Finite Element Analysis of Patient-Specific Mitral Valve with Mitral Regurgitation

Abstract

Functional mitral regurgitation (FMR) is a significant complication of left ventricular (LV) dysfunction and strongly associated with a poor prognosis. In this study, we developed a patient-specific finite element (FE) model of the mitral apparatus in a FMR patient which included: both leaflets with thickness, annulus, chordae tendineae, and chordae insertions on the leaflets and origins on the papillary muscles. The FE model incorporated human age- and gender- matched anisotropic hyperelastic material properties, and MV closure at systole was simulated. The model was validated by comparing the FE results from valve closure simulation with the in vivo geometry of the MV at systole. It was found that the FE model could not replicate the in vivo MV geometry without the application of tethering pre-tension force in the chordae at diastole. Upon applying the pre-tension force and performing model optimization by adjusting the chordal length, position, and leaflet length, a good agreement between the FE model and the in vivo model was established. Not only were the chordal forces high at both diastole and systole, but the tethering force on the anterior papillary muscle was higher than that of the posterior papillary muscle, which resulted in an asymmetrical gap with a larger orifice area at the anterolateral commissure resulting in MR. The analyses further show that high peak stress and strain were found at the chordal insertions where large chordal tethering forces were found. This study shows that the pre-tension tethering force plays an important role in accurately simulating the MV dynamics in this FMR patient, particularly in quantifying the degree of leaflet coaptation and stress distribution. Due to the complexity of the disease, the patient-specific computational modeling procedure of FMR patients presented should be further evaluated using a large patient cohort. However, this study provides useful insights into the MV biomechanics of a FMR patient, and could serve as a tool to assist in pre-operative planning for MV repair or replacement surgical or interventional procedures.

Finite element analysis of annuloplasty and papillary muscle relocation on a patient-specific mitral regurgitation model

“…The material properties of the MV apparatus and LV were obtained by fitting in-house biaxial test data of an age- and gender-matched human cadaver heart, i.e., a 69-year-old male patient. Details on the implementation of the model and material parameters of the MV apparatus were previously published [ 17 ]. Briefly, the mitral tissues are assumed to be composed of a matrix material with two families of embedded fibers, each with a preferred direction.…”

“…To simulate the tethering of the PML, posterior chords originating from a total of 8 chordal origins were shortened by translating the chordal origins towards the annulus plane along the original axes of the chords[ 17 ]. In the first step of the simulation, those chordal origins were displaced to their original locations to generate the tethering tension within the chords ( Fig 2a ).…”

“…To simulate MV closure during systole following the virtual ring implantation, the chordal origin nodes were displaced from middle diastole to middle systole based on their dynamic motion tracked from MSCT images [ 17 ]. A pressure load of 114 mmHg was applied on the ventricular surfaces of AML and PML to simulate the systolic transvalvular pressure.…”

“…To assess the impact of each procedure on MR, the coaptation depth and length, intercommissural distance, septal-lateral distance, regurgitant orifice area, and tenting area at middle systole were measured from the simulation results as described in our previous study [ 17 ]. To study the changes in LV geometry in response to ring annuloplasty and PMR treatments, the APM-MA distance and inter-PM distance were also measured.…”

“…Also, such models did not account for the presence of leaflet tethering associated with FMR with LV dilation. Recently, we presented a case study of an FMR patient where the leaflet tethering force were accounted for in the reference geometries, which is essential for accurate MV modeling and quantification of leaflet coaptation and stress distribution [ 17 , 18 ].…”