Detection of asymptomatic cerebral embolic signals with doppler ultrasound

182

116

Background and Purpose-Asymptomatic embolic signals (ES) detected using transcranial Doppler have been reported in patients with potential cerebral embolic sources. They may be useful in risk stratification and in assessing therapies. First, it is essential to show whether they predict stroke risk. Methods-A systematic review and meta-analysis was performed to determine the prognostic value of ES in different potential cerebral embolic sources. Studies were identified that used transcranial Doppler to detect ES and included prospective stroke/TIA follow-up. Numbers of ES-positive and ES-negative patients were extracted with stroke/TIA and stroke alone outcomes. Results-ES

Section: Discussionmentioning

confidence: 88%

Section: Asymptomatic Carotid Stenosismentioning

confidence: 96%

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confidence: 99%

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Doppler Embolic Signals in Cerebrovascular Disease and Prediction of Stroke Risk

King

Markus

2009

182

116

“…After the report of HITS during carotid endarterectomy, 40 similar signals occurring spontaneously were recorded in patients with symptomatic carotid artery disease. [41][42][43] These signals were presumably microembolic signals, since they were documented to disappear after carotid endarterectomy. 44 -46 Patients with asymptomatic carotid stenoses have also demonstrated HITS, but to a much lesser extent than symptomatic stenosis, [47][48][49] with a proportion of approximately 1:5.…”

Section: Results Of Motion Estimation and Plaque Morphologymentioning

confidence: 97%

Four-Dimensional Ultrasonographic Characterization of Plaque Surface Motion in Patients With Symptomatic and Asymptomatic Carotid Artery Stenosis

Meairs

Hennerici

1999

112

Background and Purpose-In vitro studies of atherosclerotic plaque fracture mechanics suggest that analysis of local variations in surface deformability may provide information on relative vulnerability to plaque fissuring or rupture. We investigated plaque surface deformations in patients with symptomatic and asymptomatic carotid artery disease using 4-dimensional ultrasonography and techniques for measuring optical flow. Methods-Four-dimensional ultrasound examinations of carotid artery plaques were performed in 23 asymptomatic and 22 symptomatic patients with 50% to 90% stenosis of the internal carotid artery. Plaque surface motion during 1 cardiac cycle was computed with a hierarchical model-based motion estimator. Results were compared with plaque echogenicity and surface structure. Results-Of the 45 patients examined, plaque surface motion estimates were obtained for 18 asymptomatic and 13 symptomatic patients. There were no significant differences in echogenicity or surface structure of asymptomatic and symptomatic plaques (PϾ0.05). Results of motion estimation showed that asymptomatic plaques had surface motion vectors of equal orientation and magnitude to those of the internal carotid artery, whereas symptomatic plaques demonstrated evidence of inherent plaque movement. There was no significant difference in maximal plaque velocity between symptomatic and asymptomatic plaques (PϽ0.14). Maximal discrepant surface velocity (MDSV) in symptomatic plaques was 3.85Ϯ1.26 mm/s (meanϮSD), which was significantly higher (PϽ0.001) than MDSV of asymptomatic plaques with 0.58Ϯ0.42 mm/s (meanϮSD). Conclusions-MDSV

“…TCD has been used to detect cerebral microemboli in patients with carotid stenosis, 8,11,12 prosthetic cardiac valves, and atrial fibrillation, 13 and during surgical procedures such as cardiac bypass surgery 14 and carotid endarterectomy. 15 However, to date there has been little information on the prevalence, timing, or source of microembolic signals detected during PTCA.…”

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confidence: 99%

Transcranial Doppler Detection of Microemboli During Percutaneous Transluminal Coronary Angioplasty

Bladin

Bingham

Grigg

et al. 1998

Background and Purpose-The use of percutaneous transluminal coronary angioplasty (PTCA) to treat coronary artery disease is now commonplace. The occurrence of microemboli during invasive procedures such as cardiac angiography and bypass surgery is well documented, although neurological complications are relatively uncommon. To date, no investigation has been undertaken of the frequency or nature of microemboli occurring during PTCA or of the correlation with aortic atheroma. Methods-Twenty patients having elective PTCA underwent examination by transcranial Doppler ultrasonography (TCD) to detect left middle cerebral artery microemboli occurring during the procedure. Blinded off-line analysis correlated microembolic signal counts on TCD with the components of each stage of the PTCA. Patients later underwent transesophageal (TEE) echocardiography, with measurements made of the thickness of the intima and atheroma in the ascending and descending thoracic aortic arch by cardiologists blinded to the TCD results. Results-A total of 973 microembolic signals were detected (meanϮSD, 48.7Ϯ36.7 per patient); 196 (20%) occurred on movement of the PTCA catheter and wire around the aortic arch, 84 (9%) with other PTCA catheter-associated movements, and 679 (70%) in association with injection of solutions (eg, saline and contrast). Mean signal counts during contrast injection were significantly greater than during the other 3 phases (PϽ0.001). No neurological events occurred in the study. Although not statistically significant, there was a trend toward greater microembolic signal counts with the number of times the catheter was passed around the aortic arch and the amount of arch atheroma detected by transesophageal echocardiography. Conclusions-Microemboli detected on TCD are a common occurrence during PTCA but are largely asymptomatic. The majority of microembolic signals are most probably gaseous in origin and do not appear to be related to the extent of aortic atheroma or to clinical events.