Electrocardiographic differentiation of the causes of left ventricular diastolic overload.

Left ventricular hypertrophy due to diastolic overload is characterized by the following in lead V6: (a) tall R wave; (b) prominent initial Q wave; (c) minimally elevated concave-upward ST segment; and (d) relatively tall symmetrical T wave. Reciprocal deep S waves are seen in lead V1. This study reflects a further evaluation of these parameters in the four main causes of left ventricular diastolic overload: mitral incompetence, aortic incompetence, patent ductus arteriosus, and ventricular septal defect. An S wave in lead V1 which is equal to or greater than the R wave in lead V6 excludes the diagnosis of mitral incompetence.