Prophylactic Use of Milrinone After Congenital Heart Surgery in Infants

Inclusion Criteria: * Age younger than 12 months * Without pre-operative low cardiac output syndrome * Bi-ventricular repair of congenital heart disease involving cardiopulmonary bypass * Informed consent obtained from each participant's parent or guardian Exclusion Criteria: * A body weight \<2 kg * Prematurity (birth \<36 weeks postconceptual age) * Renal dysfunction ( Creatinine\>1.5mg/dL 48 hours before surgery) * Low cardiac output syndrome or hypotension on arrival to ICU from OR * Cardiopulmonary resuscitation before surgery * Platelet count\<80,000/mm3 before surgery * Left ventricular outflow tract obstruction before surgery * Ventricular arrhythmia before surgery * Without femoral artery catheter before arriving in the ICU * Consent was withdrawn by participants' parent or guardian.