Regional biomechanical and histological characterization of the mitral valve apparatus: Implications for mitral repair strategies.

The aim of this study was to investigate the regional and directional differences in the biomechanics and histoarchitecture of the porcine mitral valve (MV) apparatus, with a view to tailoring tissue-engineered constructs for MV repair. The anterior leaflet displayed the largest directional anisotropy with significantly higher strength in the circumferential direction compared to the posterior leaflet. The histological results indicated that this was due to the circumferential alignment of the collagen fibers. The posterior leaflet demonstrated no significant directional anisotropy in the mechanical properties, and there was no significant directionality of the collagen fibers in the main body of the leaflet. The thinner commissural chordae were found to be significantly stiffer and less extensible than the strut chordae. Histological staining demonstrated a tighter knit of the collagen fibers in the commissural chordae than the strut chordae. By elucidating the inhomogeneity of the histoarchitecture and biomechanics of the MV apparatus, the results from this study will aid the regional differentiation of MV repair strategies, with tailored mitral-component-specific biomaterials or tissue-engineered constructs.