Paroxysmal supraventricular tachycardia: is the atrium a necessary link?

Whether or not the atrium plays an essential role in initiating and/or sustaining atrioventricular (A-V) nodal re-entrant tachycardia was evaluated in eight patients. In all eight patients, the atrium could be rendered refractory to retrograde atrial echoes during the tachycardia without interrupting the arrhythmia. This was accomplished by introducing atrial premature depolarizations prior to the time the atrium would normally be retrogradely depolarized by atrial echoes. In one patient, two atrial premature depolarizations could be introduced, producing A-V dissociation, without terminating the tachycardia. In another patient, the tachycardia could be initiated without an atrial echo. Our data suggest that most, if not all of the atrium is unnecessary for the initiation and maintenance of A-V nodal re-entrant supraventricular tachycardia.