Clinical interactions between pacemakers and automatic implantable cardioverter-defibrillators.

Concomitant use of a pacemaker and an automatic implantable cardioverter-defibrillator (AICD) is common. Seventeen percent of patients receiving an AICD at The Johns Hopkins Hospital also had a permanent pacemaker implanted before (16 patients), at the same time as (2 patients) or after (12 patients) AICD implantation. Four types of interactions were noted: 1) transient failure to sense or capture immediately after AICD discharge (seven patients); 2) oversensing of the pacemaker stimulus by the AICD, leading to double counting (one patient); 3) AICD failure to sense ventricular fibrillation resulting from pacemaker stimulus oversensing (three patients, one only at high asynchronous output); and 4) pacemaker reprogramming caused by AICD discharge (three patients). No clinical sequelae of these interactions were noted during follow-up study. Thus, potentially adverse clinical interactions are common and routine screening is recommended. With proper attention to lead placements and programming of the devices, clinical consequences of these interactions can be avoided.