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Abstract

An improved pacemaker lead including a lead body supporting at least one flexible conductor element that provides an electrical signal path between a proximal connector element and a distal electrode. The lead body includes an insulating structure that protects the flexible conductor element(s) wherein the insulating structure is realized from a polymer material comprises an isobutylene block copolymer. The polymer material of the insulating structure has a maximum tensile strength in the range between 20 MPa and 40 MPa (most preferably in a range between 25 MPa and 35 MPa). In the preferred embodiment, the hardness of the polymer material of the insulating structure can be characterized by a Shore hardness in a range between 70A and 80A. In the preferred embodiment, the isobutylene block copolymer consists of a first polymer block component containing isobutylene-derived monomer units and a second polymer block component derived from a monomer component other than isobutylene (most preferably, styrene) with mole fraction of said second polymer block component as part of said isobutylene block copolymer in a range between 30% and 40%. The flexible conductor element(s) preferably include a coiled wire conductor defining a central axis with an outer surface facing radially outward away from the central axis and an inner surface facing radially inward toward the central axis, and the insulating structure surrounds at least the outer surface of the coiled wire conductor (and more preferably encapsulates the coiled wire conductor). The polymer material of the insulating structure has reduced oxygen permeability, and thus provides improved resistance to environmental stress cracking and metal ion induced oxidation while maintaining the flexibility and desired tensile strength of the lead body.

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First Claim