IMPACT OF MICROEMBOLISM AND HEMODYNAMIC-CHANGES IN THE BRAIN DURING CAROTID ENDARTERECTOMY

Background and Purpose Monitoring of carotid endarterectomy with elect roencephalography and transcranial Doppler ultrasonography provides in stantaneous information about hemodynamic changes and embolic signals. However, a relation between these findings and intraoperative infarct s has not yet been demonstrated.Methods In this study we compared preo perative and postoperative computed tomographic scans (58 patients) or magnetic resonance imaging (40 patients) of the brain, assessed by tw o independent observers, to detect intraoperative infarcts, and we rel ated any such new lesions to the findings of intraoperative monitoring . Results In the computed tomography series one intraoperative infarct occurred, with corresponding clinical deficits. In the magnetic reson ance group four patients developed new lesions that occurred intraoper atively, all of which were clinically silent. There was a significant relation between the number of embolic signals during the surgical dis section of the carotid artery and the occurrence of intraoperative inf arcts (P<.005). Three of the four infarcts were of the lacunar type; t he fourth patient had a border-zone infarct, associated not only with many embolic signals but also with low flow during cross-clamping. The re were no demonstrable ultrasound side effects on brain tissue. Concl usions Embolic signals detected by transcranial Doppler monitoring in the dissection phase of carotid endarterectomy show a significant rela tion to new ischemic lesions and therefore are potentially harmful. Th e phenomenon should alert the vascular surgeon.