Shear Stress and Hemolysis Analysis of Blood Pump under Constant and Pulsation Speed Based on a Multiscale Coupling Model

Shuai Wang,Jianping Tan,Zheqin Yu

doi:10.1155/2020/8341827

Abstract

Current researches show that the constant speed mode adopted by the existing commercial blood pump may cause damage to the body. The way to solve this problem is to produce pulsating flow by changing the speed of the blood pump’s impeller. But at present, the flow field of the blood pump is not clear, when it changes speed, and the coupling between blood pump and body has not been considered in the simulation of the flow field. A multiscale coupling model combining hemodynamics (0D) and Computational Fluid Dynamics (3D) was established in this paper to solve the problem, and a speed change curve consistent with the ventricular motion was selected. The hemodynamics, shear stress, and hemolysis changes of 6000 rpm at different amplitude (2000, 3000, and 4000 rpm) were simulated, analyzed, and compared with the constant speed (7000 rpm). The results show that the pressure difference obtained by simulation is consistent with the experimental results, and the flow generated by the natural heart still flows through the blood pump, thus changing the working point of the blood pump. When the blood pump works at the changing speed, it could produce more pulsation, and the shear stress and hemolysis in the blood pump increase with the rising of speed and flow. But according to the hemolysis score of a single cardiac cycle, the hemolysis value of the changing speed model at an amplitude of 4000 rpm is only 11.71% higher than that of constant speed at 7000 rpm.

Highlights

At present, there are more than 20 million heart failure patients in the world [1]
Sonntag et al [17] carried out Computational Fluid Dynamics (CFD) simulation on a pulsatile total artificial heart, and the results show that the left ventricular assist pump has good pulsation and washout performance; Yang et al [18] used a high-speed camera to photograph the flow line of pulsating blood pump. e results show that pulsation will cause periodic confusion in the flow field
Establishment of Coupling Model of Hemodynamics and CFD. e coupling model established in this paper is shown in Figure 2. e hemodynamic model was based on the research of Korakianitis and Shi et al [20]

Summary

Introduction

There are more than 20 million heart failure patients in the world [1]. In the case of poor drug treatment and lack of donors, implanting a blood pump to assist the heart has become an effective treatment method. In the past ten years, nearly 20000 patients have been implanted the blood pump and achieved a certain survival rate [3]. The current commercial blood pump generally adopts the constant speed working mode. E existing researches believe that this mode will reduce the pulsatility of blood flow and cause damage to the body, such as thrombosis or aortic insufficiency [4], renal failure [5], and vascular dysfunction [6]. It has been proposed to generate pulsating blood flow by adjusting the speed of the blood pump’s impeller to solve this problem [7, 8]

Methods

Results

Conclusion