The deformation of the left atrium (LA), or its biomechanical function, is closely linked to the health of this cardiac chamber. In atrial fibrillation (AF), atrial biomechanics are significantly altered but the underlying cause of this change is not always clear. Patient-specific models of the LA that replicate patient atrial motion can allow us to understand how factors such as atrial anatomy, myocardial stiffness and physiological constraints are linked to atrial biomechanics. We created patient-specific LA models from CT images. We fitted regional model stiffness to peak CT-derived deformation during the LA reservoir phase ($\pm0.90$ mm) and used the CT deformation transients through the reservoir and conduit phase for model validation (deformation transients fell within $\pm0.38$ mm per unit time of targets). We found that myocardial stiffness varies regionally across the LA. The regional stiffness values were significant factors contributing to regional physiological LA deformation ($p=0.023$) while features of LA anatomy, including regional wall thickness and adipose volume, were less important. These findings provide insight into the underlying causes of altered LA biomechanics in AF.

翻译：左心房（LA）的变形或其生物力学功能与该心腔的健康状况密切相关。在心房颤动（AF）中，心房生物力学发生显著改变，但这种变化的根本原因并不总是明确的。能够复现患者心房运动的患者特异性左心房模型，使我们能够理解心房解剖结构、心肌硬度及生理约束等因素如何与心房生物力学相关联。我们基于CT图像构建了患者特异性左心房模型。我们将模型的区域性硬度拟合至左心房储器期CT衍生的峰值变形（$\pm0.90$ mm），并利用储器期和通道期的CT变形瞬态数据进行模型验证（变形瞬态数据落在目标值每单位时间$\pm0.38$ mm范围内）。我们发现心肌硬度在左心房内存在区域性差异。区域性硬度值是导致区域性生理性左心房变形的重要因素（$p=0.023$），而左心房解剖结构特征，包括区域性壁厚和脂肪体积，则重要性较低。这些发现为理解心房颤动中左心房生物力学改变的根本原因提供了见解。