The patient was managed in conjunction with the high-risk obstetric service who performed a biophysical profile (assessment of reactive nonstress test, fetal breathing movement, fetal body movement, fetal tone, and amniotic fluid volume), which suggested fetal distress. Because of her severe hypoxemia, respiratory distress, and newly diagnosed pulmonary hypertension, the patient was started on IV epoprostenol. No other therapies were instituted or altered. Over the ensuing 24 h, the epoprostenol was titrated up to 9 ng/kg/min with an improvement in her oxygenation to a saturation of 90% and tachycardia. She was then taken to the operating room where she underwent a cesarean section and delivered a male infant with Apgar scores of 8 and 9. Postoperatively, she received anticoagulation with enoxaparin, 80 mg bid subcutaneously. One week postpartum, a right-heart catheterization was performed while the patient was receiving IV epoprostenol (Table 1
). The atrial septal defect was easily crossed with a multipurpose catheter. Based on a measured oxygen uptake of 134 mL/min, her pulmonic blood flow calculated to 3.3 L/min and systemic blood flow to 3.5 L/min. Her pulmonary vascular resistance was 16.6 Wood units, and systemic vascular resistance was 28.2 Wood units.