Electrophysiological Findings of Vagally Mediated AV Block
Electrophysiological studies have been carried out in patients with episodes of vagally mediated second- or third-degree AV block, including pseudo-Mobitz II block. In the majority of patients, AH and HV intervals are normal or slightly prolonged; the slight prolongation is unlikely to have a cause–effect relationship with the advanced-degree or complete AV blocks, some of which are accompanied by ventricular asystole. Normal findings of AV conduction during electrophysiological study further confirm a vagal outflow and not an intrinsic abnormality of AV conduction as a cause of this form of block.