The Extremity and Circumferential Chest Lead Electrocardiogram in Induced Acute Coronary Insufficiency

The extremity and circumferential chest lead electrocardiogram (twenty-two leads) was studied in 8 patients with generalized coronary insufficiency induced by exercise. Over the right chest, posteriorly and laterally, there was noted RS-T elevation similar to but less pronounced than that occurring in lead aV_R. These leads probably represent true or mixed cavity potentials. Standard leads revealed more marked RS-T alterations after exercise than did aV leads. In the left anterior chest leads, the greatest RS-T depression occurred in the left unipolar precordial leads representing the maximal voltage of the R wave—usually V₄ or V₅. The practical application of these findings is discussed in relation to routine two step exercise tests.