Preferential Right Ventricular Breakout of Ventricular Tachycardia and Critical Slow Conduction in Left Ventricle in a Patient with Postinfarction Ventricular Septal Perforation Repair

Abstract

A 68 year-old man who had ischemic cardiomyopathy (ejection fraction 40%), with prior coronary artery bypass graft and ventricular septal perforation (VSP) repair, was admitted due to ventricular tachycardia (VT) with left bundle branch block morphology, and QR pattern in inferior leads. Electro anatomical voltage map (CARTO) during sinus rhythm (SR) demonstrated large low voltage zone (low-VZ) (<0.6 mV on amplitude of bipolar voltages) in posteroseptal (basal and mid levels) left ventricle (LV), but no low-VZ in right ventricle (RV). Optimal pace map during SR was obtained in basal posteroseptal RV, not in LV. And during VT (cycle length 459 ms), RV septal activation was earlier than LV. Delayed potential during SR was recorded at low-VZ in a basal posteroseptal LV, where mid diastolic potential during VT preceding QRS onset by 140 ms was seen. Entrainment pacing showed concealed entrainment with stimulus-QRS interval of 140 ms and post pacing interval identical to VT cycle length. Irrigated radiofrequency application terminated VT in three seconds. VT was considered that its central common pathway located in the basal posteroseptal low-VZ in LV between mitral annulus and VSP patch, with preferential breakout to septal RV.