人工心脏吻合口位置对主动脉内微栓运动的影响

目的 利用数值模拟方法阐明人工心脏吻合口位置对微栓运动的影响。方法 首先，基于心衰患者CT医学图像重建真实的主动脉三维模型，并根据临床实际建立3种吻合口位置（位于前壁、前壁和侧壁之间、侧壁）的人工心脏辅助几何模型；其次，运用离散相与有限元结合的方法，使用Fluent有限元软件进行流体数值模拟；最后，分析获得的微栓分布结果、速度矢量图和壁面切应力云图，评估血流动力学状态。结果 当人工心脏吻合口的位置分别处于前壁、前壁和侧壁之间以及侧壁时，微栓进入脑部的概率分别为23.6%、33.8%和36.7%；吻合口位置周围存在涡流。结论 人工心脏吻合口位置能够显著改变主动脉的血流动力学特性，影响微栓在主动脉中的分布规律。研究结果为临床优化人工心脏吻合口位置以降低卒中发生风险提供理论支持。
Objective To clarify the influence from left ventricular assist device （LVAD） cannula anastomosis on micro-emboli movement by numerical simulation methods. Methods Firstly, a patient-specific aorta geometric model was reconstructed based on CT scan images of a patient with heart failure. Three geometric models of LVAD support were established according to clinical practice, and the outflow cannula of LVAD was anastomosed at the three different locations of ascending aorta (the anterior wall, between anterior wall and lateral wall, the lateral wall of ascending aorta). Secondly, the computational fluid dynamic (CFD) approach combined with the discrete phase theory was used to calculate the hemodynamic states, and Fluent finite element software was used for numerical simulation of the fluid. Finally, the micro-emboli distribution flow pattern, wall shear stress (WSS) and velocity vector were extracted to evaluate the hemodynamic state. Results The probability of micro-emboli entering the brain vessel at the three different anastomosis locations were 23.6%, 33.8% and 36.7%, respectively. Besides, vortex was observed around the anastomosis locations. Conclusions The different anastomosis locations of LVAD cannula can significantly change the hemodynamic environment, which will influence micro-emboli movement in the aorta. The research findings provide some insights and theoretical support for optimizing the anastomosis to decrease occurrence risk of stroke in clinic.