具有不同移植管-宿主动脉直径比的冠状动脉搭桥术的血流动力学仿真比较

Simulation and Comparison of Hemodynamics in Coronary Artery Bypass Graft with Different Graft-Host Diameter Ratio

为了说明移植管-宿主动脉直径比对冠状动脉搭桥术的流场及壁面切应力的影响,构造了三个具有不同移植管-宿主动脉直径比的冠状动脉搭桥术模型,三个模型的移植管直径分别小于、等于和大于宿主动脉的直径;利用有限单元数值模拟方法对三个模型中的生理性脉动血流进行了仿真分析;对流场、壁面切应力及其相关系数的时空分布进行了显示和比较。结果表明,大直径比的模型具有相对较大的纵向速度、大而均匀的壁面切应力以及小的壁面切应力梯度,从而在一定程度上改善了血流动力学;在搭桥术应用中采用大于或等于1的直径比是可取的。然而,在三个模型中,与壁面切应力相关的时间参数并没有显著差别。为了提高冠状动脉搭桥术的畅通率,设计新的缝合结构是很有必要的。

In order to clarify the influence of graft-host diameter ratios on the flow patterns and the wall shear stress in coronary artery bypass graft （CABG）, three CABG models with the graft diameter smaller than, equal to and larger than that of the coronary artery, were constructed. The physiologically pulsatile blood flows in these three models were simulated with finite element method. The temporal-spatial distributions of flow patterns, wall shear stresses, and wall shear stress based parameters were depicted and compared. The results showed that the large model features with relatively large positive longitudinal velocity, uniform and large wall shear stresses, and small wall shear stress gradients. The hemodynamics in the large model was improved to some extent. Larger or isodiametric graft is favorable in the CABG surgical application. However, no distinct difference of wall shear stress based temporal parameters was found between all the three models. Alternative anastomotic designs are necessary for the improvement of CABG patency rates.