[The vectorcardiogram of Fallot's tetralogy in the first two years of life. Qualitative and quantitative analysis (author's transl)]

36 patients, less than two years old, affected by Fallot's tetralogy were studied by vectorcardiography. The configuration of the QRS loop in the three orthogonal planes, the voltage of the 0.10 sec spatial vector, RMSV and LMSV vectors, and their azimuth and elevation were evaluated. Such data have been correlated to arterial oxygen saturation. Qualitative analysis showed a clockwise or figure eight QRS loop on the H and F planes in the great majority of cases; and only in a counterclockwise loop on the H plane was the suspicion of an arterial oxygen saturation greater than 85% especially in cases older than two months. The terminal forces of the QRS loop on the H plane were always directed under the O point, Whereas in the valvular pulmonary stenosis, terminal forces are generally superior to the O point. Quantitative analysis demonstrated the constant increase of the RMSV and the direct relationship of the LMSV to arterial oxygen saturation, and so it was the principal parameter for evaluation of the left ventricular volume and the size of pulmonary flow and the degree of pulmonary stenosis. The relationship between the azimuth of 0.01 sec spatial vector to O2 saturation was highly significant, showing a progressive anterior development of the former, as the latter increased.