Retrograde perfusion through superior vena cava reaches the brain during circulatory arrest

Background: The optimal technique for brain perfusion during circulatory arrest remains controversial. Concern exists that retrograde cerebral perfusion (RCP) via the superior vena cava (SVC) is unable to perfuse the brain. We evaluated whether RCP blood circulates through the brain parenchyma in humans during deep hypothermic circulatory arrest (DHCA). We hypothesized that a significant difference in the levels of S-100 beta (a protein with very high neuro-sensitivity) between the blood infused in the SVC and the effluent blood returning in the left carotid artery (CA) during RCP, should be regarded as a sign of the circulation of RCP blood through the brain parenchyma. Methods: We enrolled 10 non-consecutive patients undergoing elective arch-surgery using DHCA and RCP. Circulating S-100 beta levels were measured at baseline and immediately before DHCA. During DHCA and RCP the difference in S-100 beta between the SVC and the CA was evaluated after 10 minutes of arrest and immediately before resumption of the circulation. S-100 beta levels were evaluated using enzyme-linked immunosorbent assay (ELISA). Results: Mean DHCA duration was 22.4 +/- 7.9 minutes. Mean S-100 beta level at baseline was 92.5 +/- 54.9 mu g/L. After 10 minutes of DHCA the level of S-100 beta in the CA was significantly higher than in the SVC (936.9 +/- 326.3 vs. 810.9 +/- 307.4 mu g/L, P=0.0021). This difference was enhanced at the second DHCA sample (1113.8 +/- 334.2 vs. 920.5 +/- 340.0 mu g/L, P=0.0002). There was a statistically significant correlation between the duration of DHCA and the percent difference in S-100 beta level between the SVC and the CA (Pearson's correlation coefficient =0.902). Conclusions: RCP is able to perfuse the brain parenchyma in humans during DHCA.