Wear of cardiac lead outer insulation due to internal cable motion

Insulation wear in implanted cardiac leads may result in serious failure modes, including inappropriate or missing therapy. A novel test apparatus intended to simulate a range of loading conditions between cardiac lead components has been developed. Wear testing performed in an aqueous environment at loads and velocities anticipated to occur in-vivo shows that a material with decreased toughness exhibited increased wear rate. Order of magnitude variability within test groups was observed, suggesting that reliability projections should incorporate the statistical nature of the wear rate. Ranking of implantable material wear rates are possible using this methodology.