The Electrocardiogram, Vectorcardiogram, and Ventricular Gradient in the Tetralogy of Fallot

The electrocardiogram, ventricular gradient, and spatial vectorcardiogram were studied in 140 patients with proved tetralogy of Fallot. The patients were separated into three groups according to hemodynamic data. The salient features of the electrocardiogram in patients of group I consisted of diminutive R waves in leads I and V6, a deep Q wave and high R wave in lead III, a prominent R wave in lead V1, which was not wide, and the absence of Q waves in leads I, V1, and V6. The electrocardiogram in patients of group II was similar to that of the patients of group I except for the appearance of more signs of left ventricular electric activity and less clock-wise rotation of the heart. The electrocardiogram of the patients of group III was similar to that previously described for ventricular septal defect. ÂQRS, ÂT, Ĝ, and sVCG reflected the same general trend as the electrocardiograms. The electrophysiologic data presented support clinical observations indicating that the tetralogy of Fallot includes patients with a wide range of hemodynamic differences.