Vectorcardiographic evaluation of postoperative changes in patients with interatrial septal defect: a review of 55 cases.

The pre- and post-operative vectorcardiograms of 55 patients with atrial septal defect (ASD) are discussed. Forty-nine were of ostium secundum type and six of ostium primum type. The criteria used to study the regression of right ventricular hypertrophy were: in the horizontal plane, the ratio of anterior-over-posterior forces, the right-over-left forces and the rotation of the body of the QRS loop; in the frontal plane, the direction of half-area vector. Using these criteria, 46 out of 49 patients with defects of the ostium secundum type had vectorcardiographic evidence of regression of right ventricular hypertrophy. Marked clinical improvement was also demonstrated in all these patients. The three patients in whom improvement was not demonstrated on the vectorcardiogram had persistence of a cardiac defect. Following surgery two children with ostium primum defects showed no change in the frontal plane, whereas in the horizontal plane a normalization of vectorial forces was observed.