Balloon catheter having non-bonded integral balloon and methods for its manufacture

A method of manufacturing a balloon catheter, said method comprising the steps of:

• a) providing a workpiece which comprises:
• i) an outer tube having a proximal end, a distal end, a longitudinal axis, a hollow lumen extending longitudinally therethrough, an outer surface, and an inner surface;
• and
• ii) an inner tube disposed within at least a portion of the lumen of the outer tube, adjacent at least the distal end of the outer tube, said inner tube having a proximal end, a distal end, a longitudinal axis, a hollow lumen extending longitudinally therethrough, an outer surface and an inner surface;
• b) irradiating a first region of said workpiece to soften the portion of said outer tube which is within said first region;
• c) inserting a first rigid mandrel into the lumen of the inner tube, such that said mandrel extends through said first region;
• d) placing a mold adjacent the outer surface of the first region of the outer tube, said mold having an inner surface, said inner surface being shaped to the desired shape of said balloon;
• e) closing off the distal end of the lumen of the outer tube, thereby preventing fluid from leaking out of the distal end of the lumen of the outer tube;
• f) introducing pressurized fluid into the lumen of the outer tube, outboard of the outer surface of the inner tube to exert outward distending pressure against the first region of the outer tube;
• g) concurrently, i) heating and ii) longitudinally drawing said first region of said workpiece while introducing said pressurized fluid, thereby facilitating distention of said first region into contact with the inner surface of said mold to form a balloon of the desired configuration on said workpiece;
• h) terminating the introduction of pressurized fluid into the lumen of the outer tube;
• i) removing said mold;
• j) trimming the distal end of the outer tube and the distal end of the inner tube, as necessary, to cause the distal end of the inner and outer tubes to be substantially coterminous;
• k) inserting a second rigid mandrel into the distal end of the lumen of the inner tube;
• l) fusing the distal end of the outer tube to the distal end of the inner tube to form a distal closure of the lumen of the outer tube lumen, wherein the second rigid mandrel is inserted, while allowing the distal end of the inner tube lumen to remain open;
• m) removing the second rigid mandrel from the inner tube lumen.