轴流血泵最佳左心辅助下的 速度变化及内流场分析

为解决轴流血泵恒压或恒转速辅助时产生的抽吸或反流现象,以自主研发的主动脉瓣轴流血泵为研究对象,建立“轴流血泵-血液循环系统”串联耦合多尺度参数模型,得到血泵变转速辅助时在各级心衰条件下达到最佳辅助状态时的转速变化曲线.相比恒转速辅助,变转速辅助的血流动力学结果与正常心脏的拟合度更高,也符合人体生理.采用CFD技术对Ⅳ级心衰下2种辅助状态在一个心动周期中的内流场进行比较分析,发现变转速辅助下,轴流血泵在等容收缩期、等容舒张期、充盈期会产生明显的涡流,过流时间较长,但剪切应力较小,不会造成溶血;在射血期,变转速辅助的流动更加稳定,没有涡流现象产生,但其剪切应力在0.10 s内高于临界值500 Pa,会产生溶血现象.

Analysis of speed and internal flow field of axial flow blood pump in optimal left heart assistance

In order to solve the phenomenon of suction or regurgitation under constant pressure or constant speed assistance of axial blood pump, the self-developed aortic valve axial blood pump was taken as the research object to establish the multi-scale parametric model, ″axial flow blood pump-blood circulation system″ in series coupling, which presents the curve of the rotating speed reaching the optimal assisted state under the condition of heart failure at all levels. Compared to constant speed assistance, the hemodynamic results obtained by the variable speed assistance were more fitted to the normal heart. CFD technology was used to compare and analyze the internal flow field of two auxiliary states in one cardiac cycle under grade Ⅳ heart failure. It is found that under the assistance of variable speed, the axial blood pump produced obvious eddy current in the isovolumic systolic period, isovolumic diastolic period and filling period, and the flow passage time is longer, but the shear stress is smaller, and hemolysis will not be produced. During the ejection period, the variable-speed assisted flow is more stable, and no vortex is generated, but its shear stress is higher than the critical value of 500 Pa in the time period of 0.10 s and hemolysis does not occur.