Rassoli Aisa, Fatouraee Nasser, Guidoin Robert
Biological Fluid Mechanics Research Laboratory, Biomedical Engineering Faculty, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.
Department of Surgery, Laval University, Quebec, Canada.
Artif Organs. 2018 Jun;42(6):630-639. doi: 10.1111/aor.13095. Epub 2018 Mar 30.
The benefit of bioprosthetic aortic valve over mechanical valve replacements is the release of thromboembolism and digression of long-term anticoagulation treatment. The function of bioprostheses and their efficiency is known to depend on the mechanical properties of the leaflet tissue. So it is necessary to select a suitable tissue for the bioprosthesis. The purpose of the present study is to clarify the viscoelastic behavior of bovine, equine, and porcine pericardium. In this study, pericardiums were compared mechanically from the viscoelastic aspect. After fixation of the tissues in glutaraldehyde, first uniaxial tests with different extension rates in the fiber direction were performed. Then, the stress relaxation tests in the fiber direction were done on these pericardial tissues by exerting 20, 30,40, and 50% strains. After evaluation of viscoelastic linearity, the Prony series, quasilinear viscoelastic (QLV) and modified superposition theory were applied to the stress relaxation data. Finally, the parameters of these constitutive models were extracted for each pericardium tissue. All three tissues exhibited a decrease in relaxation rate with elevating strain, indicating the nonlinear viscoelastic behavior of these tissues. The three-term Prony model was selected for describing the linear viscoelasticity. Among different models, the QLV model was best able to capture the relaxation behavior of the pericardium tissues. More stiffness of porcine pericardium was observed in comparison to the two other pericardium tissues. The relaxation percentage of porcine pericardium was less than the two others. It can be concluded that porcine pericardium behaves more as an elastic and less like a viscous tissue in comparison to the bovine and equine pericardium.
生物人工主动脉瓣相对于机械瓣膜置换的优势在于可减少血栓栓塞，并省去长期抗凝治疗。已知生物假体的功能及其效率取决于瓣叶组织的力学性能。因此，为生物假体选择合适的组织很有必要。本研究的目的是阐明牛、马和猪心包的粘弹性行为。在本研究中，从粘弹性方面对心包进行了力学比较。将组织固定在戊二醛中后，首先在纤维方向上以不同的延伸率进行单轴试验。然后，对这些心包组织在纤维方向上施加20%、30%、40%和50%的应变进行应力松弛试验。在评估粘弹性线性后，将Prony级数、准线性粘弹性（QLV）和修正叠加理论应用于应力松弛数据。最后，提取每种心包组织的这些本构模型参数。所有三种组织均表现出随着应变增加松弛率降低，表明这些组织具有非线性粘弹性行为。选择三项Prony模型来描述线性粘弹性。在不同模型中，QLV模型最能捕捉心包组织的松弛行为。与其他两种心包组织相比，观察到猪心包的刚度更大。猪心包的松弛百分比低于其他两种。可以得出结论，与牛心包和马心包相比，猪心包的弹性更强，粘性更小。
