Premature ventricular contractions from the outflow tract: 2 sides of the same coin!

摘要

A 17-year-old boy was referred for ablation of distressing ventricular extrasystoles not improving with beta blocker therapy. His resting ECG revealed frequent premature ventricular contractions (PVCs) of 2 morphologies of nearly equal frequency. PVC 1 had left bundle branch block (LBBB) morphology with inferior axis suggesting right ventricular outflow tract (RVOT) origin. QRS features including positive forces in Lead I, notched R waves in the inferior leads, QRS width of 140 milliseconds, late R wave transition and the R wave amplitude criteria in the limb leads all favored a posterior free wall origin.1-2 Further, the R wave index <50% and the R:S ratio <30% in the right precordial leads and late transition of R wave all favored RVOT origin as against a left ventricular outflow tract (LVOT) origin.3