PH is a significant contributor to the postoperative morbidity and mortality of congenital heart disease, especially after Fontan operation with univentricular physiology. Mild increase of pulmonary vascular resistance may lead to failure of Fontan circulation. Remodulin® has been approved for the treatment of adults with PH, but little is known about the effects in children with PH after Fontan operation. The study aim is to determine the safety and efficiency of Remodulin® to reduce the pulmonary arterial pressure and prevent PH in children after Fontan operation. Meanwhile pharmacokinetics of the drug were checked with or without the peritoneal dialysis.