Reevaluation of the VCG and ECG criteria for left ventricular enlargement.

Traditional electrocardiographic (ECG) and vectorcardiographic (VCG) criteria for left ventricular enlargement (LVE) understandably emphasize the increased tendency of the maximal electrical forces of ventricular depolarization to be directed toward the left. This tendency is manifested on the ECG by increased amplitudes of the R waves in leads I, AVL, V5 and V6 and by deeper S waves in lead V1. However, because the left ventricle is a relatively posterior as well as leftward structure in the thorax, LVE should also cause these forces to be directed posteriorly. Such changes in the anteroposterior dimension should be reflected in the VCG loop in the transverse plane and in the scalar ECG leads which are placed anterior to the heart. Therefore, we hypothesized that both the ECG and VCG criteria for LVE might be optimized if a variety of parameters that reflect alterations in the anteroposterior as well as in the right to left dimension are investigated.