Ventilatory response to exercise in patients with major aortopulmonary collateral arteries after definitive surgery

Patients with pulmonary atresia and major aortopulmonary collateral arterie s (MAPCAs) may be at risk for both ventilatory impairment and abnormal pulm onary circulation after definitive surgery. We measured the ventilatory res ponse to exercise in 16 patients with MAPCAs after definitive surgery (grou p A) and compared the results with those in 16 patients with tetralogy of F allot with pulmonary atresia and without MAPCAs after;definitive operation (group B), with 24 patients with tetralogy of Fallot after one-stage repair without previous palliation (group C), and with 48 healthy subjects (group D). Pulmonary function and treadmill exercise tests were performed. Arteri al blood gases were also analyzed and the dead space to tidal volume ratio calculated. In group A, the vital capacity, diffusion capacity, and peak ox ygen uptake were lowest (p <0.001), whereas the ventilatory equivalent for carbon dioxide was highest and its value at peak exercise correlated with a ge at time of surgery (r = 0.73, p <0.002). The arterial oxygen tension dec reased progressively in group A and its value at peak exercise inversely co rrelated with the mean pulmonary artery pressure in all patients (r = -0.75 , p <0.001). The arterial carbon dioxide tension decreased significantly at peak exercise in controls but showed no change in group A. The dead space to tidal volume ratio decreased during exercise in patients without MAPCAs and in controls but increased in group A, and the dead space to tidal volum e ratio at peak exercise was inversely correlated with vital capacity in al l patients (r = -0.77, p <0.001). Diffusion capacity independently predicte d arterial carbon dioxide tension and dead space ventilation during exercis e. Marked restrictive ventilatory impairment with low diffusion capacity al ong with a pulmonary obstructive change contributed to the abnormal pulmona ry gas exchange during exercise in group A. Earlier repair of MAPCAs may pr event the progression of the impaired ventilatory response to exercise in t hese patients. (C) 2000 by Excerpta Medico, Inc.