IMPACT OF COMPETITIVE FLOW ON HEMODYNAMICS OF LIMA-LAD GRAFTING WITH DIFFERENT STENOSIS: A NUMERICAL STUDY

Background and Aims: Competitive flow exists in the native coronary artery when using artery graft in the coronary artery bypass graft (CABG), and it is a major factor affecting the long-term patency of the arterial grafts. The purpose of this study is to investigate the effects of the competitive flow on hemodynamic characteristics of left internal mammary artery (LIMA). Materials and methods: Seven three-dimensional (3D) LIMA-left anterior decending (LAD) grafting models with different diameter stenoses at the trunk of LAD were reconstructed, including 25%, 40%, 50%, 60%, 75%, 90% and 100%. The boundary conditions of these models were provided by the same lumped parameter model (LPM; 0D sub-model) of cardiovascular circulatory system, which is based on 0D/ 3D coupling method. Results: The simulation results show that competitive flow decreases when the stenosis rate increases and backflow exists in LIMA during systole when the degree of stenosis is below 50%; the wall shear stress (WSS) of the graft increases from 0.85 Pa to 1.79 Pa with the increase of the native coronary stenosis degree, while the oscillatory shear index (OSI) decreases from 0.1557 to 0.00213. Conclusions: Competitive flow may produce adverse hemodynamic effects on artery graft, especially when the stenosis degree is below 50%, competitive flow will significantly lead the long-term patency of the artery graft worse because of the backflow, low WSS and high OSI, and the effect of OSI is more obvious than WSS.