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Objectives: To examine the association between intraoperative cerebral microembolic signals (MES) and postoperative neuropsychological deficit in patients with valve replacement (VR) and patients with coronary artery bypass grafting (CABG)., Methods: Neuropsychological examination (10 tests) was performed 1-2 days before and 2 months after surgery (VR (n=26) and CABG (n=14)). The intraoperative number of cerebral MES were monitored from the right middle cerebral artery using transcranial Doppler., Results: A higher number of cerebral MES were detected in VR patients with neurological deficit (6/26) compared with those without deficit (20/26) (MES median number 2083 v 645, p=0.04). No such difference was found in patients with CABG (2/14 v 12/14) (MES median number 50 v 112, p=0.2)., Conclusion: A high number of MES were detected in patients with VR with neuropsychological deficit. In patients with CABG with such a deficit, a low number of MES were detected. This difference in number may be explained by relatively more gaseous emboli in the first and more solid in the second. However, the results in the patients with CABG should be interpreted with caution due to the few patients in this subgroup.

Background and Purpose: We sought to determine the number of cerebral microembolic signals (MES) and their time of occurrence during the two most frequent types of cardiopulmonary bypass (CPB) surgery: coronary artery bypass grafting (CABG) and cardiac valve replacement (VR). Furthermore, we sought to examine the association between MES, patient characteristics, and intraoperative parameters., Methods: Forty-two patients were studied, 15 of whom had CABG and 27 VR. Cerebral MES were detected with the use of transcranial Doppler monitoring of the right middle cerebral artery., Results: Cerebral MES were detected in all patients. The number was significantly higher during VR (median, 1048) than during CABG (median, 82) (P < .001). In VR patients, 85% of the MES were detected when the heart regained effective ejection. During CABG, the highest number was detected when the aorta was cross-clamped (18%) and on release of the side clamp (13%). The numbers of MES during the period when the aorta was cross-clamped and in association with surgical procedures were not significantly different in the two patient groups. The total number of MES was inversely correlated to nasopharyngeal temperature (P < .01)., Conclusions: A significantly higher number of cerebral MES were detected during VR than during CABG. The highest number occurred in VR patients when effective heart ejection was regained and in CABG patients when the aorta was cross-clamped and on release of the side clamp. The total number of MES increased at lower nasopharyngeal temperatures. Transcranial Doppler monitoring may alert the surgical team when emboli enter the cerebral circulation during CPB surgery, thus allowing preventive measures to be taken.