Vectorcardiographic Studies on Congenital Heart Disease by means of Frank's Lead System Part Ⅰ Vectorcardiograms of Ventricular Septal Defect. Special reference to its hemodynamics

The vectorcardiograms and data from cardiac catheteriztion of 64 patients with VSD were analyzed and the following results were obtained. (1) The vectorcardiographic patterns of combined ventricular hypertrophy are found in 40% of the patients with mild cases. (2) QRS loops with delayed terminal conduction are found dominantly in severe cases; in 40% of VSD with pulmonary hypertension and in 75% of Eisenmemger Complex. (3) In 5 cases (7.8%), frontal QRS loops have counterclockwise rotation, and they direct superiorly and to the left. Four cases of them belong to severe group. (4) The vectorcardiograms of the second type in Kirklin's classification showed the overloading of right ventricle more sensitively than the first type. i.e. Ⅰ) Of 16 cases with the terminal conduction delay, only one case is the first type, 13 cases are the second type and 2 cases belong to the second plus third type. Ⅱ) In mild cases, 18 out of 20 patients with the rightward deflection of the posterior portion belong to the second type and only 2 cases belong to the first type. (5) The elevation of right ventricular systolic pressure results in an increase of the magnitudes of both maximum upward and rightward deflections of the terminal portion. (6)Large shunts from left to right result in an exceeding increase of the magnitude of spatial maximum QRS, T vectors, the maximum rightward deflection of the initial portion and the maximum leftward deflection. (7) The magnitudes of the maximum anterior deflection and the maximum inferior deflection increase correlatively with both hypertrophy and dilatation of the right ventricle