Catheter having sections of variable torsion characteristics

Claim 1

A flexible catheter which comprises: a plastic tube that is resilient and flexible having a proximal end and a distal end, said plastic tube carrying a single wire sheath formed of generally helically disposed and braided crossing wire strands, said wire strands defining a first strand angle to each other along a first section of the tube toward the distal end of the tube and defining a second strand angle to each other along a second section of the tube between the first section and the proximal end of the tube, said strand angle being defined as the angle that generally faces in the direction of the tube axis, said first strand angle being less than said second strand angle by at least 5 degrees whereby the second section has higher torsional stiffness and less longitudinal stiffness than said first section, said tube carrying, between its proximal end and said second section, wire strands that are generally parallel to each other to increase the longitudinal rigidity of the catheter toward its proximal end while the torsional stiffness thereof is minimized.