PERMANENT PACING SYSTEM MALFUNCTION DUE TO HIDDEN ADJACENT FRACTURES OF ATRIAL AND VENTRICULAR LEADS

Periods of failure of ventricular pacing and atrial sensing were disco vered on Holter recording in a 10-year-old boy 4 years after the impla ntation of a dual-chamber pacemaker with endocardial bipolar leads bro ught out through the right atrial wall. The old generator was explante d and the old leads tested. There was considerable atrial oversensing of an electrical artefact. The pacing threshold of ventricular lead wa s 1.8 V compared with 0.3 V 6 days post implantation. Post-operative l ateral chest X-ray disclosed fractures of both atrial and ventricular leads at the approximate site of exit from the right atriotomy. Review of the preoperative lateral film showed that the fractures had been h idden by an ECG electrode. (C) 1997 Elsevier Science Ireland Ltd.