Fluid-structure interaction analysis of mitral valve repair with papillary muscle relocation and approximation: a patient-specific analysis

Functional mitral regurgitation (FMR) is mainly caused by augmented leaflet tethering resulting from the outward displacement of the papillary muscles (PM). Recently, new subvalvular surgical procedures aiming to reduce leaflet tethering by PM relocation (PMR) and approximation (PMA) have emerged. The purpose of this study was to virtually evaluate the effect of PMA and PMR on left heart (LH) dynamics using a fluid-structure interaction (FSI) modeling approach. Cardiac multi-slice computed tomography images and Doppler echocardiography data from a 71-year-old male patient with severe MR were used to develop and validate a patient-specific 3D LH model. A FSI framework that combines smoothed particle hydrodynamics and nonlinear finite element formulation was used. PMR was simulated by displacing the chordae origins towards the mitral annulus, while PMA was modeled by decreasing the inter-PM distance. Pre- and post-MV repair FSI simulations results were compared, and the effects on cardiac hemodynamics, MR severity, and leaflets deformation state and kinematics were investigated. Results showed that PMR and PMA techniques cause differences in the intraventricular blood flow dynamics and MV mechanics, despite comparable results in restoration of leaflet coaptation and MR reduction.