Cardiopulmonary exercise parameters in children with atrial septal defect and increased pulmonary blood flow: short-term effects of defect closure

Markedly increased pulmonary blood flow because of a relevant atrial septal defect (ASD) leads to impaired cardiopulmonary function during maximum exercise in adults. No comparative preoperative and postoperative data are available on the short-term effects of shunt closure on cardiorespiratory function at peak exercise in children. Pulmonary function testing at rest and cardiopulmonary exercise testing together with haemodynamic assessment was done prospectively in children with an ASD preoperatively and again after full recovery at 3-4 mo postoperatively and compared with a matched normal population. Sixteen children, aged 6.8-16.1 y, with a defect of 8-23 mm (median 15 mm) and a pulmonary/systemic flow ratio of 1.5-3.5 (median 2.2) were tested and compared with 15 healthy children. Preoperatively, baseline pulmonary function parameters and exercise capacity were no different from normals. At peak exercise, patients with a shunt had increased pulmonary resistance, especially of the distal airways (p = 0.04), with a significantly larger proportion of children having a paradoxical increase in total airway resistance during exercise (p < 0.05). Maximum serum lactate at peak exercise was elevated (p < 0.05) in patients. In patients, maximum oxygen uptake was impaired (p = 0.03) and remained so at repeat evaluation postoperatively. The same observation was made for chronotropic response to exercise. Conclusion: Cardiopulmonary exercise parameters in patients with ASD differed only slightly from those in normal children. The most important deviations were a lower maximum oxygen uptake and an increase in airway resistance at maximum exercise.