Microembolic Signals Research Articles

A narrative review of plaque and brain imaging biomarkers for stroke risk stratification in patients with atherosclerotic carotid artery disease.

ObjectiveIn this narrative review, we aim to review imaging biomarkers that carry the potential to non-invasively guide stroke risk stratification for treatment optimization.BackgroundCarotid atherosclerosis plays a fundamental part in the occurrence of ischemic stroke. International guidelines select the optimal treatment strategy still mainly based on the presence of clinical symptoms and the degree of stenosis for stroke prevention in patients with atherosclerotic carotid plaques. These guidelines, based on randomized controlled trials that were conducted three decades ago, recommend carotid revascularization in symptomatic patients with high degree of stenosis versus a conservative approach for most asymptomatic patients. Due to optimization of best medical therapy and risk factor control, it is suggested that a subgroup of symptomatic patients is at lower risk of stroke and may not benefit from revascularization, whereas a selective subgroup of high-risk asymptomatic patients would benefit from this procedure.MethodsA literature search was performed for articles published up to December 2020 using PubMed, EMBASE and Scopus. Based on the literature found, change in stenosis degree and volume, plaque echolucency, plaque surface, intraplaque haemorrhage, lipid-rich necrotic core, thin fibrous cap, inflammation, neovascularization, microembolic signals, cerebrovascular reserve, intracranial collaterals, silent brain infarcts, diffusion weighted imaging lesions and white matters lesions have the potential to predict stroke risk.ConclusionsThe applicability of imaging biomarkers needs to be further improved before the potential synergistic prognostic ability of imaging biomarkers can be verified on top of the clinical biomarkers. In the future, the routine and combined assessment of both plaque and brain imaging biomarkers might help to improve optimization of treatment strategies in individual patients with atherosclerotic carotid artery disease.

Plaque Length Predicts the Incidence of Microembolic Signals in Acute Anterior Circulation Stroke.

Microembolic signals (MES) of the carotid artery are associated with plaque destabilization and reoccurrence of stroke. Previous studies have focused primarily on the degree of carotid artery stenosis and plaque components, and the relationship between plaque length and microembolic sign has received little attention. We aimed to find the association between carotid plaque length (CPL) and the presence of MES. We conducted a retrospective observational cross-sectional study. A total of 84 acute anterior-circulation ischemic stroke/transient ischemic attack (TIA) patients with carotid artery atherosclerosis were classified into an MES-positive (MES+) group and MES-negative (MES−) group. We measured multiple parameters of carotid plaque size (length, thickness) in each patient and evaluated the relationship between different plaque parameters and occurrence of MES. We found that male, carotid artery stenosis (CAS), CPL, carotid plaque thickness (CPT), and intima-media thickness (IMT) of the carotid artery were each significantly different between two groups (all P < 0.05). The multivariate analysis showed CPL (odds ratio (OR), 1.109; 95% CI, 1.044–1.177; P = 0.001) to be independently associated with the presence of MES. The areas under the ROC curves (AUCs) for CPL for predicting MES were 0.777 (95% CI, 0.640–0.914; P < 0.001). The cutoff value of CPL for predicting MES was 16.7 mm, with a sensitivity of 88.2% and a specificity of 77.6%. We found that CPL was a meaningful independent predictor of MES. Therefore, CPL may be useful for risk stratification of long and nonstenotic plaques in anterior circulation stroke.

Comparison of clinical and biological differences between patent foramen ovale subtypes in ischemic stroke.

The patent foramen ovale (PFO) is an atrial septal tunnel with a flap-like opening, causing a right-to-left shunt (RLS) between the atrial chambers. There are few studies on ischemic stroke characteristics based on PFO subtypes. In this study, we investigated whether there are differences in clinical characteristics, RLS amount, and the etiology of stroke defined by the Trial of ORG 10,172 in Acute Stroke Treatment (TOAST) classification between PFO subtypes. We retrospectively analyzed consecutive ischemic stroke patients with PFO who were admitted to the Jeonbuk National University Hospital from November 2013 to February 2015, and performed a microbubble test to detect RLS. The patients were divided into two groups according to RLS characteristics: constant RLS group and provoked RLS group. We compared the clinical characteristics and degree of RLS between the PFO subtypes. Out of 144 ischemic patients evaluated in this study, 83 (58%) were classified into the constant RLS group and 61 (42%) into the provoked RLS group. The proportion of microembolic signal (MES) grades 3 and 4 was significantly higher in the constant RLS group than in the provoked RLS group. There were no statistical differences in the distribution of TOAST classification between the two groups. The constant RLS group showed a higher proportion of high-grade MES than the provoked RLS group.

Simple periprocedural precautions to reduce Doppler microembolic signals during AF ablation

BackgroundDoppler microembolic signals (MES) occur during atrial fibrillation ablation despite of permanent flushed transseptal sheaths, frequent controls of periprocedural coagulation status and the use of irrigated ablation cathetersPurposeTo investigate the number and type of MES depending on the procedure time, prespecified procedure steps, the activated clotting time (ACT) during the ablation procedure and the catheter contact force.MethodsIn a prospective trial, 53 consecutive atrial fibrillation patients underwent pulmonary vein isolation by super-irrigated “point-by-point” ablation. All patients underwent a periinterventional, continuous transcranial Doppler examination (TCD) of the bilateral middle cerebral arteries during the complete ablation procedure.ResultsAn average of 686±226 microembolic signals were detected by permanent transcranial Doppler. Thereby, 569±208 signals were differentiated as gaseous and 117±31 as solid MES. The number of MES with regard to defined procedure steps were as follows: gaseous: [transseptal puncture, 26 ± 28; sheath flushing, 24±12; catheter change, 21±11; angiography, 101±28; mapping, 9±9; ablation, 439±192; protamine administration, 0±0]; solid: [transseptal puncture, 8±8; sheath flushing, 9±5; catheter replacement, 6±6; angiography, not measurable; mapping, 2±5; ablation, 41±22; protamine administration, 0±0]. Significantly less MES occurred with shorter procedure time, higher ACT and the use of tissue contact force monitoring.ConclusionThe current study demonstrates that during atrial fibrillation ablation using irrigated, “point-by-point” RF ablation, masses of microembolic signals are detected in transcranial ultrasound especially in the period of RF current application. The number of MES depends on the total procedure time and the reached ACT during ablation. The use of contact force monitoring might reduce MES during RF ablation.

Superb Microvascular Imaging Ultrasound for Cervical Carotid Artery Stenosis for Prediction of the Development of Microembolic Signals on Transcranial Doppler during Carotid Exposure in Endarterectomy

Introduction: During exposure of the carotid arteries, embolism from the surgical site is recognized as a primary cause of neurological deficits or new cerebral ischemic lesions following carotid endarterectomy (CEA), and associations have been reported between histological neovascularization in the carotid plaque and both plaque vulnerability and the development of artery-to-artery embolism. Superb microvascular imaging (SMI) enables accurate visualization of neovessels in the carotid plaque without the use of intravenous contrast. This study aimed to determine whether preoperative SMI ultrasound for cervical carotid artery stenosis predicts the development of microembolic signals (MES) on transcranial Doppler (TCD) during exposure of the carotid arteries in CEA. Methods: Preoperative cervical carotid artery SMI ultrasound followed by CEA under TCD monitoring of MES in the ipsilateral middle cerebral artery was conducted in 70 patients previously diagnosed with internal carotid artery stenosis (defined as ≥70%). First, observers visually identified intraplaque microvascular flow (IMVF) signals as moving enhancements located near the surface of the carotid plaque within the plaque on SMI ultrasonograms. Next, regions of interest (ROI) were manually placed at the identified IMVF signals (or at arbitrary places within the plaque when no IMVF signals were identified within the carotid plaque) and the carotid lumen, and time-intensity curves of the IMVF signal and lumen ROI were generated. Ten heartbeat cycles of both time-intensity curves were segmented into each heartbeat cycle based on gated electrocardiogram findings and averaged with respect to the IMVF signal and lumen ROI. The difference between the maximum and minimum intensities (ID) was calculated based on the averaged IMVF signal (ID_IMVF) and lumen (ID_l) curves. Finally, the ratio of ID_IMVF to ID_l was calculated. Results: MES during exposure of the carotid arteries were detected in 17 patients (24%). The incidence of identification of IMVF signals was significantly greater in patients with MES (94%) than in those without (57%; p = 0.0067). The ID_IMVF/ID_l ratio was significantly greater in patients with MES (0.108 ± 0.120) than in those without (0.017 ± 0.042; p < 0.0001). The specificity and positive predictive value for the ID_IMVF/ID_l ratio for prediction of the development of MES were significantly higher than those for the identification of IMVF signals. Logistic regression analysis revealed that only the ID_IMVF/ID_l ratio was significantly associated with the development of MES (95% CI 101.1–3,628.9; p = 0.0048). Conclusion: Preoperative cervical carotid artery SMI ultrasound predicts the development of MES on TCD during exposure of the carotid arteries in CEA.

Cerebral microemboli in mini-sternotomy compared to mini- thoracotomy for aortic valve replacement: a cross sectional cohort study

BackgroundRecently adopted mini-thoracotomy approach for surgical aortic valve replacement has shown benefits such as reduced pain and shorter recovery, compared to more conventional mini-sternotomy access. However, whether limited exposure of the heart and ascending aorta resulting from an incision in the second intercostal space may lead to increased intraoperative cerebral embolization and more prominent postoperative neurologic decline, remains inconclusive. The aim of our study was to assess potential neurological complications after two different minimal invasive surgical techniques for aortic valve replacement by measuring cerebral microembolic signal during surgery and by follow-up cognitive evaluation.MethodsTrans-cranial Doppler was used for microembolic signal detection during aortic valve replacement performed via mini-sternotomy and mini-thoracotomy. Patients were evaluated using Addenbrooke’s Cognitive Examination Revised Test before and 30 days after surgical procedure.ResultsA total of 60 patients were recruited in the study. In 52 patients, transcranial Doppler was feasible. Of those, 25 underwent mini-sternotomy and 27 had mini-thoracotomy. There were no differences between groups with respect to sex, NYHA class distribution, Euroscore II or aortic valve area. Patients in mini-sternotomy group were younger (60.8 ± 14.4 vs.72 ± 5.84, p = 0.003), heavier (85.2 ± 12.4 vs.72.5 ± 12.9, p = 0.002) and had higher body surface area (1.98 ± 0.167 vs. 1.83 ± 0.178, p = 0.006). Surgery duration was longer in mini-sternotomy group compared to mini-thoracotomy (158 ± 24 vs. 134 ± 30 min, p < 0.001, respectively). There were no differences between groups in microembolic load, length of ICU or total hospital stay. Total microembolic signals count was correlated with cardiopulmonary bypass duration (5.64, 95%CI 0.677–10.60, p = 0.027). Addenbrooke’s Cognitive Examination Revised Test score decreased equivalently in both groups (p = 0.630) (MS: 85.2 ± 9.6 vs. 82.9 ± 11.4, p = 0.012; MT: 85.2 ± 9.6 vs. 81.3 ± 8.8, p = 0.001).ConclusionThere is no difference in microembolic load between the groups. Total intraoperative microembolic signals count was associated with cardiopulmonary bypass duration. Age, but not micorembolic signals load, was associated with postoperative neurologic decline.Trial registry numberclinicaltrials.gov, NCT02697786 14.

June 2021 Stroke Highlights

June 2021 <i>Stroke</i> Highlights

The Prevalence of Microembolic Signals in Transcranial Doppler Sonography With Bubble Test in Acute Ischemic Stroke.

Transcranial Doppler ultrasound (TCD) is noninvasive and highly sensitive and specific for the diagnosis of patent foramen ovale (PFO). We evaluated the diagnostic implications of the TCD with a saline agitation test as a routine work-up for ischemic stroke patients. A TCD bubble study was performed in all consecutive ischemic stroke patients as a routine work-up. We evaluated the prevalence of microembolic signals (MES) for each stroke etiology and the optimal number of MES for predicting the PFO-attributable stroke. Subjects (N=499) with acute ischemic stroke were enrolled. A significant fraction of patients had MES during both normal respiration (5.7-44.4%) and the Valsalva maneuver (19.5-55.6%) across all stroke etiology categories. The optimal MES threshold for the diagnosis of PFO-attributable stroke confirmed by transesophageal echocardiography was 46 MES during the Valsalva maneuver (96% sensitivity and 95% specificity). Applying ≥46 MES during the Valsalva maneuver as a threshold effectively increased the ability to differentially diagnose PFO-attributable stroke from other etiologies. The number of MES during the Valsalva maneuver was negatively correlated with increasing age (r=-.108; P=.016). A significant fraction of patients had right to left shunt across all Trial of ORG 10172 in Acute Stroke Treatment etiologies. A threshold number of MES facilitated the differential diagnosis of PFO-attributable stroke from other etiologies, and the optimal threshold was 46 MES during the Valsalva maneuver.

Transcranial Doppler in Acute COVID-19 Infection: Unexpected Associations.

Stroke may complicate coronavirus disease 2019 (COVID-19) infection based on clinical hypercoagulability. We investigated whether transcranial Doppler ultrasound has utility for identifying microemboli and clinically relevant cerebral blood flow velocities (CBFVs) in COVID-19. We performed transcranial Doppler for a consecutive series of patients with confirmed or suspected COVID-19 infection admitted to 2 intensive care units at a large academic center including evaluation for microembolic signals. Variables specific to hypercoagulability and blood flow including transthoracic echocardiography were analyzed as a part of routine care. Twenty-six patients were included in this analysis, 16 with confirmed COVID-19 infection. Of those, 2 had acute ischemic stroke secondary to large vessel occlusion. Ten non-COVID stroke patients were included for comparison. Two COVID-negative patients had severe acute respiratory distress syndrome and stroke due to large vessel occlusion. In patients with COVID-19, relatively low CBFVs were observed diffusely at median hospital day 4 (interquartile range, 3-9) despite low hematocrit (29.5% [25.7%-31.6%]); CBFVs in comparable COVID-negative stroke patients were significantly higher compared with COVID-positive stroke patients. Microembolic signals were not detected in any patient. Median left ventricular ejection fraction was 60% (interquartile range, 60%-65%). CBFVs were correlated with arterial oxygen content, and C-reactive protein (Spearman ρ=0.28 [P=0.04]; 0.58 [P<0.001], respectively) but not with left ventricular ejection fraction (ρ=-0.18; P=0.42). In this cohort of critically ill patients with COVID-19 infection, we observed lower than expected CBFVs in setting of low arterial oxygen content and low hematocrit but not associated with suppression of cardiac output.

Microembolic signal detection in patients with atrial fibrillation treated with oral anticoagulant

BACKGROUND: Atrial fibrillation (AF) is a well-known risk factor for embolic stroke. The incidence of stroke in patients with AF is 4.5% per year. In 93% of cases, strokes in patients with AF are of embolic origin. Trans Cranial Doppler (TCD) monitoring of silent micro-embolic signals (MES) can represent an effective preclinical tool for verifying the efficacy of embolic events in patients treated with antithrombotic prophylaxis (antiplatelet agents, Vitamin K inhibitors, and new oral anticoagulants direct thrombin inhibitors). METHODS: We enrolled 16 patients, of both sexes equally distributed (M = 8 plus F = 8) with a known diagnosis of AF with Ejection Fraction greater of 40%, all in anticoagulant treatment by direct oral anticoagulants (DOACs) and we assessed, through the use of a portable TCD-X, the MES signals during physical activity of 1 h. The aim was of evaluating whether the physical activity of a subject affected by AF worsens the incidence of MES in these subjects. Result: 25% of patients presented a MES at the time of registration. Two female of 38 and 75 year-old. and two male of 70 and 71 year-old. The 75-year-old woman reported an episode of instability while walking; therefore it was increased her anticoagulant treatment. Men did not perceive the MES. CONCLUSION: Both sexes reported the presence of MES equally with a prevalence of 25%. By correlating these results with those of the literature, it is deduced that physical activity is, therefore, not a risk factor for these patients being treated with DOACs. The TDC-X registration implemented is relatively short compared to the current potential of the device which is over 6 h; therefore, it is desirable that further studies be performed in future on statistically adequate sample cohorts and simultaneous bilateral recordings of MES.

Abstract P596: How Common Are Microembolic Signals After Cerebrovascular Events and Are They Related to Recurrent Admissions?

Introduction: Microembolic signals (MES) identified by transcranial Doppler (TCD) reflect an ongoing embolic phenomenon with implications for the recurrence of cerebrovascular events and complications. In this study, we investigated the prevalence of MES detected after stroke or transient ischemic attack (TIA) and studied their relationship with future re-admissions. Method: This clinical cohort study is comprised of 961 consecutive patients (mean age 65 years, 59% male) admitted to Northwestern Memorial Hospital with the diagnosis of acute stroke (n: 872) or TIA (n: 89) and underwent TCD evaluation. TCD is performed within the first 48 hours of admission as a routine component of stroke etiology evaluation at our institution. After discharge, patients were followed for an average of 18 months for any hospital readmissions. Cox regression models were used to estimate risk of re-admissions in relation to MES. Results: MES were detected in 99 (10%, 95% CI; 8-12%) patients. During the follow up period, 356 patients had emergency room re-admissions. Compared to patients without MES, those with MES were younger ( p =0.007) and had longer index hospital stay ( p =0.008). Patients with MES, as compared to patients without MES, had 1.56-fold (hazard ratio 95% CI=1.15, 2.13; p =0.005) higher risk of readmission. This association was independent of age, sex, race, smoking, history of hyperlipidemia, diabetes, atrial fibrillation, history of pulmonary emboli, deep vein thrombosis, hypertension, coronary artery disease and heart failure. Conclusion: We show that MES are present in one tenth of patients admitted with stroke or TIA, and they are associated with higher risk of re-admission. These data highlight the importance of embolic signals in stroke complication risk stratification and suggest the need for prospective clinical trials targeting MES in secondary stroke risk and complication prevention.

How Are We Monitoring Brain Injuries in Patients With Left Ventricular Assist Device? A Systematic Review of Literature.

Despite the common occurrence of brain injury in patients with left ventricular assist device (LVAD), optimal neuromonitoring methods are unknown. A systematic review of PubMed and six electronic databases from inception was conducted until June 5, 2019. Studies reporting methods of neuromonitoring while on LVAD were extracted. Of 5,190 records screened, 37 studies met the inclusion criteria. The neuromonitoring methods include Transcranial Doppler ultrasound for emboli monitoring (TCD-e) (n = 13) and cerebral autoregulation (n = 3), computed tomography and magnetic resonance imaging (n = 9), serum biomarkers (n = 7), carotid ultrasound (n = 3), and near-infrared spectroscopy (n = 2). Of 421 patients with TCD-e, thromboembolic events (TEs) were reported in 79 patients (20%) and microembolic signals (MES) were detected in 105 patients (27%). Ischemic stroke was more prevalent in patients with MES compared to patients without MES (43% vs.13%, p < 0.001). Carotid ultrasound for assessing carotid stenosis was unreliable after LVAD implantation. Elevated lactate dehydrogenase (LDH) levels were associated with TEs. Significant heterogeneity exists in timing, frequency, and types of neuromonitoring tools. TCD-e and serial LDH levels appeared to have potential for assessing the risk of ischemic stroke. Future prospective research incorporating protocolized TCD-e and LDH may assist in monitoring adverse events in patients with LVAD.

Query to the Case Report “Microembolic signal detection by transcranial color flow imaging is useful for understanding the morbid state of cancer-related stroke”

Query to the Case Report “Microembolic signal detection by transcranial color flow imaging is useful for understanding the morbid state of cancer-related stroke”

Interdialytic weight gain of less than 2.5% seems to limit cardiac damage during hemodialysis.

Aims:To investigate if a single low-flux HD induces a rise in cardiac biomarkers and if a change in clinical approach may limit such mechanism.Material and methods:A total of 20 chronic HD patients each underwent three different study-dialyses. Dialyzers (low-flux polysulfone, 1.8 sqm) had been stored either dry or wet (Wet) and the blood level in the venous chamber kept low or high. Laboratory results were measured at baseline, 30 and 180 min, adjusted for the effect of fluid shift. Ultrasound measured microemboli signals (MES) within the return line.Results:Hemodialysis raised cardiac biomarkers (p < 0.001): Pentraxin 3 (PTX) at 30 min (by 22%) and at 180 min PTX (53%), Pro-BNP (15%), and TnT (5%), similarly for all three HD modes. Baseline values of Pro-BNP correlated with TnT (rho = 0.38, p = 0.004) and PTX (rho = 0.52, p < 0.001). The changes from pre- to 180 min of HD (delta-) were related to baseline values (Pro-BNP: rho = 0.91, p < 0.001; TnT: rho = 0.41, p = 0.001; PTX: rho = 0.29, p = 0.027). Delta Pro-BNP (rho = 0.67, p < 0.001) and TnT (rho = 0.38, p = 0.004) correlated with inter-dialytic-weight-gain (IDWG). Biomarkers behaved similarly between the HD modes. The least negative impact was with an IDWG ⩽ 2.5%. Multiple regression analyses of the Wet-High mode does not exclude a relation between increased exposure of MES and factors such as release of Pro-BNP.Conclusion:Hemodialysis, independent of type of dialyzer storage, was associated with raised cardiac biomarkers, more profoundly in patients with higher pre-dialysis values and IDWG. A limitation in IDWG to <2.5% and prolonged ultrafiltration time may limit cardiac strain during HD, especially in patients with cardiovascular risk.

Distinct systemic cytokine networks in symptomatic and asymptomatic carotid stenosis

Inflammatory processes are crucial in atherosclerosis and atherothrombosis. This study aimed to identify a cytokine-pattern that is associated with plaque-vulnerability or symptomatic state in comprehensively investigated patients with symptomatic (sCS) and asymptomatic carotid stenosis (aCS). Twenty-two patients with sCS and twenty-four patients with aCS undergoing carotid endarterectomy (CEA) were considered. A cytokine-panel was measured in plasma-specimens prior to surgery and at a 90 day follow-up. Doppler-ultrasound detecting microembolic signals (MES) in the ipsilateral middle cerebral artery was performed. Carotid plaques were analysed regarding histopathological criteria of plaque-vulnerability and presence of chemokine receptor CXCR4. Correction for multiple comparisons and logistic regression analysis adjusting for vascular risk factors, grade of stenosis, antithrombotic and statin pretreatment were applied. In sCS-patients higher plasma-levels of Fractalkine (CX3CL1), IFN-α2, IL-1β, IL-2, IL-3, IL-7 were found compared to aCS-patients. CXCR4-expression on inflammatory cells was more evident in sCS- compared to aCS-plaques and was associated with vulnerability-criteria. In contrast, plasma-cytokine-levels were not related to CXCR4-expression or other vulnerability-criteria or MES. However, in both groups distinct inter-cytokine correlation patterns, which persisted at follow-up and were more pronounced in the sCS-group could be detected. In conclusion, we identified a distinct cytokine/chemokine-network in sCS-patients with elevated and closely correlated mediators of diverse functions.

Transient ischemic attack presenting as recurrent migratory numbness by seconds: a rare case confirmed by transcranial Doppler micro-emboli monitoring

BackgroundTransient ischemic attack (TIA) is a brief episode of cerebral ischemia. However, if a symptom is not presented as drop attack or hemiplegia, and alarming to the patient and the physician, how short of a symptom duration would raise the concern of a physician for TIA? It will be more complicated if the location of the neurological deficit is vagrant. This report highlights a rare TIA case which presented a very short duration of migratory patchy distribution numbness.Case presentationA middle-aged gentleman was presented with recurrent patchy distribution numbness on the right side of the body for 2 months, with the episode lasting as short as about 10 s. The location of the numbness was erratic and migratory. Magnetic resonance angiography (MRA) revealed mild stenosis on the left middle cerebral artery (MCA). Transcranial Doppler (TCD) micro-emboli monitoring detected positive micro-emboli signals (MES), leading to the confirmation of a TIA diagnosis. After a standard dual antiplatelet treatment combined with enhanced lipid reduction therapy with statins, MES disappeared on dynamic TCD emboli monitoring, and no more episodes of TIA have been noticed on the follow-ups.ConclusionTIA caused by micro-emboli can display as recurrent migratory neurological deficit within seconds. TCD micro-emboli monitoring is very helpful to differentiate this situation from TIA mimics with follow-ups, as well as to locate unstable plague.

ЦЕРЕБРАЛЬНАЯ МИКРОЭМБОЛИЯ У ПАЦИЕНТОВ С ЗАБОЛЕВНИЯМИ СЕРДЕЧНО-СОСУДИСТОЙ СИСТЕМЫ, НАХОДЯЩИХСЯ НА РЕАБИЛИТАЦИИ ПОСЛЕ НАРУШЕНИЯ МОЗГОВОГО КРОВООБРАЩЕНИЯ, ТЯЖЕЛЫХ ПОВРЕЖДЕНИЙ ГОЛОВНОГО МОЗГА

В статье приведен анализ результатов исследования частоты выявления микроэмболии в средних мозговых артериях у пациентов с заболеваниями сердечно-сосудистой системы: стенозирующими атеросклерозом церебральных артерий, фибрилляцией предсердий, проходящих лечение и реабилитацию после нарушения мозгового кровообращения, тяжёлых повреждений головного мозга вследствие сосудистых заболеваний (аневризма сосудов головного мозга, ишемический и геморрагический инсульт), черепно-мозговой травмы, опухолей головного мозга, в том числе, после нейрохирургических вмешательств в сравнении с практически здоровыми людьми.Всем обследованным был выполнен транскраниальный допплерографический мониторинг интракраниальных артерий. Детекция микроэмболов осуществлялась в ходе двухстороннего транскраниального допплеровского мониторирования потоков в средних мозговых артериях. К патологическим относили высокоэнергетические сигналы с относительным повышением мощности более 20 dB/ms, во время которых допплеровская мощность возрастала как минимум на 5 dB и длилась не менее 4 ms. Для оценки ультразвуковых характеристик атеросклеротических бляшек с помощью дуплексного сканирования у пациентов со стенозирующим атеросклерозом брахиоцефальных артерий использовали классификацию Gray-Weale А.С с соавт. Выявление и оценка атеросклеротических бляшек осуществлялась в ходе плановых исследований магистральных артерий головы линейным датчиком ультразвукового прибора DC-8, Mindray.В ходе исследования признаки микроэмболии были зарегистрированы во всех отобранных группах. Реже всего они выявлялись в контрольной группе у практически здоровых лиц, что объясняется отсутствием явных предпосылок к образованию микроэмболов. В группе пациентов с постоянной формой фибрилляцией предсердий количество случаев выявления микроэмболии не превысила половины обследованных. В группах сравнения у пациентов со стенозирующим атеросклерозом отмечается наибольшая частота выявления микроэмболии у пациентов с гетерогенными атеросклеротическими бляшками. И это совпадает с распределением среднего количества микроэмболических сигналов.

Micro-embolic risks during radiofrequency and cryoballoon-ablation of atrial fibrillation -analysis from real-time carotid artery doppler monitoring-

Abstract Background Catheter ablation of atrial fibrillation (AF) is associated with risks of silent cerebral events. However, the timing of intraprocedural micro-embolic events or differences between open-irrigated radiofrequency (RF) and cryoballoon (Cryo) ablation are unclear. Newly developed real-time carotid artery Doppler is a simple non-invasive method to detect micro-embolic signals (MESs) during ablation. Objective We investigated the timing of detecting MESs during RF and Cryo ablation of AF. Methods During the first pulmonary vein isolation (PVI) session of AF, MESs were monitored by real-time carotid artery Doppler monitoring throughout the procedure. The MES counts were collected and evaluated separately during the different steps of the procedure (Figure). Results Thirty-three AF patients (RF/Cryo: 22/11 cases, 9 females, 69.5±11.6 y.o) were included. PVI was successfully accomplished in all patients with no major complications. The MES count was significantly greater in the RF group than Cryo group (table). In both groups, left atrial (LA) access (interatrial puncture) and sheaths insertion to the LA generated a significant number of MESs (RF: 1690 of 9116 MESs [18.5% of the total MESs], Cryo: 793 of 2285 MESs [34.7%]). In the RF group, MESs were observed incessantly during PVI (Figure). The LA dwell time was significantly longer in the RF group than Cryo group (table). In the RF group, the MES count was significantly greater in the longer LA dwell time group (LA dwell time &amp;gt;130min) than the shorter group (464.2±179.7 vs 302.6±138.2: P=0.049). During the cryo-applications in the Cryo group, the MESs were greatest during the first cryoballoon application (625 of 2285 MESs [27.4%]). Conclusions There were more MESs during RF ablation than cryoablation. MESs were recorded during a variety of steps throughout the procedure. In the RF group, most of MESs were recorded incessantly during radiofrequency ablation and greater number of MESs were recorded in patients with longer LA dwell time. In the Cryo group, most of MESs occurred during phases with a high probability of gaseous emboli. Funding Acknowledgement Type of funding source: None

Utility of transcranial color flow imaging for detecting high risk morphology of patent foramen ovale in patients with cerebral infarction

Abstract Background Micro-bubble test by using transcranial color flow imaging (TCCFI) is important as a screening evaluation for diagnosis of paradoxical cerebral embolism which requires the proof of right to left shunt at atrial septum. In addition, high risk features of patent foramen ovale (PFO) that may allow thrombus to easily pass through the PFO itself were previously reported. However, little is known about the association between the degrees on micro-bubble test by TCCFI and the features of high risk PFO. Purpose Our aim is to clarify the relationship between the degree of micro-bubble test in TCCFI and the morphology of PFO from transesophageal echocardiography (TEE). Methods Seventy-seven patients in whom cardiogenic embolism was strongly suspected by neurologists in Showa University from April to December in 2019 were retrospectively studied. 55 patients underwent both TCCFI and TEE with sufficient Valsalva stress. TCCFI grade of micro-bubble test was classified into 3 groups (A: none, B: small, and C: massive), in which signified “none” is no sign of micro-embolic signals (MES) within 30 seconds, “small” is 1 or more MES, and “massive” is so much MES look like a curtain (Figure). Evaluated high risk characteristics of PFO for cerebral embolism as previously reported were as follows; (1) tunnel height, (2) tunnel length, (3) total excursion distance into right and left atrium, (4) existence of Eustachian valve or Chiari network, (6) angle of PFO from inferior vena cava (7) large shunt (20 or more micro-bubbles). Results Of all TCCFI-positive patients (n=32; Group B=19, Group C=13) with cerebral embolism, PFOs were detected in 23 patients in TEE. Therefore, the sensitivity and specificity of TCCFI to PFO were 87% and 63% (AUC=0.75, p&amp;lt;0.001, respectively). Interestingly, all 13 patients (Group C) had manifest PFOs. Moreover, group C include 2 patients with platypnea orthodeoxia syndrome in which hypoxia in the sitting position becomes apparent. Among PFO-positive patients, tunnel height, length, total excursion distance into right and left atrium, and large shunt in TEE were significantly larger in Group C than Group B (p&amp;lt;0.05). Conclusions Micro-bubble test by using TCCFI may have screening advantages in predicting paradoxical cerebral embolism, high-risk morphology of PFO, and platypnea orthodeoxia syndrome. Figure 1 Funding Acknowledgement Type of funding source: None

Pulmonary vein isolation procedure may be associated with intracranial artery microembolism and increased risk of acute neurological incidents

Abstract Background Atrial fibrillation ablation can be associated with the microembolism detected in intracranial arteries and risk of acute neurological incidents. Purpose The aims of this study were a quantitative and a qualitative evaluation of microembolic signals (MES) during pulmonary vein isolation (PVI) and establishing the potential significance of MES for damage of brain assessed in radiological investigation and neurological state of patients. Methods To the prospective project we qualified patients with atrial fibrillation undergoing percutaneous pulmonary vein isolation (radiofrequency ablation / balloon cryoablation) with ultrasound monitoring of microembolisms in right middle cerebral artery. Baseline and up to 12 months post pulmonary vein isolation the neurological examination and brain MRI were performed in all participants. Results The study enrolled 80 patients at a mean age of 58 years. Microembolisms during the monitoring of the flow in the right middle cerebral artery were recorded in 61 (76.3%) patients in the amount of 51–489 (mean 239). Most often the microembolic signals were registered during the trans-septal puncture and the stage of ablation. In 89%, microembolisms were gaseous. Mean score on Fazekas scale for the whole group before ablation: 0.87±0.7 (0–3, med. 1); after: 0.93±0.71. In 3 (4.3%) patients the lesions worsened during the follow-up period. None of the patients revealed a cardiovascular event during the follow-up period and no changes were observed in the neurological status. Conclusions The majority of cerebral microembolism generated during PVI are gaseous in nature. The cerebral microembolism associated with PVI probably result from the technical aspects of the procedure and do not cause neither the permanent brain damage in the radiological investigation nor neurological deficit. Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): Medical University of Silesia, Katowice, Poland - statutory work