Unusual pacing observed in a biventricular pacemaker with epicardial pacing leads.

In this case report, we describe inappropriate pacing in a patient with a newly implanted biventricular pacing system with three epicardial leads. Very high pacing thresholds resulted from the use of nonsteroid eluting leads, and unusual pacing behavior was due to the chosen implant locations for the right atrial and right ventricular epicardial leads. The interplay between the programmed pacemaker parameters, the very late ventricular sensing in the setting of intrinsic right bundle branch block, and atrial lead oversensing led to ineffective biventricular pacing. The persistently elevated pacing thresholds and sensing problems led to very early battery depletion and the need to replace the epicardial system with three new endocardial leads.