[Pre- and postoperative study of arrhythmia in atrial septal defects (ostium secundum and sinus venosus)].

An electrophysiological study was carried out pre- and postoperatively in 25 patients (children and adults) presenting with an atrial septal defect of the ostium secundum type (OSASD). The purposes of the study were to find out whether early electrophysiological abnormalities were present in children, to compare the results obtained in children and in adults and to evaluate the impact of surgery by comparing preoperative and late postoperative electrophysiological data. Patients were divided into two groups. Group I was composed of 11 children (mean age 8.18 +/- 1.03 years) with a mean pulmonary/systemic blood flow ratio of 2.33 +/- 0.24. Group II comprised 14 adults (mean age 36.79 +/- 4.89 years) with a mean pulmonary/systemic blood flow ratio of 3.42 +/- 0.24. Preoperatively, in group I 55 p. 100 of the patients (6/11) had sinus node dysfunction, 18 p. 100 (2/11) had disturbances of atrioventricular conduction, and none had atrial dysrhythmia. Preoperatively, in group II 43 p. 100 of the patients (6/14) had sinus node dysfunction, 36 p. 100 (5/14) had disturbances of atrioventricular conduction, and 36 p. 100 (5/14) had sustained atrial dysrhythmia (flutter or paroxysmal atrial fibrillation). The frequency of sustained atrial dysrhythmia correlated positively with the patient's age and with the presence of sinus node dysfunction. Following surgical closure of the atrial septal defect, the electrophysiological parameters were not significantly modified in both groups. This study confirmed the presence of early electrophysiological abnormalities of sinus node function and atrioventricular conduction in children with OSASD. The most significant finding in adults was the occurrence of atrial dysrhythmias in the oldest patients.(ABSTRACT TRUNCATED AT 250 WORDS)