Atrioventricular cross-talk in biventricular pacing: A potential cause of ventricular standstill

The aim of the study was to evaluate, in recipients of biventricular pacing systems, the risk of asystole due to ventricular pacing inhibition by sensing the left atrial signals by the LV lead at conventional sensitivity. Long-term ventricular sensitivity was programmed at greater than or equal to 4 mV in 17 consecutive recipients of ventricular resynchronization systems implanted for chronic management of congestive heartfailure. Ventricular pacing inhibition due to AV cross-talk on spontaneous left atrial electrogram (AVCSA) was tested at a 2 mV ventricular sensitivity immediately after implantation of the stimulation system and 1 month later. Pacemaker dependence was also tested during temporary VVI pacing at a rate of 30 beats/min. AVCSA was observed in three patients. It was present on the day of implantation in one patient, and developed within the first month in two others. Asystole was observed in two of the three cases of AVGSA, Three pacemaker nondependent patients at the time of system implantation had become pacemaker dependent at 1 month. AVCSA was observed only with LV leads positioned in the great cardiac vein. In conclusion, asystole due to A VCSA was observed in 11% of recipients of ventricular resynchronization stimulation systems. Care should be taken in these patients to minimize the risk of atrial sensing by the LV lead, preferably avoiding its placement in the great cardiac vein. This phenomenon could be eliminated by the program m ability of a right ventricular only sensing configuration.