Key result
Posteromedial chordae tendineae are less numerous but significantly longer and stiffer than anterolateral chordae, likely due to a higher collagen core ratio and larger collagen fibril density.
Why the study?
Little was known about the biomechanical and microstructural properties of the anterior and posterior papillary muscles and their corresponding chordae tendineae.
Posteromedial papillary muscle chordae are significantly longer and stiffer than anterolateral chordae in porcine hearts, suggesting that a papillary muscle-based classification of chordae is necessary for accurate computational modeling and surgical planning of the mitral valve.
Porcine chordae differences caution against uniform mitral models; extends biomechanical data but leaves human applicability open.
The mitral valve (MV) apparatus is a complex mechanical structure including annulus, valve leaflets, papillary muscles (PMs) and connected chordae tendineae. Chordae anchor to the papillary muscles to help the valve open and close properly during one cardiac cycle. It is of paramount importance to understand the functional, mechanical, and microstructural properties of mitral valve chordae and connecting PMs. In particular, little is known about the biomechanical properties of the anterior and posterior papillary muscle and corresponding chords. In this work, we performed uniaxial and biaxial tensile tests on the anterolateral (APM) and posteromedial papillary muscle (PPM), and their respective corresponding chordae tendineae, chordaeAPM and chordaePPM, in porcine hearts. Histology was carried out to link the microstructure and macro-mechanical behavior of the chordae and PMs. Our results demonstrate that chordaePPM are less in number, but significantly longer and stiffer than chordaeAPM. These different biomechanical properties may be partially explained by the higher collagen core ratio and larger collagen fibril density of chordaePPM. No significant mechanical or microstructural differences were observed along the circumferential and longitudinal directions of APM and PPM samples. Data measured on chordae and PMs were further fitted with the Ogden and reduced Holzapfel - Ogden strain energy functions, respectively. This study presents the first comparative anatomical, mechanical, and structural dataset of porcine mitral valve chordae and related PMs. Results indicate that a PM based classification of chordae will need to be considered in the analysis of the MV function or planning a surgical treatment, which will also help developing more precise computational models of MV.
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Chen et al. (2020) studied this question. Biomechanical and morphometric analysis vs. Anterolateral vs posteromedial papillary muscles and chordae was evaluated on Biomechanical properties and microstructure. Posteromedial chordae tendineae are less numerous but significantly longer and stiffer than anterolateral chordae, likely due to a higher collagen core ratio and larger collagen fibril density.
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