Congenital heart disease and pulmonary artery hypertension. I. pulmonary vasoreactivity to 15% oxygen before and after surgery

Pulmonary vasoreactivity at sea level was studied in 22 children before and in 15 children after corrective cardiac surgery for congenital heart disease and pulmonary artery hypertension; 8 children were studied both before and after cardiac surgery. During cardiac catheterization in 28 children, pulmonary and systemic hemodynamics were determined in room air and during breathing of 15% oxygen, which corresponds to a maximal hypoxic level commonly encountered during airplane travel.Before surgery, 19 of 22 children tolerated 15% oxygen (C)2), which caused the following hemodynamic changes from room air status: the ratio of pulmonary to systemic arterial pressure increased from 0.70 to 0.78 (p < 0.05), the ratio of pulmonary to systemic flow decreased from 2.2 to 2.0 (p > 0.05) and the ratio of pulmonary to systemic vascular resistance increased from 0.33 to 0.40 (p < 0.02). In two children, severe pulmonary vasoconstriction developed within 5 minutes of 15% oxygen administration, requiring immediate discontinuation of hypoxia; neither patient had lasting deleterious effects. There was no evidence of increased pulmonary vasoreactivity in children with Down's syndrome compared with genetically normal children. After corrective surgery in 15 children (including both of the hyperreactors), no significant pulmonary vascular response to 15% oxygen was found.It is concluded that, in a small number of children with unrepaired congenital heart disease and pulmonary artery hypertension, pulmonary vascular hyperreactivity can be induced by breathing 15% oxygen; this reaction is life-threatening but reversible with the administration of 100% oxygen. Air travel without supplemental oxygen may be dangerous in these patients. It is our policy to repair the heart defect on an urgent basis when pulmonary hyperreactivity is found. One year after early surgery, pulmonary vascular status appears to be normal even in the hyperreactors