The Spatial QRS Loop in Right Ventricular Hypertrophy with Special Reference to the Initial Component

Spatial vectorcardiograms were recorded from 18 subjects with normal electrocardiograms and from 14 subjects with electrocardiograms indicative of right ventricular hypertrophy. In the latter group there was a significant incidence of deviation of the initial portion of the QRS loop from the normal direction of inscription, suggesting that activation of the interventricular septum oftenproceeds in an abnormal manner in right ventricular hypertrophy. A statistically significant difference in the direction of rotation of the entire QRS loop in the transverse and sagittal planes was noted in the two groups. The relationship between the direction of inscription of the QRS loop in the transverse plane and the timing of the intrinsicoid deflections of precordial leads is discussed.