A Comparison of the Perioperative Neurologic Effects of Hypothermic Circulatory Arrest versus Low-Flow Cardiopulmonary Bypass in Infant Heart Surgery

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Abstract
Hypothermic circulatory arrest is a widely used support technique during heart surgery in infants, but its effects on neurologic outcome have been controversial. An alternative method, low-flow cardiopulmonary bypass, maintains continuous cerebral circulation but may increase exposure to known pump-related sources of brain injury, such as embolism or inadequate cerebral perfusion. We compared the incidence of perioperative brain injury after deep hypothermia and support consisting predominantly of total circulatory arrest with the incidence after deep hypothermia and support consisting predominantly of low-flow cardiopulmonary bypass in a randomized, single-center trial. The criteria for eligibility included a diagnosis of transposition of the great arteries with an intact ventricular septum or a ventricular septal defect and a planned arterial-switch operation before the age of three months. Of 171 patients with D-transposition of the great arteries, 129 (66 of whom were assigned to circulatory arrest and 63 to low-flow bypass) had an intact ventricular septum, and 42 (21 assigned to circulatory arrest and 21 to low-flow bypass) had a ventricular septal defect. After adjustment for diagnosis, assignment to circulatory arrest as compared with low-flow bypass was associated with a higher risk of clinical seizures (odds ratio, 11.4; 95 percent confidence interval, 1.4 to 93.0), a tendency to a higher risk of ictal activity on continuous electroencephalographic (EEG) monitoring during the first 48 hours after surgery (odds ratio, 2.5; 95 percent confidence interval, 1.0 to 6.4), a longer recovery time to the first reappearance of EEG activity (only in the group with an intact ventricular septum, P<0.001), and greater release of the brain isoenzyme of creatine kinase in the first 6 hours after surgery (P = 0.046). Analyses comparing durations of circulatory arrest produced results similar to those of analyses comparing treatments. In heart surgery in infants, a strategy consisting predominantly of circulatory arrest is associated with greater central nervous system perturbation in the early postoperative period than a strategy consisting predominantly of low-flow cardiopulmonary bypass. Assessment of the effect of these findings on later outcomes awaits follow-up of this cohort.