| Traditional coronary system model focused on the mechanism of the systolic intramural impediment that result in the phasic coronary flow pattern. There are generally two shortcomings in these models. First, the two driven factors, the coronary perfusion pressure and myocardial contractility, were treated as independent inputs in their models, which are actually coupling variables of the systemic circulation. Second, analog circuit was commonly used to perform the model simulation, which is not appropriate in modeling the nonlinear or time varying behavior of the coronary system, such as the epicardial capacitance and coronary stenosis.; In this study, a novel lumped model was established to describe the hemodynamic behavior of the coronary system. It is driven by the aortic pressure and intramyocardial pressure generated with a systemic circulation model. Based on model analysis, the coronary inflow was separated into capacitive flow and resistive inflow, the theoretical effect of the time varying capacitance and viscosity on the pattern of coronary capacitive flow was analyzed, which leads to a new method to estimate the epicardial capacitance from the protosystolic peak of the coronary flow. The model established above was used to predict the coronary flow with different systemic circulation parameters, such as myocardial contractility, arterial resistance, left ventricular preload, and arterial compliance. The results of the simulation coordinate with theoretical expectation. In addition, our model was used to simulate the phasic coronary pressure flow pattern with different degree of coronary stenosis. The contribution of the viscosity, turbulence, and inertial effect on cross-stenosis pressure drop was analyzed. The model predicted stenosis index, such as fractional flow reserve (FFR), coronary flow reserve (CFR), and hyperemic stenosis resistance index (h-SRv), as well as the pressure flow pattern, is similar to the clinical measurement under different degrees of coronary stenosis. |
