Proceedings of the 9th World Congress on Momentum, Heat and Mass Transfer (MHMT'24)
London, United kingdom – April 11 – 13, 2024
Paper No. ENFHT 264
DOI: 10.11159/enfht24.264

The Impact of Left Atrial Morphology on Thrombosis Risk in Atrial
Fibrillation: revisiting Virchow’s Triad1

Yan Wang1, Kun Luo1, Jianren Fan1

State Key Laboratory of Clean Energy Utilization, Zhejiang University
Hangzhou, China
3150102590@zju.edu.cn; zjulk@zju.edu.cn; fanjr@zju.edu.cn

Extended Abstract

Objectives: 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 by a five-fold increase. The left atrial appendage(LAA) is a vital site for thrombus formation due to the high blood stasis possibility there. It is reported that about 90 % of
the intracardiac thrombi in patients with cardioembolic events is derived from the LAA. The morphology of the LAA isbelieved to have a profound effect on thrombosis in the LA [1]. 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, statingthat endothelial dysfunction, blood hypercoagulability and blood stasis are the three main factors involved in thrombus
formation. As Virchow’s triad has withstood the test of time, it may be conductive to understand the prothrombotic state inAF.
Methods: Personalized Computational fluid dynamics (CFD) analysis has been conducted for twelve AF patients basedon their medical images to get patient-specific hemodynamic parameters information. Among them, LAA thrombus isobserved in four patients and none in the others. A consistent flowrate curve is applied at the mitral valve outlet and zeropressure is assumed at all pulmonary vein inlets. Besides, a reduced coagulation cascade model we developed before [2] wasloaded to simulate the coagulation response occurring in the LAA. The performance of Virchow’s triad is estimated basedon the simulation results: endothelial dysfunction is evaluated by the distributions of endothelial cell activation potential(ECAP), blood hypercoagulability is commented based on the concentrations of coagulation factors, whereas the blood stasis
is assessed by the distributions of velocity and relative residence time (RRT). As these three factors interact with each otherto jointly regulate the formation of thrombus in the LAA, separate and comprehensive comparisons of these three factors is
also carried out based on thrombosis potential scores.
Results: The simulation results show that the LAA is more prone to thrombosis than the main region of LA, because of
the lower blood flow velocity and significantly higher ECAP values there, which indicates a higher risk of blood stasis andendothelial dysfunction, respectively. The comprehensive scores of thrombosis potential in patients with LAA thrombus are
significantly higher than that in patients without LAA thrombus, indicating that the thrombogenic mechanism in LAA canbe well analysed and explained by Virchow’s triad. Furthermore, the potential of the proposed comprehensive score toimprove stroke risk classification in patients with AF is also demonstrated. The morphology of LA has a significant influenceon the performance of the three factors in Virchow’s triad. However, the correlation between the performance of these threefactors and the morphological type of LAA is weak, whether analysed individually or in combination. Therefore, if we wantto quickly score LAA thrombosis risk in AF patients from the perspective of Virchow’s triad, we need a more refined shapescore that can better reflect patient-specific LA (including LAA) morphological features.

References[1] A. Masci, L. Barone, L. Dede, M. Fedele, C. Tomasi, A.Quarteroni, and C. Corsi, "The Impact of Left Atrium
Appendage Morphology on Stroke Risk Assessment in Atrial Fibrillation: A Computational Fluid Dynamics Study,"
Front Physiol, vol. 9, pp. 1938, 2018[2] Y. Wang, JY. Wang, K. Luo, JR. Fan, and T. Zhu, "Model reduction of coagulation cascade based on genetic algorithm,"
Int J Numer Method Biomed Eng, vol. 38, no. 11, pp. e3652, 2022

ENFHT 264-1