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. [1]

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.