Electrolysis of unipolar pacing leads

A 90-year-old man with bradycardia and Stokes-Adams attacks had a unipolar VVI pacemaker implanted. Twice within a short period of time we registered a total loss of function: the first incident was caused by a "fracture" between lead and electrode, and the second was due to partial dissolving of the lead. Both times a new lead electrode was implanted; the second time we replaced the pulse generator as well. Pacemaker analysis showed a capacitor defect leading to a 50 microampere anodal DC leakage that caused electrolysis of the helical coil conductors. The patient had no clinical symptoms besides those due to loss of pacemaker function. The present case report and others in the literature indicate that when an electrode lead fracture is found, it is necessary to check the pacemaker for DC leakage.