Cerebral Blood Flow in Single Ventricles Throughout Staged Surgical Reconstruction

Inclusion Criteria - Single Ventricle Subjects: * Males or females up to age 10 years. * Any complex congenital heart lesion that has single ventricle physiology. These single ventricle lesions will be of either right or left ventricular morphology. * Ability to undergo an MRI scan of at least 60-90 minutes under general anesthesia or deep sedation. Patients will undergo determination of their physical ability to undergo the MRI prior to being enrolled in the study by parameters such as blood pressure, heart rate, cardiac rhythm, and respiratory rate. MRI involves laying still in the supine position for at least 60-90 minutes. * Parents signing informed consent. Inclusion Criteria - Normal Control Group: * Males or females up to age 10 years. * Normal cerebral anatomy who are normocephalic and who are asymptomatic (e.g. if the scan is performed for headache) at the time of the scan. * Ability to undergo an MRI scan of at least 60-90 minutes under general anesthesia or deep sedation. Normal patients will undergo determination of their physical ability to undergo the MRI prior to being enrolled in the study by parameters such as blood pressure, heart rate, cardiac rhythm, and respiratory rate. MRI involves laying still in the supine position for at least 60-90 minutes. * Parents signing informed consent. Exclusion Criteria - Single Ventricle Patients : * Any condition judged by the patient's physician that would cause this trial to be detrimental to the patient. * Stenosis of the branch pulmonary arteries or coarctation of the aorta. * Any significant arrhythmias such as supraventricular tachycardia, trigeminy, etc. Occasional premature atrial or ventricular contractions or an occasional missed beat is permitted. * Systemic hypertension. * Primary lung disease (eg bronchopulmonary dysplasia). * Any known significant neurological disease outside of the usual state of single ventricle patients. * Any chromosomal anomalies or other major anomalies which would confound neurological outcome. * A patient with a pacemaker or cardioverter/defibrillator in place. * A ferromagnetic foreign body (with the exception of sternal wires and vascular clips in the thorax). * Parents/guardians or subjects who, in the opinion of the Investigator, may be non-compliant with study schedules or procedures. Exclusion Criteria - Normal Control Group: * Any condition judged by the patient's physician that would cause this trial to be detrimental to the patient. * Any known significant neurological disease * Any contraindication to performing an MRI. * Parents/guardians or subjects who, in the opinion of the Investigator, may be non-compliant with study schedules or procedures.