Comparison of a good orthogonal lead system and one additional chest lead with the conventional 12-lead electrocardiogram.

In a study of the McFee-Parungao system of orthogonal lead electrocardiography 452 electrocardiograms were recorded on 111 normal subjects and 201 patients with cardiovascular disease and abnormalities in the conventional 12-lead electrocardiogram. Comparison of the two lead systems and evaluation of criteria for the electrocardiographic diagnosis of normal, right ventricular hypertrophy, left ventricular hypertrophy, right and left bundle-branch block, and several types of myocardial infarction revealed good correspondence between the two systems. Because of deficient representation of the precordial midzone potential, a preferential unipolar lead resembling lead V4 was introduced. This ancillary lead contributed important information to the electrocardiographic diagnosis of localized apical myocardial infarction and also indicated ventricular hypertrophy in cases in which it was not evident in the three orthogonal leads.