Polyether polyurethanes for implantable pacemaker leads.

Two variations of a commercially available polyether polyurethane were evaluated for certain physical properties and the changes in those properties as a result of plasticization by absorbed moisture. Appropriate tests were done to establish biocompatibility. A two-year rat implant study evaluated chronic biocompatibility and biostability. Ten tumours were found in 34 animals, of which eight were considered unrelated to the materials. Two fibrosarcomas were presumed to be the result of solid-state carcinogenesis, not related to the material per se. Material testing included analysis of density, tensile strength, elongation, molecular weight, intrinsic viscosity, scanning electron microscopy, differential scanning calorimetry, and infrared spectrum changes. The polyether polyurethane was considered to be biocompatible and biostable for long-term implant.