Computer analysis of frank vectorcardiograms in normal children--maximal spatial QRS vector

Frank vectorcardiograms recorded on magnetic tape were analyzed by a computer. The study population was 835 normal children aged from 6 to 16. Magnitudes, angles (azimuth, elevation) of the maximal spatial QRS vector and QRS duration were calculated. The magnitude of maximal spatial QRS vector increased significantly in males compared to those in females at ages 9-10, 11-12 (p less than 0.01) and 15-16 (p less than 0.001). Though there was no significant difference of elevation in either sex, azimuth tended to move more anteriorly in females than in males. QRS duration in males became longer with increasing age, while in females at age 15-16, it decreased (p less than 0.001).