[Pre- and postoperative ECG-VCG study of the correction of atrioventricular septal defects].

In order to determine the possible implication of the right bundle branch block (RBBB) in the superior axis deviation of patients (pt) affected with AV septal (Canal) defect, we studied the preoperative and postsurgical ECG of 50 patients who underwent radical correction of the malformation complex. 36 pt had the complete form and 14 a partial form. In 14 of them it was also possible to perform a VCG before and after surgery. The amplitude of S1, R' in a VR and V1 modified significantly (p less than 0.0001), the AQRS showed a clockwise displacement of 19 degrees (p less than 0.002). The terminal forces in the VCG frontal plane changed significantly 62 degrees (p less than 0.0001). Nevertheless the D.I. in a VL and V6 made no difference. Postoperative ECG patterns of pt with partial or complete forms did not differ substantially. Results allowed us to conclude that the major determinant of the AV septal defect ECG pattern is the posterior (inlet) deficiency of the interventricular septum. Surgical correction of the right ventricle overload leads to a clockwise AQRS displacement in the frontal plane. The conduction asynchronism through the left branch showed no modifications.