Noninvasive evaluation of the hemodynamic effects of closure of atrial septal defects of the secundum type.

In order to examine the feasibility of using multiple noninvasive methods in monitoring the hemodynamic changes induced by operation for atrial septal defect of the secundum type, 12 consecutive patients were examined before operation and 8 days afterwards. 10 of the patients were re-examined after one year. The methods used were echocardiography calibrated apexcardiography and systolic time intervals. It was possible with echocardiography to demonstrate a decrease in right ventricular end diastolic diameter and left atrial dimension already at the first postoperative study, but these changes were more marked after one year, though the right ventricular end diastolic diameter continued to be larger than normal. The left ventricular end diastolic diameter initially increased in size probably due to increased filing, but later returned somewhat towards the preoperative value. Functionally the apexcardiogram revealed an early decrease in left ventricular compliance probably due to the increased filling, but normal compliance after one year, where also the initially prolonged early relaxation time returned towards the normal value. The other apexcardiographical measurements did not change. Systolic time intervals showed an improved cardiac performance, as evaluated by preejection period index and preejection period/left ventricular ejection time, most marked at the early postoperative measurement. This is considered to be due to the improved left ventricular filling (The Starling effect) and not to changes in the myocardium itself.