Ecole de Chirurgie Nancy-Lorraine, HVL, Université de Lorraine, Nancy, France; UMR INSERM 1116 DCAC, Nancy, France; Université de Lorraine, CNRS, Arts et Métiers ParisTech, LEM3, F-57000 Metz, France.
Laboratoire Georges Friedel, ENSM-SE, UMR CNRS 5307, Saint-Etienne, France.
J Mech Behav Biomed Mater. 2018 Jun;82:291-298. doi: 10.1016/j.jmbbm.2018.03.032. Epub 2018 Mar 28.
Implantation of a Left Ventricular Assist Device (LVAD) may produce both excessive local tissue stress and resulting strain-induced tissue rupture that are potential iatrogenic factors influencing the success of the surgical attachment of the LVAD into the myocardium. By using a computational simulation compared to mechanical tests, we sought to investigate the characteristics of stress-induced suture material on porcine myocardium.
Tensile strength experiments (n = 8) were performed on bulk left myocardium to establish a hyperelastic reduced polynomial constitutive law. Simultaneously, suture strength tests on left myocardium (n = 6) were performed with a standard tensile test setup. Experiments were made on bulk ventricular wall with a single U-suture (polypropylene 3-0) and a PTFE pledget. Then, a Finite Element simulation of a LVAD suture case was performed. Strength versus displacement behavior was compared between mechanical and numerical experiments. Local stress fields in the model were thus analyzed.
A strong correlation between the experimental and the numerical responses was observed, validating the relevance of the numerical model. A secure damage limit of 100 kPa on heart tissue was defined from mechanical suture testing and used to describe numerical results. The impact of suture on heart tissue could be accurately determined through new parameters of numerical data (stress diffusion, triaxiality stress). Finally, an ideal spacing between sutures of 2 mm was proposed.
Our computational model showed a reliable ability to provide and predict various local tissue stresses created by suture penetration into the myocardium. In addition, this model contributed to providing valuable information useful to design less traumatic sutures for LVAD implantation. Therefore, our computational model is a promising tool to predict and optimize LVAD myocardial suture.
左心室辅助装置（LVAD）的植入可能会产生过度的局部组织应力和由此产生的应变诱导的组织破裂，这是影响 LVAD 在心外膜成功附着的潜在医源性因素。通过使用计算模拟与机械测试相比，我们试图研究LVAD 在心外膜上的缝合材料的应力特性。
对大块左心室进行拉伸强度实验（n=8），以建立超弹性简化多项式本构定律。同时，对大块心室壁进行左心室缝合强度实验（n=6），采用标准拉伸测试装置。实验采用单个 U 缝线（聚丙烯 3-0）和 PTFE 补片对心室壁进行。然后，对 LVAD 缝线病例进行有限元模拟。将机械实验和数值实验的强度与位移行为进行比较。因此，对模型中的局部应力场进行了分析。
观察到实验和数值响应之间具有很强的相关性，验证了数值模型的相关性。从机械缝线测试中定义了心脏组织的 100kPa 的安全损伤极限，并将其用于描述数值结果。通过数值数据的新参数（应力扩散、三轴性应力）可以准确确定缝线对心脏组织的影响。最后，提出了理想的缝线间距为 2mm。
我们的计算模型显示出可靠的能力，可以提供和预测缝线穿透心肌时产生的各种局部组织应力。此外，该模型有助于提供有用的设计信息，以减少 LVAD 植入的创伤性缝线。因此，我们的计算模型是预测和优化 LVAD 心肌缝线的有前途的工具。
