Some immediate hemodynamic consequences of closure of atrial septal defects of the secundum type

The circumclusion method for surgical closure of atrial septal defects (ASDs) of the secundum type makes it possible, during surgery, to close and reopen the defect as desired. In each of 23 patients the following statistically significant pressure and flow changes were found when the ASD was closed: increasing mean pressures in the ascending aorta (from 74 to 87 mm Hg), left atrium (from 10 to 18 mm Hg), and right pulmonary artery (from 20 to 24 mm Hg); increasing mean flows in the ascending aorta (from 84 to 111 ml/min/kg); decreasing mean pressures in the right atrium (from 9.0 to 7.7 mm Hg); and decreasing mean flows in the right pulmonary artery (from 78 to 46 ml/min/kg). Surprisingly, no correlation between shunt size determined before and during surgery was found. However, in the calculation of the intraoperative shunt, several factors might have contributed to an erroneous result. In 17 patients a right heart catheterization was performed in the third to thirteenth postoperative month and the following statistically significant changes from the intraoperative results with closed ASD were found: The intraoperative mean pressure in the left atrium (18 mm Hg) decreased to 7.3 mm Hg after surgery (pulmonary wedge pressure), the pulmonary arterial pressure decreased from 23 to 13 mm Hg, and the right atrial pressure from 8.2 to 1.6 mm Hg.