Study On The Impact Of Competitive Flow On Hemodynamic Of LIMA-LAD Grafting

Coronary artery bypass graft(CABG) can be used to treat patients with coronary heart disease, but competitive flow exists in the native coronary artery when using artery graft in CABG. The relevant research at domestic find that competitive flow may lead to adverse hemodynamic environment, such as low wall shear stress(WSS), high oscillatory shear index(OSI), these factors may induce the intimal hyperplasia and atherosclerosis, vasospasm or “string phenomenon” may appear in artery graft. Then competitive flow is a major factor affecting the long-term patency of the arterial grafts. However, at present, surgeon lack hemodynamic theory, the intensity of competitive flow and the assessment of long-term patency of artery graft are all based on clinical experience, then it may reduce the accuracy of patency assessment.To explore the factors that affect the intensity of competitive flow, and predict the impact of competitive flow on the hemodynamics of arterial grafts, these information could provide a theoretical basis for the evaluation of the patency of the graft. In this paper, using 0D/3D coupling geometrical multiscale method could explore factors influencing the intensity of competitive flow, and it also can be used to analyze the impact of competitive flow on the hemodynamics of the arterial graft, this method provides a basis for the prediction of the long-term patency of the graft on hemodynamics. Five aspects of this study includes: firstly, rebuilding 0D/3D multiscale method and doing hemodynamics numerical study; secondly, analyzing the effect of competitive flow on hemodynamics of LIMA-LAD grafting with different stenosis(25%、40%、50%、60%、75%、90% and 100% stenosis); thirdly, analyzing the effect of competitive flow on hemodynamics of LIMA-LAD grafting with different afterload of coronary artery(1 and 1.2 afterload); fourthly, comparing the LIMA-LAD and SVG-LAD surgery analyzed the hemodynamic characteristics of the string phenomenon; fifthly, assessing long-term patency of LIMA graft by the impact of hemodynamics.The hemodynamics results show that, the degree of coronary artery stenosis determines the intensity of competitive flow, and the impact of competitive flow decreases with the increase of the stenosis rate. Competitive flow may produce adverse hemodynamic effects on artery graft, but the effect of OSI is more obvious than WSS on the patency of graft. This paper also find that the intensity of competitive flow may change when the coronary artery afterload different. If the coronary artery afterload increase, the diastolic blood flow will decrease, but systolic blood flow little change. That means intensity of competitive flow increase with high coronary artery afterload, and the long-term patency of graft will decrease.3D models in this paper are complete coronary artery model and contains aortic arch, and the boundary conditions of these models are provided by the same lumped parameter model of cardiovascular circulatory system, so the hemodynamic parameters value have good credibility. Study on the impact of competitive flow on hemodynamics of LIMA-LAD grafting with different stenosis and different afterload, it can provide theoretical basis for the quantitative analysis of the long-term patency of the graft, and it has important guiding significance for the clinical postoperative evaluation.