Far-field P-wave sensing by the right ventricular lead of conventional dual chamber pacemakers.

This report describes two cases of far-field sensing of the P wave by the ventricular channel of conventional DDD pacemakers programmed to a relatively high sensitivity to promote sensing of ventricular extrasystoles. Ventricular pacing was maintained in both cases when the ventricular channel was not inhibited. One case was caused by displacement of a bipolar ventricular lead towards the right ventricular inflow tract. The other case occurred only in relation to an atrial extrasystole in the absence of ventricular lead displacement.