DataSheet1_Left atrial appendage occlusion in ventricular assist device patients to decrease thromboembolic events: A computer simulation study.PDF

Atrial fibrillation (AF) is a common comorbidity in left ventricular assist device (LVAD) patients and has been identified as a risk factor for thromboembolic stroke. Blood stagnation within the left atrial appendage (LAA) is considered a possible major source of thrombosis and clinical studies have shown reduced thromboembolic risk after LAA occlusion (LAAO). Therefore, this study aims to investigate the effect of LAAO on thrombosis-related parameters using patient-specific simulations. Left ventricular and left atrial geometries of an LVAD patient were obtained from computed tomography and combined with hemodynamic data with either sinus rhythm (SR) or AF generated by a lumped parameter model. In four simulations applying contractile walls, stagnation volume and blood residence times were evaluated with or without AF and with or without LAAO. Reduced atrial contraction in AF resulted in unfavorable flow dynamics within the left atrium. The average atrial velocity was lower for the AF simulation when compared to SR, resulting in a 55% increase in the atrial stagnation volume (from 4.2 to 6.5 cm3). Moreover, blood remained in the LAA for more than 8 cardiac cycles. After LAAO the atrial stagnation decreased from 4.2 to 1.4 cm3 for SR and from 6.5 to 2.3 cm3 for the AF simulation. A significant stagnation volume was found in the LAA for both SR and AF, with larger values occurring with AF. These regions are known as potential sources for thrombus formation and can be diminished by LAAO. This significantly improved the thrombus-related flow parameters and may also lower the risk of thromboembolic events from the appendage.

心房颤动（Atrial fibrillation, AF）是左心室辅助装置（left ventricular assist device, LVAD）患者常见的合并症，且已被证实为血栓栓塞性卒中的危险因素。左心耳（left atrial appendage, LAA）内的血液淤滞被认为是血栓形成的主要潜在来源，临床研究表明，实施左心耳封堵术（LAA occlusion, LAAO）后，患者的血栓栓塞风险有所降低。因此，本研究旨在通过患者特异性模拟，探究左心耳封堵术对血栓形成相关参数的影响。
本研究从计算机断层扫描影像中获取了一名左心室辅助装置患者的左心室及左心房几何模型，并结合由集总参数模型生成的窦性心律（sinus rhythm, SR）或心房颤动状态下的血流动力学数据。本研究共开展四组收缩壁模拟实验，分别在有无心房颤动、有无左心耳封堵术的条件下，对血液淤滞容积与血液驻留时间进行评估。
心房颤动状态下心房收缩减弱，导致左心房内血流动力学状态恶化。与窦性心律模拟组相比，心房颤动模拟组的平均心房流速更低，致使心房淤滞容积增加55%（从4.2 cm³升至6.5 cm³）。此外，血液在左心耳内的驻留时间超过8个心动周期。
实施左心耳封堵术后，窦性心律组的心房淤滞容积从4.2 cm³降至1.4 cm³，心房颤动模拟组则从6.5 cm³降至2.3 cm³。无论处于窦性心律还是心房颤动状态，左心耳内均存在显著的淤滞容积区域，且心房颤动状态下该区域面积更大。上述区域被认为是血栓形成的潜在源头，而左心耳封堵术可有效缩小此类区域，显著改善与血栓形成相关的血流动力学参数，或可降低源自左心耳的血栓栓塞事件风险。