McGill Case 108

This case report is kindly provided by Michael Rosengarten from McGill and is part of the McGill Cases. These cases come from the McGill EKG World Encyclopedia. Previous Case: McGill Case 107 | Next Case: McGill Case 109

The reason why the pacer was pacing at 75/min in the DDD mode was because there is a supraventricular tachycardia (note atrial activity, marked with the turquise arrows, moving through the ventricular complexes) at about 150/min and the DDD pacer was producing 2:1 A/V block. In tracing above with the pacemaker set to a VVI mode, the pacemaker no longer senses the atrium and paces at the set rate of 70/min.