左心室辅助装置与主动脉吻合角度对主动脉瓣膜影响的血流动力学研究

Effects of Left Ventricular Assist and Aortic Graft Angle on Aortic Valve:A Hemodynamic Study

目的 探究左心室辅助装置(left ventricular assist device,LVAD)与主动脉吻合角度对主动脉瓣膜的血流动力学影响。方法 分别构建LVAD与主动脉吻合角度为45°、60°、90°的3个主动脉模型和主动脉瓣膜模型,搭建体外搏动台用于体外实验。运用粒子图像测速(particle image velocimetry,PIV)系统,选取心动周期中的3个时刻(T_(1)收缩峰值期,T_(2)瓣膜快速闭合时期和T_(3)舒张峰值期)探究主动脉瓣膜处血流动力学状态。结果 采用速度矢量、涡量、黏性剪切力指标评价LVAD吻合角度对主动脉瓣膜血流动力学的影响。瓣膜快速闭合时期,吻合角度增大时,瓣膜近壁面血流速度、平均涡量和最大黏性剪切力均增大。结论 吻合角度较低时,血流对主动脉瓣膜的冲击速度较小,瓣膜受到较小的剪切力,使瓣膜处于较好的血流动力学环境。研究结果为临床手术中吻合角度的选择提供参考。

Objective To investigate the effect of left ventricular assist device(LVAD) and aortic graft angle on hemodynamics of aortic valve.Methods Three models of aorta and aortic valve with 45°,60° and 90° anastomosis angles between LVAD and aorta were constructed,and an in vitro pulsating table was built for in vitro experiments.Using particle image velocimetry(PIV) system,three moments in the cardiac cycle(T_(1) systolic peak,T_(2) rapid closure,T_(3) diastolic peak),were selected to study the hemodynamic state of aortic valve.Results Velocity vector,vorticity and viscous shear stress were used to evaluate the effect of LVAD anastomosis angle on hemodynamics of aortic valve.During the period of rapid valve closure,with the increase of graft angle,the blood flow velocity near the valve wall,the average vorticity and the maximum viscous shear stress all increased.Conclusions When the graft angle is lower,the impact velocity of blood on the valve is smaller,and the shear force on the valve decreases,so that the valve is in a better hemodynamic environment.This study provides references for the selection of anastomotic angles in clinical operations.