Yun Zhong, Yao Jinfu, Wang Liang, Tang Xiaoyan, Feng Yunhao
School of Mechanical and Electrical Engineering, Central South University, Changsha, China.
Front Physiol. 2023 May 11;14:1169905. doi: 10.3389/fphys.2023.1169905. eCollection 2023.
Blood pump design efforts are focused on enhancing hydraulic effectiveness and minimizing shear stress. Unlike conventional blood pumps, interventional microaxial blood pumps have a unique outflow structure due to minimally invasive technology. The outflow structure, composed of the diffuser and cage bridges, is crucial in minimizing the pump size to provide adequate hemodynamic support. This study proposed four outflow structures of an interventional microaxial blood pump depending on whether the diffuser with or without blades and cage bridges were straight or curved. The outflow flow structure's effect on the blood pump's hydraulic performance and shear stress distribution was evaluated by computational fluid dynamics and hydraulic experiments. The results showed that all four outflow structures could achieve the pressure and flow requirements specified at the design point but with significant differences in shear stress distribution. Among them, the outflow structure with curved bridges would make the blood dispersed more evenly when flowing out of the pump, which could effectively reduce the shear stress at the cage bridges. The outflow structure with blades would aggravate the secondary flow at the leading edge of the impeller, increasing the risk of flow stagnation. The combination of curved bridges and the bladeless diffuser had a relatively better shear stress distribution, with the proportion of fluid exposed to low scalar shear stress (<50 Pa) and high scalar shear stress (>150 Pa) in the blood pump being 97.92% and 0.26%, respectively. It could be concluded that the outflow structure with curved bridges and bladeless diffuser exhibited relatively better shear stress distribution and a lower hemolysis index of 0.00648%, which could support continued research on optimizing the microaxial blood pumps.
血泵的设计工作主要集中在提高水力效率和最小化剪切应力上。与传统血泵不同，介入式微轴血泵由于采用了微创技术而具有独特的流出结构。由扩散器和笼式桥组成的流出结构对于最小化泵的尺寸以提供足够的血流动力学支持至关重要。本研究根据带叶片或不带叶片的扩散器以及笼式桥是直的还是弯曲的，提出了四种介入式微轴血泵的流出结构。通过计算流体动力学和水力实验评估了流出流动结构对血泵水力性能和剪切应力分布的影响。结果表明，所有四种流出结构都能达到设计点规定的压力和流量要求，但在剪切应力分布上存在显著差异。其中，带有弯曲桥的流出结构会使血液流出泵时分布更均匀，能有效降低笼式桥上的剪切应力。带叶片的流出结构会加剧叶轮前缘的二次流，增加流动停滞的风险。弯曲桥和无叶片扩散器的组合具有相对较好的剪切应力分布，血泵中暴露于低标量剪切应力（<50 Pa）和高标量剪切应力（>150 Pa）的流体比例分别为97.92%和0.26%。可以得出结论，带有弯曲桥和无叶片扩散器的流出结构表现出相对较好的剪切应力分布和较低的溶血指数0.00648%，这可为微轴血泵的优化持续研究提供支持。
