[Changes in ventricular depolarization and repolarization in 116 cases of surgically treated interauricular...

The postoperative changes of ventricular depolarization and repolarization were studied in 116 cases of atrial septal defect 3 to 8 years after surgical treatment. High fidelity multiple unipolar registries as well as the vectorcardiographic curves in three planes were obtained. Before surgery there were 101 RBBB (87.07% of this series). Of 22 minor degree RBBB, 17 (77.27%) showed no changes, 2 (9.09%) became distal blocks and 3 (13.64%) became intermediate degree RBBB. Of 77 preoperative intermediate degree RBBB, 20 (25.97%) diminished to a minor degree, 1 (1.3%) became a distal block and 2 (2.6%) augmented to an advanced degree. Fifteen distal right blocks (12.93% of the total of cases) persisted postoperatively. Signs of right ventricular enlargement disappeared in all the cases. The right Q-Tc, previously prolonged in 38 cases (32.76% of this series), was normal after surgery. Peaked or negative interpolated T waves disappeared in right precordial and transitional leads. The electrocardiographic features of ventricular repolarization seem to reflect hemodynamic improvement better than those of depolarization. The electrocardiogram permits classification of the disturbances of right ventricular conduction, while the vectorcardiogram shows variations in dimensions of the right ventricle.