The nonlinear elastic and viscoelastic passive properties of left ventricular papillary muscle of a Guinea pig heart
The nonlinear elastic and viscoelastic passive properties of left ventricular papillary muscle of a Guinea pig heart
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DOI：
10.1016/j.jmbbm.2011.08.011
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发表时间：
2012-01-01
影响因子：
3.9
通讯作者：
Noma, A.
中科院分区：
文献类型：
--
作者：
Hassan, M. A.;Hamdi, M.;Noma, A.
心肌组织的力学行为是人工心脏收缩、兴奋传播和发育有限元模拟的核心问题。在体外精密单轴和松弛实验的基础上，测定了豚鼠心脏左心室乳头肌的非线性弹性和粘弹性被动材料特性。非线性弹性行为采用亚弹性模型和不同的超弹性应变能函数，如Ogden和Mooney-Rivlin。在MatLab和MSC.MARC环境下进行了非线性最小二乘拟合和约束优化，得到了模型材料参数。利用实验拉伸数据得到了心肌的非线性弹性力学行为。然而，应力松弛数据被用来确定组织的松弛行为和粘度。粘超弹性行为由瞬时变形的标准Ogden应变能函数W和松弛函数R(T)以Prony级数形式相乘分解而成。研究表明，低弹性和超弹性(Ogden)模型很好地拟合了组织的力学行为，可以安全地用于心脏力学模拟。由于心肌组织的特征驰豫时间(900S)与心脏跳动周期的实际时间(800ms)相比非常大，因此粘度的影响可以合理地忽略。实验数据的数量和类型对Ogden参数有很大的影响。体外被动力学性能是开始运行心脏力学生物模拟程序的良好初始值。然而，一种基于临床完整心脏测量的优化算法被开发出来，以估计和重新校正材料参数，以获得非常精确的生物模拟和人工心脏新材料开发所需的体内力学性能。(C)2011爱思唯尔有限公司。保留所有权利。
The mechanical behavior of the heart muscle tissues is the central problem in finite element simulation of the heart contraction, excitation propagation and development of an artificial heart. Nonlinear elastic and viscoelastic passive material properties of the left ventricular papillary muscle of a guinea pig heart were determined based on in-vitro precise uniaxial and relaxation tests. The nonlinear elastic behavior was modeled by a hypoelastic model and different hyperelastic strain energy functions such as Ogden and Mooney-Rivlin. Nonlinear least square fitting and constrained optimization were conducted under MATLAB and MSC.MARC in order to obtain the model material parameters. The experimental tensile data was used to get the nonlinear elastic mechanical behavior of the heart muscle. However, stress relaxation data was used to determine the relaxation behavior as well as viscosity of the tissues. Viscohyperelastic behavior was constructed by a multiplicative decomposition of a standard Ogden strain energy function, W, for instantaneous deformation and a relaxation function, R (t), in a Prony series form. The study reveals that hypoelastic and hyperelastic (Ogden) models fit the tissue mechanical behaviors well and can be safely used for heart mechanics simulation. Since the characteristic relaxation time (900 s) of heart muscle tissues is very large compared with the actual time of heart beating cycle (800 ms), the effect of viscosity can be reasonably ignored. The amount and type of experimental data has a strong effect on the Ogden parameters. The in vitro passive mechanical properties are good initial values to start running the biosimulation codes for heart mechanics. However, an optimization algorithm is developed, based on clinical intact heart measurements, to estimate and re-correct the material parameters in order to get the in vivo mechanical properties, needed for very accurate bio-simulation and for the development of new materials for the artificial heart. (C) 2011 Elsevier Ltd. All rights reserved.