Undersensing of demand pacemakers in acute myocardial infarction.

Trasient asynchronous pacing due to abnormal sensing function is reported in two patients with inserted demand pacemakers during the early phase of acute myocardial infarction. The hazards of the pacemaker induced parasystole with R on T phenomenon in conditions of enhanced electrical instability could be successfully overcome applying overdrive suppression of the inserted pacing system by external chest wall stimulation.