Mitral Valve Finite Element Modeling: Implications of Tissues' Nonlinear Response and Annular Motion
Mitral Valve Finite Element Modeling: Implications of Tissues' Nonlinear Response and Annular Motion
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DOI：
10.1115/1.4000107
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发表时间：
2009-12-01
影响因子：
1.7
通讯作者：
Redaelli, Alberto
中科院分区：
文献类型：
--
作者：
Stevanella, Marco;Votta, Emiliano;Redaelli, Alberto
有限元建模代表了理解二尖瓣功能和模拟有趣临床场景的既定方法。然而，目前的模型仍然没有包括真实的系统的所有关键方面。我们实施了一种新的结构有限元模型，该模型考虑（i）瓣膜的准确形态描述，（ii）考虑各向异性和非线性的组织机械特性描述，以及（iii）模拟瓣环和乳头肌收缩的动态边界条件。通过将计算结果与通过固定瓣环和乳头肌的所有辅助模型获得的结果进行比较，评估这种收缩对瓣膜生物力学的影响。在收缩期峰值时，瓣叶最大主应力等值线在前叶支柱腱索插入区（300 kPa）和瓣环附近（200-250 kPa）显示峰值，而在后叶检测到低得多的值。两个瓣叶在纵向方向上都经历了较大的拉伸应变，而在周向瓣叶中，前瓣叶经历了高达18%的标称拉伸应变，后瓣叶经历了高达23%的压缩应变，这与连合折叠和旁连合相关，与组织冗余一致。收缩峰值时乳头肌施加的力等于4.11 N，主要由边缘腱索承担（76%的力）。计算瓣环上的局部反力尖端为45 mN，导致其前束和后束的张力分别为89 N/m和54 N/m。与辅助模型的结果比较表明，瓣环收缩主要影响瓣叶的周向应变。当它被抑制时，不能观察到更多的压缩应变，峰值应变值位于前叶的腹部。计算。结果与文献中的实验数据在很大程度上吻合。他们提供了对正常二尖瓣功能特征的一些了解，例如瓣环收缩和瓣叶的组织各向异性和非线性。某些计算结果可用于外科器械和技术的设计。特别是，周围组织施加在瓣环上的力可被视为瓣环假体设计的指示。[DOI：10.1115/1.4000107]
Finite element modeling represents an established method for the comprehension of the mitral function and for the simulation of interesting clinical scenarios. However current models still do not include all the key aspects of the real system. We implemented a new structural finite element model that considers (i) an accurate morphological description of the valve, (ii) a description of the tissues' mechanical properties that accounts for anisotropy and nonlinearity, and (iii) dynamic boundary conditions that mimic annulus and papillary muscles' contraction. The influence of such contraction on valve biomechanics was assessed by comparing the computed results with the ones obtained through all auxiliary model with fixed annulus and papillary muscles. At the systolic peak, the leaflets maximum principal stress contour showed peak values in the anterior leaflet at the strut chordae insertion zone (300 kPa) and near the annulus (200-250 kPa), while much lower values were detected in the posterior leaflet. Both leaflets underwent larger tensile strains in the longitudinal direction, while in the circumferential one the anterior leaflet experienced nominal tensile strains up to 18% and the posterior one experienced compressive strains up to 23% associated with the folding of commissures and paracommissures, consistently with tissue redundancy The force exerted by papillary muscles at the systolic peak was equal to 4.11 N, mainly borne by marginal chordae (76% of the force). Local reaction forces tip to 45 mN were calculated on the annulus, leading to tensions of 89 N/m and 54 N/m for its anterior and posterior tracts, respectively The comparison with the results of the auxiliary model showed that annular contraction mainly affects the leaflets' circumferential strains. When it was suppressed, no more compressive strains could be observed and peak strain values were located in the belly of the anterior leaflet. Computational. results agree to a great extent with experimental data from literature. They provided insight into some of the features characterizing normal mitral function, such as annular contraction and leaflets' tissue anisotropy and nonlinearity. Some of the computed results may be useful in the design of surgical devices and techniques. In particular forces applied on the annulus by the surrounding tissues could be considered as an indication for annular prostheses design. [DOI: 10.1115/1.4000107]