Pseudo crosstalk behavior in a patient with atrio-ventricular block and implanted biventricular defibrillator.

We present a 59-year-old man with a dilated cardiomyopathy (ejection fraction = 20%), congestive heart failure and atrio-ventricular (AV) block who underwent implantation of a biventricular defibrillator (BiV ICD). While undergoing cardiac transplant evaluation for drug-refractory ventricular fibrillation, his telemetry recorded findings resembling crosstalk inhibition. Device interrogation was normal. All episodes occurred at 1:00 a.m. suggesting a routine device operation. Left ventricular capture management, a new feature that automatically measures left ventricular pacing thresholds at 1:00 a.m., had been programmed to Monitor. Understanding this sophisticated pacing algorithm might avoid confusion when operative in patients with AV block.