During the time of your child's first surgery for hypoplastic left heart syndrome, a monitor was placed on your child's forehead to measure the oxygen levels in the brain. This monitor is called Near Infrared Spectrometry (NIRS). The researchers involved in this study want to know if oxygen levels in the blood vessels of the brain have any effect on developmental disabilities later in life in children with hypoplastic left heart syndrome. The researchers plan to enroll 60 research subjects.