Quaglini Virginio, Villa Tomaso, Migliavacca Francesco, Carmo Michele, Settembrini Piergiorgio, Contro Roberto, Pietrabissa Riccardo
Laboratory of Biological Structure Mechanics, Department of Structural Engineering, Politecnico di Milan, Italy.
Artif Organs. 2002 Jun;26(6):555-64. doi: 10.1046/j.1525-1594.2002.06886_5.x.
The main problem in the replacement of pathological segments of the aorta with vascular prostheses consists of matching the fluid admittance of the host artery and the graft. This mismatch results from the different compliance between natural and prosthetic vessels and from the plastic dilatation of the prosthesis diameter that occurs after implantation. An experimental procedure was set up for evaluating the mechanical properties of aortic vascular prostheses. An MTS 858 MiniBionix testing machine was equipped with a purposely designed testing apparatus, which allows loading a ring-shaped prosthesis specimen with forces that can be related easily to the transmural pressure acting on the prostheses in vivo. The reference pressure waveforms are simulated from a lumped parameter model of the cardiovascular system. Preliminary tests on 3 different (woven, warp knitted, and carbon-coated warp knitted fabric) aortic prostheses point out a good reproducibility of the results. The fabric strongly affects the circumferential elasticity and the dimensional stability of the graft. Simulation of hypertension promotes larger diameter dilatation and reduction in compliance. Agreement between in vitro and clinical diameter measurements has been assessed for 8 prosthesis samples and found to be adequate. This method is thus a potentially useful means for preclinical evaluation of compliance of vascular prostheses for the purpose of matching to native vessels.
用血管假体替换主动脉病变节段的主要问题在于使宿主动脉与移植物的流体导纳相匹配。这种不匹配是由天然血管和人工血管之间不同的顺应性以及植入后假体直径的塑性扩张导致的。建立了一种用于评估主动脉血管假体力学性能的实验方法。一台MTS 858 MiniBionix测试机配备了专门设计的测试装置，该装置能够以易于与体内作用于假体的跨壁压力相关的力加载环形假体样本。参考压力波形由心血管系统的集总参数模型模拟得出。对3种不同（机织、经编和碳涂层经编织物）的主动脉假体进行的初步测试表明结果具有良好的可重复性。织物对移植物的周向弹性和尺寸稳定性有很大影响。高血压模拟会促进更大的直径扩张并降低顺应性。已对8个假体样本的体外和临床直径测量结果进行了评估，发现两者相符。因此，该方法对于血管假体顺应性的临床前评估是一种潜在有用的手段，目的是使其与天然血管相匹配。
