Tachycardia induced tachycardia: case report of right ventricular outflow tract tachycardia and AV nodal reentrant tachycardia.

Tachycardia induced tachycardia, or so called double tachycardia, is rare. A 34 year old woman is described who had a history of syncope, frequent extrasystoles, and episodes of non-sustained ventricular tachycardia, perceived as palpitation, without syncope. At electrophysiological study, during infusion of isoprenaline, an episode of non-sustained ventricular tachycardia arising from the right ventricular outflow tract initiated sustained atrioventricular nodal reentrant tachycardia, thought to be the cause of the patient's syncope. Ablation of the right ventricular outflow tract focus abolished the ventricular ectopy; the slow AV nodal pathway was also ablated. The patient no longer has either syncope or palpitation.