| 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. |
