Cardiac surgery under extracorporeal circulation (ECC) in newborns with congenital heart disease causes significant morbidity and mortality. The perioperative period is a period of major vulnerability implicated in the appearance of these sequelae, and it is therefore essential to monitor brain function during ECC. The quality of cerebral oxygenation in the perioperative period is routinely monitored non-invasively by infra-red spectroscopy, which makes it possible to estimate cerebral tissue oximetry from a surface electrode (NIRS). The association between time spent outside the limits of cerebral autoregulation and the occurrence of perioperative encephalopathy is not known. The purpose of this study is to determine whether disturbances in brain autoregulation during the operative period are associated with the occurrence of postoperative encephalopathy in children operated on for congenital heart disease in the neonatal period. The main objective of the research is to determine the association between time spent outside individually determined cerebral autoregulation limits and the appearance of brain lesions suggestive of low brain output. Secondary objectives will investigate the association between time spent outside autoregulatory limits and the occurrence of postoperative encephalopathy defined by clinical and encephalographic criteria and will study factors predictive of the development of postoperative encephalopathy.

Inclusion Criteria:

• Any newborn (0-28 days) with congenital heart disease, hospitalized in the preoperative period at the Nantes University Hospital, for whom a decision is made to perform an operation under extracorporeal circulation, suitable to be transported for an MRI without risk, advice taken from the treating team.

Exclusion Criteria:

• emergency cardiac surgery
• Preoperative extracorporeal assistance
• Preoperative intubation
• Preoperative administration of inotropes
• Pre-operative instability contra-indicating pre-operative MRI
• Dependence on a pace maker contra-indicating MRI Imaging.
• Parental consent refusal
• Non-affiliation to a health security insurance