Incidence of transcranial Doppler-detected cerebral microemboli in patients referred for echocardiography.

Abstract

Transcranial Doppler can detect cerebral microemboli. These emboli may be a risk factor for embolic stroke. We studied the prevalence of microemboli in patients referred for echocardiography. Forty-two patients were evaluated. Patients were studied with continuous monitoring over one middle cerebral artery for 30 minutes, and the number of microemboli was recorded. Patients were divided into three groups, those with prosthetic heart valves (group A, n = 15), atrial fibrillation (group B, n = 14), and no major cardiac risk factor (group C, n = 14). Seventeen percent (7 of 42) of all patients had microemboli. In group A, 5 of 15 (33%) had microemboli. In group B, 2 of 13 (15%) patients had microemboli. Twenty-five percent (7 of 28) of patients in groups A and B combined (A+B) had microemboli. No patients (0 of 14) in group C had microemboli. Groups A and A+B had significantly more emboli than group C (P < .05). Prosthetic heart valve patients with emboli more commonly had a history of prior stroke than valve patients without emboli (3 of 5 versus 2 of 10). The number of emboli seen per 30-minute monitoring session was greater in patients with a prior history of stroke than in patients without (10 microemboli versus 3). Microemboli can be found in a significant percentage of selected patients referred for echocardiography. The prevalence of microembolism is greater in patients with a known high risk of embolization (eg, prosthetic valves) and less in patients with a lower risk of embolization (eg, atrial fibrillation). These microemboli may be associated with an increased prevalence of previous stroke in patients with prosthetic valves.

Association Between Large Aortic Arch Atheromas and High-Intensity Transient Signals in Elderly Stroke Patients

“…However, several studies have found an association between HITS and increased risk of stroke. 14,17-19,25-29 Tong et al 19 found an association of HITS with known cardioembolic risk factors and history of prior stroke. In patients with carotid stenosis, HITS have been related to the degree of stenosis and associated with an increased risk of subsequent stroke or transient ischemic attack.…”

Clusters of Microembolic Signals: A New Form of Cerebral Microembolism Presentation in a Patient With Middle Cerebral Artery Stenosis

“…Although the definition of HITS did not mention the temporal profile of the signal distribution, our own experience and previous reports [11][12] found HITS with an aleatory but homogeneous distribution over the monitoring time. MES have been detected in a variety of conditions, including prosthetic valve replacement, 13 high-grade carotid stenosis, 14 atrial fibrillation, 15 and acute cerebral ischemia, 16 but only a few studies 17,18 have reported MES in relation to intracerebral artery stenosis. MCA stenosis is a relatively rare disease in the Caucasian population, but it is strongly associated with a high rate of stroke recurrence.…”

Alterations of Neuropsychological Function and Cerebral Glucose Metabolism After Cardiac Surgery Are Not Related Only to Intraoperative Microembolic Events

“…4 TCD is a useful technique to detect air, platelet, thrombus, atheroma, and fat microemboli as short-duration HITS. [17][18][19][20] With the aid of TCD, HITS can be quantified and their source located during CABG, 1,11,13,[21][22][23][24] carotid endarterectomy, 25,26 angioplasty, 27 or angiography, 28 as well as in patients with carotid stenosis, 29 -32 prosthetic cardiac valves, 29,[32][33][34][35][36] atrial fibrillation, 36 myocardial infarction, and stroke. [37][38][39] However, the clinical sequelae of HITS detected by TCD are still under debate.…”