This is a study to determine the safety and efficacy of liothyronine sodium/triiodothyronine (Triostat), a synthetic thyroid hormone, when given to infants with congenital heart disease during cardiopulmonary bypass surgery.

Patients will be randomized to receive study drug or placebo and randomization will occur stratified to each diagnostic category. All patients undergo preoperative echocardiograms to provide preoperative cardiac function data. The study drug or placebo will be provided in the operating room as an iv bolus just prior to cardiopulmonary bypass and as a bolus delivered on release of the aortic cross-clamp. This will be followed by iv for 12 hours. Operative data will be collected including CPB time, aortic cross-clamp time, length and degree of hypothermia. These data will be extracted from the anesthesia record.

Inclusion criteria:

Diagnosis of one of the following:

• Ventricular septal defect (VSD)
• Infant coarctation of the aorta
• Transposition of the great arteries
• Tetralogy of Fallot
• Complete atrioventricular canal defect
• Hypoplastic left heart, including patients who undergo a Norwood type procedure for aortic or mitral atresia

Patient must be scheduled for surgery.

Exclusion criteria:

• Certain additional defects and/or requirement for additional surgery.