24-hour Holter monitoring of a 59 year-old man with DDDR pacemaker (programmed mode:
DDD) implanted for sick sinus syndrome with paroxysmal atrial fibrillation was performed
one month after implantation, due to palpitations. Several episodes of rapid pacing of decreasing
rate were detected. Intracardiac recording stored in the pacemaker memory had shown episodes
of atrial lead oversensing, which led to the mode switch, resulting in DDIR mode. Signals
which caused oversensing were not seen in Holter tracing. (Cardiol J 2011; 18, 1: 94-96
