Continuous retrograde cerebral perfusion supplies substrates for brain metabolism during hypothermic circulatory arrest.

Ten patients underwent replacement of ascending aorta and/or aortic arch with aneurysm or dissection, using hypothermic circulatory arrest (HCA) with retrograde cerebral perfusion (RCP). RCP was administered through the superior vena cava cannula continuously during HCA (15 degrees C to 20 degrees C). Mean HCA time was 32 minutes (range, 18-45 minutes). To assess the metabolic changes during RCP, blood samples were taken from carotid arteries and the superior vena cava cannula simultaneously, five minutes after the onset and five minutes prior to termination of continuous retrograde cerebral perfusion (CRCP) for analysis of blood gas and glucose level. One patient died intraoperatively due to left ventricular failure. Nine patients survived their operations and all except one with stroke due to partial intimal flap obstruction of innominate artery awoke neurologically intact within four to six hours. One patient died on the postoperative fifth day due to septic shock following resection of ischaemic bowel due to dissection involving the mesenteric artery. Oxygen saturation, pH and glucose level were all found to be lower in blood back-bleeding from the carotid arteries than in blood perfused through the superior vena cava cannula at all sampling times during HCA and CRCP (p < 0.05). Although oxygen and glucose extraction is not only from brain tissue, these data demonstrate the efficacy of CRCP in supplying substrates for brain protection. CRCP is a reliable method as an adjunct to HCA for brain protection.