PROLONGED CIRCULATORY ARREST IN MODERATE HYPOTHERMIA WITH RETROGRADE CEREBRAL PERFUSION - IS BRAIN ISCHEMIC

Background Circulatory arrest (CA), which provides a bloodless field a nd good visualization without the need of aortic cross-clamp, is commo nly used to facilitate repair of aortic lesions. However, extended per iods of CA may impair cerebral metabolism and cause ischemic injury. S tudies were performed to evaluate the efficacy of retrograde cerebral perfusion (RCP) in protecting the brain from ischemic injury during a prolonged period of CA in moderate hypothermia. Methods and Results Tw enty-three patients (18 men and 5 women) were operated on for aortic l esions (17 acute type A aortic dissection and 6 chronic type A aortic dissection with Marfan's syndrome). The aortic operations were perform ed with CA (58 to 104 minutes; mean+/-SD, 75+/-12 minutes) at a rectal temperature of 23.3+/-0.5 degrees C (21 degrees C to 25 degrees C). F or RCP, cold (14 degrees C to 18 degrees C) oxygenated blood (300 mL/m in)was pumped to the superior vena cava with internal jugular venous p ressure of 15+/-5 mm Hg. The cardiopulmonary bypass time was 157+/-18 minutes. Cortical blood how during RCP detected by subdural laser Dopp ler probe was 10+/-5% of baseline. Percent oxygen extraction and pyruv ate and lactate levels (26+/-2% and 0.43+/-0.17 and 45+/-16 mg/dL) wer e insignificantly different from those before CA (28+/-3% and 0.71+/-0 .08 and 62+/-20 mg/dL, P>.05). Creatine kinase-BB isoenzyme was undete ctable. All but 1 patient survived the operation (95.5%) and woke up w ithout neurological deficit. Follow-up (mean, 13 months) was complete in all survivors. There were no late deaths. Cerebral functional studi es performed 3 months after discharge showed results insignificantly d ifferent from those of the normal control subjects. Conclusions There is no evidence of ischemia of the brain during prolonged moderate hypo thermic CA with the aid of RCP. Retrograde cerebral perfusion effectiv ely extends the safe time of CA. Deep hypothermia during CA seems unne cessary.