Peripheral vascular trauma due to injuries of the upper and lower limbs are life-threatening, and their treatment require rapid diagnosis and highly-qualified surgical procedures. Experienced surgeons have recognized that subclavian arteries, affected by injuries of the upper limbs, require a more careful handling due to fragility than common iliac arteries, which are may be affected by injures of the lower limbs. We investigated these two artery types with comparable diameter to evaluate the differences in the biomechanical properties between subclavian and iliac arteries. Human subclavian and common iliac arteries of 14 donors either from the right or the left side (age: 63 yrs, SD: 19,9$19,9$ female and 5 male) were investigated. Extension-inflation-torsion experiments at different axial strains (0–20%), transmural pressures (0–200 mmHg) and torsion (±25^∘$\pm {25}^{\circ }$) on preconditioned arterial tubes were performed. Residual stresses in both circumferential and axial direction were determined. Additionally, the microstructure of the tissues was determined via second-harmonic generation imaging and by histological investigations. At physiological conditions (p_i=13.3$p_{\mathrm{i}}=13.3$ kPa, λ_z=1.1${\lambda }_z=1.1$) common iliac arteries revealed higher Cauchy stresses in circumferential and axial directions but a more compliant response in the circumferential direction than subclavian arteries. Both arteries showed distinct stiffer behavior in circumferential than in axial direction. Circumferential stiffness of common iliac arteries at physiological conditions increased significantly with aging (r=-0.67,p=0.02$r=-0.67,p=0.02$). The median inversion stretches, where the axial force is basically independent of the transmural pressure, were determined to be 1.05$1.05$ for subclavian arteries and 1.11$1.11$ for common iliac arteries. Both arteries exhibited increased torsional stiffness, when either axial prestretch or inflation pressure was increased. Residual stresses in the circumferential direction were significantly lower for subclavian arteries than for common iliac arteries at measurements after 30 mins (p=0.05$p=0.05$) and 16 hrs (p=0.01$p=0.01$). Investigations of the collagen microstructure revealed different collagen fiber orientations and dispersions in subclavian and iliac arteries. The difference in the collagen microstructure revealed further that the adventitia seems to contribute significantly to the passive mechanical response of the tested arteries at physiological loadings. Histological investigations indicated pronounced thickened intimal layers in subclavian and common iliac arteries, with a thickness comparable to the adventitial layer. In conclusion, we obtained biomechanical differences between subclavian and common iliac arteries, which possibly resulted from their different mechanical loadings/environments and respectivein vivo movements caused by their anatomical locations. The biomechanical differences explored in this study are well reflected by the microstructure of the collagen and the histology of the investigated arteries, and the results can improve trauma patient care and endovascular implant design.

Statement of significance

During surgical interventions surgeons experienced that subclavian arteries (SAs) supplying the upper extremities, appear more fragile and prone to damage during surgical repair than common iliac arteries (CIAs), supplying the lower extremities. To investigate this difference in a systematic way the aim of this study was to compare the biomechanical properties of these two arteries from the same donors in terms of geometry, extension-inflation-torsion behavior, residual stresses, microstructure, and histology. In regard to cardiovascular medicine the material behavior of aged human arteries is of crucial interest. Moreover, the investigation of SA is important as it can help to improve surgical procedures at this challenging location. Over the long-term it might well be of value in the construction of artificial arteries for substituting native arteries. In addition, the analysis of mechanical stresses can improve design and material choice for endovascular implants to optimize long-term implant function.

中文翻译：

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锁骨下和I动脉对伸展，膨胀和扭转的机械反应

由于上肢和下肢受伤而引起的周围血管损伤危及生命，其治疗需要快速诊断和高质量的外科手术程序。有经验的外科医生已经认识到，受脆弱性影响的锁骨下动脉由于其脆弱性而比普通的动脉要更谨慎地处理，common动脉可能会受到下肢的伤害。我们研究了直径可比较的这两种动脉类型，以评估锁骨下动脉和动脉之间生物力学特性的差异。右侧或左侧有14个供体的人锁骨下和common总动脉（年龄：63岁，SD：19,9$19，9$女性和5位男性）进行了调查。在不同的轴向应变（0–20％），透壁压力（0–200 mmHg）和扭转（± ^25∘$\pm {25}^{\circ }$）在预处理的动脉管上进行。确定了圆周方向和轴向方向上的残余应力。另外，通过二次谐波成像和组织学研究确定了组织的微观结构。在生理条件下（p _i = 13.3$p_{\mathrm{一世}}=13.3$ 千帕，λ _ž = 1.1${\lambda }_{ž}=1.1$）总动脉与锁骨下动脉相比在圆周和轴向上显示出更高的柯西应力，但在圆周方向上具有更柔顺的响应。两条动脉在圆周上的表现都比在轴向上的表现出明显的更僵硬的行为。生理条件下of总动脉的周向刚度随衰老而显着增加（r = -0.67，p = 0.02$\mathrm{[R}=--0.67，p=0.02$）。轴向力基本上与穿膜壁压力无关的中位反转拉伸被确定为1.05$1.05$用于锁骨下动脉和1.11$1.11$用于常见的动脉。当轴向预拉伸或充气压力增加时，两条动脉都显示出增加的扭转刚度。在30分钟后的测量中，锁骨下动脉在圆周方向上的残余应力显着低于普通（动脉（p = 0.05）$p=0.05$）和16小时（p = 0.01$p=0.01$）。对胶原微结构的研究表明，锁骨下和动脉的胶原纤维取向和分散性不同。胶原微结构的差异进一步表明，在生理负荷下，外膜似乎对受测动脉的被动机械反应有显着贡献。组织学研究表明，锁骨下动脉和common总动脉内膜层明显增厚，其厚度与外膜层相当。总之，我们获得了锁骨下动脉和common总动脉之间的生物力学差异，这可能是由于它们的机械负荷/环境不同以及各自体内的差异所致。由其解剖位置引起的运动。胶原蛋白的微结构和所研究动脉的组织学很好地反映了这项研究中的生物力学差异，其结果可以改善创伤患者的护理和血管内植入物的设计。

重要声明

在外科手术中，外科医生经历了锁骨下动脉（SAs）的供应较上肢下颌骨的普通动脉（CIAs）更为脆弱，并且在手术修复过程中更容易受到损害。为了以系统的方式研究这种差异，本研究的目的是比较来自同一供体的这两条动脉的生物力学特性，包括几何形状，伸展-扭曲行为，残余应力，微观结构和组织学。关于心血管医学，老年人动脉的物质行为至关重要。此外，对SA的研究很重要，因为它可以帮助改善这一具有挑战性的位置的手术程序。从长远来看，在人工动脉的建造中替代天然动脉可能很有价值。此外，机械应力的分析可以改善血管内植入物的设计和材料选择，以优化长期植入物的功能。