Polyisobutylene urethane, urea and urethane/urea copolymers and medical leads containing the same

A method of manufacturing an implantable medical lead comprising:

• forming a main tubular lead body portion from a polyisobutylene-based urethane copolymer comprising a polyisobutylene segment and a polyether segment selected from the group consisting of linear, branched and cyclic homopoly(alkylene oxide) and copoly(alkylene oxide) segments, the main lead body ranging from about 5 cm to about 125 cm in length and having a Shore hardness ranging from about 75 A to about 100 A;
• forming a distal tip portion positioned distal to the main lead portion, said distal tip portion ranging from about 1 cm to about 12 cm in length and having a lower Shore hardness that the main lead body portion ranging from about 30 A to about 80 A;
• associating at least the main tubular lead body portion with a conductor and an electrode connected to the conductor.

An implantable medical lead comprising an elongated polymeric component comprising:

• an elongated polymeric component disposed over at least one electrical conductor, wherein the elongated component comprises a polyisobutylene-based urethane, urea or urethane/urea copolymer comprising a polyisobutylene segment and a polytetramethylene oxide segment, wherein the lead includes at least one spiral loop when in a relaxed state, and wherein the Shore hardness of a surface of the elongated polymeric component that faces radially outward from the center of the spiral loop ranges between about 90 A and about 100 A and the Shore hardness of a surface of the elongated polymeric component that faces radially inward toward a center of the spiral loop ranges between about 50 A and less than 90 A.