The effects of simple deep hypothermia and surface cooling combined cardiopulmonary bypass with circulatory arrest on the brain were evaluated by electroencephalogram (EEG) and computerized tomography (CT) of the brain. In 69 children with congenital heart diseases undergoing open-heart surgery, 60 patients were operated on under simple deep hypothermia and 9 under surface cooling combined bypass method with hypothermic circulatory arrest. The following results were obtained. 1)The appearance time of EEG after resuscitation in simple hypothermia was required two times as long as circulatory arrest time. On the other hand, in the combined bypass method, it was so shortened that there seemed the good results for cerebral functions. 2) Judging from the postoperative EEG and CT findings, the safe limited times of hypothermic circulatory arrest should be within 60 min. at 20℃ of the lowest esophageal temperature in simple deep hypothermia. 3) Among all the patients, the postoperative cerebral disorders were found in 6 children (10%) by simple hypothermia. Four patients out of them showed abnormal changes of CT scans of the brain. However, their CT changes recovered from 6 months to 1 year after operation.
