Site Of Thrombus Formation Research Articles

Morphology and Function Assessment of Left Atrial Appendage in Patients With Atrial Fibrillation.

Atrial fibrillation (AF) is among the most prevalent forms of clinically significant arrhythmia, and stroke incidence is among the most serious AF-related complications, causing high rates of morbidity and mortality among affected patients. The European Society of Cardiology guidelines recommend a thromboembolic event risk assessment based on the CHA2DS2-VASC score. However, stroke also occurs in some patients with a low CHA2DS2-VASC score. Therefore, it is necessary to improve thromboembolic risk stratification in AF patients. The left atrial appendage (LAA) is considered to be the most frequent site of thrombus formation. Approximately 47% of thrombi in valvular AF and 91% of thrombi in nonvalvular AF are localized in the LAA. Therefore, identification or exclusion of LAA thrombi is critical in many clinical situations. It is essential to assess LAA morphology and function using imaging modalities (particularly echocardiography) before, during, and after interventional procedures such as AF ablation and LAA occlusion. This review article describes the anatomical, physiological, and LAA assessment in daily practice.

Recombinant neorudin and its active metabolite hirudin: the fate in vivo of a novel anticoagulant drug.

Thrombosis, a prevalent condition, can provoke severe health issues like acute coronary syndrome (ACS), deep vein thrombosis (DVT), and pulmonary embolism (PE). The rising incidence of these diseases annually significantly impacts patient wellbeing and poses a substantial burden on healthcare systems. Recombinant neorudin is a developing anticoagulant drug for thrombotic diseases whose phase I clinical trials has been completed. The distribution pattern of it and its active metabolite, hirudin, in thrombi, blood surrounding the thrombus and peripheral blood remains uncertain. This study explored their distribution using a rat arteriovenous bypass thrombosis model, revealing higher neorudin levels in blood surrounding the thrombus and elevated hirudin concentrations in thrombus. Recombinant neorudin significantly increased Thrombin Time (TT) in both plasma surrounding the thrombus and peripheral blood, and reduced the wet weight of the thrombus. The results above demonstrated the anticoagulant and antithrombotic efficacy of recombinant neorudin in vivo. Give the distribution pattern of neorudin and hirudin, we hypothesized that neorudin was cleaved at the site of thrombus formation to produce hirudin, leading to the rapid accumulation of hirudin within local thrombi and resulting in a higher concentration inside the thrombus. This insight was crucial for understanding the action mechanisms of anticoagulants in thrombosis management and provided a valuable guidance for therapeutic strategies in treating thrombotic diseases.

The impact of left atrial morphology on thrombosis risk in atrial fibrillation

Atrial fibrillation (AF) is an arrhythmia disease that can disrupt the movement of the left atrium (LA), which will facilitate thromboembolism in LA and further exacerbate the stroke risk. The left atrial appendage (LAA) is a vital site for thrombus formation. The morphology of the LAA is believed to have a profound effect on thrombosis. However, due to the limitation of observation and monitoring methods, the mechanism of this effect is still unrevealed. Virchow's triad is a theory of thrombogenic mechanisms, stating that endothelial injury, blood hypercoagulability, and blood stasis are the three main factors involved in thrombus formation. In this study, we conducted personalized simulation analyses for 12 AF patients and discussed simulation results from the perspective of Virchow's triad. The simulation results indicate the effectiveness of Virchow's triad in elucidating the thrombosis mechanism within the LAA. The LAA is more prone to thrombosis than the other region of LA, because of the lower blood flow velocity and significantly higher endothelial cell activation potential values there, which indicates a higher risk of blood stasis and endothelial injury, respectively. Furthermore, a comprehensive score is proposed to assess the performance of Virchow's triad in the LAA. The morphology of LA has a significant influence on the performance of the three factors in Virchow's triad. Hence, for a quickly assessment of LAA thrombosis risk in AF patients through the lens of Virchow's triad, we need a more refined shape scoring system that can better reflect patient-specific morphological features of the entire LA.

Reduced Monocyte and Neutrophil Infiltration and Activation by P-Selectin/CD62P Inhibition Enhances Thrombus Resolution in Mice.

Venous thromboembolism is a major health problem. After thrombus formation, its resolution is essential to re-establish blood flow, which is crucially mediated by infiltrating neutrophils and monocytes in concert with activated platelets and endothelial cells. Thus, we aimed to modulate leukocyte function during thrombus resolution post-thrombus formation by blocking P-selectin/CD62P-mediated cell interactions. Thrombosis was induced by inferior vena cava stenosis through ligation in mice. After 1 day, a P-selectin-blocking antibody or isotype control was administered and thrombus composition and resolution were analyzed. Localizing neutrophils and macrophages in thrombotic lesions of wild-type mice revealed that these cells enter the thrombus and vessel wall from the caudal end. Neutrophils were predominantly present 1 day and monocytes/macrophages 3 days after vessel ligation. Blocking P-selectin reduced circulating platelet-neutrophil and platelet-Ly6Chigh monocyte aggregates near the thrombus, and diminished neutrophils and Ly6Chigh macrophages in the cranial thrombus part compared with isotype-treated controls. Depletion of neutrophils 1 day after thrombus initiation did not phenocopy P-selectin inhibition but led to larger thrombi compared with untreated controls. In vitro, P-selectin enhanced human leukocyte function as P-selectin-coated beads increased reactive oxygen species production by neutrophils and tissue factor expression of classical monocytes. Accordingly, P-selectin inhibition reduced oxidative burst in the thrombus and tissue factor expression in the adjacent vessel wall. Moreover, blocking P-selectin reduced thrombus density determined by scanning electron microscopy and increased urokinase-type plasminogen activator levels in the thrombus, which accelerated caudal fibrin degradation from day 3 to day 14. This accelerated thrombus resolution as thrombus volume declined more rapidly after blocking P-selectin. Inhibition of P-selectin-dependent activation of monocytes and neutrophils accelerates venous thrombosis resolution due to reduced infiltration and activation of innate immune cells at the site of thrombus formation, which prevents early thrombus stabilization and facilitates fibrinolysis.

Tailoring left ventricular assist device cannula implantation using coupled multi-scale multi-objective optimization

BackgroundThe frequent occurrence of thromboembolic cerebral events continues to limit the widespread implementation of Ventricular Assist Devices (VAD) despite continued advancements in VAD design and anti-coagulation treatments. Recent studies point to the optimal positioning of the outflow graft (OG) as a potential mitigator of post implantation thromboembolism. ObjectiveThis study aims to examine the tailoring of the OG implantation orientation with the goal of minimizing the number of thrombi reaching the cerebral vessels by means of a formal shape optimization scheme incorporated into a multi-scale hemodynamics analysis. MethodsA 3-D patient-specific computational fluid dynamics model is loosely coupled in a two-way manner to a 0-D lumped parameter model of the peripheral circulation. A Lagrangian particle-tracking scheme models and tracks thrombi as non-interacting solid spheres. The loose coupling between CFD and LPM is integrated into a geometric shape optimization scheme which aims to optimize an objective function that targets a drop in cerebral embolization, and an overall reduction in particle residence times. ResultsThe results elucidate the importance of OG anastomosis orientation and placement particularly in the case that studied particle release from the OG, as a fivefold decrease in cerebral embolization was observed between the optimal and non-optimal implantations. Another case considered particle release from the ventricle and aortic root walls, in which optimal implantation was achieved with a shallow insertion angle. Particle release from all three origins was investigated in the third case, demonstrating that the optimal configurations were generally characterized by VAD flow directed along the central lumen of the aortic arch. Because optimal configurations depended on the anatomic origin of the thrombus, it is important to determine, in clinical studies, the most likely sites of thrombus formation in VAD patients.

Two-dimensional speckle tracking imaging analyses of the correlations between left atrial appendage function and stroke risk in nonvalvular atrial fibrillation patients.

Stroke incidence is the most severe complication associated with atrial fibrillation (AF), and the most common site of thrombus formation in AF patients is the left atrial appendage (LAA). This study was developed to use two-dimensional speckle tracking imaging (2D-STI) to explore associations between LAA strain/strain rate and stroke incidence and to evaluate the value of utilizing LAA strain and strain rate values to support the stratification of nonvalvular AF (NVAF) patients based on stroke risk. A total of 486 AF patients who had undergone transesophageal echocardiography to exclude potential intracardiac thrombosis between March 2021 and November 2022 were consecutively enrolled. Patients meeting the inclusion criteria were separated into two groups according to their history of stroke/transient ischemic attack (TIA). LAA strain and strain rate values in these patients were measured via 2D-STI. Multivariable logistic regression analysis was employed to determine independent risk factors for the construction of a combined predictive model. Of the 333 analyzed patients (134 females, aged 65 (56,72) years), 39 (11.71%, 39/333) had a history of stroke at the time of evaluation. Multivariate logistic regression analysis demonstrated that nonparoxysmal AF, CHA2DS2VASc score, LAA thrombus/spontaneous echo contrast (SEC), LAA strain, and strain rate were all predictors of stroke incidence among NVAF patients. The combined predictive model demonstrated excellent discriminative ability, with an AUC of 0.91 (95%CI 0.87-0.95, P < 0.001), and a sensitivity and specificity of 79.49% and 89.46%, respectively. The Hosmer-Lemeshow test confirmed good calibration, yielding a value of 0.98. Comparative decision curve analysis showed that the model provided superior net benefits compared to the CHA2DS2VASc score. Furthermore, the model exhibited improved predictive performance and reclassification for stroke when compared to the CHA2DS2VASc score (AUC 0.91 vs. 0.88, Z = 2.32, P = 0.02), accompanied by a significant increase in the net reclassification index (+ 5.44%, P < 0.001) and integrated discrimination improvement (8.21%, P < 0.001). These data demonstrate that LAA strain and strain rate, as measured via 2D-STI, can offer value when assessing LAA function in AF patients, potentially providing further predictive value to extant clinical risk scoring strategies.

Abstract 15625: Left Atrial Appendage Volumetric and Functional Assessment Using Cardiac CT-Derived Three-Dimensional Models

Introduction: The left atrial appendage (LAA) is the most common site of thrombus formation in atrial fibrillation (AF) patients who develop strokes, yet its dynamic volumetric parameters remain uncharacterized. We present a quantitative analysis of cardiac phase-specific LAA volumes and function using cardiac CT-derived three-dimensional (3D) models of 920 LAA segmentations. Methods: We measured LAA volumes at 10% increments of the cardiac cycle (R-R interval) in patients with AF and controls with sinus rhythm (SR). After identifying the LAA orifice using anatomical landmarks on multiplanar CT images, we performed computational LAA segmentation using specialized software. For precise mapping, we used iterative active region-growing and cutting tools to separate the LAA from surrounding structures. We used the resulting 3D model for volumetric assessment of the LAA during the cardiac cycle. Results: We analysed 580 LAA segmentations in patients with AF and 340 segmentations in patients with SR. Both groups displayed LAA volume increase from 0 to 40% of the cardiac cycle followed by a gradual decrease during diastole. LAA volumes were significantly higher in AF at 0%, 10%, 70%, 80%, and 90% of the cardiac cycle (p =0.01, 0.021, 0.047, 0.025 and 0.011, respectively). LAA volumetric variance within the AF group was significantly greater (p&lt;0.001). LAA ejection fraction was significantly lower in AF compared to SR (40.8±16.1% vs 49.7±12.6%, p=0.003). Polynomial plots of incremental volume changes showed an accelerated rate of LAA filling in early systole in the SR, which was significantly dampened in AF. Conclusions: We present the first comparative analysis of LAA volumetric and functional assessment in patients with AF and SR. We conclude that impaired LAA filling and emptying in AF can contribute to blood stasis and thrombogenicity. Further investigations into the utility of LAA metrics as prognostic and risk-stratification tools in patients with AF are warranted.

The Left Atrial Appendage and Atrial Fibrillation—A Contemporary Review

In patients with atrial fibrillation, the left atrial appendage may serve as the site of thrombus formation due to stasis that occurs within the appendage because of its shape and trabeculations. Although thrombus formation can be reduced by using anticoagulants, this may be contraindicated in some patients. The need for a better alternative treatment prompted the study of left atrial appendage occlusion for thromboembolism prophylaxis. Due to this, procedures that excise or occlude the left atrial appendage have gained attention because of their ability to prevent thromboembolic events. This article provides a comprehensive review of the left atrial appendage and its associated procedures’ clinical utility.

A Comparative Study of Thoracoscopic Left Atrial Appendage Clipping vs Stapled Resection

BackgroundThe left atrial appendage (LAA) is the predominant site of thrombus formation in atrial fibrillation (AF), which is associated with ischemic stroke. This study comparatively evaluated the complete LAA closure rates between LAA clipping and stapled resections. MethodsThe study included 333 patients who underwent thoracoscopic operation with both preoperative and postoperative computed tomographic scans. Propensity score matching (4:1 ratio) was applied, matching 90 LAA clipping patients with 206 stapled resection patients. The primary end point was complete LAA closure, defined as a residual LAA depth of <1 cm on computed tomographic images obtained 1 year postoperatively. ResultsNo 30-day death was observed. Complete LAA closure was achieved in 85.9% (286 of 333) of patients. After propensity score matching, the clipping group demonstrated a significantly higher complete LAA closure rate than the stapled resection group (95.6% vs 83.0%, P = .003). The residual LAA stump depth was also shorter in the clipping group compared with the stapled resection group (2.9 vs 5.3 mm, P = .001). Two patients with a residual LAA stump exhibited an association with ischemic stroke during follow-up. ConclusionsThe clipping group demonstrated a higher rate of complete LAA closure compared with the stapled resection group. Close monitoring of patients with residual LAA stumps is essential. Further research with larger cohorts is needed to elucidate impact of the residual LAA stump on thromboembolic events.

A correlation study between mean platelet volume and platelet aggregation study in acute coronary syndrome patients.

Platelets play an important role in cardiovascular disease mainly in the development of acute thrombotic events. Elevated platelet indices have been proposed as a risk factor for acute coronary syndrome (ACS). It remains uncertain whether increased platelet indices are the result or the cause of ACS. This study aimed to correlate mean platelet volume (MPV) and platelet aggregation response to know the functional status of platelets based on their size. A total of 50 patients with ST-segment elevation ACS (STE-ACS) or non-ST-segment elevation ACS (NSTE-ACS) were included and their MPV was measured and platelet aggregometry was performed. Patients were divided into two groups, patients with MPV ≤9.1 fl as group 1 and those with MPV >9.1 fl as group 2. The mean maximum platelet aggregation response (MMPAR) with ADP, Collagen, and Epinephrine, of both the groups, were compared. MMPAR to ADP, Collagen, and Epinephrine in group 1 was 74.47%, 66.13%, and 72.9%, respectively, and in group 2, 72.94%, 59.97%, and 72.43%, respectively. There was no statistically significant difference in the MMPAR to ADP, Collagen, and Epinephrine among the two groups. Increased MPV does not indicate the platelets are hyperreactive. An increase in MPV may be because of the increased release of immature platelets from bone marrow as there is increased consumption of platelets at the site of thrombus formation in ACS.

The WATCHMAN Device Review: A New Era for Stroke Prophylaxis.

Atrial fibrillation (AF) is a major risk factor for ischemic stroke, accounting for more than 37 million cases worldwide. In AF, the left atrial appendage (LAA) is the most common site of thrombus formation, and its ligation/closure with the WATCHMAN device is a good alternative to long-term oral anticoagulation, especially in patients with contraindications to warfarin. However, the implantation procedure is associated with various risks and complications. A short-term anticoagulant and antithrombotic administration are essential after implantation. However, no consensus has been reached on the optimal regimen. The WATCHMAN device is non-inferior to warfarin and is a safe alternative for the prevention of stroke and systemic embolization related to non-valvular atrial fibrillation (NVAF). Important procedure-related complications include pericardial effusion (PE), device embolization, procedure-related ischemic stroke, and device-related thrombosis (DRT) formation. It is essential to optimize post-implantation therapy according to individual patient bleeding risk, DRT formation, and contraindication to direct oral anticoagulants (DOACs). Recent studies have also shown that DOACs are a convenient and non-inferior substitute for warfarin. Furthermore, patients with absolute contraindications to OACs/DOACs can only be managed with dual antiplatelet therapy (DAPT). Transesophageal echocardiography (TEE) should be used to assess residual peridevice flow and possible DRT formation at days 45 and 12 months. Low molecular weight heparin (LMWH) and OAC are excellent choices for DRT treatment if detected. This review summarizes the most important complications of the WATCHMAN device in the existing literature and discusses various anticoagulation strategies and challenges post-implementation.

Assessment of left atrial appendage function by echocardiography.

The left atrial appendage (LAA) is considered not only to be the most frequent site of thrombus formation, but also to play a pivotal role in maintaining normal cardiac function. Transesophageal echocardiography (TEE) is widely used to assess LAA function. TheLAA flow velocityhasbeen used as a surrogate for LAA function, and it varies with multiple interrelated factors including age, hemodynamics, type of arrhythmia, and antiarrhythmic interventions. Relatively great importance ofLAA function is involved with intraatrial thrombus formation and subsequent thromboembolism, and thus, understanding of characteristics and behaviors of the LAA under various clinical conditions may help determine strategies against atrial thrombosis. Also, techniques other than TEE-derived Doppler to assess LAA function, such as tissue Doppler imaging, have been proposed. In this review, we introduce clinical and echocardiographic correlates of LAA function, the LAA flow velocity in particular, its significance, and how to interpret functional patterns of the LAA each relevant to specific clinical settings.

517 RIGHT ATRIAL THROMBUS IN A PATIENT WITH CARDIAC AMYLOIDOSIS: A MULTIMODALITY IMAGING APPROACH

Abstract Case Presentation A 47-year-old man was referred to our outpatient clinic for dyspnea and chest pain. His past medical history was remarkable for an admission of acute congestive heart failure, occurred two weeks before presentation. On that occasion, the patient was discharged after a few days of diuretic therapy. Diagnostic Workup at presentation, the patient was symptomatic for dyspnea with signs of systemic congestion. The ECG showed sinus rhythm, inferolateral negative T waves and absent progression of R wave in precordial leads. Transthoracic echocardiography revealed markedly thickened left ventricular (LV) walls (maximum interventricular septum dimension 19 mm) with a granular-sparkling appearance of the myocardium, bi-atrial enlargement, preserved LV ejection fraction, restrictive mitral flow pattern thickened interatrial septum and atrio-ventricular valves. No significant valvular regurgitations were detected. Global LV longitudinal strain was significantly reduced (-9.4%), with relative apical sparing. Given the high suspicion for infiltrative disease we performed further investigations. The cardiac computed tomography (CCT) excluded significant coronary artery disease, but it raised the suspicion of a thrombus at the level of the right atrial appendage, that was confirmed by a transesophageal echocardiography showing a mobile round mass of 14×12 mm. Finally, tissue characterization by cardiac magnetic resonance exhibit a diffuse myocardial delayed enhancement, with a dark blood pool and, an increase in extracellular volume and T1 mapping values (1266.3 ms). Laboratory tests showed increased levels of creatinine, BNP and, lambda light chains. Bone scintigraphy imaging didn't identify any uptake of radiotracers at myocardial level. These findings were suggestive for cardiac light-chain (AL) amyloidosis. Accordingly, a treatment with warfarin, beta-blockers, steroid, and diuretics was initiated. Conclusions cardiac amyloidosis is an infiltrative disease characterized by the deposition of aggregates of amyloid fibrils in the myocardium. Multimodality imaging is pivotal to determine the diagnosis, assess the potential complications, and stratify the patients’ prognosis. Our case demonstrates that cardiac AL amyloidosis is associated with an increased thromboembolic risk, irrespective of the presence of atrial fibrillation. Moreover, although the left atrial appendage is most frequently the site of thrombus formation, it is advised to look for them also in uncommon sites as the right atrial appendage.

Insights into Sickle Cell Disease through the Retinal Microvasculature: Adaptive Optics Scanning Light Ophthalmoscopy Correlates of Clinical OCT Angiography.

Clinical OCT angiography (OCTA) of the retinal microvasculature offers a quantitative correlate to systemic disease burden and treatment efficacy in sickle cell disease (SCD). The purpose of this study was to use the higher resolution of adaptive optics scanning light ophthalmoscopy (AOSLO) to elucidate OCTA features of parafoveal microvascular compromise identified in SCD patients. Case series of 11 SCD patients and 1 unaffected control. A total of 11 eyes of 11 SCD patients (mean age, 33 years; range, 23-44; 8 female, 3 male) and 1 eye of a 34-year-old unaffected control. Ten sequential 3 × 3 mm parafoveal OCTA full vascular slab scans were obtained per eye using a commercial spectral domain OCT system (Avanti RTVue-XR; Optovue). These were used to identify areas of compromised perfusion near the foveal avascular zone (FAZ), designated as regions of interest (ROIs). Immediately thereafter, AOSLO imaging was performed on these ROIs to examine the cellular details of abnormal perfusion. Each participant was imaged at a single cross-sectional time point. Additionally, 2 of the SCD patients were imaged prospectively 2 months after initial imaging to study compromised capillary segments across time and with treatment. Detection and characterization of parafoveal perfusion abnormalities identified using OCTA and resolved using AOSLO imaging. We found evidence of abnormal blood flow on OCTA and AOSLO imaging among all 11 SCD patients with diverse systemic and ocular histories. Adaptive optics scanning light ophthalmoscopy imaging revealed a spectrum of phenomena, including capillaries with intermittent blood flow, blood cell stasis, and sites of thrombus formation. Adaptive optics scanning light ophthalmoscopy imaging was able to resolve single sickled red blood cells, rouleaux formations, and blood cell-vessel wall interactions. OCT angiography and AOSLO imaging were sensitive enough to document improved retinal perfusion in an SCD patient 2 months after initiation of oral hydroxyurea therapy. Adaptive optics scanning light ophthalmoscopy imaging was able to reveal the cellular details of perfusion abnormalities detected using clinical OCTA. The synergy between these clinical and laboratory imaging modalities presents a promising avenue in the management of SCD through the development of noninvasive ocular biomarkers to prognosticate progression and measure the response to systemic treatment.

Association Between Ischemic Stroke and Left Atrial Appendage Morphology in Patients With Atrial Fibrillation and Low CHA2DS2-VASc Scores.

Patients with atrial fibrillation are at risk for ischemic stroke, even with low CHA2DS2-VASc scores. The left atrial appendage is a known site of thrombus formation in individuals with atrial fibrillation. We conducted a prospective study, enrolling patients with nonvalvular atrial fibrillation and CHA2DS2-VASc scores of 0 or 1. Patients were divided into groups based on left atrial appendage morphology (determined by computed tomography): the "chicken wing" group and the non-chicken wing group. We followed patients for more than 1 year to observe the incidence of stroke. Of 509 patients with a mean (SD) age of 48.9 (11.6) years; 332 (65.2%) were men. The chicken wing group had fewer left atrial appendage lobes, a lower left atrial appendage depth, and a smaller left atrial appendage orifice area (all P &lt; .001). During the follow-up period, 5 of the 133 patients (3.8%) in the chicken wing group and 56 of the 376 patients (14.9%) in the non-chicken wing group experienced ischemic stroke (P &lt; .001). The following findings were significantly associated with the incidence of stroke: left atrial appendage depth (hazard ratio [HR], 1.98; 95% CI, 1.67-3.12; P = .03), left atrial appendage orifice area (HR, 2.16; 95% CI, 1.59-3.13; P &lt; .001), and non-chicken wing left atrial appendage morphology (HR, 1.16; 95% CI, 1.10-1.23; P &lt; .001). For patients with atrial fibrillation and a low CHA2DS2-VASc score, the non-chicken wing left atrial appendage morphology type is independently associated with ischemic stroke.

Innovative experimental animal models for real-time comparison of antithrombogenicity between two oxygenators using dual extracorporeal circulation circuits and indocyanine green fluorescence imaging.

Antithrombogenicity of extracorporeal membrane oxygenation (ECMO) devices, particularly oxygenators, is a current problem, with numerous studies and developments underway. However, there has been limited progress in developing methods to accurately compare the antithrombogenicity of oxygenators. Animal experiments are commonly conducted to evaluate the antithrombogenicity of devices; however, it is challenging to maintain a steady experimental environment. We propose an innovative experimental animal model to evaluate different devices in a constant experimental environment in real-time. This model uses two venous-arterial ECMO circuits attached to one animal (one by jugular vein and carotid artery, one by femoral vein and artery) and real-time assessment of thrombus formation in the oxygenator by indocyanine green (ICG) fluorescence imaging. Comparison studies were conducted using three pigs: one to compare different oxygenators (MERA vs. CAPIOX) (Case 1), and two to compare antithrombotic properties of the oxygenator (QUADROX) when used under different hydrodynamic conditions (continuous flow vs. pulsatile flow) (Cases 2 and 3). Thrombi, visualized using ICG imaging, appeared as black dots on a white background in each oxygenator. In Case 1, differences in the site of thrombus formation and rate of thrombus growth were observed in real-time in two oxygenators. In Case 2 and 3, the thrombus region was smaller in pulsatile than in continuous conditions. We devised an innovative experimental animal model for comparison of antithrombogenicity in ECMO circuits. This model enabled simultaneous evaluation of two different ECMO circuits under the same biological conditions and reduced the number of sacrificed experimental animals.

Stroke risk evaluation for patients with atrial fibrillation: Insights from left atrial appendage.

Left atrial appendage (LAA) is believed to be a common site of thrombus formation in patients with atrial fibrillation (AF). However, the commonly-applied stroke risk stratification model (such as. CHA2DS2-VASc score) does not include any structural or hemodynamic features of LAA. Recent studies have suggested that it is important to incorporate LAA geometrical and hemodynamic features to evaluate the risk of thrombus formation in LAA, which may better delineate the AF patients for anticoagulant administration and prevent strokes. This review focuses on the LAA-related factors that may be associated with thrombus formation and cardioembolic events.

Real world outcomes of minimally invasive epicardial surgical left atrial appendage exclusion in atrial fibrillation patients with high risk of stroke and bleeding

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): AtriCure, Inc Introduction The left atrial appendage (LAA) is the site of thrombus formation in patients with atrial fibrillation (AF) and first line therapy for reducing the risk of stroke is oral anticoagulation (OACs). A subset of patients with AF carry a very high risk of stroke and bleeding and are ineligible for OAC and percutaneous LAA occlusion; these patients may be suitable for minimally invasive thoracoscopic epicardial surgical LAA exclusion (LAAE) which can be used with a wide variety of LAA morphologies with a ~98% rate of complete exclusion. While use of LAAE is well studied as a concomitant procedure, there are relatively few data on its use as a stand-alone procedure. Purpose To compare real-world outcomes of LAAE versus no-LAAE in AF patients at high risk of stroke and bleeding who are not on OACs. Methods We performed an analysis of Medicare beneficiaries with AF who were not on OACs and received LAAE (ICD10-PCS code 02L74CK, Oct 2015 – Dec 31, 2017) in the absence of a concomitant surgical or catheter AF ablation procedure. Patients were propensity-matched (1:4) to otherwise similar patients who did not receive LAAE (control), using age, gender, race, region, AF type, CHA2DS2-VASc, HAS-BLED, and co-morbidities. The primary endpoint was hospital readmission for a thromboembolic event (ischemic stroke, systemic embolism, or transient ischemic attack). Kaplan Meier event rates were calculated and 95% CI were generated via bootstrapping. Results A total of 243 patients who underwent LAAE and 1.7M control patients met study criteria. In the matched cohort, the mean age was 75 years, 61% were men, 77% had non-paroxysmal AF, and the mean CHADS2-VASC and HAS-BLED scores were 5.5 and 4.2, respectively. The 1-year rate of thromboembolism in the LAAE and control arms were 7.3% (95% CI 4.3% -10.9%) and 13.6 (95% CI 11.0% -16.4%) (Figure), respectively, with an absolute and relative risk reduction of 6.2% (95% CI 2.0-10.3, p-value=0.001, NNT 17) and 0.54 (95% CI 0.29-0.68, p=0.001). Conclusion Among high-risk AF patients who were not on OAC, LAAE was associated with a clinically meaningful and significantly lower risk of TE. Additional studies are needed to confirm these finding.

Capabilities of transesophageal echocardiography in patients with atrial fibrillation

Transesophageal echocardiography is widely used in clinical practice in patients with atrial fibrillation and it is mainly applied to determine the morphology of the heart, the presence of intracardiac thrombi, quantify the structures of the heart, as well as to determine the tactics for surgical interventions. Transesophageal echocardiography has an advantage over transthoracic echocardiography in visualizing the left atrium and left atrial appendage, common sites of thrombus formation in patients with atrial fibrillation. Due to the anatomical proximity of the esophagus to the heart, the transesophageal access avoids signal fading and incorrect interpretation of the study results. The possibilities of transesophageal echocardiography in patients with atrial fibrillation have expanded with the development of medical technology, and three-dimensional transesophageal echocardiography has become widespread. In recent years, the studies on the use of the transesophageal echocardiography in patients with atrial fibrillation during the coronavirus pandemic have been published. The review presents the results of studies, meta-analyzes of pooled samples, as well as clinical cases, demonstrating capabilities of transesophageal echocardiography in patients with atrial fibrillation. A brief history of the development of the method, work on the study of the technology features and capabilities of transesophageal echocardiography for pulmonary vein ablation, cardioversion, occlusion of the left atrial appendage in patients with atrial fibrillation, as well as studies on disadvantages of the transesophageal echocardiography and possible options for their elimination are presented. Comparison of the transesophageal echocardiography with transthoracic and intracardial echocardiography is also highlighted. In preparing the review, the literature search method in PubMed databases for the period 20122021 was used, as well as data from an earlier period to indicate the history of the method development.

A Comparison of the Accuracy of WATCHMAN and WATCHMAN FLX Device Sizing between CT, TEE, and Patient Specific 3D Models

Background and Hypothesis: In patients with Atrial fibrillation (AF), the Left Atrial Appendage (LAA) is the most common site of thrombus formation. The LAA occlusion procedure using the WATCHMAN device implant is an alternative for stroke prevention in AF patients. Transesophageal echocardiogram (TEE) and Computed tomography (CT) scans aid in measuring the LAA to predict implant device sizes. However, due to varying LAA anatomy and limited spatial resolution, the current imaging techniques often predict one of two sized devices. The objective of this retrospective study is to compare the accuracy of measurements made preoperatively of the LAA with those on 3D models to determine if they can be used in preoperative planning. We hypothesize 3D models will be more accurate in predicting device size and any anatomical impediments than traditional TEE planning.&#x0D; Project Methods: There were 21 subjects selected who underwent the WATCHMAN FLX procedure at Parkview Heart Institute in 2021. 3D models of LAA were created from CT scans using a Form 2 3D printer. The device sizes predicted for the procedure were determined from Boston Scientific FLX guidelines based on the maximum LAA orifice diameter from TEE, CT, and 3D models.&#x0D; Results: Two-proportion z-test between the 3D model predicted sizes to the actual size deployed demonstrated no statistical significance (p=0.298) demonstrating no difference between 3D model predicted sizes and actual size deployed. Two-proportion z-test between TEE vs actual size and CT vs actual size demonstrated statistical significance, suggesting a difference between the group's predictions. 3D models predicted the accurate device size for 20/21(95%) subjects. TEE measurements of maximum orifice diameter were, on average, lower compared to CT and 3D model measurements.&#x0D; Conclusion and Potential Impact: 3D printed models provide the most accurate device size predictions and can be used to optimize presurgical planning while reducing intraoperative complications.