S-100β release in hypothermic circulatory arrest and coronary artery surgery

Background. Aortic surgery utilizing profound hypothermic circulatory arrest (HCA) has a higher incidence of neurological injury than coronary artery bypass grafting (CABG). S-100 beta is a potential marker of cerebral ischemic injury. The aim of this study is to assess its use in investigating cerebral injury during HCA. Methods. We studied 40 patients (10 CABG, 30 HCA). The mean cardiopulmonary bypass (CPB) times were 72 and 158 minutes, respectively. Mean HCA duration was 27.6 min, with retrograde cerebral perfusion (RCP) used in 18 patients (mean 28.5 minutes, 95% CI 16-25). Perioperative venous blood samples were subjected to S100 beta assay. Results. S100 beta levels with HCA (peak: 2.68 mu g/L, 95% CI 1.99-3,38 mu g/L; calculated area under the curve [AUC]: 1596 mu g/L/min, 95% CI 825-2368 mu g/L/min) were significantly higher (peak, p = 0.028 and AUG, p = 0.007) than with CABG (peak: 1.16 mu g/L, 95% CI 0.25-2.1 mu g/L and AUG: 53.4 mu g/L/min 95% CI 3.0-103.8). Peak S100 beta correlated with CFB time in CABG cases (r = 0.76, p < 0.05), and with both CPB and HCA time in HCA cases: without RCP (r = 0.46 and 0.21, respectively, p > 0.05) and with RCP (r = 0.88 and 0.33, respectively, p < 0.05). There was no significant difference in the S100 beta levels between HCA groups with and without RCP, but HCA time was longer in the RCP group (p = 0.05). Conclusions. S100 beta release correlates with duration of CPB and HCA. Elevated serum S100 indicates astrocyte death or activation, and suggests blood-brain barrier dysfunction. The continuing release of S100 after the end of operation suggests that HCA may be associated with greater injury than CABG. RCP did not influence S-100 beta release in this study. (C) 1999 by The Society of Thoracic Surgeons.