Left ventricular functional reserve in adult patients with atrial septal defect: pre- and postoperative studies.
Authors: R O Bonow, J S Borer, D R Rosing, S L Bacharach, M V Green, K M Kent
Journal: Circulation (1981)

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 ab- normal preoperative LVEF responses to exercise.LV diastolic dimension by echocardiography, subnormal be- fore 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.ABNORMALITIES in left ventricular performance have been reported frequently in patients with ostium secundum atrial septal defect. - However, the etiology of such abnormalities is unclear.Left ventricular dysfunction may occur only as a secondary mechanical response to chronic right ventricular volume over- load, or may develop as a primary process.'Assess- ment of the reversibility of functional abnormalities after closure of the defect might help to determine the etiology of left ventricular dysfunction, but such assessments have not been reported.Various investi- gators, using contrast angiography and echocardiography, have noted subnormal left ventricular volumes, stroke volume, and ejection fraction, as well as sub- normal left ventricular distensibility.2'7However, ro- tation of the left ventricle by the large right ventricle in patients with atrial septal defect might cause inac- curacies in contrast angiographic assessment of volumes, and hence, ejection fraction.3' 8Earlier studies have been performed at rest and have not evaluated the functional reserve of the left ventricle during exercise, a sensitive index of left ventricular dysfunction in patients with other forms of heart dis-