Smith K J, Mathur M, Meador W D, Phillips-Garcia B, Sugerman G P, Menta A K, Jazwiec T, Malinowski M, Timek T A, Rausch M K
The University of Texas at Austin, Austin, TX 78712.
The University of Texas at Austin Austin, TX 78712.
Shi Yan Li Xue. 2021 Jan;61(1):19-29. doi: 10.1007/s11340-020-00594-5. Epub 2020 Jun 8.
Tricuspid valve chordae tendineae play a vital role in our cardiovascular system. They function as "parachute cords" to the tricuspid leaflets to prevent prolapse during systole. However, in contrast to the tricuspid annulus and leaflets, the tricuspid chordae tendineae have received little attention. Few previous studies have described their mechanics and their structure-function relationship.
In this study, we aimed to quantify the mechanics of tricuspid chordae tendineae based on their leaflet of origin, insertion site, and size.
Specifically, we uniaxially stretched 53 tricuspid chordae tendineae from sheep and recorded their stress-strain behavior. We also analyzed the microstructure of the tricuspid chordae tendineae based on two-photon microscopy and histology. Finally, we compared eight different hyperelastic constitutive models and their ability to fit our data.
We found that tricuspid chordae tendineae are highly organized collageneous tissues, which are populated with cells throughout their thickness. In uniaxial stretching, this microstructure causes the classic J-shaped nonlinear stress-strain response known from other collageneous tissues. We found differences in stiffness between tricuspid chordae tendineae from the anterior, posterior, or septal leaflets only at small strains. Similarly, we found significant differences based on their insertion site or size also only at small strains. Of the models we fit to our data, we recommend the Ogden two-parameter model. This model fit the data excellently and required a minimal number of parameters. For future use, we identified and reported the Ogden material parameters for an average data set.
The data presented in this study help to explain the mechanics and structure-function relationship of tricuspid chordae tendineae and provide a model recommendation (with parameters) for use in computational simulations of the tricuspid valve.
三尖瓣腱索在我们的心血管系统中起着至关重要的作用。它们就像三尖瓣小叶的“降落伞绳索”，在收缩期防止小叶脱垂。然而，与三尖瓣环和小叶相比，三尖瓣腱索受到的关注较少。以前很少有研究描述它们的力学特性及其结构 - 功能关系。
在本研究中，我们旨在根据三尖瓣腱索的起源小叶、插入部位和大小来量化其力学特性。
具体而言，我们对来自绵羊的53条三尖瓣腱索进行单轴拉伸，并记录其应力 - 应变行为。我们还基于双光子显微镜和组织学分析了三尖瓣腱索的微观结构。最后，我们比较了八种不同的超弹性本构模型及其拟合我们数据的能力。
我们发现三尖瓣腱索是高度有序的胶原组织，在其整个厚度中都有细胞分布。在单轴拉伸时，这种微观结构导致了其他胶原组织中已知的经典J形非线性应力 - 应变响应。我们发现仅在小应变时，来自前叶、后叶或隔叶的三尖瓣腱索在刚度上存在差异。同样，我们也发现仅在小应变时，基于其插入部位或大小也存在显著差异。在我们拟合数据的模型中，我们推荐奥格登双参数模型。该模型对数据拟合得非常好，并且所需参数数量最少。为了未来使用，我们确定并报告了平均数据集的奥格登材料参数。
本研究中呈现的数据有助于解释三尖瓣腱索的力学特性及其结构 - 功能关系，并为三尖瓣的计算模拟提供了一个模型推荐（包括参数）。
