the non - deployable stent of the present invention may be used in conjunction with a conventional balloon catheter . a pta or ptca catheter ( dilatation catheter ) may be a coaxial catheter with inner and outer members comprising a guide wire lumen and a balloon inflation lumen , respectively . each member can have up to 3 layers and can be reinforced with braids . the proximal end of the catheter has a luer hub a guidewire and for connecting an inflation means , and a strain relief tube extends distally a short distance from the luer hub . the distal ends of the outer and inner members may include a taper . the catheter shaft is built using conventional materials and processes . a catheter having multi - durometer tubing with variable stiffness technology is also a possibility . the catheter should be compatible with standard sheaths and guide catheters which are well known in the art . optionally , the catheter may be a multi - lumen design . the balloon 1 may be made of either nylon or nylon copolymer ( compliant , non - puncture ) or pet ( high pressure , non - compliant ) with a urethane , polymer , or other material and coating known in the art to provide tackiness and / or puncture resistance . the balloon may be a multi - layered balloon with a non - compliant inner layer to a most compliant outer layer or multilayered with similar material . for example , a inner most layer of pet , which provides a higher pressure balloon , surrounded by an outer layer of nylon , which provides a more puncture - resistant surface . the balloon may be from 1 . 5 - 12 mm in diameter ( 1 . 5 - 4 mm for coronary and 4 - 12 mm for peripheral vessels ) and 15 - 60 mm in length ( 5 - 40 mm for coronary and up to 60 mm for peripheral vessels ). the balloon inflation rated pressure will be from 8 - 20 atmospheres , depending on the wall thickness of the balloon . when inflated , the balloon ends or necks are cone - shaped . in keeping with the invention , the balloon is provided with a nitinol ( niti ) or another material such as for example liquid metal , stainless steel , or other similar material , structure , generally designated 2 , that incorporates bends for both radial and longitudinal expansion of the nitinol structure 2 in response to longitudinal and radial expansion of the balloon during inflation , so that the nitinol structure 2 maintains the balloon in its intended position during inflation . this nitinol structure 2 can be described as a non - deployable or temporary stent that provides for both controlled cracking of vessel occlusion and gripping of vessel wall during an angioplasty procedure . the nitinol structure 2 comprises a laser cut hypo tube that expands upon inflation of the balloon , but collapses upon deflation of the balloon because of the super - elastic properties of the nitinol material , rather than remain expanded in the deployed condition , as would stents in general . the nitinol structure or non - deployable stent 2 has a proximal end 3 , a distal end 4 , and , therebetween , anywhere from 3 - 12 struts or wires 5 ( depending on balloon size — but most likely 3 - 4 struts ) with a pattern of radial and longitudinal bends . the use of laser cutting in connection with stent manufacture is well known ( see , e . g ., meridan et al . u . s . pat . no . 5 , 994 , 667 ), as is the use of the super - elastic nickel - titanium alloy nitinol ( see e . g ., huang et al . u . s . pat . no . 6 , 312 , 459 ). as seen in fig1 - 4 , each end of the four struts 5 has a sinusoidal type bend 6 that allows the laser cut hypo tube to expand longitudinally when the balloon 1 is inflated . the linear length of the sinusoidal type bends 6 is sized to accommodate the longitudinal expansion of the balloon 1 due to inflation . the strut or wire 5 cross sectional shape can be round , triangular , elliptical , oval , or rectangular . preferred thickness of the struts 5 ranges from 0 . 003 to 0 . 010 inch . at the longitudinal center of the hypo tube , a u - shaped circumferential connector 7 joins each strut 5 to its adjacent strut . as best seen in fig3 and 4 , the u - shaped connectors 7 are on opposing sides of the central radial axis . the distal end 4 of the hypo tube is adhered to the distal neck of the balloon or the distal end of the catheter shaft , and the proximal end 3 of the hypo tube is either attached to the proximal neck of the balloon or to the proximal end of the catheter shaft . the struts 5 may be attached to the working region of the balloon 1 to assist the hypo tube in staying with the balloon as it inflates and deflates . catheter shafts to which the balloon and laser cut hypo tube are attached can have diameters ranging from 2 . 5 f to 8 f , and the distal end may be tapered and slightly less in diameter than the proximal end . in fig6 , the dimensions of the laser cut hypo tube are for use with a 3 mm ( 0 . 118 in ) diameter by 20 mm length balloon . the circumference of a 3 mm balloon is . pi . d = 3 . 14 ( 3 mm )= 9 . 42 mm or 0 . 37 in . as can be readily appreciated , the total length of all u - shaped connectors 7 ( up and back ) must be greater than the circumference of the inflated balloon 1 . the length of each u - shaped connector 7 ( up and back ), may be calculated using the following equation : where d is the diameter of the inflated balloon and n is the number of struts . the total length of the u - shaped bends ( up and back ) must exceed this length . the resulting number is divided by 2 to get the length which each up - and - back side of the u - shaped connector should exceed . for example : for a 3 mm balloon compatible , laser - cut hypo tube with four struts , the length of each u - shaped connector ( up and back ) is 0 . 37 inch divided by 4 = 0 . 0925 in . further divide by 2 and to get 0 . 04625 in . this is the length that each side of the u - shaped connector must exceed . there is also one or more sets of u - shaped connectors 7 in between the sinusoidal bends 6 . the set includes one u - shaped connector for each strut ( 3 struts — a set of 3 u - shaped connectors ; 4 struts — a set of 4 u - shaped connector ; and so on ). the number of u - shaped connector sets depends on the length of the balloon and thus , the length of the laser cut hypo tube . for a 20 mm length balloon , there is one set of u - shaped connectors spaced 10 mm from the end ( at the halfway point along length of balloon ). for a 40 mm length balloon , there are three sets of u - shaped connectors spaced in 10 mm increments ( the first set is spaced 10 mm from one end ; the second set is spaced 10 mm from first set ; and the third set is spaced 10 mm from each the second set and the other end ). the equation for number of sets of u - shaped connectors . where l = length of balloon in mm . other embodiments , such as those shown in fig7 and 8 , do not incorporate the intermediate u - shaped connectors . fig1 is directed to another embodiment of a non - deployable stent 102 which can be used with a conventional balloon catheter , in accordance with the present invention . the stent of this embodiment preferably has a nitinol structure , though other materials can be used as discussed supra , that incorporates bends for both radial and longitudinal expansion of the stent in response to radial and longitudinal expansion of the balloon during inflation , so that the stent 102 maintains the balloon in its intended position . similar to the stents of the other embodiments of the present invention discussed supra , the stent comprises a laser cut hypo tube that expands upon inflation of the balloon and collapses upon deflation of the balloon . further , the stent is preferably secured to the balloon with some type of anchoring means . preferably , such anchoring means are utilized at the ends of the stent and around the neck of the balloon . examples of such anchoring means include an adhesive such as for example a uv adhesive , cyanoacrylate , or a two - part epoxy , rf heat welding , solvent bonding , or crimping or swaging the ends of the stent to the shaft . alternatively , a mechanical anchoring means can be used to anchor the stent to the balloon . with such a means , a small sleeve 24 made of a similar material as the shaft 26 of the catheter is mounted over the ends 28 of the stent 30 and heat welded together where the ends of the stent are sandwiched between the shaft and the sleeve ( fig5 a ). fig1 shows the hypo tube of the stent in an unrolled ( flat ) and non - extended state . the stent 102 has a proximal end 103 and a distal end 104 . at each end , there are cage mounted flanges 110 . these flanges can be used to attach the stent to the neck of the balloon . the flanges also spring open radially to permit insertion of the balloon during assembly . between the ends , the stent 102 includes extension sections 112 , serpentine rings 114 and elongation links 116 . serpentine rings 114 have a serpentine shape and allow the stent 102 to expand radially when a balloon in the stent is inflated . however , as the balloon expands , the serpentine rings 114 will shorten in length . accordingly , extension sections 112 and elongation links 116 expand longitudinally to compensate for any shortening of the length of serpentine rings 114 . preferably , elongation links 116 have a z - shape , s - shape or accordion shape , as shown in fig1 . fig1 is an alternative embodiment showing a stent 202 having the same features as the stent in fig1 except that stent 202 in fig1 has elongated links 216 with a different pattern than the elongated links 116 in stent 102 of fig1 . more specifically , elongated links 216 have a zig zag pattern . stent 202 of fig1 operates in a substantially similar manner to that of stent 102 in fig1 . while the present invention is not limited in the number of serpentine rings , extension sections and elongated links used in the stent , fig1 illustrates a preferred embodiment . the stent 202 in fig1 has from proximal end 103 to distal end 104 , a first extension section 112 , a first set of serpentine rings 114 , a first set of elongated links 216 , a second set of serpentine rings 114 , a second set of elongated links 216 , a third set of serpentine rings 114 , a third set of elongated links 216 , a fourth set of serpentine rings 114 , and a second extension section 112 . fig1 also shows an example of possible dimensions , in inches , of each of the components of the stent 202 . these dimensions would also be used for each of the similar components in stent 102 in fig1 . it will be understood that the embodiments and examples of the present invention , which have been described , are illustrative of some of the applications of the principles of the present invention . numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention .
an angioplasty balloon including a non - deployable stent to prevent or reduce the potential for slippage of the inflated balloon with respect to the vessel wall being treated . the balloon includes a non - deployable stent that is adapted to be secured to the balloon or angioplasty balloon catheter . the stent has a proximal end , a distal end , and at least one extension section , at least one set of serpentine rings and at least one set of elongation links that allow expansion of the strut to accommodate the inflation of the balloon . the stent is made of a material so that the stent collapses upon deflation of the balloon .