Atrioventricular nodal reentrant tachycardia with ventriculoatrial block and unsuccessful ablation of the slow pathway.

We report the case of failed slow pathway ablation in a woman with typical AV nodal reentrant tachycardia (AVNRT) and periods of Wenckebach-like second-degree VA block and 2:1 VA block. The occurrence of VA block during AVNRT suggests the upper turnaround point of the circuit is confined to the AV node. This supports the notion that, at least in some cases, the location of the reentrant circuit for AVNRT is completely in the compact AV node.