Hemodynamic Abnormalities in Response to Mild and Intense Upright Exercise following Operative Correction of an Atrial Septal Defect or Tetralogy of Fallot
Patients are often asymptomatic after operative correction of an atrial septal defect (ASD) or tetralogy of Fallot (TF). However, the maximal functional capacity of their hearts relative to that of normal subjects has not been defined. Twelve asymptomatic patients who had ASDs closed and 10 asymptomatic patients who had total correction of tetralogy of Fallot were evaluated by catheterization studies at rest and during mild and intense treadmill exercise. Except for small right ventricular outflow gradients in the tetralogy of Fallot group (2-21 mm Hg), data recorded at rest were normal or nearly so in each subject. However, at a level of upright exercise sufficiently intense to lower pulmonary arterial oxygen saturation to 30%, cardiac output was below that attained by normal subjects (mean, 8.9 ± 0.3 liters/min/m2) in seven of 12 ASD patients (mean, 6.6 ± 0.6 liters/min/m2) and in eight of 10 tetralogy of Fallot patients (mean, 6.1 ± 0.3 liters/min/m2). Right ventricular (RV) outflow gradients, measured during upright exercise in six TF patients, increased in each; RV systolic pressures reached levels of 75-106 mm Hg in four of the six patients studied. No outflow gradients were observed in the ASD group. Thus, patients with operative closure of an ASD and normal hemodynamic findings at rest may have impairment of their cardiac output response to intense upright exercise in the absence of residual shunts, arrhythmias, or pulmonary arterial hypertension. Although the cardiac output response in patients with corrected tetralogy of Fallot is consistently reduced, it is remarkably good considering the complicated nature of their defect and operative repair; however, the RV outflow gradient and RV systolic pressure may increase markedly with exercise. The longterm significance of these findings remains to be determined.
- Received November 6, 1972.
- Accepted January 25, 1973.
- © 1973 American Heart Association, Inc.