The Vectorcardiogram in the Differential Diagnosis of Atrial Septal Defect in Children

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Abstract
Vectorcardiograms have been analyzed in 32 atrial septal defects of the secundum type and 23 endocardial cushion defects, as well as 6 patients in special groups. All but 1 patient in both major groups showed right ventricular hypertrophy, with clear-cut evidence of additional right bundle-branch block being present in only 3. The principal difference between ostium secundum and endocardial cushion defects consists in the loop being inferior in the former, superior in the latter. The direction of inscription in the frontal plane tends to be clockwise in the ostium secundum lesions, counterclockwise in the endocardial cushion group. The 6 patients in special groups could be readily distinguished from the 2 major groups with the use of the vectorcardiogram. The superior position of the vector loop (left axis deviation in the electrocardiogram) characteristic of endocardial cushion defects, is thought not to be secondary to left ventricular hypertrophy but rather to a congenital anomaly in the conduction system. A correlation was attempted between the vectorcardiogram and hemodynamic data in 22 patients in each group. The ratio of right to left ventricular work appeared to relate well to the vectorcardiogram. As the ratio increased, more right ventricular hypertrophy appeared.