ABSTRACT
The use of deep hypothermic cardiopulmonary bypass (CPB) with or without deep hypothermic circulatory arrest (DHCA) has substantially improved operating conditions for children undergoing congenital heart surgery, resulting in improved survival and reduced cardiac morbidity. Hypothermia reduces cerebral blood flow and metabolism and preserves cellular stores of high-energy phosphates. The hypothermic methods that can be employed—either moderate hypothermia, deep hypothermia, or deep hypothermia with circulatory arrest—have differing effects on cerebral physiology and should be considered separately. The cerebral impact of moderate hypothermic CPB on children is similar to that observed in adults. Several authors have demonstrated ongoing basal cerebral metabolism during deep hypothermic circulatory arrest. The temporal sequence of infant cardiac surgery is designed so that the actual cardiac repair occurs during DHCA or continuous flow CPB. This is a high risk period for injury due to the conditions of total circulatory arrest or low flow.
