RETROGRADE CEREBRAL PERFUSION DOES NOT PERFUSE THE BRAIN IN NONHUMAN-PRIMATES

Background. Recently retrograde cerebral perfusion (RCP) has been advo cated as an alternative to complete circulatory arrest during aortic a rch surgery. Methods. In 19 baboons, we compared brain protection usin g hypothermic circulatory arrest or RCP. Animals were placed on cardio pulmonary bypass, cooled to 18 degrees C, underwent 1 hour of circulat ory arrest or RCP, and were reperfused for 3 hours. Biochemical variab les, cerebral blood now (colored microsphere technique), and brain his tology were assessed. Results. Release of the brain-specific ischemic marker CK-BB was similar in both groups (peak values, 123 +/- 97 U/L i n the circulatory arrest group and 164 +/- 88 U/L in the RCP group; p > 0.05), as were the arteriovenous differences in glucose uptake and l actate production (p > 0.05). During RCP, significant brain how could not be detected (0.5 +/- 0.5 mL.min(-1).100 g(-1)). About 90% of the b lood was shunted to the inferior caval vein, and an equilibrium in cir culating microspheres was found between RCP inflow and caval vein outf low. Less than 1% of the RCP inflow returned to the aortic arch. Histo logic signs of brain damage were minimal in both groups, although slig htly more glial edema was found in the RCP group. Conclusions. These d ata suggest that in nonhuman primates, retrograde cerebral perfusion d oes not perfuse the brain because of venovenous shunting.