This study was designed to investigate treatment of postoperative pulmonary hypertension by iloprost inhalation in children with congenital heart defects. It was a controlled single-blind randomized multi-center prospective study in order to explore the efficacy of this method in the treatment and prevention of pediatric pulmonary hypertension after corrective open-heart surgery for congenital heart defects.

Primary objectives:

1. To evaluate the effect of iloprost inhaled on postoperative PH after biventricular repair for CHD.
2. To verify the benefits of iloprost inhaled in improving the hemodynamics after biventricular repair for CHD.

Secondary objectives:

1. To investigate the preventive effect of iloprost inhaled on the life-threatening PHC occurring immediately after complex congenital heart surgery or occurring just after weaning off cardiopulmonary bypass.
2. To explore the potential of iloprost inhaled to reduce the early mortality after PHC and to decrease the use of ECMO/VAD.

Inclusion Criteria:

• CHD children who have associated PH risk factors and have accepted biventricular repair
• Pp/Ps >= 0.75 (before surgery) or Pp/Ps >= 0.5 (after surgery)

Exclusion Criteria:

• severe mitral stenosis
• obstructive drainage of pulmonary veins
• platelet count < 50,000,000,000/L & obvious bleeding