We introduce a multiphysics and geometric multiscale computational model, suitable to describe the hemodynamics of the whole human heart, driven by a four-chamber electromechanical model. We first present a study on the calibration of the biophysically detailed RDQ20 activation model (Regazzoni et al., 2020) that is able to reproduce the physiological range of hemodynamic biomarkers. Then, we demonstrate that the ability of the force generation model to reproduce certain microscale mechanisms, such as the dependence of force on fiber shortening velocity, is crucial to capture the overall physiological mechanical and fluid dynamics macroscale behavior. This motivates the need for using multiscale models with high biophysical fidelity, even when the outputs of interest are relative to the macroscale. We show that the use of a high-fidelity electromechanical model, combined with a detailed calibration process, allows us to achieve remarkable biophysical fidelity in terms of both mechanical and hemodynamic quantities. Indeed, our electromechanical-driven CFD simulations - carried out on an anatomically accurate geometry of the whole heart - provide results that match the cardiac physiology both qualitatively (in terms of flow patterns) and quantitatively (when comparing in silico results with biomarkers acquired in vivo). We consider the pathological case of left bundle branch block, and we investigate the consequences that an electrical abnormality has on cardiac hemodynamics thanks to our multiphysics integrated model. The computational model that we propose can faithfully predict a delay and an increasing wall shear stress in the left ventricle in the pathological condition. The interaction of different physical processes in an integrated framework allows us to faithfully describe and model this pathology, by capturing and reproducing the intrinsic multiphysics nature of the human heart.

翻译：我们提出了一种多物理场与几何多尺度计算模型，适用于描述由四腔电机械模型驱动的人体心脏血流动力学。首先展示了基于生物物理细节的RDQ20激活模型（Regazzoni等，2020）的校准研究，该模型能复现血流动力学生物标志物的生理范围。继而证明：力生成模型在复现微观机制（如力对纤维缩短速度的依赖性）方面的能力，对捕捉整体生理力学与流体动力学宏观行为至关重要。这凸显了使用高生物物理保真度多尺度模型的必要性——即使研究目标输出仅涉及宏观尺度。研究表明，采用高保真电机械模型结合精细校准流程，可在力学与血流动力学两方面实现显著的生物物理保真度。事实上，基于全心脏解剖精确几何结构的电机械驱动CFD仿真，既能在定性层面（流场模式）也能在定量层面（将仿真结果与体内生物标志物对比）匹配心脏生理学。我们针对左束支传导阻滞病理案例展开研究，借助多物理场集成模型探究电异常对心脏血流动力学的影响。所提计算模型能准确预测病理状态下左心室的延迟收缩与壁剪切应力升高。通过在集成框架中耦合不同物理过程，该模型能忠实描述并复现人类心脏固有的多物理场特性，从而有效建模该病理机制。