Polarcardiographic and vectorcardiographic study of 70 normal children aged 3‐4 years

This polarcardiographic and vectorcardiographic study of 70 normal children, aged three to four years using the Frank lead system, provides data on an important age group that were not previously available. High‐resolution xyz signals, recorded on magnetic tape, were edited, digitized, compressed, and fed into a digital computer together with typed information. Computer outputs included measurements, analysis, VCG loops, Aitoff plots of P̌, Ř, and Ť directions, derived 12‐lead ECGs, and polar tracings. Conventional ECGs were also recorded; differences from the derived ECG were not clinically significant. Various normal bounds for polar coordinate variables were established, such as criteria for diagnosing left ventricular hypertrophy. There was a significant sex difference in the Ť directions, which were more posterior than those previously reported for adults. Among the VCGs, it was interesting to note several patterns suggesting persistence of right ventricular forces.