fig1 is a surface depiction of a balloon catheter capable of incorporating the various aspects of this invention . fig2 a is a schematic representation of the distal portion of the above catheter wherein various aspects of this invention are revealed . fig2 b is a schematic representation of a cross - section of the distal portion shown in fig2 a . fig2 c is another schematic representation of a cross - section of the distal portion shown in fig2 a wherein the walls of the two tubes are depicted as layers of material . fig3 a is a schematic representation of a braided reinforcing member of this invention . fig3 b is a schematic representation of a cross - section of a single strand of the braided reinforcing member shown in fig3 a . fig4 is a schematic representation of a section of the outer tube comprising the distal end of a catheter of this invention wherein longitudinally varying the composition of the material from which the tube is formed is depicted . fig5 a is a schematic representation of the balloon - forming structure of a catheter of this invention about to be butt - welded to the outer tube of the body of the catheter . fig5 b is a schematic representation of a balloon - forming structure butt - welded to the outer tube of a catheter showing a braided reinforcing member of this invention overlapping the weld . fig6 is a schematic representation of the distal end of a catheter of this invention showing the braided reinforcing member extending from the distal end of the outer tube completely over the balloon - forming structure . fig7 is a schematic representation of the distal end of a catheter of this invention showing a separate reinforcing member extending from the distal end of the balloon - forming structure over the weld and onto the outer tube of the catheter . fig8 is a schematic representation of a channel created in the distal end of the balloon forming structure to permit escape of air when the structure if filled with liquid to expand it . this invention relates to the distal portion of a balloon catheter . the distal portion is generally anywhere from the distal 2 cm to the distal 30 cm of the catheter although , depending on the tissue area to be reached , the distal end may be of any desired length and , regardless of the length , would be within the scope of this invention . the distal portion has a small over - all cross - section that allows it to be used to reach remote areas of tissue such as the brain and the liver . the small cross - section is achieved by reducing the wall thickness of both the tubes making up the catheter . structural integrity of the outer tube , which is subjected to high pressures during inflation of the balloon - forming structure is maintained by incorporating a reinforcing member into the wall of the outer tube . in a presently preferred embodiment of this invention , the reinforcing member is comprised of braided strands . a braided reinforcing member provides kink resistance to the outer tube when the tube is being bent to traverse tortured pathways in the vascular system . the inner tube likewise includes a reinforcing member , the purpose of which is to provide structural integrity against kinking when the tube is being bent to conform to the shape of the outer tube . the inner reinforcing member is also a braided reinforcing member in a presently preferred embodiment of this invention , fig1 is an exterior view of a typical balloon catheter 100 . catheter 100 is shown solely for the purpose of aiding in the understanding of the present invention and does not constitute the only assembly covered by this invention . any manner of balloon catheter assembly incorporating the aspects of this invention is within the scope hereof . in any event , catheter 100 consists of a luer assembly 110 for guide - wire 112 manipulation and for liquid introduction into the balloon - forming structure 120 . within balloon - forming structure 120 are radiopaque regions ( not shown ) which permit visualization of the position of the distal end of the catheter in a patient &# 39 ; s body . catheter 100 is shown as having several portions 102 , 104 and 106 . these portions have differing degrees of flexibility with portion 106 being the lease flexible , portion 104 being intermediate in flexibility and portion 102 being the most flexible . a catheter of this invention , however , is not limited to any particular number of such portions and may have fewer than three areas of different flexibility or many more . as described with regard to catheter 100 , in general , as one progresses toward the distal end of the catheter , the assembly becomes increasingly flexible . the present invention relates to the most distal and most flexible portion 102 of a balloon catheter . fig2 a is an isolated blow - up of portion 102 of catheter 100 . portion 102 comprises two tubular sheaths 200 an 210 , tubular sheath 210 being disposed within tubular sheath 200 as shown in fig2 b . each tubular sheath , hereinafter referred to simply as a “ tube ,” has an inner and an outer surface . that is tube 200 has inner surface 201 and outer surface 202 and tube 210 has inner surface 212 and outer surface 211 . the two surfaces of either tube may constructed of the same or of different materials . if they are comprised of different materials , then the tube is composed of layers with the inner surface of a tube comprising the surface of one layer and the outer surface of that tube comprising , a surface of another layer . that is , inner surface 201 of tube 200 may be comprises of a layer of material 201 a and outer surface 202 may be comprised of a different layer of material 202 a . the composition of tube 200 or tube 210 is not limited to two layers and there may optionally be additional layers of different materials between the layers having surfaces 201 and 202 . a wide variety of materials may be used to make tubes 200 and 210 . for example , without limitation , polytetrafluoroethylene ( teflon ), polyethylene , polypropylene , the nylons , polyesters , polyimides , polyamides and the like . presently preferred polymers for use in manufacture of the various aspects of this invention are various pebax ( polyether block amide ) thermoplastic elastomer resins such as pebax 4033 , pebax 5533 and pebax 6333 , alone or in combination . disposed between surfaces 201 and 202 or layers 201 a and 202 a is a reinforcing member . while the reinforcing member may have a number of different structures including , but not limited to , helically wound strands , longitudinal strands , etc ., in a presently preferred embodiment of this invention the reinforcing member is a braided reinforcing member 220 . braided reinforcing member 220 is comprised of a plurality of strands 221 each having a ribbon - like structure , that is , each strand has a cross - section having a width 223 and a thickness 222 where the width is greater than the thickness as shown in fig3 b . fig3 shows a blow - up of a portion of braided reinforcing member 220 . braided reinforcing member 220 is comprises of individual strands 221 . individual strands 221 may be constructed of a variety of different materials . they may be metallic or nonmetallic . metals that may be used include , without limitation , stainless steel , platinum , palladium , gold , rhodium , tantalum and the like . metal alloys may also be used such as , again without limitation , nitinol ( a titanium / nickel alloy ). non - metallic substances that can be used include , without limitation , aramids ( e . g ., kevlar ), liquid crystal polymers and carbon fibers . when individual strands 221 are metallic or alloy , each strand 221 has a width 223 of from about 0 . 002 inches to about 0 . 004 inches with about 0 . 003 inches being presently preferred . the thickness 222 of such metallic strands 221 is from about 0 . 0004 to about 0 . 00075 inches with about 0 . 0005 inches being presently preferred . braided reinforcing member 220 is disposed between surface 201 and surface 202 of tube 200 . if the surfaces are of the same materials , i . e ., there are no layers of materials as discussed above , braided reinforcing member 220 may simply be embedded in the material of which tube 200 is constructed . or , if surface 201 is of a different material than surface 202 , that is , if tube 200 is composed of at least two layers of different materials , braided reinforcing member 220 may be sandwiched between any two layers . when tube 200 is constructed of layers of different materials , an adhesive may be placed between the layers to assist in binding braided reinforcing member 220 to the materials and the materials to one another . in order to accommodate braided member 220 while maintaining as small an overall cross - section as possible , the thickness of the materials of which wall 225 of tube 200 ( fig2 b ) is comprised must be reduced . when tube 200 is made of a single material , this amounts to simply using less material to encapsulate braided member 220 . when two or more different materials are used , the thickness of any of them may be reduced . in a presently preferred embodiment of this invention , inner layer 201 a is necked down , which can be accomplished during the fabrication or some of the material can be removed by , for example , laser milling . braided reinforcing member 220 can then simply be slid onto inner layer 201 a and outer layer 202 a can then be applied over the entire structure to encapsulate braided reinforcing member 220 . it is also within the scope of this invention that each layer of tube 200 is constructed of different materials longitudinally . fig4 shows such a structure wherein outer surface 202 is constructed of materials 300 , 301 and 302 along its length . as shown in fig2 the distal end of catheter 100 comprises a balloon - forming structure 120 . balloon - forming structure 120 is shown in its inflated state in fig2 and the other figures herein so as to more easily depict the aspects of the present invention . it is understood , however , that , in its deflated state , balloon - forming structure 120 compresses down until it has essentially the same profile , i . e ., cross - section , as portion 102 of catheter 100 proximal to it . balloon - forming structure 120 is coupled at its proximal end to the distal end of outer tube 200 . this may be accomplished by overlapping a proximal portion 121 of balloon - forming structure 120 with a distal portion of tube 200 and binding the two portions using an adhesive ( fig2 a ). in making this sort of connection , a bead 122 is usually created where the overlap occurs and the adhesive is applied ( fig2 a ). this bead may adversely affect the cross - sectional profile of the catheter . thus , it is an aspect of this invention that the proximal end 330 of balloon - forming structure 120 is butt - welded to the distal end 340 of tube 200 as shown in fig5 a . this can be accomplished by , for example , laser welding . regardless of whether balloon - forming structure 120 is overlapped and adhesively bonded to tube 200 or whether it is butt - welded to tube 200 , braided reinforcing member 220 overlaps the joint as shown in fig5 b to add strength and rupture resistance to the joint . it is also within the scope of this invention that braided member 220 extends completely over balloon - forming structure 120 to provide rupture resistance to the structure as shown in fig6 . to accommodate the increased diameter of balloon - forming structure 120 when inflated , the weave may be relaxed , that is , the distance between strands of braided reinforcing member 220 may be increased . alternatively , balloon - forming structure 120 may incorporate a separate reinforcing member 430 that extends from its distal end 415 to beyond its proximal end 420 , as shown in fig7 . braided member 220 is then terminated at a distance 400 from the distal end 410 of tube 200 . when proximal end 420 of balloon - forming structure 120 is bonded to the distal end 410 of tube 200 , reinforcing member 430 can overlap the joint to provide additional strength and rupture resistance . inner tube 210 ( fig2 ) is constructed similarly to outer tube 200 . that is , inner tube 210 has an inner surface 212 and an outer surface 211 . the two surfaces of may constructed of the same or of different materials , in the latter case the surfaces can be considered as comprising layers . that is , inner surface 212 may comprise the surface of a layer of material 212 a and outer surface 211 may comprise the outer surface of a different layer of material 211 a . as before , the structure of tube 210 is not limited to any particular number of layers and the number and types of materials used can be varied depending on the characteristics to be imparted on tube 210 . disposed between surfaces 211 and 212 or layers 211 a and 212 a is a reinforcing member 500 ( fig2 b , 2 c ). reinforcing member 500 may be a braided member such as braided reinforcing member 220 in tube 200 . in such case , reinforcing member 500 is likewise comprised of more than 4 individual braided strands each having a ribbon - like structure , that is , each strand has a cross - section having a width and a thickness where the width is greater than the thickness . the width and thickness of each strand are also similar to that of braided member 220 . the materials from which reinforcing member 500 may be constructed are also the same as those described above for braided member 220 . that is , the strands of reinforcing member 500 may be metallic or non - metallic . if metallic , the metals that may be used include , without limitation , stainless steel , platinum , palladium , gold , rhodium , tantalum and the like . in addition , metal alloys may also be used such as , again without limitation , nitinol ( a titanium / nickel alloy ). non - metallic substances that can be used include , without limitation , aramids ( e . g ., kevlar ), liquid crystal polymers and carbon fibers . in a catheter of this invention , the material from which reinforcing member 500 is constructed may be the same as that used to construct braided reinforcing member 220 or it may be another material selected from those described . when metallic strands are used to form reinforcing member 500 , the dimensions of each strand are similar to those of each strand of braided reinforcing member 220 . that is , each strand has a width of from about 0 . 002 inches to about 0 . 004 inches with about 0 . 003 inches being presently preferred . likewise , when the strands are metallic , the thickness of each strand is from about 0 . 0004 to about 0 . 00075 inches with about 0 . 0005 inches being presently preferred . reinforcing member 500 need not , however , be braided . it may , for example be a single helically - wound strand . it may comprise a single helical wrap in one direction , proximal or distal or it may be wrapped in two directions , e . g ., a first helical wrap going from proximal to distal and then a second wrap on top of the first going from distal to proximal . jointly owned u . s . pat . no . 6 , 152 , 912 describes such helically - wound reinforcing members and is incorporated by reference as if fully set forth herein . reinforcing member 500 , like braided reinforcing member 220 is disposed between surface 211 and surface 212 or layers 211 a and 212 a of tube 210 . if the two surfaces are made of the same material , reinforcing member 500 may simply be embedded in that material or a first layer of the material can be formed into a tube , reinforcing member 500 may then be wrapped around that tube and then additional material may be applied over reinforcing member 500 to complete the structure . if , on the other hand , surface 211 is of one material and surface 212 is of another such that tube 200 is made of at least two layers , 211 a and 212 a , reinforcing member 500 is sandwiched between them by wrapping layer 212 a with reinforcing member 500 and than applying layer 211 a over it . when tube 210 is constructed of layers of different substances , an adhesive may be used to assist in binding reinforcing member 500 to the layers the layers to one another . as with tube 200 , in order to accommodate reinforcing member 500 while maintaining a small overall cross - section , the thickness of the materials of which the wall of tube 210 is made must be reduced . in a presently preferred embodiment of this invention , inner layer 212 a is necked down , either during manufacture or by subsequent laser milling , a braided reinforcing member is slid onto inner layer 212 a and outer layer 211 a is applied over the structure to encapsulate the braided reinforcing member . it is also within the scope of this invention that each layer of tube 210 is constructed of different materials longitudinally as shown in fig5 for tube 200 a final aspect of this invention is a channel 600 created at the distal end of the balloon - forming structure 120 ( fig8 ). the channel is constructed such that , when pressurized liquid is injected into annular space 610 between the outer surface 201 of tube 200 and the outer surface 212 of tube 210 , any air trapped in the annular space is expelled through the channel . the channel is small enough , however , that the viscosity of the injected liquid keeps it from following the air through the channel resulting in deflation of balloon - forming structure 120 . in addition , when liquid is being withdrawn from the annular space to collapse balloon - forming structure 120 , usually by applying a vacuum to the system , channel 600 will also collapse thus preventing any significant amount of blood or other bodily fluid from being drawn into the annular space . thus , it will be appreciated that the devices disclosed herein will be useful in catheters , particularly the distal end of high - pressure vascular balloon catheters , wherein they will provide structural strength to resist bursting under pressure , torsional and longitudinal directivity and kink resistance while maintaining the small diametric profile necessary for traversing small tortuous vascular channels . although certain embodiments and examples have been used to describe the present invention , it will become apparent to those skilled in the art that changes in the embodiments and examples may be made without departing from the scope of the invention herein .
the present invention relates to a high pressure vascular balloon catheter wherein the walls of the tube attached to the balloon - forming segment are reinforced with a braided ribbon member . the walls of the inner tube that provides the lumen for a guidewire may also be reinforced in the same way . the reinforcement has the dual effect of providing strength against rupture under pressure and prevention of ovalizing or kinking during insertion into tortuous vessels of a vascular system .