The permanent form of junctional reciprocating tachycardia: further elucidation of the underlying mechanism.

A case of the permanent form of junctional reciprocating tachycardia studied by endocardial and epicardial mapping is presented. The ability of the retrograde impulse to penetrate the atrium in 2 different areas, one near the region of the recorded His potential and the other near the orifice of the coronary sinus, is demonstrated. Retrograde conduction persisted after the surgical creation of complete antegrade heart block suggesting the existence of an accessory ventriculo-atrial connection. The decremental properties of retrograde conduction observed suggest that an accessory ventriculo-artrial nodal structure may be the underlying substrate of this arrhythmia.