Influence of Annular Dynamics and Material Behavior in Finite Element Analysis of Barlow’s Mitral Valve Disease

Abstract

Barlow’s disease affects the entire mitral valve apparatus, by altering several of the fundamental mechanisms in the mitral valve which ensures unidirectional blood flow between the left atrium and the left ventricle. In this paper, a finite element model of a patient diagnosed with Barlow’s disease with patient-specific geometry and boundary conditions is presented. The geometry and boundary conditions are extracted from the echocardiographic assessment of the patient prior to surgery. Material properties representing myxomatous, healthy human and animal mitral valves are implemented and computed response are compared with each other and the echocardiographic images of the patient. This study shows that the annular dilation observed in Barlow’s patients controls several aspects of the mitral valve behavior during ventricular systole. The coaptation of the leaflets is observed to be highly dependent on annular dilation, and the coaptation area reduces rapidly at the onset of mitral regurgitation. Furthermore, the leaflet material implementation is important to predict lack of closure in the FE model correctly. It was observed that using healthy human material parameters in the Barlow’s diseased FE geometry gave severe lack of closure from the onset of mitral regurgitation, while myxomatous material properties showed a more physiological leakage.

A Doppler-exclusive non-invasive computational diagnostic framework for personalized transcatheter aortic valve replacement

“… and are material constants for the isotropic neo-Hookean material model for the matrix. Incompressibility of the aortic valve tissue 115 forces the second term of the isotropic component ( ) to zero. To avoid divergence, we assume a conservative incompressibility value (i.e., a Poisson's ratio of 0.475) in our simulations.…”

“…To avoid divergence, we assume a conservative incompressibility value (i.e., a Poisson's ratio of 0.475) in our simulations. In several studies, the assumption of nearly compressible behaviour was used to simulate cardiac tissues using finite elements 115 – 118 .…”

Finite element analysis of mitral valve annuloplasty in Barlow’s disease

“…The studied subject gave written informed consent, and the study protocol was approved by the Regional Committees on Biomedical Research Ethics. The patient-specific Barlow's MV model was created by following the pipeline presented in Aguilera et al (2021). The FE modeling is summarized below.…”

“…The Gasser-Ogden-Holzapfel (GOH) material model, available in the Abaqus material library (Abaqus, 2014;Gasser et al, 2006), was used with the fitted material parameters of myxomatous degenerative leaflet tissue presented in Aguilera et al (2021). Briefly, 𝐽 = det 𝐅 where 𝐅 is the deformation gradient, Ī1 = 𝐽 −2∕3 𝟏 ∶ (𝐅 T 𝐅) and Ī4 = 𝐽 −2∕3 (𝐅 T 𝐅) ∶ 𝐚 0 ⊗ 𝐚 0 , where 𝐚 0 is a unit vector denoting the collagen fiber orientation in the undeformed configuration.…”

A toolbox for generating scalable mitral valve morphometric models

“…Computational studies have focused on diseased MV shapes (Caballero et al, 2019, Biffi et al, 2019, Aguilera et al, 2021 and surgical procedures (Choi et al, 2020, Kong et al, 2018, either using structure-only finite element (FE) analysis (which allows to study leaflet stress patterns), or fluid-structure interaction (FSI) simulations (which accounts for the interaction between blood flow and the structure of the valve). The accuracy of these models is sensitive to valve geometry; however, even though several MV models from the literature are based on patient-specific geometries obtained from medical imaging, the associated generation process can be time consuming and computationally expensive, especially when employing numerical mesh-based approaches (Zhang et al, 2019).…”