Left ventricular function reserve in adult patients with atrial septal defect: Pre- and postoperative studies

To assess left ventricular (LV) function in patients with atrial septal defect (ASD), we used radionuclide cineangiography at rest and during exercise in 11 patients (ages 16-59 years, mean 36 years) without other cardiac abnormalities. All patients had normal LV ejection fraction (EF) at rest (mean 59 ± 3% vs normal 57 ± 1%; NS); during exercise, four patients increased LVEF normally, four had no change in LVEF with exercise, and three decreased LVEF to 56%, 54%, and 44% (lower limit of normal 55%). These three patients had orthopnea and paroxysmal nocturnal dyspnea; the other eight were asymptomatic or mildly symptomatic. While the LVEF response to exercise did not correlate directly with hemodynamic or echo data, the two patients with the greatest decrease in LVEF during exercise had higher pulmonary-to-systemic flow ratios than the other nine patients (mean 4.8 vs 2.0, P < 0.001). All patients had abnormalities of ventricular septal motion on echocardiography with subnormal LV diastolic dimensions secondary to the right ventricular volume overload. Six months after operation, all 11 patients were asymptomatic and all had normal rest and exercise LVEFs (mean EF 58 ± 2% rest, 65 ± 3% exercise, P <0.001), including the seven patients with abnormal preoperative LVEF responses to exercise. LV diastolic dimension by echocardiography, subnormal before operation in all 11 patients, increased into the normal range in all patients postoperatively. These data suggest that diminished LV functional reserve in adult patients with ASD is related, at least in part, to reversible mechanical factors related to right ventricular volume overload with abnormal diastolic-systolic relations of the interventricular septum, rather than to intrinsic, irreversible myocardial dysfunction.