To date, the families of more than 60 babies have enrolled in our study that aims to understand the response of the baby brain to congenital heart disease and its treatment. Most of these newborns have undergone two MRI examinations, before and after surgery and more than half of these children have returned for neurodevelopmental assessment at one year. We have expanded the follow-up of this cohort and hope to follow our study babies at 2 1/2 and 4 years of age as they become toddlers and preschool age children. To date we have learned:

• Brain injury can be safely detected both before and after surgery.
• The nature and timing of brain injury is related to the exact type of congenital heart disease. For certain forms of heart disease, injury is more commonly detected before surgery and for others, the injury appears after surgery and the post-surgical recovery period. Understanding when injury occurs will give us the clues necessary to design treatments that may prevent brain injury. These treatments will need to be tailored to each form of congenital heart disease, of which there are dozens.
• Congenital heart disease is associated with disordered brain cell metabolism.
• For babies with transposition of the great arteries, brain lactate, a marker of anaerobic metabolism, is elevated before surgery. This marker normalizes after surgery. Increase in N-acetyl aspartate, a marker of brain cell integrity, is delayed in certain brain locations following surgery.
• Abnormal development of brain microstructure and connectivity can be detected with advanced magnetic resonance imaging techniques – diffusion tensor tractography, in babies with acquired brain injury before or after surgery.
• We are using advanced imaging techniques to visualize not only brain structure, but to monitor specific aspects of brain development, including the formation of connections required for complex brain functions.
• Balloon atrial septostomy, a life-saving procedure for some babies with transposition of the great arteries, is associated with preoperative brain injury.
• Sensitive magnetic resonance imaging techniques have detected small focal injuries in babies receiving this life-saving procedure. Detection of these injuries helps the Heart Center team determine the best time for surgery. We are using these findings to develop trials of modified septostomy techniques that will make this necessary procedure safer for the baby brain.