Risk stratification of patients with asymptomatic carotid artery stenosis: Transcranial Doppler-based evaluation of asymptomatic cerebral microemboli

Transcranial Doppler (TCD) is a non-invasive ultrasonic technique that monitors blood flow velocity and blood flow direction in large intracranial arteries.1 In 1982 Aaslid and colleagues introduced TCD to clinical practice by monitoring blood flow in the basal cerebral arteries.2 Since then, TCD has been utilized to detect microemboli during carotid endarterectomy (CEA),3,4cardiac surgery,5 stroke associated with atrial fibrillation (AF),6 and in patients with prosthetic heart valves (PHVs).7 Recent reports suggest that these microembolimay indicate an increased risk of stroke or have clinical sequelae.8-13 Nonetheless, studies have yet to clearly show that the reduction of cerebral emboli detected by TCD results in improved outcomes.14.