Action Potential Alternans in the Right Ventricular Outflow Tract in a Patient With Asymptomatic Brugada Syndrome

Abstract

A 71-year-old man with frequent ventricular premature contractions after right hip joint surgery was referred to the Cardiology Division. Twelve-lead ECG showed type II Brugada-type ECG and signal-averaged ECG showed positive ventricular late potentials. The 12-lead ECG changed to type I Brugada-type after administration of the class Ic antiarrhythmic drug, pilsicainide. Ventricular fibrillation (VF) was reproducibly induced with double premature stimuli from the right ventricular outflow tract (RVOT) at a basic cycle length (BCL) of 400 ms. Monophasic action potentials (MAPs) recorded from the RVOT at a BCL of 400 ms showed MAP alternans and VF was only induced when extrastimuli were applied after a shorter MAP of the alternans. (Circ J 2009; 73: 580 - 583)