Balloon catheter shaft having high strength and flexibility and method of making same

A method of making a balloon catheter having an elongated shaft and a balloon on a distal shaft section, comprising:

• a) melt-extruding a thermoplastic polymeric material having a relatively low Shore durometer hardness, to form a tube having a lumen, and a first inner and outer diameter, and cooling the extruded tube to a temperature less than an elevated temperature of the melt-extrusion;
• b) placing the extruded tube within a capture member and biaxially orienting the polymeric material of the extruded tube, with the extruded tube at an elevated temperature, by radially expanding the extruded tube with pressurized media in the tube lumen and simultaneously or sequentially axially expanding the extruded tube with a load applied on at least one end of the tube, to a second outer diameter which is about equal to the inner diameter of the capture member and a second inner diameter which is at least about 5 times larger than the first inner diameter of the extruded tube;
• and
• c) cooling the expanded tube to room temperature, the cooled, expanded tube being a biaxially oriented nonporous thermoplastic polymer tubular member, and sealingly securing a balloon to a distal end of the tubular member, such that the tubular member forms at least a portion of the catheter shaft and the balloon has an interior in fluid communication with the tubular member lumen.

A method of making a balloon catheter having an elongated shaft and a balloon on a distal shaft section, comprising:

• a) melt-extruding a thermoplastic polymeric material having a relatively low Shore durometer hardness, to form a tube having a lumen, and a first inner and outer diameter, and cooling the extruded tube to a temperature less than an elevated temperature of the melt-extrusion;
• b) placing the extruded tube in a lumen of a capture member and biaxially orienting the polymeric material of the extruded tube, with the extruded tube at an elevated temperature, by radially expanding the extruded tube with pressurized media in the tube lumen and simultaneously axially expanding the extruded tube with a load applied on at least one end of the tube, to a second outer diameter which is about equal to the inner diameter of the capture member and to a second inner diameter which is at least about 5 times larger than the first inner diameter of the extruded tube;
• c) cooling the expanded tube to room temperature, the cooled, expanded tube being a biaxially oriented nonporous thermoplastic polymer tubular member, which forms at least a portion of the catheter shaft and which has a Shore durometer hardness of not greater than about 55D to about 75D, such that the tubular member has a Gurley bending stiffness of not greater than about 50 to about 150 mg, a rupture pressure of at least about 20 to about 50 atm, and a tensile strength of at least about 1 to about 5 lbf;
• and
• d) sealingly securing a balloon to a distal end of the tubular member such that the balloon has an interior in fluid communication with the tubular member lumen and a rated burst pressure which is significantly less than the rupture pressure of the shaft tubular member and which is at least about 14 atm.