Surgical treatment in early infancy is sometimes necessary in children with congenital heart disease either because of intractable cardiac failure or arterial hypoxia. The combined mortality from early palliation followed by later total correction led to attempts at complete correction as a primary procedure. However, early experience with standard cardiopulmonary bypass in infancy was associated with major problems in most centres and although cardiopulmonary bypass has now successfully been used, many centres continue to use deep hypothermia with circulatory arrest for these patients. The technique offers the surgeon almost ideal operating conditions in an empty, still, and bloodless heart and several malformations have been reported. The vulnerability of the developing brain to a number of insults has been well documented and concern has existed regarding the long-term intellectual development of children subjected to periods of circulatory arrest in infancy. Although reports of neurological damage severely curtailed the use of deep hypothermia in the early 1960's, the incidence of serious neurological complications in the infants reported by Mori et al. (1972) was low, and subsequent reports have suggested that in the longer term, intellectual function remains within the normal range in most cases. Nevertheless, in each series abnormal neurological behavior in the immediate postoperative period and later intellectual retardation was seen in a significant number of patients, and further evaluation of the technique is needed. 38 children were assessed 22 mth to 6 yr after open heart surgery using circulatory arrest with deep hypothermia. The mean IQ of the group was 99.2 (SD 19.5). No correlation was found between IQ and the age or weight at operation or the duration of circulatory arrest. The results suggest that the technique gives effective protection to the brain during periods of circulatory arrest for up to 60 min.
