Microembolic Signals Counts Research Articles

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.

Incidence of cerebral microembolization in patients with nonvalvular atrial fibrillation using transcranial Doppler

Background and aim Atrial fibrillation (AF)-related stroke represented more than 79% of all strokes of cardiogenic origin. AF is the crucial factor of cardiogenic stroke. AF-related stroke is manifested with severe clinical manifestation, significant disability, high mortality, and easier relapse. The incidence of mortality is twice as high as non-AF-related stroke. The AF type is usually of nonvalvular origin. The current work is aiming to determine the incidence of cerebral microembolization in nonvalvular AF patients. Patients and methods The current study was a prospective study of two groups of individuals: control and nonvalvular asymptomatic AF cardiac condition, hypertension, age, diabetes, sex, and stroke (CHADS) score 2 or more. Patients were collected from the cardiology clinic and department (Al-Azhar University Hospital, New Damietta, Egypt). Patients were submitted to history taking, clinical assessment, echocardiography, and transcranial Doppler ultrasonography, and microembolic signal detection and count. Also, the transcranial Doppler was used to monitor both middle cerebral arteries. Results There was a statistically significant difference between the control and study groups in relation to the number of microembolic signals. Signals of microembolizations were detected in eight cases (all were in the study group). There was a positive correlation between embolic signals and patient age (r=0.424, P=0.020) and there was a significant association with female sex. In addition, there was a positive correlation between embolic signals and left-atrium dimension (r=0.502). Regarding correlation, there was a negative interaction between embolic signals and anticoagulation use (r=−0.413, P=0.023). Conclusion Asymptomatic embolic signals occur in patients with nonvalvular AF who are not being treated with anticoagulants at a significantly greater frequency than in age-matched controls.

Estimation of patent foramen ovale size using transcranial Doppler ultrasound in patients with ischemic stroke

Background and PurposePatent foramen ovale (PFO)is associated with cryptogenic stroke, especially in young adults. Transcranial Doppler (TCD) ultrasound is used as a screening tool before transesophageal echocardiography (TEE). However, the use of Valsalva maneuver (VM) to identify a right‐to‐left‐shunt underlies interindividual variability. Here, we aimed to assess whether a pressure‐controlled standardization of VM is useful to estimate PFO size.MethodsWe included patients aged 18–80 years with a PFO according to TEE. Subjects underwent TCD with microembolic signals (MES) counted under four pressure conditions (i.e., at rest, 15 mbar, 40 mbar, and maximum expiratory pressure). Findings were correlated with TEE‐based PFO size. The predictive value of TCD at rest and VM‐based TCD for PFO size estimation was assessed by stepwise multivariate linear regression models and multiple cross‐tab‐analyses.ResultsWe screened 203 subjects after a cerebrovascular event, of which 78 (48 males [61.5%], median age 55 years [22–80]) with PFO were included. We found an association between MES count and expiratory pressure (p < .001). Predefined MES count categories at TCD pressure conditions correlated significantly with PFO size measured by TEE. We propose a PFO size estimation model based on TCD at rest and under VM, which classified PFO size correctly in 64.1% with the highest accuracy for small PFOs.ConclusionOur data provide evidence that TCD with step‐wise barometric standardization allows an estimation of PFO size with good accuracy. Though TCD will not replace TEE in future, this might be of clinical value in circumstances where TEE cannot be easily performed.

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.

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

Cerebral Microembolization in Left Ventricular Assist Device Associated Ischemic Events

IntroductionThe significance of microembolic signals (MES) detected by transcranial Doppler ultrasound emboli monitoring (TCD-e) in patients supported with left ventricular assist devices (LVAD) remains unclear. We aimed to investigate the relationship between cerebral microembolization detected by TCD-e and acute ischemic events in LVAD patients. MethodsWe reviewed consecutive patients with acute ischemic stroke or transient ischemic attack (TIA) in a prospectively collected database of LVAD patients. TCD-e exams consisted of monitoring the middle cerebral arteries for microembolic signals (MES) over 30 minutes. ResultsOf 515 persons with LVAD, 41 TCD-e studies were performed in 35 patients with acute ischemic stroke or transient ischemic attack (TIA) in a median of 1 day (Interquartile range [IQR]: 0-2) after the event. MES were present in 15 (44%) TCD-e studies with a median MES count of 4 (IQR: 2-15.5). Bloodstream infections were more common in patients with MES (38% versus 8%, P = .039). There were trends for lower international normalized ratio (1.39 versus 1.69, P = .214), lower activated partial thromboplastin (33.2 versus 36.6, P = .577), higher lactate dehydrogenase (531 versus 409, P = .323) and a higher frequency of pump thrombosis (13% versus 8%, P = .637) in patients with MES compared with those without MES. ConclusionsLVAD patients with acute ischemic stroke or TIA have a high prevalence of MES on TCD-e, which may serve as a marker for a prothrombotic state. Further study of MES in LVAD patients is warranted.

Carotid Wallstent Versus Roadsaver Stent and Distal Versus Proximal Protection on Cerebral Microembolization During Carotid Artery Stenting

ObjectivesThe aim of this study was to randomly compare the double-layer Roadsaver stent (RS) (Terumo, Tokyo, Japan) with the single-layer Carotid Wallstent (CW) (Boston Scientific, Santa Clara, California) in association with either distal embolic protection with the FilterWire (FW) device (Boston Scientific) or proximal protection with the Mo.Ma Ultra device (Medtronic, Santa Rosa, California) in patients with lipid-rich carotid plaques. BackgroundThe role of both stent type and brain protection during carotid artery stenting (CAS) remains unsettled. MethodsA total of 104 consecutive patients with carotid artery stenosis were randomized to CAS with FW + RS (group 1, n = 27), FW + CW (group 2, n = 25), Mo.Ma + RS (group 3, n = 27), or Mo.Ma + CW (group 4, n = 25). The primary endpoint was the number of microembolic signals (MES) on transcranial Doppler among groups in the following CAS steps: 1 and 2) target vessel access; 3) lesion wiring; 4) pre-dilation; 5) stent crossing; 6) stent deployment; 7) stent dilation; and 8) device retrieval and deflation. ResultsNo significant differences in baseline characteristics were found among the 4 groups. Compared with the FW device, the Mo.Ma Ultra device significantly reduced mean MES count (p < 0.0001) during lesion crossing, stent crossing, stent deployment, and post-dilation. Compared with the CW, the RS significantly reduced MES count (p = 0.016) in steps 6 to 8, including spontaneous MES (29% of patients). The combination of Mo.Ma + RS performed significantly better than Mo.Ma + CW (p = 0.043). Clinical major adverse cardiac and cerebrovascular events occurred in 3 patients (p = 0.51). After CAS, peak systolic velocity significantly decreased in all patients. In-stent restenosis developed in 1 patient (0.98%) at 6-month follow-up. The RS was an independent predictor of external carotid artery patency over time. ConclusionsIn patients with high-risk, lipid-rich plaque undergoing CAS, Mo.Ma + RS led to the lowest microembolic signals count. (Role of the Type of Carotid Stent and Cerebral Protection on Cerebral Microembolization During Carotid Artery Stenting. A Randomized Study Comparing Carotid Wallstent vs Roadsaver® Stent and Distal vs Proximal Protection; NCT02915328)

Impact of plaque dilation before carotid artery stent deployment

ObjectivePlaque stability is of utmost importance for stroke prevention in the perioperative period (within 24 hours) following carotid artery stenting (CAS). Although carotid plaque is entrapped between stent struts after stent deployment, postdilation can cause a scissoring effect on the plaque, increasing the risk of postprocedural embolic events due to plaque prolapse. Maximum carotid plaque dilation before stent deployment may reduce this risk. This study analyzed the effect of maximum dilation of the carotid plaque before stent deployment (max-pre-SD) or after stent deployment (post-SD) on macroscopic plaque debris, hemodynamic depression (HD), and immediate major adverse events. MethodsThis prospective nonrandomized multicenter study analyzed patients treated for carotid artery stenosis with CAS from January 2014 to August 2016. Clinical and morphologic characteristics and operative details were analyzed with logistic regression analysis for macroscopic debris and HD. The number of microembolic signals (MESs) was assessed by transcranial Doppler and analyzed. ResultsA total of 309 patients were enrolled and treated with standard CAS performed using a proximal occlusion cerebral embolic protection device; 149 received max-pre-SD and 160 were treated with post-SD. Technical success was achieved in 100% of cases. Macroscopic debris and HD were significantly different between the two groups in favor of max-pre-SD (P < .001). A significant difference in intraprocedural MESs between the groups was detected. Compared with post-SD, max-pre-SD significantly reduced mean MES counts (8.1% vs 68.1%; P < .001). Patients treated with post-SD had a significantly increased risk of MESs in the immediate postoperative period compared with patients treated with max-pre-SD (41.9% vs 1.3%; P < .001).This result was mainly due to the small number of events encountered. Patients treated with post-SD had a 12-fold increased risk of macroscopic debris collection (odds ratio [OR], 12.36; 95% confidence interval [CI], 5.68-26.87; P < .001) and an 18 times increase in HD risk (OR, 17.80; 95% CI, 5.27-60.17; P < .001) compared with patients treated with max-pre-SD. The heterogeneous, mainly echolucent plaque type significantly highly increased the risk of macroscopic debris (OR, 78.45; 95% CI, 8.70-707.09; P < .001) while acting as a protective factor against HD (OR, 0.02; 95% CI, 0.006-0.11; P < .001) along with echogenic or echolucent complex plaques with irregular surface plaque types (OR, 0.10; 95% CI, 0.031-0.336; P < .001). No significant differences between groups (max-pre-SD group and post-SD) were detected in immediate major adverse events (minor stroke, 2.0% and 2.5% [P = .461]; major stroke, 0% and 0.6% [P = .334], respectively). ConclusionsMax-pre-SD seems to be a safe and feasible technical modification to the CAS procedure. Macroscopic debris, HD, and MESs are significantly reduced compared with CAS with post-SD. Further research with larger, randomized cohorts of patients is required to establish the superiority of this technical modification.

RF70 RESULTS FROM AN IN VIVO COMPARISON OF THE OPTIFLOW AND EZ GLIDE AORTIC DISPERSION CANNULAE

Background: Morbidity associated with embolization during cannulation in coronary artery bypass grafts (CABG) is strongly related to patient characteristics/comorbidities, the arterial cannulation site and the shape of the arterial cannula tip.. The desired features of an arterial cannula should be to prevent those morbid effects and focus on achieving higher flows with lower cannula pressures. Methods: To evaluate the in vivo performance of two aortic dispersion flow cannulas: Optiflow (Sorin Group, Italy) and EZ Glide (Edwards Lifesciences, USA) in relation to cannula pressures, pump flow rates and plasma free hemoglobin. Over a 12 month period we collected data on a prospective, randomized (1:1), non-blinded, monocentric study with a cohort of 30 patients (Optiflow group N = 15; EZ Glide group N = 15). Results: The Optiflow cannula was found to have decreasing cannula pressures as pump flow rates increased (112.3 ± 10.9 mmHg vs 131.1 ± 11.4 mmHg, p &lt; 0.0001). Results also indicated no significant differences between groups in plasma free hemoglobin increases (p = 0.41) or total microembolic signals counts during cardiac surgery (p = 0.63). Conclusions: Both Optiflow and EZ Glide dispersion flow arterial cannulas performed well, but the Optiflow cannula demonstrated an ability to increase pump flow rates with lower arterial line and cannula pressures than the EZ Glide cannula. This implies an ability to improve peripheral perfusion while reducing cannula shear stress and reducing the risk of endothelial damage in an area where the cannula jet hits the intraluminal aortic wall, thereby having the potential to reduce the risk of atherosclerotic plaque dislodgement.

Thromboembolic Risks of the Procedural Process in Second-Generation Cryoballoon Ablation Procedures: Analysis From Real-Time Transcranial Doppler Monitoring.

Atrial fibrillation ablation is associated with substantial risks of silent cerebral events (SCEs) or silent cerebral lesions. We investigated which procedural processes during cryoballoon procedures carried a risk. Forty paroxysmal atrial fibrillation patients underwent pulmonary vein isolation using second-generation cryoballoons with single 28-mm balloon 3-minute freeze techniques. Microembolic signals (MESs) were monitored by transcranial Doppler throughout all procedures. Brain magnetic resonance imaging was obtained pre- and post-procedure in 34 patients (85.0%). Of 158 pulmonary veins, 152 (96.2%) were isolated using cryoablation, and 6 required touch-up radiofrequency ablation. A mean of 5.0±1.2 cryoballoon applications was applied, and the left atrial dwell time was 76.7±22.4 minutes. The total MES counts/procedures were 522 (426-626). Left atrial access and Flexcath sheath insertion generated 25 (11-44) and 34 (24-53) MESs. Using radiofrequency ablation for transseptal access increased the MES count during transseptal punctures. During cryoapplications, MES counts were greatest during first applications (117 [81-157]), especially after balloon stretch/deflations (43 [21-81]). Pre- and post-pulmonary vein potential mapping with Lasso catheters generated 57 (21-88) and 61 (36-88) MESs. Reinsertion of once withdrawn cryoballoons and subsequent applications produced 205 (156-310) MESs. Touch-up ablation generated 32 (19-62) MESs, whereas electric cardioversion generated no MESs. SCEs and silent cerebral lesions were detected in 11 (32.3%) and 4 (11.7%) patients, respectively. The patients with SCEs were older than those without; however, there were no significant factors associated with SCEs. A significant number of MESs and SCE/silent cerebral lesion occurrences were observed during second-generation cryoballoon ablation procedures. MESs were recorded during a variety of steps throughout the procedure; however, the majority occurred during phases with a high probability of gaseous emboli.

Prognostic Role of Microembolic Signals After Endovascular Treatment in Anterior Circulation Ischemic Stroke Patients.

Endovascular treatment (EVT) is an effective therapy for acute ischemic stroke due to large artery occlusion of the anterior circulation. Yet some patients do not experience clinical improvement despite successful recanalization and reperfusion. The reasons are unknown, but one possible explanation is microvessel obstruction downstream. The aim of this study was to assess the presence of microembolic signals (MES) with transcranial Doppler and define their role as predictors of clinical outcome in stroke patients after EVT. We enrolled 40 consecutive patients (23 men, mean age 65.8 ± 7.6 years) with an acute ischemic stroke caused by large artery occlusion of the anterior circulation who underwent EVT. Presence and rate of MES were assessed by 60-minute transcranial Doppler monitoring at the end of the procedure and after 15 days from stroke onset. MES were detected in 65% (26/40) of patients after EVT. Ipsilateral carotid occlusion (P= 0.05), ≥50% ipsilateral carotid stenosis (P= 0.05), incomplete recanalization (P= 0.03), and inadequate collaterals (P= 0.04) were associated with a significantly higher MES count, which was correlated with a worse functional prognosis (P= 0.03), higher mortality (P= 0.02), higher distal embolization burden even outside the original ischemic territory (P= 0.02), and higher risk of cardiovascular events (P= 0.04). MES monitoring in stroke patients after EVT provides useful prognostic information, sheds light on the lack of clinical improvement despite successful recanalization, and might guide medical treatment in higher risk patients.

Clinical Impact of the Microembolic Signal Burden During Catheter Ablation for Atrial Fibrillation: Just a Lot of Noise?

Microembolic signal detection by transcranial Doppler ultrasonography may be considered a surrogate for cerebral events during invasive cardiac procedures. However, the impact of the microembolic signal count during pulmonary vein isolation on the clinical outcome is not well evaluated. We investigated the effect of the microembolic signal count on the occurrence of new silent cerebral embolism measured by diffusion-weighted imaging (DWI)-magnetic resonance imaging (MRI), changes in neuropsychological testing, and the occurrence of clinical events during long-term follow-up after pulmonary vein isolation. Pulmonary vein isolation was performed in 41 patients. The total microembolic signal burden (classified into "solid," "gaseous," and "equivocal") and sustained thromboembolic showers of greater than 30 seconds were recorded. Diffusion-weighted imaging-MRI and neuropsychological testing were performed before and after pulmonary vein isolation to assess for silent cerebral embolism and neuropsychological sequelae. Long-term follow-up was performed by telephone to assess for stroke/transient ischemic attack. A total of 68,729 microembolic signals (14,893 solid, 11,909 gaseous, and 41,927 equivocal) with an average of 1676 signals per patient and 42 thromboembolic showers were recorded. No correlation between the microembolic signal/thromboembolic shower count and the occurrence of new DWI lesions or neuropsychological capability was found. After a mean follow-up ± SD of 49 ± 4 months, 1 patient had an overt transient ischemic event, which was not associated with a high microembolic signal count. In this multicenter study, we found no impact of the intraprocedural microembolic symbol/thromboembolic shower count on the occurrence of new DWI lesions, neuropsychological capability, or overt neurologic deficits after pulmonary vein isolation. Thus, not only the microembolic signal count but also procedural/individual factors may contribute to commensurable clinical damage, which may challenge this method as a valid biomarker during pulmonary vein isolation.

Cerebral micro-embolization during pulmonary vein isolation: Relation to post-ablation silent cerebral ischemia.

High incidences of silent cerebral ischemia (SCI) have been revealed by diffusion-weighted magnetic resonance imaging (DW MRI) after pulmonary vein isolation (PVI) for atrial fibrillation. A high number of mostly gaseous micro-embolic signals (MESs) was detected by transcranial Doppler (TCD) during PVI. In this investigation the possible relationship between MESs detected intraoperatively by TCD and new SCI on DW MRI post-ablation is reported. 27 consecutive atrial fibrillation patients (6 female, age median: 64 interquartile range: 13.23) undergoing PVI with the pulmonary vein ablation catheter, pre- and post-ablation DW MRI and intra-operative MES detection by TCD were included in the study. Procedures were performed on a therapeutic international normalized ratio (2-3) and with a target activated clotting time ≥ 350 s in all patients. DW MRI scans performed pre- and post-ablation revealed new SCI in 6 out of 27 (22%) patients. The median (interquartile range) MES count recorded during the whole procedure was 1642 (912) in patients with and 1019 (529) in those without SCI (p = 0.129). The number of MESs recorded during pulmonary vein angiography was significantly higher in patients as compared to those without a new lesion on the post-ablation DW MRI: 257 (249) vs. 110 (71), respectively (p = 0.0009). On mul-tivariate logistic regression, the total MES count was predictive of SCI in patients older than 68 years. Micro-embolus generation detected by TCD during pulmonary vein angiography significantly correlates with new SCI on DW MRI post-ablation.

Influence of Clinical Parameters and Anticoagulation on Intraprocedural Cerebral Microembolic Signals during Pulmonary Vein Isolation.

ObjectiveWe had the objective to determine the impact of clinical parameters and anticoagulation status on cerebral microembolic signals (MES) during pulmonary vein isolation (PVI) for atrial fibrillation (AF).BackgroundThromboembolism and stroke are the most feared complications of PVI. MES can help to evaluate embolic burden. It is unknown whether clinical parameters have an impact on embolic risk during PVI.MethodsIn this retrospective analysis we investigated the impact of clinical parameters, including the CHADS2- and CHA2DS2-VASc-score, pulmonary vein variants and echocardiographic parameters on MES rates in patients that underwent PVI using three different ablation approaches (radiofrequency ablation (iRF), pulmonary vein ablation catheter (PVAC) with deactivated electrode pair 1 or 5 (PVAC-red) or PVAC without deactivation (PVAC-all).Results118 AF patients (61±12 years) were included between 2011 and 2013 (Median: 489 MES during PVI). Patients were more likely to have more MES (within 4th quartile) with the PVAC-all approach (60.7% vs. 25.0% (iRF) vs. 14.3% (PVAC-red) respectively (p<0.001). Patients with oral anticoagulation (OAC) pre-ablation were more likely to have lower MES-counts (1st-3rd quartile); (65.6% vs. 35.7%; p = 0.005). Additionally, patients with lower MES counts (1st-3rd quartile) had significantly higher INR values than those in the 4th quartile (1.78 vs. 1.09; p = 0.029). 2 patients developed a potentially thromboembolic event during the procedure.ConclusionClinical predictors of cerebral emboli and stroke do not correlate with cerebral embolic burden during PVI. Pre-ablation OAC and increased INR values correlate with decreased MES-rates. Therefore, it might be beneficial to perform PVI with pre-ablation anticoagulation even in low risk patients.

Predictors of cerebral microembolization during phased radiofrequency ablation of atrial fibrillation: Analysis of biophysical parameters from the ablation generator

Pulmonary vein isolation with phased radiofrequency current and use of a pulmonary vein ablation catheter (PVAC) has recently been associated with a high incidence of clinically silent brain infarcts on diffusion-weighted magnetic resonance imaging and a high microembolic signal (MES) count detected by transcranial Doppler. The purpose of this study was to investigate the potential correlation between different biophysical parameters of energy delivery (ED) and MES generation during PVAC ablation. MES counts during consecutive PVAC ablations were recorded for each ED and time stamped for correlation with temperature, power, and impedance data from the GENius 14.4 generator. Additionally, catheter-tissue contact was characterized by the template deviation score, calculated by comparing the temperature curve with an ideal template representing good contact, and by the respiratory contact failure score, to quantify temperature variations indicative of intermittent contact due to respiration. A total of 834 EDs during 48 PVAC ablations were analyzed. A significant increase in MES count was associated with a lower average temperature, a temperature integral over 62°C, a higher average power, the total energy delivered, higher respiration and template deviation scores (P <.0001), and simultaneous ED to the most proximal and distal poles of the PVAC (P <.0001). MES generation during ablation is related to different indicators of poor electrode-tissue contact, the total power delivered, and the interaction between the most distal and the most proximal electrodes.

Biophysical background of cerebral microembolization during phased radiofrequency ablation of atrial fibrillation: analysis of high resolution data from the ablation generator

Background: Asymptomatic cerebral emboli (ACE) after catheter ablation of atrial fibrillation (AF) have been recently demonstrated on diffusion MRI. The highest incidence of new lesion on postablation diffusion MRI have been consistently found after ablation with the circular, multipolar pulmonary vein ablation catheter (PVAC) and phased refiofrequency (RF) energy. Our group has also demonstrated, that the total number of microembolic signals (MES) detected by transcranial Doppler (TCD) in the middle cerebral arteries (MCA) is significantly higher during phased RF as compared to during cryoballoon ablation. Limited data are available regarding the mechanism of MES generation during ablation with the PVAC. Therefore, we investigated different biophysical parameters of RF delivery with the phased RF technique in order to find potential correlation with the MES counts detected by TCD during the ablation. Methods and results: 48 consecutive patients (female:17, mean age:60, SD:10 years) undergoing PVI with phased RF for non-valvular, paroxysmal or persistent atrial fibrillation formed the study population. Preprocedural anticoagulation consisted of uninterrupted vitamin K antagonist to maintain an INR in the therapeutic range (2.0-3.0). Unfractionated Heparin was used intravenously to maintain the ACT level above 350 seconds during the ablation. MES counts were recorded with bilateral TCD monitoring of MCAs for each session of energy delivery and time stamped for correlation with the high resolution data on power, temperature and impedance collected from the GENius 14.4 generator. Significant correlation was demonstrated between MES count during RF delivery and the following biophysical parameters: average power, total energy delivered, the number of electrodes turned on for simultaneous RF delivery, temperature overshoot (temperature integral over 62°C) and improper contact caused by respiration (P<0.0001). Furthermore, ablations of the left sided PVs also resulted in higher MES counts as compared to RF applications on the right side (P=0.0003). The bipolar/unipolar ratio of energy delivery and the average temperature reached during an ablation session had no effect on MES generation. Conclusions: Several biophysical parameters of energy delivery demonstrated a significant correlation with a higher rate of microemboli production during PVI with the PVAC. Most of these parameters can be linked to a variable or poor electrode-tissue contact. Modifications in the catheter design and in the software regulation of power/temperature handling of the generator might improve the safety of this technology.

Assessment of Reverse Flow as a Means of Cerebral Protection during Carotid Artery Stent Placement with Diffusion-weighted and Transcranial Doppler Imaging

PurposeTo assess the effectiveness of flow reversal as an alternative means of cerebral protection by using transcranial Doppler recordings and diffusion-weighted imaging (DWI) as surrogate markers of brain injury. Materials and MethodsEighteen patients with symptomatic carotid artery disease were recruited. Magnetic resonance imaging was performed before the intervention and at 3 and 24 hours and 30 days after the intervention to detect new ischemic lesions with DWI. Transcranial Doppler recordings were made during the procedure to assess for microembolic signals (MESs). Data were compared against data from a historical control cohort of patients who underwent CAS placement with or without filter protection (n = 15 each) under the same protocol in a different study. ResultsThere were fewer periprocedural new lesions on DWI in the reverse-flow cohort compared with the historical control cohort with filter protection (P = .084). Reverse flow revealed significantly fewer MESs during the whole procedure compared with the filter-protected group (P = .01) but not the unprotected group (P = .55). There was a marked decrease in MES counts for reverse flow protection during the embologenic stages of the procedure (P = .004). ConclusionsUse of the reverse flow device was associated with fewer overall lesions on DWI and proportionately fewer positive scans compared with the use of filter-type devices (P = .08, not significant). Transcranial Doppler recordings demonstrated a significant reduction in embolization to the brain during carotid artery stent placement with the use of reverse-flow cerebral protection.

075 Significant Reduction in Microemboli During Pulmonary Vein Isolation With Multipolar Duty-Cycled Radiofrequency Pulmonary Vein Ablation Catheter Using the Modified Version of the GENius™ Generator

BACKGROUND: Pulmonary vein isolation (PVI) techniques have been increasingly used to cure atrial fibrillation (AF). Recently, concerns have been raised that subclinical brain damage may occur due to microembolisation during these procedures, mostly when multipolar duty-cycled radiofrequency (RF) catheters (PVAC) are used. Technical modification of the GENiusTM 14.0 generator has been recently implemented to avoide high fluctuations in temperature at the electrode-tissue interface and to prevent overheating in order to reduce thrombus formation. We compared the occurence of microembolic signals (MES) detected by transcranial Doppler (TCD) which occured when the older GENiusTM 14.0 versus the modified GENiusTM 14.4 generator was used. METHODS/RESULTS: Data of 7 patients who had PVI for paroxysmal or persistent atrial fibrillation using the PVAC and the GENiusTM 14.0 generator were compared to those 10 who underwent the procedure using the GENiusTM 14.4 generator.There were no significant differences between the two groups regarding demographics, type of AF, CHADS2-score, left atrial size, and intraoperative anticoagulation protocol. Transcranial Doppler was used to detect MESs in middle cerebral arteries (MCA) in different stages of the procedures as follows: transseptal puncture (TP), pulmonary vein angiography (PVA), energy delivery (ED), and the rest of the porcedure (ROP). Mean total number of MESs during the procedures were 4766/ MCA SD:855 with the use of the GENiusTM 14.0 generator versus 1100/MCA SD:343with the GENiusTM 14.4 (p 0.001). Difference in the total number of MES was due to the difference in MES count detected during energy delivery period, while no difference was observed during the other stages of the procedures (figure 1). CONCLUSION: Significant reduction in the number of MES was achieved with the modified version of the GENiusTM generator during PVI. Canadian Cardiovascular Society (CCS) CCS033 Poster PRECLINICAL AND CLINICAL STUDIES IN HYPERTENSION Sunday, October 28, 2012

Clopidogrel Load for Emboli Reduction in Patients With Symptomatic Carotid Stenosis Undergoing Urgent Carotid Endarterectomy

Microembolic signals (MES) on transcranial Doppler are an independent risk factor for recurrent stroke in patients with extracranial symptomatic/asymptomatic carotid artery stenosis (CARAS). Clopidogrel load (300 mg) combined with dual antiplatelet therapy has been shown to reduce MES in patients with symptomatic CARAS. We sought to determine feasibility of clopidogrel load in decreasing asymptomatic embolization in patients with symptomatic CARAS undergoing urgent carotid endarterectomy within the first 2 weeks from the index event. Subjects and Consecutive patients with symptomatic CARAS (70%-99%) and presence of MES on 1-hour baseline (<24 hours from the index event) transcranial Doppler monitoring of ipsilateral middle cerebral artery were treated with clopidogrel load followed by clopidogrel (75 mg)±aspirin (100 mg) during the elapsed time period between hospital admission and urgent carotid endarterectomy at 3 tertiary-care stroke centers. Repeat 1-hour transcranial Doppler monitoring was performed the day before surgery. Bleeding complications during surgery and recurrent strokes or transient ischemic attacks during the first month of ictus were prospectively recorded. A total of 11 symptomatic CARAS patients (mean age, 66±7 years; 73% men; 64% acute ischemic strokes) were treated with clopidogrel load followed by dual (67%) or single (33%) antiplatelet therapy. MES count was significantly reduced between baseline (median count, 8 MES/h; interquartile range, 6-19) and repeat transcranial Doppler monitoring (0 MES/h; interquartile range, 0-3; P=0.003). No bleeding complications, recurrent strokes, or transient ischemic attacks were documented. Our pilot observational study provides preliminary nonrandomized data regarding the potential efficacy of clopidogrel load to reduce asymptomatic embolization in patients with symptomatic CARAS before urgent carotid endarterectomy.

Abstract 2684: Clopidogrel Load For Emboli Reduction In Patients With Symptomatic Carotid Artery Stenosis Undergoing Urgent Carotid Endarterectomy (CEA): A Multicenter Pilot Feasibility Study

Background&amp;Purpose: Microembolic signals (MES) on transcranial Doppler (TCD) are an independent risk factor for recurrent stroke and neurological deterioration in patients with extracranial symptomatic and asymptomatic carotid artery disease (CARAD). Clopidogrel load (300mg) combined with dual antiplatelet therapy has been shown to reduce asymptomatic embolization in patients with symptomatic CARAD. We sought to determine feasibility of clopidogrel load in decreasing asymptomatic embolization in patients with symptomatic CARAD undergoing urgent CEA within the first 8 days from the index event. Subjects&amp;Methods: Consecutive patients with symptomatic CARAD (70%-99% stenosis) and presence of MES on 1-hour baseline (&lt;24 hours from the index event) TCD-monitoring of ipsilateral middle cerebral artery (MCA) were treated with clopidogrel load followed by clopidogrel 75mg±aspirin 100mg during the elapsed time period between hospital admission and urgent CEA at three tertiary care stroke centers. Repeat 1-hour TCD monitoring was performed the day before surgery. Bleeding complications during surgery and recurrent strokes/TIAs during the first month following the index event were prospectively documented. Functional independence at three months was evaluated using the modified Rankin Scale (mRS) Score. Results: A total of 9 symptomatic CARAD patients (mean age 66±6years, 89% men, 56% ischemic strokes, median NIHSS 4 points, interquartile range 0-8, 44% TIAs) were treated with clopidogrel load followed by dual (66%) or single (33%) antiplatelet therapy. MES count was significantly reduced between baseline (&lt;24 hours from index event, median count 8 MES/hr, interquartile range 6-17) and repeat (4-7 days from index event, median count 0 MES/hr, interquartile range 0-4; p=0.008 by Wilcoxon Signed Ranks Test) TCD-monitoring. The mean MES frequency reduction (compared to baseline) was 89% (95%CI:77%-100%). No bleeding complications (0%) or recurrent strokes (0%) were documented. All patients were functionally independent (mRS-scores of 0-1) at three months. Conclusions: Our pilot study shows feasibility of administering clopidogrel load followed by dual or single antiplatelet therapy to reduce asymptomatic embolization in patients with symptomatic CARAD who are scheduled to undergo urgent CEA. The present findings are subject of a larger ongoing multi-center study.