Modeling active muscle contraction in mitral valve leaflets during systole: a first approach |
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Authors: | B Skallerud V Prot and I S Nordrum |
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Institution: | (1) Department of Mechanical Engineering, San Diego State University, San Diego, CA 92182-1323, USA;(2) Department of Mechanical Engineering, San Diego State University, San Diego, CA 92182-1323, USA; |
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Abstract: | The present study addresses the effect of muscle activation contributions to mitral valve leaflet response during systole.
State-of-art passive hyperelastic material modeling is employed in combination with a simple active stress part. Fiber families
are assumed in the leaflets: one defined by the collagen and one defined by muscle activation. The active part is either assumed
to be orthogonal to the collagen fibers or both orthogonal to and parallel with the collagen fibers (i.e. an orthotropic muscle
fiber model). Based on data published in the literature and information herein on morphology, the size of the leaflet parts
that contain muscle fibers is estimated. These parts have both active and passive materials, the remaining parts consist of
passive material only. Several solid finite element analyses with different maximum activation levels are run. The simulation
results are compared to corresponding echocardiography at peak systole for a porcine model. The physiologically correct flat
shape of the closed valve is approached as the activation levels increase. The non-physiological bulging of the leaflet into
the left atrium when using passive material models is reduced significantly. These results contribute to improved understanding
of the physiology of the native mitral valve, and add evidence to the hypothesis that the mitral valve leaflets not are just
passive elements moving as a result of hemodynamic pressure gradients in the left part of the heart. |
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