静脉-静脉ECMO上腔灌注管与下腔引流管间距对右心房内血流动力学影响的数值研究

A numerical study on the influence of the distance between superior vena cave supplying cannulas and inferior vena cave draining cannulas in veno-venous ECMO on right atrial hemodynamics

目的阐明静脉-静脉ECMO(veno-venous extracorporeal membrane oxygenation,VV-ECMO)上腔灌注管与下腔引流管间距对右心房内血流动力学环境的影响规律。方法基于一名呼吸衰竭患者的心脏MRI影像数据建立右心房三维模型,以Medtronic 23Fr型插管为基础建立上腔灌注管模型和下腔引流管模型;分别建立上腔灌注管与下腔引流管间距与上下腔静脉距离之比为38%、88%、126%三种情况的流固耦合模型。采用瞬态计算流体力学方法研究右心房内血流动力学状态。采用血流速度云图、再循环率(recirculation fraction,RF)、右心房内低流速区域体积和相对停滞时间(relative residence time,RRT)等参数来评价不同上腔灌注管与下腔引流管间距下右心房内的血流动力学变化。结果随着上下腔静脉插管距离的增加,右心房内低流速区域总体积先降低后增加(468 mm 3 vs.327.47 mm 3 vs.357.7 mm 3);相对停滞时间最大值先降低后增加(103.54 Pa-1 vs.70.60 Pa-1 vs.95.15 Pa-1);再循环率不断降低(23.295%vs.20.918%vs.10.88%)。结论低流速区域体积和RRT的改善与插管间距的增大并不是线性的,当插管间距增加到一定距离时,继续增加插管间距,低流速区域体积和相对停滞时间指标反而会变差。再循环率则随着插管间距的增大而不断改善。

Objective To clarify the effect of veno-venous extracorporeal membrane oxygenation(VV-ECMO)superior and inferior Cannula distance on hemodynamic environment in right atrium.Methods A three-dimensional model of the right atrium was established based on the MRI image data of a respiratory failure patient's heart.The superior vena cava supplying and inferior vena cava draining models were established based on the Medtronic,23Fr cannulas.Then,three fluid-structure interaction models were established for the ratio of the distance between the superior vena cava supplying and inferior vena cava draining and the distance between the superior and inferior vena cava,which were 38%,88%,and 126%,respectively.Finally,transient computational fluid dynamics methods were used to study the hemodynamic state in the right atrium.The parameters such as blood flow velocity cloud maps,recirculation fraction(RF),wall shear stress,volume of low flow velocity areas in the right atrium,and relative residence time(RRT)were used to evaluate hemodynamic changes in the right atrium at different distances of superior and inferior cannula.Results As the distance between the superior vena cava supplying and inferior vena cava draining increased,the total volume of the low flow velocity area in the right atrium first decreased and then increased(468 mm 3 vs.327.47 mm 3 vs.357.7 mm 3),the maximum relative residence time first decreased and then increased(103.54 Pa-1 vs.70.60 Pa-1 vs.95.15 Pa-1)and the recirculation fraction rate continues to decrease(23.295%vs.20.918%vs.10.88%).Conclusions The improvement of volume in the low flow rate area and relative residence time is not linear with the increase of cannula spacing.When the cannula spacing increases to a certain distance,continuing to increase the cannula spacing will actually worsen the volume in the low flow rate area and relative residence time.The recirculation fraction continuously improves with the increase of cannula spacing.