Effect of Axial Flow Blood Pump's Pulsation Speed Regulation on Key Hemodynamic Parameters

Implantation of the blood pump is an important method to treat heart failure (HF) at present. Many studies have shown that the pressure waveform produced by the constant speed of the rotary blood pump lacks fluctuation, which may cause a series of body damage. Therefore, it is believed that it is beneficial for the body to produce higher pressure fluctuation by rapidly adjusting the speed of the blood pump, but how to set the parameters in the speed waveform is a big challenge. The purpose of this study is to obtain the regularity of the blood pump's changing speed on hemodynamics. In this study, a lumped parameter coupling model of the blood pump and cardiovascular system was established, and the blood pump model was improved by introducing the pulsation characteristic component. A velocity regulation waveform that is consistent with the trend of the ventricular activation function was selected. The effects of different speed control parameters on hemodynamic parameters were analyzed, and comparisons with the constant speed were made. The results show that the pulse pressure (PP) is higher at variable speed. The hemolysis value under variable speed is higher than constant speed, and increases with the decreases of speed modulation frequency. We also found that the PP will increase with the decrease of the speed control frequency. To explain this phenomenon, a dimensionless parameter S that combines the integral of the speed pulsation amplitude with the modulation cycle and the heartbeat cycle was proposed. By comparing the S and PP values, it shows that the change rules of the two are compatible. Therefore, the speed modulation of the blood pump should also consider the integral effect of the rotation speed in the cardiac cycle.