• To determine the effects of prophylactic N-acetylcysteine (NAC) on the severity of postoperative myocardial dysfunction following surgical repair of complex congenital heart disease in neonates. [ Time Frame: 24 hours ] [ Designated as safety issue: No ]
  

• To determine the relationship between postoperative myocardial dysfunction and morbidity [ Time Frame: 24 hours ] [ Designated as safety issue: No ]
  
• To determine the effects of prophylactic NAC on postoperative morbidity [ Time Frame: 24 hours ] [ Designated as safety issue: No ]
  

Drug: N-acetylcysteine
Loading dose: Subjects randomized to IV NAC will receive a total loading dose of 100 mg/kg of 10% (100 mg/mL) solution. Acetadote is supplied as a 20% solution (200 mg/mL) and will be diluted 1:1 with an equal volume of D5W. The volume of the loading dose will be 1 mL/kg, anticipated to be 2.5-5 mL in our patient population. The loading dose will be administered over 1 hr beginning 1 hr prior to the patient's OR time. Subjects in the placebo group will receive 1 mL/kg of D5W over 1 hr. Maintenance infusion: Subjects randomized to IV NAC will receive an infusion of 10 mg/kg/hr of 10% (100 mg/mL) solution for 24 hrs, starting in the OR after weaning from CPB. Acetadote is supplied as a 20% solution (200 mg/mL) and will be diluted 1:1 with an equal volume of D5W. The volume of the maintenance infusion will be 0.1 mL/kg/hr, anticipated to be 0.25-0.5 mL/hr in our patient population. Subjects in the placebo group will receive 0.1 mL/kg/hr of D5W for 24 hrs.

This is a randomized, placebo-controlled, blinded study of intravenous N-acetylcysteine (NAC) for the prevention of postoperative myocardial dysfunction and apoptosis in infants undergoing arterial switch for D-transposition of the great arteries. Subjects will be age 0-3 months, and no distinctions will be made based on gender or race. Infants operated before 36 weeks post-conceptional age or with birth weight less than 1.8 kilograms will be excluded.

Informed consent will be obtained from the patient's parent by one of the investigators in the hospital before the infants undergo surgery.

Subjects will be randomized based on a block randomization scheme to receive placebo or NAC infusion, starting with a loading dose 1 hour prior to surgery. If there is any concern by the ICU physician that the patient is developing toxicity to the medicine, the study drug will be discontinued and the patient removed from the study. Patients will have a thermodilution catheter placed during surgery for postoperative direct measurement of cardiac output. Endomyocardial biopsy will be performed by the surgeon pre- and post-bypass for measurement of markers of apoptosis. Postoperatively, patients will continue to receive an infusion of IV NAC for 24 hours. Blood draws will be through existing arterial and central venous catheters. Serum labs collected will include serial lactate values (already collected routinely), liver and renal function tests, CK-MB and troponin-I levels as a marker of myocardial injury, and S100b level as a marker of brain injury. Total additional blood removed for research purposes will be less than 15 mL. Cardiac output will be measured serially by thermodilution. Serial transthoracic echocardiography will be used to determine left ventricular function.

Inotropic score, duration of mechanical ventilation, length of ICU stay, and length of hospitalization will be recorded.