| A large number of studies had shown that myocardial bridge has certain impacts on morphology of coronary artery and haemodynamics, and the proximal is one of the areas with high incidence of atherosclerosis. Nowadays there were a few reports about the relationships between abnormal haemodynamics of proximal and proximal atherosclerosis-prone.As haemodynamic factors play an important part in the occurrence and development of atherosclerosis, it is of significance to understand pathogenesis of atherosclerosis by extensive studies on the mural coronary artery haemodynamics changing caused by myocardial bridge and studies on the relationships between the changing and proximal atherosclerosis, which has a potential clinical value on treatment of myocardial bridge.In this paper, atherosclerosis-prone proximal is regarded as a point of view, and then we set up simulation of haemodynamic model and vitro simulative device from numerical simulation and experimental simulations according to the main feature of myocardial bridge, with which we study and analyze the haemodynamic mechanism of atherosclerosis caused by myocardial bridge.Main worksNumerical simulation(1) Establish mild stenosis myocardial bridge model and linear Navier-Stokes haemodunamic equation. Pressure equation of virtual variables coefficient and mathematical expression of haemodynamic indexes are derived by harmonic superposition according to the characteristic of blood flow pulsation cycle. Solve the pressure equation, and find the haemodynamic indexes:pressure P, pressure gradient dP/dz, wall shear stress WSS and oscillation shear index OSI. We use these indexes to work:a. Compare haemodynamics of normal coronary artery with myocardial bridge coronary artery;b. Compare hemodynamics of myocardial bridge coronary artery which affected by vascular compliance;c. Compare hemodynamics of myocardial bridge coronary artery which affected by heart rate.(2) Establish an ordinary myocardial bridge model and myocardial bridge haemodynamic basic equations of one-dimensional pipe flow. Viscous friction of equations of one-dimensional pipe flow is got from the solution of "Boundary layer flow" Karman momentum integral equation. Solve equation with typical line.a. Compare haemodynamics of normal coronary artery with myocardial bridge coronary artery;b. Compare haemodynamics of myocardial bridge proximal with distal;c. Analyze the impacts on haemodynamics respectively by the degree stenosis and two myocardial bridges.The result shows that there are great differences between myocardial bridge coronary artery haemodynamics and normal one; there are several abnormal haemodynamic indexes beneath myocardial bridge and proximal, whose pressure, wall shear stress, wall shear stress gradient, gradient oscillatory number change greater than other areas. It offers a haemodynamic mechanism explanation for myocardial bridge proximal easily inducing atherosclerosis from numerical simulation.Development of vitro simulative device and simulative experiment(1) Develop a coronary artery-myocardial bridge haemodynamic vitro simulative device assembled with blood flow module, parameters measurement module, myocardial bridge module, flexible tubulose cells culture module.This device provides a myocardial bridge coronary artery haemodynamic environment approached to human physiological condition, whose parameters are controllable. It provides a experimental condition and investigative measurements for studying the relationship between haemodynamic parameters changing of mural coronary artery cased by myocardial bridge and proximal atherosclerosis and exploring mechanism of atherosclerosis.(2) Performance evolution of coronary artery-myocardial bridge haemodynamic vitro simulative devicePerformance evolution of simulative device proves that every functional system is running in a good condition, function is stable and experimental conditions are easily controlled. It could perfectly simulate three-dimensional flow field and relevant stress environments when blood flow circulates in myocardial bridge coronary artery.(3) Vitro simulative experiment of simulative devicea. Results from vitro simulative experiment with myocardial bridge mural coronary artery haemodynamic simulative device show that the existence of myocardial bridge totally impacts on the average stress (wall shear stress, direct stress and circumferential stress) and undulating stress in the mural coronary artery. From the recent results, the more serious the myocardial bridge is, the higher the average stress and stress oscillatory number are at proximal in mural coronary artery, and even proximal is greater than distal. Contacting with the phenomenon that the proximal is atherosclerosis-prone, we have reasons to conclude there is certain relationships between stress level, increasing oscillatory stress and atherosclerosis.b. Take endothelial cells culture preliminary experiment in the flexible tubulose cells culture module.Characteristic and innovation(1) Establish myocardial bridge haemodynamic numerical simulative model and calculate haemodynamic indexes of myocardial bridge, explain the relationships between abnormal haemodynamics and proximal atherosclerosis-prone from numerical simulation for the first time.(2) Develop a myocardial bridge coronary artery haemodynamic vitro simulative device, which simulate the wall shear stress, direct stress, circumferential stress of proximal and distal; complete a vitro simulative experiment, and analyze the internal connections between abnormal haemodynamics of myocardial bridge coronary artery and proximal atherosclerosis-prone.(3) Develop the flexible tubulose endothelial cells culture device, with which we take an endothelial cells culture preliminary experiment successfully. It provides a further technology to explore the haemodynamic mechanism of atherosclerosis caused by myocardial bridge from cells. The endothelial cells culture device is not only used to study atherosclerosis caused by myocardial bridge, but also be used as the experimental measurement and device to study cardiovascular disease related to cells.
|
PDF Full Text Request