- Thirty patients in the age range 2-24 months scheduled for surgical closure of ventricular septal defect (VSD) associated with postoperative pulmonary hypertension [diagnosed in all patients by preoperative echocardiography and confirmed invasively by the pulmonary catheter before transfer to ICU by Mean Pulmonary Arterial Pressure (MPAP) > 25 mmHg or Mean Pulmonary Arterial Pressure (MPAP) /Mean Systemic Arterial Pressure (MAP) > 0.33] were enrolled in this study.