Endocardial left atrial appendage occlusion in atrial fibrillation: computational fluid dynamics simulations to assess stroke risk

Abstract Funding Acknowledgements Type of funding sources: None. Background Percutaneous endocardial left atrial appendage (LAA) occlusion (LAAO) in non-valvular atrial fibrillation (AF) seems comparable to anticoagulation therapy (OAC) as regards thromboembolic risk reduction with a possible additional decrease in major bleeding. LAAO is currently limited to patients with contraindications to OAC, due to its high costs and procedural risks, but better pre-procedural planning and operative techniques might improve the outcome widening practical indications. Computational fluid dynamics (CFD) represents a valuable non-invasive approach to estimate physiologically significant hemodynamic parameters in a complex fluid dynamics system. It might provide a helpful in silico simulation of blood flow patterns within the LA and LAA by using 3D patient-specific models, allowing LAAO planning and effects prediction. Purpose This study’s aim was to simulate the fluid dynamics effects of LAAO in AF patients to predict patient-specific hemodynamic changes caused by applying the two most popular devices. Methods LAAO was simulated on the 3D LA anatomical models obtained from CT data in 5 AF patients, considering the device specific shape. CFD simulations in AF condition were performed both on the whole LA model and on the models with the LAAO performed with the two devices. Significant fluid dynamics indices (blood velocity, vortex structures, LAA ostium velocity, LA blood stasis) were computed to evaluate the changes in the flow patterns after LAAO in relation to the thrombogenic risk. Results Overall we found a more effective washout within the LA after LAAO, in terms of a different spatial distribution of velocities (see figure for a qualitative evaluation of LA blood flow velocity in one patient: (A) model with LA and LAA; models after LAAO applying the Amulet (B) and the Watchman (C) device) and vortex structures (after LAAO, they were decreased in number and increased in size). Moreover, a higher velocity at the mitral valve and at the LAA ostium (peak velocity: 12-17 cm/s in the models with LAA, 40-60 cm/s in LAAO_A and 35-65 in LAAO_W) was detected together with a slightly improved washout effect in terms of blood stasis with the Watchman device (stasis: 3.1-5.7% in the models with LAA, 1.9-4.1% in LAAO_A, 1.7-3.7% in LAAO_W). Conclusions A workflow for simulating the fluid dynamics effects of endocardial LAAO in AF was developed and tested. CFD provides a valuable tool to quantify hemodynamic changes after LAAO and assess thrombogenic risk in patient-specific LA and LAA. Our preliminary results suggest that endocardial LAAO favourably affects blood fluid dynamics in the LA. Abstract figure

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DEVELOPMENT OF A NOVEL COMPUTATIONAL FLUID DYNAMICS MODEL APPLIED ON CARDIAC COMPUTED TOMOGRAPHY FOR ASSESSMENT OF REGIONAL HEMODYNAMIC CHANGES IN THE LEFT ATRIAL APPENDAGE DURING ATRIAL FIBRILLATION OR SINUS RHYTHM

Journal of the American College of Cardiology ◽

10.1016/s0735-1097(20)34121-8 ◽

2020 ◽

Vol 75 (11) ◽

pp. 3494

Author(s):

Ioanna Kosmidou ◽

Grigoris Grigoriadis ◽

Antonis Sakellarios ◽

Mengdan Liu ◽

Katerina Naka ◽

...

Keyword(s):

Fluid Dynamics ◽

Computed Tomography ◽

Atrial Fibrillation ◽

Computational Fluid Dynamics ◽

Left Atrial ◽

Left Atrial Appendage ◽

Cardiac Computed Tomography ◽

Dynamics Model ◽

Hemodynamic Changes ◽

Computational Fluid Dynamics Model

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The Value of 3D Printing Models of Left Atrial Appendage Using Real-Time 3D Transesophageal Echocardiographic Data in Left Atrial Appendage Occlusion: Applications toward an Era of Truly Personalized Medicine

Cardiology ◽

10.1159/000447444 ◽

2016 ◽

Vol 135 (4) ◽

pp. 255-261 ◽

Cited By ~ 22

Author(s):

Peng Liu ◽

Rijing Liu ◽

Yan Zhang ◽

Yingfeng Liu ◽

Xiaoming Tang ◽

...

Keyword(s):

Atrial Fibrillation ◽

3D Printing ◽

Real Time ◽

Left Atrial ◽

Left Atrial Appendage ◽

3D Models ◽

Atrial Appendage ◽

Patient Specific ◽

The Real ◽

Echocardiographic Image

Aims and Objectives: The objective of this study was to assess the clinical feasibility of generating 3D printing models of left atrial appendage (LAA) using real-time 3D transesophageal echocardiogram (TEE) data for preoperative reference of LAA occlusion. Background: Percutaneous LAA occlusion can effectively prevent patients with atrial fibrillation from stroke. However, the anatomical structure of LAA is so complicated that adequate information of its structure is essential for successful LAA occlusion. Emerging 3D printing technology has the demonstrated potential to structure more accurately than conventional imaging modalities by creating tangible patient-specific models. Typically, 3D printing data sets are acquired from CT and MRI, which may involve intravenous contrast, sedation, and ionizing radiation. It has been reported that 3D models of LAA were successfully created by the data acquired from CT. However, 3D printing of the LAA using real-time 3D TEE data has not yet been explored. Methods: Acquisition of 3D transesophageal echocardiographic data from 8 patients with atrial fibrillation was performed using the Philips EPIQ7 ultrasound system. Raw echocardiographic image data were opened in Philips QLAB and converted to ‘Cartesian DICOM' format and imported into Mimics® software to create 3D models of LAA, which were printed using a rubber-like material. The printed 3D models were then used for preoperative reference and procedural simulation in LAA occlusion. Results: We successfully printed LAAs of 8 patients. Each LAA costs approximately CNY 800-1,000 and the total process takes 16-17 h. Seven of the 8 Watchman devices predicted by preprocedural 2D TEE images were of the same sizes as those placed in the real operation. Interestingly, 3D printing models were highly reflective of the shape and size of LAAs, and all device sizes predicted by the 3D printing model were fully consistent with those placed in the real operation. Also, the 3D printed model could predict operating difficulty and the presence of a peridevice leak. Conclusions: 3D printing of the LAA using real-time 3D transesophageal echocardiographic data has a perfect and rapid application in LAA occlusion to assist with physician planning and decision making.

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Non-Pharmacological Therapy for Atrial Fibrillation: Managing the Left Atrial Appendage

Cardiology Research and Practice ◽

10.1155/2012/304626 ◽

2012 ◽

Vol 2012 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Sushil Allen Luis ◽

Damian Roper ◽

Alexander Incani ◽

Karl Poon ◽

Haris Haqqani ◽

...

Keyword(s):

Atrial Fibrillation ◽

Blood Flow ◽

Blood Flow Velocity ◽

Left Atrial ◽

Left Atrial Appendage ◽

Thrombus Formation ◽

Pharmacological Therapy ◽

Atrial Appendage ◽

Ageing Population ◽

Increased Risk

The prevalence of atrial fibrillation (AF) is increasing in parallel with an ageing population leading to increased morbidity and mortality. The most feared complication of AF is stroke, with the arrhythmia being responsible for up to 20% of all ischemic strokes. An important contributor to this increased risk of stroke is the left atrial appendage (LAA). A combination of the LAA's unique geometry and atrial fibrillation leads to low blood flow velocity and stasis, which are precursors to thrombus formation. It has been hypothesized for over half a century that excision of the LAA would lead to a reduction in the incidence of stroke. It has only been in the last 20–25 years that the knowledge and technology has been available to safely carry out such a procedure. We now have a number of viable techniques, both surgical and percutaneous, which will be covered in this paper.

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Demonstration of Patient-Specific Simulations to Assess Left Atrial Appendage Thrombogenesis Risk

Frontiers in Physiology ◽

10.3389/fphys.2021.596596 ◽

2021 ◽

Vol 12 ◽

Author(s):

Manuel García-Villalba ◽

Lorenzo Rossini ◽

Alejandro Gonzalo ◽

Davis Vigneault ◽

Pablo Martinez-Legazpi ◽

...

Keyword(s):

Residence Time ◽

Left Atrial ◽

Left Atrial Appendage ◽

Blood Stasis ◽

Bleeding Risk ◽

Atrial Appendage ◽

Patient Specific ◽

Immersed Boundary ◽

Moving Wall ◽

And Function

Atrial fibrillation (AF) alters left atrial (LA) hemodynamics, which can lead to thrombosis in the left atrial appendage (LAA), systemic embolism and stroke. A personalized risk-stratification of AF patients for stroke would permit improved balancing of preventive anticoagulation therapies against bleeding risk. We investigated how LA anatomy and function impact LA and LAA hemodynamics, and explored whether patient-specific analysis by computational fluid dynamics (CFD) can predict the risk of LAA thrombosis. We analyzed 4D-CT acquisitions of LA wall motion with an in-house immersed-boundary CFD solver. We considered six patients with diverse atrial function, three with either a LAA thrombus (removed digitally before running the simulations) or a history of transient ischemic attacks (LAAT/TIA-pos), and three without a LAA thrombus or TIA (LAAT/TIA-neg). We found that blood inside the left atrial appendage of LAAT/TIA-pos patients had marked alterations in residence time and kinetic energy when compared with LAAT/TIA-neg patients. In addition, we showed how the LA conduit, reservoir and booster functions distinctly affect LA and LAA hemodynamics. Finally, fixed-wall and moving-wall simulations produced different LA hemodynamics and residence time predictions for each patient. Consequently, fixed-wall simulations risk-stratified our small cohort for LAA thrombosis worse than moving-wall simulations, particularly patients with intermediate LAA residence time. Overall, these results suggest that both wall kinetics and LAA morphology contribute to LAA blood stasis and thrombosis.

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CLINICAL CASE OF RESUMPTION OF ANTICOAGULANT THERAPY AFTER IMPLANTATION OF THE AMPLATZER CARDIAC PLUG LEFT ATRIAL APPENDAGE OCCLUDER

Atherothrombosis Journal ◽

10.21518/2307-1109-2019-1-82-91 ◽

2019 ◽

pp. 82-91

Author(s):

R. V. Guchaev ◽

D. V. Pevzner ◽

E. V. Merkulov ◽

M. I. Makeev ◽

N. S. Zhukova ◽

...

Keyword(s):

Risk Factors ◽

Atrial Fibrillation ◽

Blood Flow ◽

Anticoagulant Therapy ◽

Left Atrial ◽

Clinical Case ◽

Left Atrial Appendage ◽

Atrial Appendage ◽

Thromboembolic Complications ◽

Thrombosis Risk

The article demonstrates a clinical case of forced renewal of anticoagulant therapy after the endovascular closure of the left atrial appendage. Patient with atrial fibrillation and high risk of thromboembolic complications and bleeding on the background of warfarin administration and inappropriate INR values had an acute hemorrhagic cerebral blood flow disorder developed. Endovascular closure of the left atrial appendage was performed. However, the thrombosis of the area of the delivery system fastening revealed after 12 months was an indication for the resumption of anticoagulant therapy.The article presents modern data on the use of occluders for closing the left atrial appendage, the frequency of complications and antiplatelet therapy schemes depending on the presence of thrombosis risk factors and bleeding.

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Deep Learning Surrogate of Computational Fluid Dynamics for Thrombus Formation Risk in the Left Atrial Appendage

Statistical Atlases and Computational Models of the Heart. Multi-Sequence CMR Segmentation, CRT-EPiggy and LV Full Quantification Challenges - Lecture Notes in Computer Science ◽

10.1007/978-3-030-39074-7_17 ◽

2020 ◽

pp. 157-166

Author(s):

Xabier Morales ◽

Jordi Mill ◽

Kristine A. Juhl ◽

Andy Olivares ◽

Guillermo Jimenez-Perez ◽

...

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Deep Learning ◽

Left Atrial ◽

Left Atrial Appendage ◽

Thrombus Formation ◽

Atrial Appendage

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Abstract 16439: Is Pulmonary Venous Flow Pulsatility a Critical Determinant of Left Atrial Appendage Blood Stasis Risk?

Circulation ◽

10.1161/circ.142.suppl_3.16439 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Soroosh Sanatkhani ◽

Sotirios Nedios ◽

Sandeep K Jain ◽

Samir Saba ◽

Prahlad G Menon ◽

...

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Left Atrial ◽

Left Atrial Appendage ◽

Blood Stasis ◽

Atrial Appendage ◽

Cfd Analysis ◽

Computed Tomography Images ◽

Subject Specific ◽

Flow Pulsatility

Introduction: Atrial fibrillation (AF) is the most common arrhythmia that leads to thrombus formation, most commonly in the left atrial appendage (LAA), and a resultant five-fold increase in the risk of ischemic stroke. The current standard of stratifying stroke risk, based on the CHA 2 DS 2 -VASc score, does not consider subject-specific LAA hemodynamics and blood stasis risk. We have developed a methodology for computing mean residence time of blood-borne particles in the LAA ( t m ), an index of LAA blood stasis, using 3D left atrial (LA) and LAA geometries and pulmonary venous (PV) inlet blood flow data. While subject-specific 3D geometry can be obtained readily, it is not easy to measure all LA inlet blood flow waveforms in vivo . Therefore, a sensitivity study of LAA t m to the inlet blood flow waveform characteristics (shape and magnitude) is needed. Hypothesis: PV flow pulsatility does not affect LAA t m . Methods: Cardiac computed tomography images of 10 AF subjects were obtained and LA and LAA geometries were reconstructed in 3D and subsequently meshed for computational fluid dynamics (CFD) analysis. We employed CFD analysis, modeling blood cells as neutrally buoyant tracers transported in the blood and used a systems-based approach, to quantify LAA t m . Each subject was simulated using four PV blood flow characteristics: (1) Normal-S , steady PV flow with cardiac output (CO) of 5.5 L/min; (2) AF-S , steady PV flow with reduced CO of 4.4 L/min; (3) Normal-P , normal pulsatile PV flow with normal CO = 5.5 L/min; and (4) AF-P , a typical AF pulsatile waveform where systolic phase and the reversal phase are diminished with reduced CO of 4.4 L/min. Results: Comparing the two steady flow groups, LAA t m significantly increased as CO was decreased ( Normal-S: 2.6±0.3 s, AF-S: 3.1±0.3 s, P =0.02). However, the presence of pulsatility did not affect LAA t m at both levels of CO: Normal-P: 2.4±0.2 s; Normal-S: 2.6±0.3 s, P =0.2 and AF-P: 2.9±0.3 s; AF-S: 3.1±0.3 s, P =0.3. Conclusions: LAA blood stasis risk, as quantified by LAA t m , is significantly affected by the steady PV flow magnitude (i.e., cardiac output) and not by PV flow pulsatility. Therefore, the subject-specific LAA blood stasis risk can be reliably estimated using subject-specific LA and LAA 3D geometries and subject-specific CO.

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