BACKGROUND: Recently retrograde cerebral perfusion (RCP) has been advocated as an alternative to complete circulatory arrest during aortic arch surgery. METHODS: In 19 baboons, we compared brain protection using hypothermic circulatory arrest or RCP. Animals were placed on cardiopulmonary bypass, cooled to 18 degrees C, underwent 1 hour of circulatory arrest or RCP, and were reperfused for 3 hours. Biochemical variables, cerebral blood flow (colored microsphere technique), and brain histology were assessed. RESULTS: Release of the brain-specific ischemic marker CK-BB was similar in both groups (peak values, 123 +/- 97 U/L in 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 lactate production (p > 0.05). During RCP, significant brain flow could not be detected (0.5 +/- 0.5 mL.min-1 x 100 g-1). About 90% of the blood was shunted to the inferior caval vein, and an equilibrium in circulating microspheres was found between RCP inflow and caval vein outflow. Less than 1% of the RCP inflow returned to the aortic arch. Histologic signs of brain damage were minimal in both groups, although slightly more glial edema was found in the RCP group. CONCLUSIONS: These data suggest that in nonhuman primates, retrograde cerebral perfusion does not perfuse the brain because of venovenous shunting.
BACKGROUND: Recently retrograde cerebral perfusion (RCP) has been advocated as an alternative to complete circulatory arrest during aortic arch surgery. METHODS: In 19 baboons, we compared brain protection using hypothermic circulatory arrest or RCP. Animals were placed on cardiopulmonary bypass, cooled to 18 degrees C, underwent 1 hour of circulatory arrest or RCP, and were reperfused for 3 hours. Biochemical variables, cerebral blood flow (colored microsphere technique), and brain histology were assessed. RESULTS: Release of the brain-specific ischemic marker CK-BB was similar in both groups (peak values, 123 +/- 97 U/L in 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 lactate production (p > 0.05). During RCP, significant brain flow could not be detected (0.5 +/- 0.5 mL.min-1 x 100 g-1). About 90% of the blood was shunted to the inferior caval vein, and an equilibrium in circulating microspheres was found between RCP inflow and caval vein outflow. Less than 1% of the RCP inflow returned to the aortic arch. Histologic signs of brain damage were minimal in both groups, although slightly more glial edema was found in the RCP group. CONCLUSIONS: These data suggest that in nonhuman primates, retrograde cerebral perfusion does not perfuse the brain because of venovenous shunting.