Studies of poly(ether)urethane pacemaker lead insulation oxidation.

Published reports suggest that silver ions may catalyze the oxidation of poly(ether)urethane soft-segments resulting in the failure of urethane insulations of specific models of pacemaker leads. Attempted oxidation of soft-segment models, poly(tetra-methylene ether)glycols, by silver nitrate has shown that metal-ion catalyzed oxidative-reduction (MICOR) does not adequately explain observed failures unless antioxidants are removed in process. Such cracking can, however, be explained in terms of a metal ion enhanced environmental stress cracking.