Microembolic Signals Research Articles

Incidence of Microembolic Signals on Transcranial Doppler among Patients with Symptomatic Carotid Near Occlusion

Incidence of Microembolic Signals on Transcranial Doppler among Patients with Symptomatic Carotid Near Occlusion

Validation of an algorithm that separates gaseous micro-embolic signals and artifacts during transcranial Doppler persistent foramen ovale examinations

ObjectivePersistent foramen ovale (PFO) is a risk factor for young stroke. Agitated saline serum is used to deliver small gaseous emboli to the brain in transcranial Doppler ultrasound (TCD) for the detection and grading of PFO. In this study we validated a PFO algorithm that can differentiate between gaseous emboli and artifacts. MethodsThe validation cohort comprised 18 patients with positive PFO examinations. The PFO algorithm uses a binary tree that separates high-intensity transients signals (HITs) into gaseous emboli or artifacts based on intensity, zero-crossing, and velocity parameters. ResultsThe cohort exhibited 385 macroscopic gaseous emboli meeting the >3 dB criterion. An additional 137 gaseous emboli were noticed below the 3-dB intensity cutoff value. The low-intensity gaseous emboli included both macroscopic and microscopic air bubbles observed in curtains. Nearly all emboli (98 %) above the 3-dB level showed overt frequency modulation. The overall accuracy of the PFO algorithm in discriminating macroscopic gaseous emboli and artifacts was 96.4 %, with a similar percentage of sensitivity and specificity (96.4 %). The inter-observer agreement of human experts was excellent (ic-CC 0.989 and 0.953). ConclusionsMacroscopic gaseous emboli and artifacts during PFO exams can be accurately discriminated by the PFO algorithm. The PFO algorithm cannot be used as a standalone system as microscopic air bubbles might escape proper identification. This knowledge will be important in the design of future PFO algorithms which should make it possible to classify the PFO grade without the interference of humans.

Microembolizations in the arterial cerebral circulation during atrial fibrillation ablation: cryoballoon technique advantages and neurocognitive safety-results of a prospective observational study.

The significance of micro-embolic signals (MESs) during atrial fibrillation (AF) ablation is unclear. Previous studies had limitations, and cryoballoon (CB) ablation patients were under-represented. Minimizing MESs is recommended due to their uncertain neurocognitive impact. This prospective observational study included AF patients from a German centre between February 2021 and August 2022. Patients were equally divided into paroxysmal (Group A) and persistent (Group B) AF. Group A received cryoballoon-pulmonary vein isolation only, while Group B also had left atrial roof ablation. MESs were detected using transcranial Doppler ultrasonography during ablation. Neurocognitive status was assessed pre- and post-procedure and at 3 months using the CERAD Plus battery. The study analyzed 100 patients with a median age of 65.5 years. A total of 19 698 MESs were observed, with 80% being gaseous and 20% solid in origin, primarily occurring during pulmonary vein angiography and the balloon freeze and thawing phase. The median MES per patient was 130 (IQR: 92-256) in total, 298 (IQR: 177-413) in bilateral (36%), and 110 (IQR: 71-130) in unilateral (64%) recordings. No significant difference in total MES counts was found between the groups. None of the 11 neuropsychological tests showed cognitive decline post-procedure or at 3 months. Our observations confirm that neurocognitive abilities are not affected either 24 h or 3 months after AF ablation using the CB technique. However, despite the low MES burden associated with the CB, more work is needed to reduce small embolic events during AF ablation.

The impact of COVID-19 on left ventricular remodeling and systolic function, cerebral blood flow and microembolic signals burden in patients with stable coronary artery disease

The impact of COVID-19 on left ventricular remodeling and systolic function, cerebral blood flow and microembolic signals burden in patients with stable coronary artery disease

Association of Transcranial Doppler Microembolic Signal With Short-Term Mortality in Acute Ischemic Stroke and Active Cancer.

This study aimed to clarify the characteristics and survival prediction value of transcranial Doppler microembolic signals (MES) in patients with acute cerebral infarction and active cancer. Between 2017 and 2022, 1089 cases of acute cerebral infarction were recorded within 7 days of disease onset. Among them, transcranial Doppler was successful in 33 patients who had active cancer, and these data were analyzed in this study. The primary outcomes were stroke recurrence and mortality at 3 months. The study population had the following characteristics [median (interquartile range)]: age, 70 years (63-78); body mass index, 21.6 (20-24), National Institutes of Health Stroke Scale 3 (1-6), and modified Rankin Scale score at discharge 1 (1-4). The most common cancer types were lung (24%), pancreatic (24%), and intestinal (18%). MES was present in 16 of 33 patients (48.5%). The presence and number of MES were significantly associated with the levels of D-dimer (P <0.001) and C-reactive protein (P=0.012). Moreover, the presence of MES was associated with multiple ischemic lesions and the 3-territory sign on magnetic resonance imaging. Of the 33 patients, 9 died at 3 months, and 1 had stroke recurrence. On Cox multivariate analysis, using the MES-negative group as a reference, the presence of MES was significantly associated with all-cause death (adjusted hazard ratio, 12.19 [95% CI, 1.45-216.85]; P=0.020). In patients with acute ischemic stroke and active cancer, the presence of MES was associated with D-dimer and C-reactive protein levels and multiple and 3-territory ischemic lesions, and was predictive of short-term survival.

The role of citicoline in the correction of cerebral blood flow disorders in patients with coronary artery disease in combination with COVID-19

OBJECTIVE. To evaluate the effect of citicoline on cerebral blood flow and microembolic signals (MES) after 6 months of treatment in patients with coronary artery disease combined with coronavirus disease (COVID-19). MATERIALS AND METHODS. A prospective study of 68 patients with coronary artery disease with confirmed COVID-19 by PCR was conducted. Group I (n=35) included patients with coronary artery disease in combination with COVID-19, who, in addition to standard therapy of cerebrovascular disease, received citicoline (500 mg twice daily) for 6 months after discharge from the hospital. The comparison group (group II; n=33) consisted of patients who did not receive citicoline. Cerebral blood flow, peak systolic velocity in extracranial and intracranial vessels were determined, and 1-hour transcranial monitoring to detect MES were performed. Patients were re-examined in 6 months. RESULTS. At the initial examination of patients, cerebral blood flow and the number of MES did not differ significantly. After 6 months, there was an increase in cerebral blood flow in the cerebral arteries, as well as a decrease in MES in patients taking citicoline, whereas in group II there was no positive dynamics of this ratio. A direct correlation between plasma C-reactive protein, D-dimer and MES was found in patients of both groups. After 6 months of treatment, C-reactive protein and D-dimer decreased in both groups equally. CONCLUSIONS. The obtained results of improvement of cerebral perfusion, blood rheology, due to the anti-inflammatory effect, stabilising function of citicoline on phospholipid membranes of cerebral vascular endothelium, neurons and glial elements allow the use of citicoline in patients with coronary artery disease in combination with COVID-19 to reduce the negative impact of COVID-19 on the central nervous system.

Evaluation of microembolic signals on carotid ultrasound during pulmonary vein isolation with high-power short-duration and cryoballoon ablations: When and where do bubble and solid emboli arise?

The underlying risks of asymptomatic embolization during high-power short-duration (HPSD) ablation for atrial fibrillation remain unclear. We aimed to evaluate microembolic signals (MESs) during HPSD ablation with power settings of 50and 90 W in comparison with those during cryoballoon (CB) ablation using a novel carotid ultrasound-Doppler system that classifies solid and air bubble signals using real-time monitoring. Forty-seven patients underwent HPSD ablation using radiofrequency (RF), and 13 underwent CB ablation. MESs were evaluated using a novel pastable soft ultrasound probe equipped with a carotid ultrasound during pulmonary vein isolation. We compared the detailed MESs and their timing between RF and CB ablations. The number of MESs and solid signals were significantly higher in the RF group than in CB group (209 ± 229 vs. 79 ± 32, p = .047, and 83 ± 89 vs. 28 ± 17, p = .032, respectively). In RF ablation, the number of MESs, solid, and bubble signals per ablation point, or per second, was significantly higher at 90 W than at 50 W ablation. The MESs, solid, and bubble signals were detected more frequently in the bottom and anterior walls of the left pulmonary vein (LPV) ablation. In contrast, many MESs were observed before the first CB application and decreased chronologically as the procedure progressed. Signals were more prevalent during the CB interval rather than during the freezing time. Among the 28 patients, 4 exhibited a high-intensity area on postbrain magnetic resonance imaging (MRI). The MRI-positive group showed a trend of larger signal sizes than did the MRI-negative group. The number of MESs was higher in the HPSD RF group than in the CB group, with this risk being more pronounced in the 90 W ablation group. The primary detection site was the anterior wall of the LPV in RF and the first interval in CB ablation.

Carotid artery elongation (carotid dolichoarteriopathy): some features of the structure and hemodynamics

The purpose of the study. Multimodal study of the state of the brachiocephalic arteries, with assessment of blood flow in the extra- and intracranial portions of the carotid arteries and brain perfusion, as well as the structure of the brain in patients with different types of elongation of the carotid arteries (ECA).Material and methods. The data of examinations of 79 patients (45 men (57.0%, average age – 61.0 ± 10.1 years) and 34 women (43.0%, 65.3 ± 13.6 years), average age 62.8 ± 11.8 years) during the year after ischemic stroke in posterior circulation were analyzed. ECA was verified by multispiral computed tomographic angiography (msCTA) in 44 patients (55.7% of the total number of cases), the control group was selected by gender and age with “case-control” elements and consisted of 35 (44.3%) patients without a mustache. All underwent msCTA of the thoracic aorta and BCA and CT perfusion examination, magnetic resonance imaging of the brain, duplex scanning of BCA and transcranial duplex scanning, transthoracic echocardiography, transcranial Doppler monitoring with microembolodetection.Results. We have registered intergroup differences, which can be divided into structural and functional. The former include: higher aortic arch location in patients with DCA: ThII – 6.3% vs. 0%, ThIII – 43% vs. 0%; ThIV – 28.1% vs. 62.9%* and ThV 21.9% vs. 37.1% (p &lt; 0.0005); lower values of cervical spine height (114.70 ± 11.03 mm, vs. 120.46 ± 9.75 mm, p = 0.022), greater absolute length of the ICA (on the right – 101.32 ± 14.59 mm vs. 85.06 ± 12.07 mm, p &lt; 0.0005; on the left – 100.00 ± 14.03 mm vs. 84.66 ± 12.63 mm, p &lt; 0.0005). The presence of ECA was associated (p &lt; 0.05) with a higher frequency of vertebral artery elongation. The severity of small vessel disease during MRI in individuals with ECA was slightly higher (not at the trend level, p = 0.076). Functional differences consisted in the registration of lower (p = 0.019) values of the end diastolic velocity in M1 of the middle cerebral arteries. The values of some perfusion indices in the blood supply of elongation arteries were lower than in persons without ECA. There were no cases of registration of microembolic signals in the ECA patients examined by us.Conclusion. In the individuals with ECA we examined, a complex of anatomical and hemodynamic features was determined, which, both individually and collectively, cannot lead to a decrease in the level of blood flow or be a source of arterio-arterial embolism in the carotid system, regardless of the configuration of the ICA.

Potential microemboli formation risk and its management during the heated saline–enhanced radiofrequency needle-tip catheter ablation

BackgroundThe potential risk of embolic events during ablation in the left ventricle (LV) with a heated saline–enhanced radiofrequency (SERF) needle-tip ablation catheter has not been characterized. ObjectiveThis study aimed to investigate the formation of microemboli or other untoward events during SERF ablation. MethodsNinety-three radiofrequency (RF) ablation procedures were performed in the LV of 14 pigs by using a SERF catheter (35 W, 70 seconds, and 60°C; normal or degassed saline [NS or DS] irrigation with a flow rate of 10 mL/min) vs a standard irrigated-tip radiofrequency (S-RF) catheter (30 or 50 W, 30 seconds, and 17 mL/min). Microbubble formation was graded on the basis of intracardiac echocardiography. Microbubbles, microembolic signals, and microparticles were monitored using our established model. ResultsThere was no significant difference in microbubble volume among SERF-NS, SERF-DS, and S-RF 30 W with “grade 1” intracardiac echocardiography microbubbles (median and 25th–75th percentiles 0.201 [0.011–3.13], 0.455 [0.06–2.66], and 0.004 μL [0.00–0.16 μL], respectively). There was no significant difference in microembolic signals among SERF-NS, SERF-DS, and S-RF 30 W with grade 1 bubbles (n = 8.0 ± 5.8, n = 7.6 ± 4.2, and n = 6.1 ± 6.1, respectively). Both SERF-NS and SERF-DS created larger lesions than did both S-RF 30 W and S-RF 50 W deliveries (mean 1241.5 ± 658.6, 1497.7 ± 893.4, 75.0 ± 24.8, and 184.0 ± 93.8 mm3; P < .001). There was no significant difference in microparticle incidence among groups (P = .675). No evidence of embolic events was found in the brain and other organs at the histology assessment. ConclusionIn the setting of SERF ablation, significantly large LV lesions can be created without any increment in embolic microbubble or particle events. Grade 1 microbubble is related to the efficacy and safety.

Transcranial Doppler emboli monitoring for stroke prevention after flow diverting stents.

Flow diverting stents (FDS) are increasingly used for the treatment of intracranial aneurysms. While FDS can provide flow diversion of parent vessels, their high metal surface coverage can cause thromboembolism. Transcranial Doppler (TCD) emboli monitoring can be used to identify subclinical embolic phenomena after neurovascular procedures. Limited data exists regarding the use of TCDs for emboli monitoring in the periprocedural period after FDS placement. We evaluated the rate of positive TCDs microembolic signals and stroke after FDS deployment at our institution. We retrospectively evaluated 105 patients who underwent FDS treatment between 2012 and 2016 using the Pipeline stent (Medtronic, Minneapolis, MN, USA). Patients were pretreated with aspirin and clopidogrel. All patients were therapeutic on clopidogrel pre-operatively. TCD emboli monitoring was performed immediately after the procedure. Microembolic signals (mES) were classified as "positive" (<15 mES/hour) and "strongly positive" (>15 mES/hour). Clinical stroke rates were determined at 2-week and 6-month post-operatively. A total of 132 intracranial aneurysms were treated in 105 patients. TCD emboli monitoring was "positive" in 11.4% (n=12) post-operatively and "strongly positive" in 4.8% (n=5). These positive cases were treated with heparin drips or modification of the antiplatelet regimen, and TCDs were repeated. Following medical management modifications, normalization of mES was achieved in 92% of cases. The overall stroke rates at 2-week and 6-months were 3.8% and 4.8%, respectively. TCD emboli monitoring may help early in the identification of thromboembolic events after flow diversion stenting. This allows for modification of medical therapy and, potentially, preventionf of escalation into post-operative strokes.

Edoxaban for the treatment of hypercoagulability and cerebral thromboembolism associated with cancer: A randomized clinical trial of biomarker targets.

This study aimed compare efficacy of edoxaban and enoxaparin upon biomarkers of hypercoagulability in patients with cancer-related embolic stroke of undetermined source (ESUS). In this open-label, randomized, pilot trial, patients with cancer-related ESUS within 30 days of diagnosis were randomly assigned (1:1) to receive edoxaban (60 mg once daily) or enoxaparin (1 mg/kg twice daily) for 90 days. The primary endpoint was interval change of serum D-dimer level between days 0 and 7. The secondary endpoints were microembolic signals detected by transcranial Doppler at 7 and 90 days, the modified Rankin scale score, and stroke recurrence during 90 days. Safety outcomes included major bleeding and all-cause death at 90 days. Of 303 patients with ischemic stroke and cancer, 40 fully met enrollment criteria and were randomized. Baseline D-dimer levels were numerically higher in the edoxaban group (22.9 ± 15.9 μg/mL vs 16.9 ± 16.9 μg/mL). D-dimer level change (%) between days 0 and 7 was similar in the two groups (53.2 ± 25.7 vs 52.2 ± 52.0; P = 0.11). Microembolic signals were detected in 41.1% and 43.8% at baseline, 41.2% and 42.9% at day 7, and 25.0% and 28.6% at day 90 in the edoxaban and enoxaparin groups, respectively. Non-significantly higher major bleeding (35.0% vs 10.0%, P = 0.06) and 90-day mortality (40.0% vs 25.0%, P = 0.31) were noted in the edoxaban group. Edoxaban and enoxaparin were comparable with respect to the biomarkers of hypercoagulability and cerebral thromboembolism. Larger trials are warranted to compare effects of edoxaban and enoxaparin upon recurrent stroke and major bleeding in patients with cancer-related ESUS. clinicaltrials.gov Identifier: NCT03570281 (https://clinicaltrials.gov/ct2/show/NCT03570281).

Cerebrovascular disease in patients with antiphospholipid antibody syndrome: a transcranial Doppler and magnetic resonance imaging study.

Transcranial Doppler (TCD) and brain MRI may be useful in evaluating patients with APS, helping to stratify the risk of cerebrovascular ischaemic events in this population. This study aimed to assess the frequency of brain MRI abnormalities in patients with primary antiphospholipid syndrome, secondary antiphospholipid syndrome and SLE and correlate to TCD findings. The study, conducted over four years at two autoimmune disease referral centres, included 22 primary antiphospholipid syndrome patients, 24 secondary antiphospholipid syndrome patients, 27 SLE patients without APS and 21 healthy controls. All participants underwent TCD to assess cerebral haemodynamics, detect microembolic signals and evaluate right-to-left shunts, followed by brain MRI and magnetic resonance angiography. MRI scans were reviewed for acute microembolism, localized cortical infarctions, border infarctions, lacunar infarctions, ischaemic lesions, white matter hyperintensity, micro and macro haemorrhages and arterial stenosis ≥50% of the cervical carotid artery, by two neuroradiologists blinded to the clinical data. Brain MRI findings were similar between the groups, except for lacunar infarction, more frequent in patients with secondary antiphospholipid syndrome (P = 0.022). Patients with intracranial stenosis detected by TCD had a higher frequency of territorial infarction (40% vs 7.5%, P = 0.02), lacunar (40% vs 11.3%, P = 0.075) and border zone infarcts (20% vs 1.9%, P = 0.034). Patients with intracranial stenosis presented a higher frequency of territorial, lacunar and border zone infarcts, suggesting that evaluating the intracranial vasculature should not be neglected in patients with APS and stroke.

Diagnosis of fat embolism syndrome using point‐of‐care ultrasound

AbstractFat embolism (FES) is a condition that can lead to severe organ effects and death in patients with long bone fractures. Diagnosis is challenging due to multiple criteria. This case report presents the use of point‐of‐care ultrasound (POCUS) in diagnosing right ventricular dysfunction associated with fat embolism syndrome. A 36‐year‐old patient with a history of obesity presented with multiple fractures and respiratory failure after a road accident. Bedside echocardiography showed evidence of dilated right chambers, right ventricular outflow tract shortened acceleration time, and mild tricuspid insufficiency. Venous ultrasonography showed microembolic signals (MES) interpreted as fat embolism. The patient was treated with fracture reduction and osteosynthesis, which showed improvement in right ventricular dysfunction and the disappearance of MES. FES is a clinical syndrome that occurs after an identifiable bone injury. This case highlights the utility of POCUS in the diagnosis of FES.

Detection of microemboli in patients with acute ischaemic stroke and atrial fibrillation suggests poor functional outcome.

We investigated the burden of microembolic signals (MES) in patients with acute ischaemic stroke (AIS) and atrial fibrillation (AF), assessing their impact on functional outcomes. This multicentre international prospective cohort study involved patients with AIS and either a known or newly diagnosed anticoagulant-naïve AF. All centres utilised the same transcranial Doppler machine for 1-h monitoring with bilateral 2 MHz probes within 24 h of symptom onset. Recordings underwent MES analysis by a blinded central reader. The primary objectives were to ascertain the MES proportion and its association with functional outcomes assessed by the modified Rankin scale (mRS) score at 90 days. Between September 2019 and May 2021, we enrolled 61 patients, with a median age of 78 years (interquartile range 73-83) and a median stroke severity score of 11 (interquartile range 4-18). MES were observed in 14 patients (23%), predominantly unilateral (12/14, 86%), with a median rate of 6 counts/hour (interquartile range 4-18). MES occurrence was higher post-thrombectomy and among those with elevated brain natriuretic peptide levels (p < 0.05). A worse mRS score of 3-6 was more frequent in patients with MES, occurring in 11/14 (79%), compared to those without MES, 20/47 (43%), with an adjusted odds ratio of 5.04 (95% CI, 1.15-39.4), p = 0.04. Nearly a quarter of patients with AIS and AF exhibited silent microembolization after the index event. Detecting MES within 24 h post-stroke (using transcranial Doppler) could signify a marker of poor functional outcomes. Subsequent trials will assess if very early antithrombotic treatment might enhance outcomes in this highly selective group of cardioembolic stroke patients. (Clinicaltrials.gov ID: NCT06018090).

Diagnostic Accuracy of an Algorithm for Discriminating Presumed Solid and Gaseous Microembolic Signals During Transcranial Doppler Examinations.

The aim of the work described here was to assess the diagnostic accuracy of a new algorithm (SGA-a) for time-domain analysis of transcranial Doppler audio signals to discriminate presumed solid and gaseous microembolic signals and artifacts (SGAs). SGA-a was validated by human experts in an artifact cohort of 20 patients subjected to a 1-h transcranial Doppler exam before cardiac surgery (cohort 1). Emboli were validated in a cohort of 10 patients after aortic valve replacement in a 4-h monitoring period (cohort 2). The SGA misclassification rate was estimated by testing SGA-a on artifact-free test files of solid and gaseous emboli. In cohort 1 (n=24,429), artifacts were classified with an accuracy of 94.5%. In cohort 2 (n=12,328), the accuracy in discriminating solid/gaseous emboli from artifacts was 85.6%. The 95% limits of agreement for, respectively, the numbers of presumed solids and gaseous emboli, artifacts and microembolic signals of undetermined origin were [-10, 10], [-14, 7] and [-9, 16], and the intra-class correction coefficients were 0.99, 0.99 and 0.99, respectively. The rate of misclassification of solid test files was 2%, and the rate of misclassification of gaseous test files was 12%. SGA-a can detect presumed solid and gaseous microembolic signals and differentiate them from artifacts. SGA-a could be of value when both solid and gaseous emboli may jeopardize brain function such as seen during cardiac valve and/or aortic arch replacement procedures.

Abstract 17178: Rates of Micro Embolic Signals at Different Stages of Carotid Artery Revascularization

Background: The American Heart Association currently estimates that over 160,000 people die every year due to new or recurrent strokes, many from carotid artery stenosis. This association has led to increased use of carotid revascularization procedures such as carotid endarterectomy (CEA) and carotid artery stenting (CAS). In this study we aim to describe the different rates of micro embolic signals (MES) at different stages of carotid artery revascularization. Methods: Before elective carotid revascularization 57 patients (mean age 72±8 years; 15 males, 21 females) underwent 3-T MRI. After localization of the carotid bifurcation using phase contrast imaging, Time-of-Flight, 3D T1 weighting, transverse T1 and T2 weightings and proton density sequences were acquired. The different plaque components: lipid core, intraplaque hemorrhage, calcification and the characterization of the fibrous cap were assessed. While 34 patients underwent CEA, 20 patients had CAS. CES was divided into 9 stages: 1- Pre-procedure, 2- Dissection, 3- IC clamp, 4- Shunt placement, 5- Shunt open, 6- Endarterectomy, 7- Clamped, 8- IC opened, 9- Post-procedure. Similarly, CAS was divided into 9 stages: 1- Pre-procedure, 2- Arch-carotid angiography, 3- Wire insertion, 4- Filter deployment, 5- Pre-dilation, 6- Stent deployment, 7- Post-dilation, 8- Final angiography, 9- Post-procedure. Patients were monitored continuously with transcranial doppler (TCD) to detect pre-procedural, intra-procedural and post-procedural MES rates. Results: MES was detected in 20 (87%) patients undergoing CAS compared to 18 (53%) patients undergoing CES during the IC Clamp/Wire Insertion stage (p=0.004). Greater mean micro embolic signals were also found in symptomatic patients undergoing CAS than in asymptomatic patients during arch-carotid angiography (10.8 vs 2.4, p= 0.022), post-dilation (3.1 vs 1.1, p=0.047), and post-procedure (4.8 vs 1.3, p=0.044). Conclusion: MES is increased during the wire insertion stage of CAS in addition to post-dilation and post-procedure stages. Also, the finding of increased MES during arch-carotid angiography suggests that less invasive alternatives to diagnostic angiography should be considered in symptomatic patients.

Abstract 17231: Importance of Intra Plaque Hemorrhage During Carotid Artery Revascularization

Introduction: The American Heart Association currently estimates that every 3 minutes a person dies from a stroke. Carotid artery stenosis, a major risk factor for new and recurrent strokes, can be treated with carotid artery revascularization. Vascular emboli released during this procedure are non-invasively detected by transcranial doppler (TCD) ultrasound as micro embolic signals (MES). In this study we aim to show the relationship between carotid plaque characteristics and MES rates that were detected by TCD-monitoring throughout the stages of the carotid artery revascularization procedures. Methods: Before elective carotid revascularization 30 patients (mean age 72±8 years; 16 males, 14 females) underwent 3-T MRI. After localization of the carotid bifurcation using phase contrast imaging, Time-of-Flight, 3D T1 weighting, transverse T1 and T2 weightings and proton density sequences were acquired. The different plaque components: lipid core, intraplaque hemorrhage, calcification and the characterization of the fibrous cap were assessed. While 20 patients underwent carotid endarterectomy (CEA), 10 patients had carotid artery stenting (CAS). CES was divided into 9 stages: 1- Pre-procedure, 2- Dissection, 3- IC clamp, 4- Shunt placement, 5- Shunt open, 6- Endarterectomy, 7- Clamped, 8- IC opened, 9- Post-procedure. Similarly, CAS was divided into 9 stages: 1- Pre-procedure, 2- Arch-carotid angiography, 3- Wire insertion, 4- Filter deployment, 5- Pre-dilation, 6- Stent deployment, 7- Post-dilation, 8- Final angiography, 9- Post-procedure. Patients were monitored continuously with TCD to detect pre-procedural, intra-procedural and post-procedural MES rates. Results: Intraplaque hemorrhage was observed in 18 patients (60%). Patients with intra plaque hemorrhage had more MES during carotid artery dissection/arch-carotid angiography (p=0.028) and IC clamping/wire insertion (p=0.009) compared to patients without intra plaque hemorrhage in the pre-procedural stage. Conclusions: Carotid plaques with intra plaque hemorrhage is associated with higher MES during carotid artery revascularization procedures.

Analysis of Variables Associated with Positive Micro-Embolic Signals Detected by Transcranial Doppler in Patients with Atrial Fibrillation and Their Predictive Value for Embolic Risk.

This study examined the factors associated with positive micro-embolic signals (MES) on transcranial Doppler monitoring in patients with atrial fibrillation (AF), as well as the predictive value of MES for the risk of embolism in AF. Sixty-six patients who had micro emboli with AF were included in the positive group, and 75 patients who did not have micro emboli with AF served as the control group. The clinical data, congestive heart failure, hypertension, age ≥ 75 (doubled), diabetes mellitus, prior stroke or transient ischemic attack (doubled), vascular disease, age 65-74, female (CHA2DS2-VASc) score, D-dimer (D-d) level, echocardiography results, and brain magnetic resonance imaging (MRI) findings were compared between the two groups. Logistic regression models were used to analyze the relationship between positive micro emboli with CHA2DS2-VASc score, D-d, left atrial anteroposterior diameter (LAD), and silent cerebral ischemia (SCI) occurrence. The CHA2DS2-VASc score, D-d level, and LAD were significantly higher in the positive group than in the control group (P < 0.05) and were accompanied by a higher detection rate of SCI by brain MRI (P < 0.01). Elevated D-d levels, increased LAD, and the detection rate of SCI were all highly positively correlated with positive micro emboli. Also, CHA2DS2-VASc score ≥ 2 showed a significant positive correlation with positive micro emboli, and the higher CHA2DS2-VASc score was associated with a stronger correlation. The multivariate regression analysis demonstrated that positive micro-embolic was independently associated with SCI and a CHA2DS2-VASc score of ≥ 4. Positive micro emboli in patients with persistent AF are consistent with an increased risk of embolism, and are independently associated with a higher CHA2DS2-VASc score and SCI, which can be used as an indicator of individual embolic risk inpatients with AF.

The Relationship of Carotid Artery Plaque and Stenosis with Microemboli

Objective: Microembolic signals (MES) are markers that can be detected by Transcranial Doppler Ultrasonography (TCD) and are risk factors for stroke. The aim of our study is to explore the relationship between the number of MES and the extent of carotid stenosis as well as plaque morphology. Our goal is to provide a fresh perspective on the treatment of carotid stenosis. Materials and Methods: A total of 95 patients, who were admitted to the emergency department of Sultan 2.Abdülhamid Han Training and Research Hospital and were hospitalized with a diagnosis of stroke, were enrolled in the study. Patients with high-risk cardiac diseases were excluded from the study. Detailed medical histories, risk factors, and current medical treatments of the patients were documented, and microemboli detection was conducted using Transcranial Doppler (TCD). The number of microemboli in TCD was obtained by averaging the results of 2 consecutive half-hour follow-ups in a region. Carotid stenosis rates of the patients were determined by computed tomography angiography (CTA) according to the North American Symptomatic Endarterectomy Trial (NASCET) classification, and the plaque morphology was determined according to the Gray-Weale scale of carotid ultrasonography. Patients were categorized into symptomatic and asymptomatic carotid stenosis groups, and the number of microembolic signals (MES) was compared between these groups. Result: MES numbers of 95 patients with symptomatic carotid stenosis; while MES was not detected in 47.4% (n=45); 35.8% (n=34) had 1-2 MES, 8.4% (n=8) had 3-4 MES and 8.4% (n=8) 5 or more MES were detected. The relationship between the MES obtained and carotid stenosis was statistically significant (p&lt;0.001). According to the type of plaque; while there is no MES in 68.2% (n=15) of Type-4 symptomatic stenosis, this rate is only 15% (n=3) in Type-1 stenosis. In addition, 20% (n=4) of Type-1 symptomatic stenosis had MES between 3-4 and 30% (n=6) of 5 or more MES. According to these results, the relationship between plaque type and the presence of MES is statistically significant. (p&lt;0.001) Similar results were obtained in asymptomatic carotid stenosis. Conclusion: TCD is an easy-to-apply, non-invasive imaging technique, and MES detectable by TCD are risk factors for stroke. The relationship between MES and carotid stenosis rate and plaque type heterogeneity is statistically significant.

Approaches to classification of microembolic signals in patients recovering from ischemic stroke

Introduction. Microembolus detection by transcranial Doppler (TCD) is the only non-invasive modality for visualization of cerebral embolism. Currently, there is no unified classification of recorded microembolic signals (MES) that could be used in clinical practice.&#x0D; The aim of the study is to investigate biophysical MES parameters in patients with ischemic stroke, as well as to assess approaches to microemboli differentiation by structure and origin to improve the diagnostic accuracy of the method and to reduce the risk of recurrent ischemic events.&#x0D; Materials and methods. The inclusion criterion was TCD-detected signs of MES. We analyzed the data of 28 patients with ischemic stroke (9 women and 19 men; mean age was 58 years 13). We recorded power, duration, and frequency for each MES, and calculated an energy index.&#x0D; Results. A total of 938 MES were reported. In patients with cardioembolic stroke and all other pathogenetic stroke subtypes, biophysical parameter limits were as follows: 14.65 dB for the average power, 9.45 ms for the average duration, and 0.16 J for the average energy index. For patients with atrial fibrillation, characteristic MES power was found to be 13 dB. The MES frequency limit was determined to be 650 Hz for microemboli differentiation by acoustic density.&#x0D; Conclusion. The data obtained can be used to further search for optimal limit ranges for biophysical parameters of various MES in order to establish a single MES classification, which will increase the diagnostic value of microembolus detection by TCD in stroke treatment practice.