The incidence of perioperative brain injury after deep hypothermia with circulatory arrest was compared to that associated with low-flow cardiopulmonary bypass during repair of D-transposition of the great arteries in 171 patients operated within the first three months of age at the Children’s Hospital, Boston. Circulatory arrest was associated with a higher likelihood of clinical and EEG seizures, a longer time to the recovery of normal EEG activity, and a greater release of the brain isoenzyme of creatine kinase in the first 6 hours after surgery. The duration of total circulatory arrest was of equal importance to the method of support treatment in predicting the neurologic outcomes. Clinical seizures occurred in 11% of infants with circulatory arrest, but EEG seizure activity was detected in 26%. At time of discharge, the two treatment groups were similar in overall incidence of neurologic abnormalities. 
COMMENT. The assessment of the effect of total circulatory arrest on later neurologic and developmental outcome awaits further follow-up by the neurologists who collaborated in this large prospective, randomized clinical study. In an editorial, Dr Julie A Swain of the University of Nevada outlines three mechanisms of neurologic injury in infants undergoing cardiac surgery: 1) mechanical injury from microemboli; 2) alterations in blood flow, distribution, and pressure; and 3) neuropsychological effects of neuroleptic drugs, anxiety, pain, and postoperative isolation. Some protection from cerebral injury is provided by hypothermia and drugs that decrease cerebral metabolism.