Thermoplastic polyurethanes as insulating materials for long-life cardiac pacing leads

Historically, the material most widely used for permanent cardiac pacing lead insulation has been silicone elastomer. We have recently evaluated a variety of polyether polyurethanes and found them also to be suitable as insulating materials for cardiac pacing leads. Test results showed that these polyurethanes are extremely tough, hydrolytically very stable, non-toxic, non-carcinogenic, and very inert in a biological environment. In addition, because polyurethane has a higher tensile strength than silicone elastomer, a thinner insulating layer can be used to construct smaller diameter leads. This facilitates the introduction of one or two leads through small veins or split sheath introducers. The smooth polyurethane material is also very easy to advance through the venous circulation, thus improving the handling characteristics of the lead or leads.