Proximal common pathway in the circuit of atrioventricular nodal reentrant tachycardia.

Whether atrium tissue is involved in the reentrant circuit of atrioventricular nodal reentrant tachycardia (AVNRT) has been debated for decades. Animal models, clinical electrophysiological studies, surgery and catheter ablation have all documented that the perinodal tissue forms part of the tachycardia circuit. However, the occasional clinical finding of AVNRT with ventriculoatrial block suggests the presence of a proximal common pathway. We describe a 43-year-old woman who developed recurrent AVNRT with new onset of complete ventriculoatrial block after an attempted radiofrequency ablation at the posterior septal area. This case demonstrates the anatomical existence of a proximal common pathway and the topological location of such a pathway for typical AVNRT. This case also demonstrates the isolated nature of the AVNRT circuit and the delicate nature of the responsible reentrant substrate.