Quantifying drivers of valve failure in bicuspid aortic valves: Raphe-dependent strain concentration

Bicuspid aortic valve (BAV), the most common congenital heart disease, is associated with a high surgical disease burden. BAVs fail with a fusion of two aortic valve leaflets, creating raphe, which contributes to further leaflet calcification (strongly correlated with localized strain concentration), thickening, and immobility. Leveraging our computational platform that considers 2-way fluid-structure interactions, we simulated the mechanical environment of BAVs with varying extents of the raphe. A 3-parameter Mooney-Rivlin hyper-elastic material model was employed and input pressure waveforms were measured using an in vitro experimental setup with a bioprosthetic valve module. Leaflets sutured to several extents mimicked the congenital raphe. Simulation results revealed that the raphe in BAV modulates strain concentration, amplifying the strain value in selected regions ̶ a determinant factor and potential predictive metric of aortic valve calcification. Though more extensive studies are warranted to couple in silico predictions to in vivo events, engineering tools akin to the one presented herein could provide a robust and reliable means for a mechanistic understanding of pathophysiology to inform the timing of interventional planning and design of emerging prosthetic valves.