Parker Louis, Bollache Emilie, Soulez Shannon, Bouazizi Khaoula, Badenco Nicolas, Giese Daniel, Gandjbakhch Estelle, Redheuil Alban, Laredo Mikael, Kachenoura Nadjia
Laboratoire d'Imagerie Biomédicale (LIB), Institut National de La Recherche Médicale (INSERM), Centre National de La Recherche Scientifique (CNRS), Sorbonne Université, Paris, France.
ICAN Imaging, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France.
Biomech Model Mechanobiol. 2025 Feb;24(1):139-152. doi: 10.1007/s10237-024-01901-y. Epub 2025 Jan 19.
Atrial fibrillation (AF) is characterized by rapid and irregular contraction of the left atrium (LA). Impacting LA haemodynamics, this increases the risk of thrombi development and stroke. Flow conditions preceding stroke in these patients are not well defined, partly due the limited resolution of 4D flow magnetic resonance imaging (MRI). In this study, we combine a high-resolution computed tomography (CT) LA reconstruction with motion and pulmonary inflows from 4D flow MRI to create a novel multimodal computational fluid dynamics (CFD) model, applying it to five AF patients imaged in sinus rhythm (24 ± 39 days between acquisitions). The dynamic model was compared with a rigid wall equivalent and the main flow structures were validated with 4D flow MRI. Point-by-point absolute differences between the velocity fields showed moderate differences given the sensitivity to registration. The rigid wall model significantly underestimated LA time-averaged wall shear stress (TAWSS) (p = 0.02) and oscillatory shear index (OSI) (p = 0.02) compared to the morphing model. Similarly, in the left atrial appendage (LAA), TAWSS (p = 0.003) and OSI (p < 0.001) were further underestimated. The morphing model yielded a more accurate mitral valve waveform and showed low TAWSS and high OSI in the LAA, both associated with thrombus formation. We also observed a positive correlation between indexed LA volume and endothelial cell activation potential (ECAP) (R = 0.83), as well as LAA volume and LAA OSI (R = 0.70). This work demonstrates the importance of LA motion in modelling LAA flow. Assessed in larger cohorts, LAA haemodynamic analysis may be beneficial to refine stroke risk assessment for AF.
心房颤动（AF）的特征是左心房（LA）快速且不规则收缩。这会影响左心房血流动力学，增加血栓形成和中风的风险。这些患者中风前的血流状况尚未明确界定，部分原因是四维血流磁共振成像（MRI）的分辨率有限。在本研究中，我们将高分辨率计算机断层扫描（CT）左心房重建与来自四维血流MRI的运动和肺血流相结合，创建了一种新的多模态计算流体动力学（CFD）模型，并将其应用于五名窦性心律成像的房颤患者（两次采集之间间隔24±39天）。将动态模型与等效刚性壁模型进行比较，并用四维血流MRI验证主要血流结构。考虑到配准的敏感性，速度场之间的逐点绝对差异显示出中等差异。与变形模型相比，刚性壁模型显著低估了左心房时间平均壁面切应力（TAWSS）（p = 0.02）和振荡切变指数（OSI）（p = 0.02）。同样，在左心耳（LAA）中，TAWSS（p = 0.003）和OSI（p < 0.001）被进一步低估。变形模型产生了更准确的二尖瓣波形，并且在左心耳中显示出低TAWSS和高OSI，这两者都与血栓形成有关。我们还观察到左心房指数体积与内皮细胞活化潜能（ECAP）之间存在正相关（R = 0.83），以及左心耳体积与左心耳OSI之间存在正相关（R = 0.70）。这项工作证明了左心房运动在模拟左心耳血流中的重要性。在更大的队列中进行评估，左心耳血流动力学分析可能有助于完善房颤的中风风险评估。
