Abstract: Objective To compare the effect of cerebral protection between retrograde cerebral perfusion(RCP)and selective antegrade cerebral perfusion(SACP)during deep hypothermic circulatory arrest(DHCA)in canine models.Methods Fifteen healthy adult dogs were randomly divided into 3 groups(n=5),namely the simple DHCA group(group I),DHCA+RCP group(group Ⅱ)and DHCA+SACP group(groupⅢ).Extrocorporeal circulatory was established routinely in the dogs,and DHCA commenced when the nasopharyngeal temperature was reduced to 18 ℃.During DHCA,RCP and SACP were applied in groupsⅡand Ⅲ,respectively.All the models were rewarmed after 90 min of DHCA and the cerebral reperfusion continued for 90 min.Cerebral oxygenous metabolic function,cerebral temperature and ultrastructural changes of the neurons were observed in the 3 groups at different time points during the operation.Results The jugular venous oxygen saturation(SjvO2)increased with the temperature reduction,and then decreased after DHCA commencement,showing significant changes at different time points in groups I and Ⅱ.SjvO2 in group Ⅲ were significantly higher than that in the other two groups after 90 min of DHCA(P=0.000).Brain temperature significantly increased in groupⅠ during DHCA as compared with that in groups Ⅱand Ⅲ(P=0.000),but showed no significant difference between the latter two groups(P=0.195).The ultrastructure of the neurons underwent obvious changes after reperfusion for 30 min in groupⅠ.In groupⅡ the neuronal ultrastructure was basically normal at 60 min during DHCA and changed slightly at 90 min,but in group Ⅲ no obvious changes were seen at 90 min during DHCA and only slight changes occurred at 30 min of reperfusion.Conclusions RCP can not supply enough oxygen but can maintain low cerebral temperature,and provide short-term brain protection.DHCA+SACP provides better brain protection than simple DHCA and DHCA +RCP,and has a promising prospect in cardiac surgery.