Research On Cardiovascular And Coronary System Assisted By A Catheter Pump Using A Multi-scale Model

As a short-term left ventricular assist device,catheter pump can increase the perfusion of the cardiovascular and coronary artery system,becoming a new method of treating heart failure and maintaining the physiological state in percutaneous coronary intervention.However,there are few studies on the changing mechanism of cardiovascular and coronary hemodynamics when assisted by catheter pumps,and there is a lack of research on the effect of assist modes of catheter pumps on interventional therapy.Therefore,this paper develops a multi-scale model of the cardiovascular and coronary system under the assistance of a catheter pump to simulate the pathological state and the physiological state with the assistance of the catheter pump,which will provide a theoretical base for percutaneous coronary intervention and the optimization of catheter pump.Among them,a lumped parameter model is used to analyze the effects of assist modes of the catheter pump on the hemodynamics of patients with heart failure and coronary stenosis,and a multiple-scale model is used to analyze its microdynamics behavior.The main contents are as follows:Firstly,a lumped parameter model of the cardiovascular and coronary system is developed based on physiology,and the lumped parameter model is coupled with the catheter pump model to construct a cardiovascular-coronary-catheter pump coupled model.Numerical simulations study the perfusion effect of the cardiovascular system on the coronary system and investigate the hemodynamic behavior of the cardiovascular and coronary arteries under healthy and heart failure conditions.The results are consistent with the human physiological parameters,proving the feasibility of the model.Secondly,the coupled lumped parameter model is used to construct a stenotic coronary artery model and analyze the influence of the catheter pump on the coronary artery system.Research on the coronary artery stenosis model shows that the degree of coronary stenosis and the branches of the stenosis have a significant impact on coronary perfusion.Stenosis causes a rapid decrease in coronary blood flow with a negative correlation with the level of stenosis aggravates the decrease in coronary blood flow.Among the branches,left coronary stenosis has a greater impact on blood flow than right coronary stenosis.Left main stenosis will cause a decrease in the overall flow of the left coronary.Under the same degree of stenosis,multiple branch stenosis has lower perfusion than a single branch.Different assist modes of the catheter pump can effectively increase the blood flow of the stenotic coronary artery,and the variable speed assist mode can maintain higher pulsatility of coronary blood flow than the constant speed assist mode.In short,due to its special implantation position,the catheter pump assist can increase the flow of the stenotic coronary artery.Finally,a multi-scale coupled system is put forward after a three-dimensional model of the coronary system is constructed,and the outputs of the zero-dimensional model are used as the boundary conditions.The effects of the stenosis and the catheter pump on microscopic hemodynamics are analyzed.The results show a rapid increase of the blood velocity,wall shear stress,and a blood pressure drop of the stenosis are found,and low-velocity domain,turbulence including vortex appear at the distal end.A higher level of coronary stenosis aggravates the turbulence development.These irregular flow patterns increase the risk of coronary atherosclerosis.In addition,by analyzing the influence of the catheter pump on the blood parameters of the stenosis,it is proved that the catheter pump can effectively increase the coronary blood flow,and reduce the extreme value of the shear stress and the vascular pressure drop,and thus reduce the side effect of the stenosis on the blood vessel wall.The research can achieve the macroscopic blood flow parameters of the cardiovascular system and the microscopic hemodynamic behavior of the stenosis,which provides technical support for percutaneous coronary intervention.