Left ventricular performance in patients with atrial septal defect: evaluation with noninvasive methods

Eighteen patients with an atrial septal defect (Group I) and 45 patients whose defect had been repaired (Group II) were studied with echocardiography and systolic time Intervals. All patients In Group I had an increased right ventricular diameter (mean 24.5 mm/m²) that showed a direct linear relation to the size of the shunt (Qp/Qs ratio). In Group II the right ventricular diameter was significantly smaller (mean 15.6 mm/m²) (P < 0.001). The left ventricular diameter measured less than the mean normal value in 13 of the 18 patients in Group I (mean 23.2 mm/m²) and was significantly larger in the 45 in Group II (mean 27.7 mm/m²) (P < 0.001).Comparison of systolic time intervals in Groups I and II showed that patients in the former group had shorter mean left ventricular ejection time index (LVETI) (407.9 versus 420.8 msec, P < 0.05), a longer mean preejection period index (PEPI) (140.9 versus 126.7 msec, P < 0.001) and a higher mean ratio of preejection period to ejection time (PEP/LVET) (0.39 versus 0.33, P < 0.001). A direct linear relation existed between both the preejection period index and the PEP/LVET ratio and the size of the shunt (Qp/Qs) in Group I. In three patients the abnormal systolic time intervals were consistent with mildly diminished left ventricular performance preoperatively but promptly returned to normal postoperatively. However, echocardiographic assessment revealed that left ventricular wall contractility was normal or hyperdynamic in all cases.The mildly diminished overall left ventricular performance as shown by systolic time intervals appears to be related to the volume overload of the right ventricle and to the concomitantly diminished volume of the left ventricle rather than to any impairment of myocardial contractility. After closure of the defect the size of the ventricle and its performance return to normal.