Frequent microembolic signals detected by transcranial color-coded sonography in a patient with severe aortic stenosis: a case report

A 91-year-old woman with symptomatic severe aortic stenosis (AS) was admitted for transcatheter aortic valve implantation (TAVI). Preoperative carotid ultrasonography showed no significant stenosis or unstable plaque, but high-intensity transient signals were incidentally detected during pulse Doppler examination. Subsequently, we performed transcranial color-coded sonography (TCCS), which revealed microembolic signals (MES) occurring approximately once per minute in both middle cerebral arteries. Contrast-enhanced CT showed no stenosis in the aortic arch branches or the right common carotid artery origin. Transthoracic echocardiography demonstrated severe AS with significant valve calcification. After the TAVI procedure, we performed TCCS again, and no MES were detected. She has remained free of cerebrovascular events for more than six years following TAVI. MES are known to be detected in patients with carotid artery stenosis, atrial fibrillation, or mechanical valves and are considered a risk factor for stroke. In contrast, we found no previous reports of MES detection in patients with severe AS. Our findings suggest that severe AS can be a source of MES and that TAVI may help eliminate such signals, providing new insights into the pathophysiology of MES.