Tricuspid Valve Leaflet Strains in Full Heart Preparations via Digital Image Correlation

Tens of millions across the world have tricuspid valve disease. Understanding the mechanics of the valve is important to diagnosing and treating those patients. The objective of our current work is to fill the remaining gaps in our knowledge about tricuspid valve mechanics. Specifically, we are interested in quantifying the between-leaflet and within-leaflet strain heterogeneity under varying hemodynamic and mechanical boundary conditions. To this end, we mounted whole porcine hearts in-vitro, speckled their leaflets, and measured leaflet strains using 3D digital image correlation. We did so while varying peak pressure (20-80 mmHg) and annular dilation (0-60%). To analyze our multi-level data, we used linear mixed models. We found that leaflet strains show high within- and between-leaflet heterogeneity, with both depending on pressure but not on annular dilation. Additionally, we found strains to be directionally dependent. The ratio between radial and circumferential strains, i.e., their anisotropy, also depended on pressure. Finally, we found no apparent pattern of strain distributions across the anterior or posterior leaflet. That is, strains near the annulus, in the belly, and near the free edge did not differ significantly. In contrast, we found that strains in the septal leaflet decreased between the annulus and the free edge. Given the complexity of our data, we make all our raw data openly available for others to access and analyze. In conclusion, our data provides a detailed account of the strains in the tricuspid valve leaflets and may form a foundation for future leaflet-specific diagnostic and therapeutic approaches.