Coronary artery disease (CAD) are characterized with epicardial stenosis and microcirculation dysfunction. And the coronary artery hemodynamics are affected both by the epicardial stenotic coronary artery impede and microcirculation load. Regulation of coronary blood flow is quite complex [
1], epicardial stenosis severity and microcirculatory resistance may affect each other [
2,
3]. However, the complex interrelationship between the coronary microcirculation and the epicardial coronary arteries contributing to the coronary artery hemodynamics remains poorly understood and is controversial [
4]. Some recent studies have suggested that microvascular resistance at maximal vasodilation will increase when the severity of epicardial disease increases [
5]. While other studies showed that coronary microcirculatory resistance is independent of epicardial coronary artery stenosis [
6], and coronary microcirculatory resistance is not influenced by the epicardial stenosis severity [
7]. Now, epicardial coronary artery stenosis is regarded to exert their pathological role mainly through a limitation on maximal flow capacity in the distal vascular bed. However, how the distal microcirculation bed impact the hemodynamics of coronary artery was unknown. It’s believed that the microcirculation load has a great influence on the bloodstream, and has important influence on various phenomena in the flow field [
8]. Moreover, such microvascular alterations with altered microvascular resistance may partly obscure Fractional flow reserve (FFR) measurements [
9,
10]. Therefore, a complete hemodynamic model is needed to take into account the influence of microcirculation load effect.
Computational fluid dynamics (CFD) simulation has been widely used to study the hemodynamic parameters in coronary arteries due to the limitation of in vivo measurements [
11]. FFR is currently used as a gold standard for the assessment of functional significance of stenosis severity and is applied for guiding cardiovascular intervention. Recently, the CFD approach has been used to determine the FFR from the clinical medical image or numerical simulation. In these CFD hemodynamics simulations, boundary conditions are vital for obtaining accurate flow patterns. Hewever, there are lack of numerical simulation studies to determine FFR and hemodynamic changes due to microcirculation impedance outlet boundary conditions.
The resistance offered by microcirculation to blood flow can be conceived as the resistance encountered by fluid passing through porous medium [
12]. It has been established that the flow in microcirculation can be simulated by using a porous flow model [
13,
14]. Based on seepage theory [
15], the seepage flow could be specified as a boundary condition which shows that the resistance caused by the seepage condition in microcirculation. To obtain the large and complex microvascular anatomy is difficult, a porous medium model may replicate the downstream capillary structures, which can supply the essential characteristics of the seepage flow in microcirculation. Therefore, a load of porous media seepage could be imposed at the outlet of the artery stenosis model to simulate the microcirculation. In this study, a 3D computational coronary stenotic artery model with outlet condition of microcirculation load (ML) and constant pressure load (PL) was constructed. The purpose of this study is to investigate the effect of porous media of the microcirculation on coronary artery stenosis hemodynamics.