Ventricular Tachycardia Localization using 12 Lead ECG

Features useful in localizing the VT

QRS width. Septal VTs are narrower than VTs on the free wall
QRS axis. Right superior-axis VTs arise from apical septal or apical lateral regions, often demonstrating QS complexes in leads I, II, and III and QS or rS in V5 and V6. Inferior-axis VTs arise high in the basal areas of the heart, right ventricular outflow tract, high left ventricular septum, or high lateral left ventricle.
Bundle branch block pattern. Left bundle branch block morphologies are present in virtually all right ventricular tachycardias but also may be noted in tachycardias arising from the left ventricular side of the septum
Concordance. Positive concordance is seen only in VTs arising at the base of the heart. Negative concordance is seen only in VTs originating near the apical septum.
Presence of QR complexes. QS complexes in the inferior leads suggest that the activation is originating in the inferior wall. QS complexes recorded in the precordium leads indicate activation moving away from the anterior wall.