[Electrocardiographic changes in children with surgery for defects of the atrial septum].

Electrocardiograms obtained prior to surgery, after surgery and in the period between 6 months and 2 years following the surgery were analyzed in 44 children operated because of atrial septal defect. The following electrocardiographic parameters were selected: the P wave, PQ interval, QRS complex and right bundle branch block The P wave narrowing developed gradually, i.e. not earlier than the follow-up period, and it was statistically significant (p = 0.001). The duration of the PQ interval decreased significantly right after the operation (p = 0.001). No changes were seen in the width of the QRS complex neither following the surgical procedure nor in the later postoperative period. The number of children with right bundle branch block decreased significantly immediately after the surgery (p = 0.0108). Willson's right bundle branch block disappeared gradually after operation (p = 0.0282).