Abstract：
Numerical models of the cardiovascular system have largely focused on the function of the ventricles, with atrial function often neglected. Furthermore, the time-varying elastance method that prescribes the pressure-volume relationship rather than calculating it consistently is frequently used for the ventricles and atrium. This method has yet to be validated however, so its applicability for cardiac modelling is frequently questioned. To overcome this challenge, we propose a synergistic model of left atrium (LA) and left ventricle (LV) by self-consistently integrating various feedback mechanisms among the electro-mechanical and chemical functions of the micro-scale myofiber, the macro-scale dynamics of the LA and LV, the atrioventricular node (AV), and circulation. The model is tested and shown to reproduce the essential features of the atrium cycling, such as the characteristic figure of eight pressure-volume loops. Our model is further developed to investigate the effect of dysfunctions of the mechanical-electric feedback (MEF) in the atrium. Our model not only successfully reproduces key experimental MEF observations such as prolonged action-potential and increases in action-potential magnitude induced by atrial stretch but also shows how MEF and arrhythmia of the atrium lead to a degradation of cardiac output and pumping power with significant consequences. In particular, MEF reproduces arrhythmia such as ectopic and erratic cycling, missed heart beats and restricted function.
摘要：
心血管系统的数值模型主要集中在心室的功能上，与心房功能经常被忽视。此外，规定压力-容积关系而不是一致计算的时变弹性方法经常用于心室和心房。然而，这种方法尚未得到验证，因此，它在心脏建模中的适用性经常受到质疑。为了克服这一挑战，我们提出了左心房（LA）和左心室（LV）的协同模型，通过自洽地整合微尺度肌纤维的机电和化学功能之间的各种反馈机制，LA和LV的宏观动力学，房室结（AV），和流通。该模型经过测试和显示，可以重现心房循环的基本特征，例如八个压力-容积回路的特征图。进一步开发了我们的模型，以研究心房中机电反馈（MEF）功能障碍的影响。我们的模型不仅成功地再现了关键的实验性MEF观察结果，例如延长的动作电位和心房牵张引起的动作电位幅度的增加，而且还显示了MEF和心房的心律失常如何导致心输出量和泵送功率的下降，并产生重大后果。特别是,MEF重现心律失常，如异位和不稳定的自行车，错过心跳和功能受限。
