Atrioventricular nodal reentry with retrograde lower common pathway block: a case report.

Retrograde lower common pathway block during AV nodal reentrant tachycardia has rarely been reported. In this report, we demonstrate retrograde ventriculoatrial block during sinus rhythm and during AV nodal reentrant tachycardia in a woman with recurrent supraventricular tachycardia. In addition, evidence of antegrade decremental lower common pathway conduction is presented that produced variable HA intervals despite a constant atrial cycle length. These features may lead to the misdiagnosis of atrial tachycardia if not recognized.