During the surgical repair of infants with congenital cardiac defects, there can be periods of decreased cerebral blood flow, particularly during deep hypothermic circulatory arrest. As a result, these infants are at increased risk for seizures and long-term neurodevelopmental difficulties.

Thirty-two infants with congenital heart disease had continuous video-electroencephalographic (EEG) monitoring pre-, intra-, and postoperatively for 48 hours after surgery.

For patients requiring deep hypothermic circulatory arrest (n = 17) the EEG pattern for all patients became suppressed and eventually isoelectric below 25°C. Two of the 32 infants had electrical seizures within the 48-hour monitoring period. Both required deep hypothermic circulatory arrest, and the burst pattern during recovery had rhythmic, sharp components that were high amplitude and often asynchronous between the hemispheres. The interval between the onset of seizure activity and initiation of the sharp burst pattern during surgery was 29 and 40 hours. This pattern was not observed during isoelectric recovery from infants who did not develop postoperative seizures.

The EEG in infants during deep hypothermic circulatory arrest displayed predictable changes. We identified an electroencephalographic pattern following the isoelectric period that may predict seizure development in the subsequent 48 hours.