The In-Situ Mechanics of the Tricuspid Valve: Strain Heterogeneity and Anisotropy via 3D Digital Image Correlation

Background: The mechanics of the tricuspid valve are a critical determinant of its function and dysfunction. With millions suffering from tricuspid regurgitation, there is a pressing need to fill persistent knowledge gaps. A better understanding of the valve's mechanics is essential for improving repair strategies and biomaterial-based replacements. Objective: This study aimed to quantify the differences in strains within leaflets and between leaflets under both physiological and pathological loads. Methods: We mounted six whole porcine heart preparations in vitro and measured full-field leaflet strains using three-dimensional digital image correlation.We varied peak transvalvular pressures between 20, 50, and 80 mmHg and applied three levels of annular dilation (0%, 30%, and 60%). Strain data were transformed into leaflet-specific radial and circumferential components, and compared statistically using linear mixed-effects models. Results: Leaflet strains exhibited significant within- and between-leaflet heterogeneity. Strain magnitude increased with pressure but not with annular dilation. Additionally, strains were directionally dependent. Furthermore, we found that anterior and posterior leaflet strains near the annulus, in the belly, and near the free edge did not differ significantly. In contrast, strains in the septal leaflet increased from the annulus to the free edge. Conclusions: These data provide spatially and directionally resolved strain maps of all three tricuspid valve leaflets in whole-heart preparations. By filling a critical knowledge gap, these findings may guide the design of biomaterials for valve repair and replacement.