A reliable witness: dual-chamber pacemaker prolonged intracardiac recordings of a resuscitated cardiac arrest episode.

We report the case of a patient with a previously implanted pacemaker, who suffered cardiac arrest due to ventricular fibrillation requiring cardiopulmonary resuscitation (CPR) manoeuvres and electrical cardioversion to restore sinus rhythm. Analysis of the pacemaker's stored electrograms showed the arrhythmia progression from monomorphic ventricular tachycardia to ventricular fibrillation and the electrophysiological effects of CPR manoeuvres and epinephrine administration before successful cardioversion.