McClarty Davis B, Kuhn David C S, Boyd April J
Department of Mechanical Engineering, University of Manitoba, Winnipeg, Manitoba, Canada.
Department of Surgery, University of Manitoba, Winnipeg, Manitoba, Canada.
J Vasc Res. 2021;58(3):172-179. doi: 10.1159/000514237. Epub 2021 Mar 29.
Computational fluid dynamics were used to assess hemodynamic changes in an actively rupturing abdominal aortic aneurysm (AAA) over a 9-day period. Active migration of contrast from the lumen into the thickest region of intraluminal thrombus (ILT) was demonstrated until it ultimately breached the adventitial layer. Four days after symptom onset, there was a discrete disruption of adventitial calcium with bleb formation at the site of future rupture. Rupture occurred in a region of low wall shear stress and was associated with a marked increase in AAA diameter from 6.6 to 8.4 cm. The cross-sectional area of the flow lumen increased across all time points from 6.28 to 12.08 cm2. The increase in luminal area preceded the increase in AAA diameter and was characterized by an overall deceleration in recirculation flow velocity with a coinciding increase in flow velocity penetrating the ILT. We show that there are significant hemodynamic and structural changes in the AAA flow lumen in advance of any appreciable increase in aortic diameter or rupture. The significant increase in AAA diameter with rupture suggests that AAA may actually rupture at smaller sizes than those measured on day of rupture. These findings have implications for algorithms the predict AAA rupture risk.
采用计算流体动力学方法评估了主动破裂的腹主动脉瘤（AAA）在9天内的血流动力学变化。造影剂从管腔向腔内血栓（ILT）最厚区域的主动迁移得到证实，直到最终突破外膜层。症状出现4天后，外膜钙出现离散性破坏，在未来破裂部位形成小泡。破裂发生在低壁面剪应力区域，并且与AAA直径从6.6厘米显著增加到8.4厘米有关。在所有时间点，血流腔的横截面积从6.28平方厘米增加到12.08平方厘米。管腔面积的增加先于AAA直径的增加，其特征是再循环流速总体减慢，同时穿透ILT的流速增加。我们表明，在主动脉直径或破裂有任何明显增加之前，AAA血流腔内就存在显著的血流动力学和结构变化。AAA破裂时直径的显著增加表明，AAA实际破裂时的尺寸可能比破裂当天测量的尺寸更小。这些发现对预测AAA破裂风险的算法具有启示意义。
