1例Stanford B型主动脉夹层TEVAR术后新发破口的血流动力学分析

Hemodynamic Analysis of Redissection after Endovascular Repair for One Stanford Type B Aortic Dissection Case

目的基于血流动力学分析,探究1例B型主动脉夹层在腔内修复术(thoracic endovascular aortic repair,TEVAR)后发生新发破口的原因。方法对1位B型主动脉夹层患者在TEVAR术后1、6、12、24月定期复查主动脉CT血管造影检查(computed tomography angiography,CTA)。基于各时期CTA影像,重建三维模型,进行形态学和血流动力学数值模拟分析。结果相比于术后1月,术后12月真腔直径增加1.8倍,且主动脉整体扭曲度增加16.67%;术后1、6、12月,在心脏收缩期新发破口处最大血流速度分别高于支架远端锚定区平均流速69.6%、33.7%、92.1%,最大壁面剪切应力分别为平均剪切力的2.52、2.32、3.52倍;此外,最大时均壁面切应力(time-averaged wall shear stress,TAWSS)在术后1、6、12月分别为平均TAWSS的1.88、2.53、3.62倍。结论TEVAR术后新发破口处主动脉真腔直径存在明显突变,且持续增大。导致该处主动脉血流流速加快,内膜长期承受高壁面剪切应力,进而引起新发破口。

Objective Based on hemodynamic analysis,to investigate the cause of distal re-entry tear in Stanford type B aortic dissection after thoracic endovascular aortic repair(TEVAR).Methods A patient with type B aortic dissection was reexamined regularly with computed tomography angiography(CTA)at 1^(st) month,6^(th) month,12^(th) month and 24^(th) month after TEVAR.Based on the CTA images in each period,three-dimensional(3D)aorta models were reconstructed to perform morphological analysis and hemodynamic simulation.Results Compared with the diameter at 1^(st) month after TEVAR,the diameter of true lumen at 12 months after TEVAR increased by 1.8 times and the global distortion of aorta increased by 16.67%.At postoperative 1^(st),6^(th) and 12^(th) month,the maximum blood velocities at the new entry tear in systole were 69.6%,33.7%and 92.1%higher than the average ones at distal landing zone,and the maximum wall shear stresses(WSSs)were 2.52,2.32 and 3.52 times of the average WSSs respectively.In addition,the maximum time-averaged WSS(TAWSS)at 1^(st),6^(th) and 12^(th) month after TEVAR were 1.88,2.53 and 3.62 times of the mean TAWSS respectively.Conclusions The morphology of the aorta remodeled after TEVAR,and a sudden change in the diameter of true lumen occurred at distal anchoring zone and continued to increase.As a result,the blood flow velocity in this area accelerated,and the intima was continuously exposed to high WSS,leading to the redissection.