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.

The blood pump is an implantable device with strict performance requirements. Any effective structural improvement will help to improve the treatment of patients. However, the research of blood pump structure improvement is a complex optimization problem with multiple parameters and objectives. This study takes the splitter blade as the object of structural improvement. Computational fluid mechanics and neural networks are combined in research and optimization. And hydraulic experiments and micro particle image velocimetry technology were used. In the optimization study, the number of blades, axial length and circumferential offset are optimization parameters, and hydraulic performance and hemolytic prediction index are optimization targets. The study analyzes the influence of each parameter on performance and completes the optimization of the parameters. In the results, the optimal parameters of number of blades, axial length ratio, and circumferential offset are 2.6° and 0.41°, respectively. Under optimized parameters, hydraulic performance can be significantly improved. And the results of hemolysis prediction and micro particle image velocimetry experiments reflect that there is no increase in the risk of hemolytic damage. The results of this study provide a method and ideas for improving the structure of the axial spiral blade blood pump. The established optimization method can be effectively applied to the design and research of axial spiral blade blood pumps with complex, high precision, and multiple parameters and targets.

The blood pump is a medical device used to assist or replace the diseased heart. Research on the structure of blood pumps has been committed to achieving better hemolysis and hydraulic performance. The purpose of this study was to find some effective ways to improve design methods and hydraulic structures. The research contents of improvement include: (1) improved blade streamline design method; (2) conical impeller hub; (3) additional auxiliary blades. Characteristic analysis and parameter design were carried out on the above three aspects. The methods used in this study included Dynamics (CFD) simulation, hydraulic experiments, and Particle Image Velocimetry (PIV) experiments. The results showed that this improved streamline design method could improve the distortion of blades and ensure a smaller impeller length. And, in the enhanced design of the hub, it is designed to be conical with inlet and outlet diameters of 7.5 and 12.8 mm, respectively. Furthermore, the auxiliary blades between the main blades are analyzed and designed. The results have the best performance optimization effect when the length of the auxiliary blades is 55% of the main blades. In general, the structural improvements in this study achieved the effect of improving hydraulic performance and avoiding increased hemolysis. These methods can be considered as an effective means of improving blood pump performance.