P-WAVE OVERSENSING IN A UNIPOLAR VVI-PACEMAKER

A 45-year-old male had a VVI pacemaker implanted 20 years ago because of complete heart block. Because of perforation of the lead the pulse generator was removed after 4 weeks and a second lead wets implanted f rom the contralateral side. Recently, the patient presented with sympt oms of lightheadedness and syncope associated with prolonged pauses in the electrocardiogram. From the ECG, the ECG interpretation channel, and intracardiac electrogram telemetry it was concluded that the VVI p acemaker was inhibited by P waves. The most likely explanation for thi s phenomenon was an insulation defect in the functioning lead caused b y friction with the abandoned lead at the level of the high right atri um.