Martufi Giampaolo, Lindquist Liljeqvist Moritz, Sakalihasan Natzi, Panuccio Giuseppe, Hultgren Rebecka, Roy Joy, Gasser T Christian
Department of Civil Engineering, University of Calgary, Alberta, Canada
Department of Solid Mechanics, Royal Institute of Technology, Stockholm, Sweden.
J Endovasc Ther. 2016 Dec;23(6):957-966. doi: 10.1177/1526602816657086. Epub 2016 Jul 12.
To investigate the influence of the local diameter, the intraluminal thrombus (ILT) thickness, and wall stress on the local growth rate of abdominal aortic aneurysms.
The infrarenal aortas of 90 asymptomatic abdominal aortic aneurysm (AAA) patients (mean age 70 years; 77 men) were retrospectively reconstructed from at least 2 computed tomography angiography scans (median follow-up of 1 year) and biomechanically analyzed with the finite element method. Each individual AAA model was automatically sliced orthogonally to the lumen centerline and represented by 100 cross sections with corresponding diameters, ILT thicknesses, and wall stresses. The data were grouped according to these parameters for comparison of differences among the variables.
Diameter growth was continuously distributed over the entire aneurysm sac, reaching absolute and relative median peaks of 3.06 mm/y and 7.3%/y, respectively. The local growth rate was dependent on the local baseline diameter, the local ILT thickness, and for wall segments not covered by ILT, also on the local wall stress level (all p<0.001). For wall segments that were covered by a thick ILT layer, wall stress did not affect the growth rate (p=0.08).
Diameter is not only a strong global predictor but also a local predictor of aneurysm growth. In addition, and independent of the diameter, the ILT thickness and wall stress (for the ILT-free wall) also influence the local growth rate. The high stress sensitivity of nondilated aortic walls suggests that wall stress peaks could initiate AAA formation. In contrast, local diameters and ILT thicknesses determine AAA growth for dilated and ILT-covered aortic walls.
研究局部直径、腔内血栓（ILT）厚度和壁应力对腹主动脉瘤局部生长速率的影响。
对90例无症状腹主动脉瘤（AAA）患者（平均年龄70岁；77例男性）的肾下腹主动脉进行回顾性分析，这些患者至少接受了2次计算机断层血管造影扫描（中位随访时间1年），并采用有限元方法进行生物力学分析。每个个体的AAA模型均自动沿管腔中心线正交切片，并由100个具有相应直径、ILT厚度和壁应力的横截面表示。根据这些参数对数据进行分组，以比较变量之间的差异。
直径增长在整个动脉瘤囊内呈连续分布，绝对和相对中位峰值分别达到3.06mm/年和7.3%/年。局部生长速率取决于局部基线直径、局部ILT厚度，对于未被ILT覆盖的壁段，还取决于局部壁应力水平（所有p<0.001）。对于被厚ILT层覆盖的壁段，壁应力不影响生长速率（p=0.08）。
直径不仅是动脉瘤生长的一个强大的全局预测指标，也是局部预测指标。此外，独立于直径之外，ILT厚度和壁应力（对于无ILT的壁）也会影响局部生长速率。未扩张主动脉壁的高应力敏感性表明壁应力峰值可能引发AAA的形成。相比之下，局部直径和ILT厚度决定了扩张的和被ILT覆盖的主动脉壁的AAA生长。
