo clement (not shown) placed in the center of die balloon, could be delivered to the fluid filling die balloon causing it to heat, or the balloon itself could be caused to vibrationally heat if it were piezoelectric in nature. In the first preferred embodiment of the balloon of the present invention shown in Figures 1-3, the cone or end portions 16 of the balloon spontaneously dissolve or degrade and separate from body 14 upon the application of energy thereto while the body portion 14 hardens.

The hardcnablc balloon body material is preferably a mixture of poly-L-lactic acid (molecular weight > 1.4M), polyethylene glycol(Mw=600) dimethacrylate, isobornyl aciylatc, neopentyl glycol diacrylate, and 2-hydroxy- 2-medιyl-l-phcnylpropan-l-onc. A second preferred balloon body material may be formulated from all the above components, with the substitution of poly-DL-lactic acid or poly caprolaclonc for the poly-L-lactic acid. The end or cone portions 16 of the balloon may comprise a polymer which has labile components adapted to cause a chain scission reaction or may incorporate a polymer which arc cleaved by a secondary, energy activated compound and which break down into components which arc soluble and disperse. The polymers which may be used for die end portions of the balloon can be natural, synthetic or a modified natural polymer such as a conjugated protein. An example of a material for the scission regions 18 is a linear polyester prepared from 2-hydroxy-l-[4-(2-hydiOxycthoxy)phcnyl]-2- mcthyl-1-propanonc, dimethyl succinatc and zinc stcaratc. Along with die linear polyester is mixed 4-mcthoxyphcnol. A second polymer would be a linear polyester prepared from 2-hydroxy-l-[4-(2-hydiOxycthoxy)phcnyl]-2- mcthyl-l-proponc, dimethyl fumaratc, dimcthylscbacatc, and zinc stcarate mixed with 4-hydroxyphcnyloctyl ether.

In anodicr cmodiment, the cones of a balloon may detach from die cylindrical body of the balloon by the degradation of material at the scission regions 18 (Sec Fig. 2) attaching the cones 16 to the body 14. The degradation is initiated by the application of energy from the cadieter. In yet another embodiment, the cones 16 of die balloon 10 detach by shrinking away from the hardening body section 14 of the balloon and adhere to the shaft 12 of the catheter upon delivery of energy as seen in Figure 2. Such an arrangement is made possible if the cones arc made of polyethylene, or polyolcfin copolymcr that has been formed into a cone. In such an embodiment, the cone material changes its physical properties sufficient to become soft and easily pulled away from the hardened balloon portion upon the application of energy thereto.

In order to provide a conventional angioplasty balloon widi a low profile and to protect it from tearing, many manufacturers often wrap or coil a conventional angioplasty balloon inside a protective tube or sleeve, which is removed from die balloon prior to the procedure. It would be extremely advantageous if die protective sleeve did not have to be removed but could serve an additional purpose, such as a stcnt. This is provided by d e second embodiment of this invention as seen in Figures 4-5.

In that embodiment of the present invention, a conventional angioplasty balloon 20, sec Figure 4, is folded and encased in a balloon sleeve 22 comprising a material having the same properties as the body portion 14 of the balloon 10 described above in connection with Figures 1-3. The sleeve 22 cylindrically encases a conventional angioplasty balloon 20, giving the balloon 20 a low profile for insertion into a diseased area anαNprotccts the balloon from ripping or tearing. In use, the balloon 20 encased in the sleeve 22 is positioned adjacent the diseased portion of the vessel and is enlarged from a first insertion diameter to a second enlarged diameter as shown in Figure 5 upon expansion of die balloon. Thereafter, the sleeve 22 is caused to harden or become rigid in its enlarged slate. The sleeve material stretches during die primary cxpansion phase, conforming first to the shape of the balloon and then, as die balloon impinges on the vessel wall, to the shape of the combination of the balloon and wall.

The sleeve 22 is generally cylindrical in shape as seen in Figures 2 and 3 and is comprised of a polymer material which is capable of stretching to and maintaining a second, enlarged diameter configuration. The sleeve is formed by immersion of a mandrel in a solution or by spraying a mandrel. The transformation of the sleeve material lo a rigid or hardened state can be induced by any of the methods previously described. Thus, the application of energy may be used to initiate polymerization and cross-linking reactions, which causes the sleeve material to harden. Alternately, the transformation may also be caused by the release of chemical components encapsulated in the wall of the sleeve induced by stretching or the application of energy.

Figures 6 and 7 show a stcnt as in Figure 4 except diat in place of slots or slits, the stcnt is comprised of a microporous material in which die slots or slits increase in cross sectional area as the balloon expands die stcnt. In order to perform both functions, i.e., encasing the balloon and as an arterial lining, the sleeve material must be able to maintain sufficient strength to keep the folds of the balloon in place. It must also be capable of being expanded by the balloon without the addition of any form of energy prior to expansion, since this may lock the uncxpandcd sleeve in place. The sleeve will be relatively thin walled and sufficiently flexible to negotiate bends and curves encountered in the coronary and other arteries. The sleeve will generally range before expansion from about lmm to 3mm ID with wall thickness typically ranging from about 0.1 to 0.5mm. The wall thickness will decrease depending on the expansion of the sleeve. Also, the thickness will decrease in proportion to the differences determined by Area - pi(rl ^A2-r^*2 ^'2) where rl and r2 arc the inner and outer radius, generally speaking.

The sleeve may be comprised of a single polymeric material or multiple layers of different polymeric materials. Λ sleeve comprising multiple layers may, for example, include an interior layer of a non-adhcsivc swcllablc hydrogcl such as collagen or polyvinylpyrrolidone which is suiLablc for release from the balloon surface, one or more middle layers such as polylactic acid (PLΛ), specifically poly-L-lactic acid (PLLΛ), and cross-linking which arc suitable for uniform expansion under stress (plastic and formation) and cross- linking and an exterior layer such as collagen or other polyesters, which arc suitable for adhesion to the vessel wall by cross-linking or the like. In addition, the sleeve may comprise a polymer or polymers which contain therapeutic or pharmacological agents incorporated thereon.

Both the polymcrizable balloon and sleeve embodiments of the present invention may comprise materials such as PLA which will biodcgradc after a predetermined amount of time and/or may comprise materials capable of releasing drugs or other pharmaceuticals into die surrounding tissue. It should be appreciated that the device and methods of the present invention arc capable of being incorporated in the form of a variety of embodiments, only a few of which have been illustrated and described above. The invention may be embodied in other foπns without departing from its spirit or essential characteristics. The described embodiments arc lo be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by all the appended claims rather dian by the foregoing description. All changes which come within die meaning and range of equivalency of the claims arc to be embraced with their scope.

Claims

What Is Claimed Is As Follows:

1. A balloon for catheters, the balloon comprising a body portion and two end portions, the balloon being adapted to be inflated from a first condition to a second enlarged condition, and wherein said body porlion of the balloon comprises a material adapted to undergo a transformation from a flexible, clastic condition to a rigid, inelastic condition upon the application of energy thereto.

2. The device of claim 1 wherein said two end portions comprise a material adapted to degrade upon application of energy thereto.

3. The device of claim 1 wherein said two end portions detach from said body portion by the degradation of a scission material, said degradation initiated by the application of energy thereto.

4. The device of claim 1 wherein said end portions detach from said body portion and adhere to the shaft of the catheter upon application of energy thereto.

5. The device of claim 1 wherein said body portion comprises a material adapted to undergo a transformation from a flexible, elastic condition to a rigid, inelastic condition and said end portions comprise a material adapted to degrade, both transformations occurring upon the application of energy to the balloon.

6. A sleeve adapted to encase a conventional catheter balloon and to enlarge from a first diameter to a second diameter upon inflation of said balloon within a vessel lumen, said sleeve further adapted to undergo a transformation such that it maintains its second enlarged diameter upon application of energy thereto and wherein said sleeve comprises a material adapted to undergo a transformation from a flexible, clastic condition to a rigid, inelastic condition upon the application of energy thereto.

7. The sleeve of claim 6 wherein the sleeve comprises a hydrophilic material which is cross-linkable with the surface of a body vessel.

8. The sleeve of claim 6 wherein the sleeve comprises a polymer which contains therapeutic or pharmacological agents within the bulk of the polymer.

9. The device of claim 6 wherein the sleeve comprises multiple layers, an outermost layer adapted lo adhere to the vessel wall, a middle layer adapted to be formable under plastic deformation, and an inner layer adapted to release the balloon.

10. Λ method of treating a damaged section of a body vessel comprising the steps of: positioning a catheter adjacent die area lo be treated, said cadietcr comprising an angioplasty balloon having a body portion and two end portions; inflating said angioplasty balloon sufficient to impinge upon die inner luminal surface of the vessel wall; causing the body portion of said balloon to become rigid and inelastic in its inflated state; wid drawing said cadicter from the body vessel, the body portion of said angioplasty balloon remaining inside die body vessel.

11. The method of claim 10 wherein the application of energy to die balloon causes the body portion of the balloon to become rigid and inelastic.

12. The method of claim 10 wherein die release of chemical components encapsulated in the wall of the body portion of die balloon causes the body portion to become rigid and inelastic.

13. The method of claim 11 wherein die end portions of the balloon degrade upon the application of energy lo said balloon.

14. The mcdiod of claim 11 wherein die end portions of die angioplasty balloon detach from said body portion upon the application of energy to said balloon.

15. The method of claim 11 wherein the end portions of the angioplasty balloon shrink away from said body portion upon the application of energy to said balloon.

16. A mediod of enlarging a vessel lumen comprising the steps of: inserting into a body vessel a balloon angioplasty catheter having an angioplasty balloon encased in a sleeve, said sleeve adapted lo enlarge from a first diameter to a second enlarged upon inflation of said balloon, positioning said angioplasty balloon adjacent d e damaged section of the body vessel, causing said sleeve to enlarge from a first diameter to a second diameter, said second enlarged diameter being sufficient to enlarge the lumen of the body vessel, causing the sleeve to become rigid in its enlarged diameter configuration; and withdrawing said balloon angioplasty catheter from die body vessel.

17. The mediod of claim 16 wherein energy is applied to said sleeve to cause it to become rigid.

18. The method of claim 16 wherein die release of chemical components encapsulated in d e wall of die sleeve causes the sleeve to become rigid.

19. A method of providing support to die luminal surface of a body vessel comprising die steps of: inserting a catheter having an angioplasty balloon encased by a sleeve into a body vessel, said sleeve adapted to enlarge from a first insertion diameter to a second enlarged diameter upon inflation of the angioplasty balloon, positioning said angioplasty balloon adjacent die damaged scclion of the body vessel; causing said sleeve to enlarge lo its second enlarged diameter, said second enlarged diameter being sufficient lo impinge upon the luminal surface of the vessel, causing said sleeve lo assume an inflexible condition in its enlarged condition, and withdrawing said catheter from the body vessel.