Ventricular Conduction Disturbance in Normal Children

¹ Western Reserve University School of Medicine and University Hospitals
² Assistant Professor of Pediatrics and Director of Pediatric Cardiology

Analysis of the Frank vectorcardiogram and right intracavitary electrocardiograms of four children with congenital conduction disturbances is presented. Two, both 11 years of age, had terminally slowed forces to the right, posterior and abnormally superior. Two, aged seven months and seven years, had right bundle branch block with the terminally slowed forces abnormally to the right and anterior. Three were hemodynamically completely normal, confirmed by cardiac catheterization and angiography. In one, with congenital right bundle branch block, a patent ductus arteriosus was divided five years previously and an insignificant isolated peripheral pulmonic stenosis was found.

All patients had similar right ventricular intracavitary electrocardiograms characterized by extra positive deflections in the middle of the complex. In one of the two with conduction delay to the right, posterior and superior, there was a very prominent late positive deflection in the right ventricular outflow tract.

The interval between the onset of the QRS (L_II) and right ventricular contraction was prolonged in patients with right bundle branch block; but in the other two cases, there was minimal, if any, delay.

This study suggests that in children with terminally slowed forces to the right, positerior and abnormally superior, there could be an abnormal course of the left bundle's superior branch and its peripheral distribution. The result is delay in activation of the upper ventricular septum and the posterobasal free wall of the left ventricle, with activation initiated lower in the septum.