This study intends to provide a detailed overview of the types and rates of peri-operative complications after surgical correction of an isolated ASD II. The transvenous approach to the occlusion of atrial septal defects has yielded promising results during its first 5 years of clinical trials, but before it can be established as a routine measure, definite proof is needed to demonstrate that its rate of serious complications does at least not exceed that of the surgical closure. Between 1985 and 1992, 232 consecutive patients underwent surgical closure of a secundum atrial septal defect. Among the patients 118 were children (< 18 years; 79 girls and 39 boys) with a mean age of 8.9 +/- 5.2 years (4 months-17 years) and 114 adults (74 women and 40 men) with a mean age of 28.5 +/- 10.8 years (18-69 years). Pre-operatively eight children (6.8%) and eight adults (7%) were treated for right heart failure. Mean pulmonary artery pressure was 20.4 +/- 10.4 mmHg for the children and 19.3 +/- 7 mmHg for the adults. The average pulmonary artery to systemic flow ratios were 2.9:1 and 3:1 for children and adults, respectively. Thirty children (25.4%) and 15 adults (13.2%) underwent patch closure while direct suture was the method used for the remaining patients. Average cardiopulmonary bypass time was 35.7 +/- 17.9 min for the children and 41.5 +/- 19.9 min for the adults. The length of the procedure (skin to skin) was a mean of 116 min in the young group, and 141 min in the adult group.(ABSTRACT TRUNCATED AT 250 WORDS)