TRANSCRANIAL DOPPLER - PREVENTING STROKE DURING CAROTID ENDARTERECTOMY

Carotid endarterectomy (CEA) is more effective at preventing strokes t han medical therapy alone in those patients with severe symptomatic st enosis of the internal carotid artery and this benefit persists despit e a perioperative stroke/death rate of approximately 5%. Thromboemboli sm has been established as the underlying cause of the majority of per ioperative strokes, but this could not be detected using the existing methods of monitoring or quality control. Early studies demonstrated t hat transcranial Doppler monitoring (TCD) could detect intraoperative embolism, but the clinical significance of this finding was questioned as the incidence of these emboli far exceeded the incidence of periop erative strokes. This study aimed to establish the clinical relevance of TCD-detected emboli during CEA by differentiating emboli into two b road categories; air and particulate, and comparing the quantity of ea ch with a variety of clinical outcomes including neurological and cogn itive function, retinal fundoscopy, automated visual fields and CT/MRI brain scans. This prospective study was performed on 100 consecutive patients undergoing CEA with all assessments performed pre- and postop eratively by independent specialists in the relevant fields. Embolisat ion was detected in 92% of successfully monitored operations. Most emb oli were characteristic of air microbubbles and not associated with th e development of adverse clinical events. However, emboli characterist ic of particulate material were detected during the initial dissection phase and in the recovery phase after final restoration of flow. Thes e particulate emboli were associated with the development of both neur ological and cognitive deficits. In particular, persistent embolisatio n after final restoration of flow heralded incipient carotid artery th rombosis and the development of stroke. Early intervention based on th e TCD evidence of continuing embolisation can prevent the stroke from occurring.