Preventing strokes associated with carotid endarterectomy: Detection of embolisation by transcranial doppler monitoring

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Intraoperative embolisation has been estimated as the cause of perioperative stroke in up to 80% of carotid endarterectomies (CEA), while reduced cerebral blood flow is responsible for less than 20%. 1 Monitoring or quality control methods which are unable to detect embolisation are unlikely to reduce perioperative mortality and morbidity associated with CEA. Because the majority of monitoring methods are used primarily to detect haemodynamic abnormalities, this may be one reason Why no study has convincingly established the clinical advantage for perioperative monitoring and why a significant number of surgeons performing CEA do not employ this strategy. 2 For any monitoring method to have an impact on perioperative morbidity/ mortality it must detect the majority of abnormalities while there is still time to correct the defect and prevent permanent damage. There is accumulating, evidence that transcranial Doppler (TCD) monitoring can not only detect embolisation, but also that it can identify clinically significant patterns of embolisation early enough to permit therapeutic intervention to prevent stroke. 3 Even surgeons with low perioperative stroke rates have a du ty to ensure that small numbers of preventable strokes are eliminated. The evidence emerging from studies of the perioperative use of TCD may be making the argument that there is no clinical advantage in monitoring more difficult to sustain. The introduction of transcranial Doppler (TCD) monitoring of the middle cerebra ! artery (MCA) during CEA enabled emboli to be detected directly for the first time, whilst simultaneously providing haemodynamic data on the adequacy of cerebral blood supply. 4 Emboli