Effect of postconditioning on cardiac protection in children undergoing tetralogy repair

INTERVENTION: In the experimental group, the aorta is crossclamped for two cycles of 30 seconds clamping and 30 seconds unclamping onset of reperfusion after cardioplegic arrest. In control group,the patients receive cold blood cardioplegic arrest alone without postconditioning. CONDITION: Infants and children with Tetralogy undergoing radical repair ; Circulatory System ; Infants and children with Tetralogy undergoing radical repair PRIMARY OUTCOME: 1. Postoperative Creatine Kinase ‐ Myocardial Band (CKMB); 2. Cardiac Troponin I (cTnI); 3. Inotropic use SECONDARY OUTCOME: 1. Mortality; 2. Morbidity; 3. Intensive Care Unit (ICU) stay INCLUSION CRITERIA: 1. Patients with Tetralogy undergoing radical surgery 2. Less than 14 years old