## 4 Discussion  
The standard treatment of a coronary artery bifurcation stenosis is performed by a technique of coronary artery stenting [34]. The in-stent restenosis may still occur after coronary bifurcation stenting in the clinic. In-stent restenosis is caused by chronic inflammatory symptoms of the persistent mechanism stress by the metal stent [35], or the stent-induced disturbances of blood flow changes the wall shear stress of the endothelial cell that causes the endothelial cell dysfunction [36]. Coronary artery bifurcation is a predilection of restenosis because of the complex hemodynamic local blood flow that the coronary bifurcation contributes to the restenosis [37; 38; 39]. Time-average wall shear stress and Oscillatory shear index of computational fluid dynamics analysis have been used as parameters to evaluate hemodynamics. Wall shear stress is the shear stress that the fluid acts on the arterial wall, and has a recognized effect on the arterial wall biology [40]. Stent implantation affects the regional arterial geometry by changing the local blood flow, causing the turbulence flow [41; 42]. Low wall shear stress (<0.5 Pa) induces neointimal and increases the risk of inflammatory symptoms [43; 44]. The OSI is a non-dimensional scalar variable that explains the degree of deviation of the WSS from the antegrade flow direction. A high oscillatory shear stress index (OSI > 0.2) is associated with an increased risk of neointimal hyperplasia, inflammation, and thrombosis [43; 44]. Therefore, both TAWSS < 0.5 Pa and OSI > 0.2 were selected as the restenosis threshold of detrimental hemodynamic indicators. The velocity results showed that the artery B was higher than the artery A, and the velocity of the LAD was higher than the LCX in this study. The different stenting techniques showed that the velocity was lower at the leading edges of LAD and LCX, and the recirculatory flow concentrates at the leading edge of the LCX proximal, which becomes more obvious as the bifurcation increases. The recirculatory flow in the T-stenting was more significant than other stenting techniques. The T-stenting was a small area of the coronary bifurcation into the LCX proximal without stent coverage. In the two other stenting techniques, the stent extends completely from the main branch to the side branches. In the T-stenting, the small area without stent coverage at the proximal LCX induced blood recirculatory when the blood flux moved through from the LMCA into the bifurcation branch of a segment of the area without stent coverage, and then blood flowed into a stent-covered area of the LCX branch to further disturb the obviously blood-steady situation influenced by the structure of the stent strut. The Kissing technique was detected in a particular area without stent attachment at the bifurcation carina, which was evidenced to increase extensively in proportion to the bifurcation angles, to confirmeffects of the low-velocity recirculatory near the bifurcation carina. In addition, the index of the artery wall pressure was also considered an important role to investigate the stenting restenosis with three types of stenting techniques in the different arteries. [PERSON] et al. [45] indicated that the arterial wall pressure and accompanying stretch is one of the contributing factors to the atherosclerotic lesions. Excessive wall pressure will cause atherosclerotic plaques and the plaques to rupture [46]. In the wall pressure distribution, results showed that the three stenting techniques caused the wall pressure to significantly increase in the two arteries. In the three stenting techniques, the wall pressure of the artery B with the Kissing stenting technique had the most significant increase than the other models. The distribution of the specific low TAWSS in the artery A was wider than the artery B, and the area of the specific low TAWSS seemed to be increased with the bifurcation degree.