. . "As shown in FIG. 3, proximal portion 14 may comprise coaxial, extruded layers including an outer layer 16 which may be made of polyurethane, nylon, or the like, and a central layer 18 which includes embedded tubular woven wire braiding of conventional design for catheters, with the nylon or other compatible plastic material permeating the interstices of the tubular braiding in conventional manner." . .