US Patent 7942849 Catheter with multilayer tube

An interventional catheter for angioplasty and the like, comprising a catheter tube including an outer tubular member, an inner tubular member disposed within the lumen of the outer tubular member, and a balloon attached to the distal end of the outer tubular member and the distal end of the inner tubular member. The outer tubular member includes a first portion having a first stiffness and a second portion having a second stiffness less than the first stiffness. The inner tubular member has an inner surface having a first coefficient of friction and an outer surface having a second coefficient of friction greater than the first coefficient of friction.