Life-threatening pulmonary hypertensive crises occurring preoperatively.

A 10-week-old infant with left atrial isomerism and a primum atrioventricular septal defect presented with life-threatening episodes of collapse. They proved due to paroxysmal pulmonary hypertension, although her pulmonary artery pressure was virtually normal between attacks. The pulmonary hypertensive crises persisted early but resolved late after surgical correction. Labile pulmonary vascular resistance may prove a problem preoperatively if the ventricular septum is intact.