A 31P-magnetic resonance study of antegrade and retrograde cerebral perfusion during aortic arch surgery in pigs

To evaluate the effect of hypothermic circulatory arrest on brain metabolism, we used 31P-magnetic resonance spectroscopy to monitor brain metabolites in pigs during 2 hours of ischemia and 1 hour of reperfusion. Twenty-eight pigs were divided into five groups. Anesthesia (n=5) and hypothermic cardiopulmonary bypass groups (n=5) served as controls. In the circulatory arrest (n=6), antegrade perfusion (n=6), and retrograde (n=6) brain perfusion groups, the bypass flow rate was 60 to 100 ml·kg−1·min−1. In the antegrade group, the brain was perfused via the carotid arteries at a blood flow rate of 180 to 200 ml·min−1 during circulatory arrest at 15° C. In the retrograde group, the brain was perfused through the superior vena cava at a flow rate of 300 to 500 ml·min−1 during circulatory arrest at 15° C. The intracellular pH was 7.1±0.1 and 7.3±0.1 in the anesthesia and hypothermic cardiopulmonary bypass groups, respectively. In the circulatory arrest group, the intracellular pH decreased to 6.2±0.1 and did not recover to its initial value (7.0±0.1) during reperfusion (p