Ventricular tachycardia initiated by both normally and aberrantly conducted atrial premature beats.

Electrophysiologic studies were performed in a 72-year-old female with recurrent ventricular tachycardia in whom all documented spontaneous episodes were initiated by atrial premature beats. These studies confirmed the diagnosis of ventricular tachycardia and its initiation by atrial premature beats. Both normally and aberrantly conducted atrial premature beats were capable of initiating the tachycardia. With aberrant prematures the onset of the tachycardia was delayed in proportion to the delay in the right bundle branch. Triggered automaticity and re-entry were equally plausible as underlying mechanisms for this arrhythmia.