Kontopodis Nikolaos, Metaxa Eleni, Papaharilaou Yannis, Georgakarakos Efstratios, Tsetis Dimitrios, Ioannou Christos V
Vascular Surgery Department, University Hospital of Heraklion & University of Crete Medical School, PO Box 1352, Heraklion, Crete 711 10, Greece.
Theor Biol Med Model. 2013 Dec 5;10:67. doi: 10.1186/1742-4682-10-67.
Abdominal aortic aneurysms (AAA) are currently being treated based on the maximum diameter criterion which has often been proven insufficient to determine rupture risk in case of every AAA. We analyzed a rare case of an AAA which presented an extremely fast growth focusing on biomechanical determinants that may indicate a high risk profile. The examination of such a case is expected to motivate future research towards patient-specific rupture risk estimations.
An initially small AAA (maximum diameter: 4.5 cm) was followed-up and presented a growth of 1 cm in only 6-months of surveillance becoming suitable for surgical repair. Changes of morphometric characteristics regarding AAA, thrombus and lumen volumes, cross-sectional areas, thrombus maximum thickness and eccentricity, and maximum centerline curvature were recorded. Moreover biomechanical variables concerning Peak Wall Stress, AAA surface area exposed to high stress and redistribution of stress during follow-up were also assessed.
Total aneurysm volume increased from 85 to 120 ml which regarded thrombus deposition since lumen volume remained stable. Thrombus deposition was eccentric regarding anterior AAA segment while its thickness increased from 0.3 cm to 1.6 cm. Moreover there was an anterior bulging over time as depicted by an increase in maximum centerline curvature from 0.4 cm-1 to 0.5 cm-1. Peak Wall Stress (PWS) exerted on aneurysm wall did not change significantly over time, slightly decreasing from 22 N/cm2 to 21 N/cm2. At the same time the area under high wall stress remained practically constant (9.9 cm2 at initial vs 9.7 cm2 at final examination) but there was a marked redistribution of wall stress against the posterior aneurysmal wall over time.
Aneurysm area under high stress and redistribution of stress against the posterior wall due to changes in geometric configuration and thrombus deposition over time may have implications to aneurysms natural history and rupture risk.
腹主动脉瘤（AAA）目前依据最大直径标准进行治疗，但该标准常常被证明不足以确定所有腹主动脉瘤的破裂风险。我们分析了一例罕见的腹主动脉瘤病例，该病例呈现出极快的生长速度，重点关注可能表明高风险特征的生物力学决定因素。对这样一个病例的检查有望推动未来针对患者特异性破裂风险评估的研究。
对一个最初较小的腹主动脉瘤（最大直径：4.5厘米）进行随访，在仅6个月的监测期内其生长了1厘米，变得适合手术修复。记录了腹主动脉瘤、血栓和管腔体积、横截面积、血栓最大厚度和偏心度以及最大中心线曲率等形态学特征的变化。此外，还评估了与峰值壁应力、承受高应力的腹主动脉瘤表面积以及随访期间应力重新分布有关的生物力学变量。
总动脉瘤体积从85毫升增加到120毫升，这是由于血栓沉积所致，因为管腔体积保持稳定。血栓沉积在腹主动脉瘤前壁段呈偏心状，其厚度从0.3厘米增加到1.6厘米。此外，随着时间的推移出现了前凸，最大中心线曲率从0.4厘米-1增加到0.5厘米-1。施加在动脉瘤壁上的峰值壁应力（PWS）随时间没有显著变化，从22牛/平方厘米略微降至21牛/平方厘米。同时，高壁应力下的面积基本保持不变（初始时为9.9平方厘米，最终检查时为9.7平方厘米），但随着时间的推移，壁应力明显向后动脉瘤壁重新分布。
由于几何构型变化和血栓随时间沉积导致的高应力下的动脉瘤面积以及后壁应力重新分布，可能对动脉瘤的自然病程和破裂风险产生影响。
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