 Participants in this trial will be randomly classified into one of two groups: the experimental group will undergo cross clamping of the aorta with a single clamp and be given retrograde cardioplegia for heart protection, and the control group will undergo cross clamping of the aorta with multiple clamps and be given antegrade cardioplegia for heart protection. Neurobehavioral assessments will be accomplished with a comprehensive battery of neurological and neuropsychological tests. 