Shifting the aortic valve leaflet belly curve from native to a linear profile progressively decreased average leaflet effective stress but localized maximum stress to leaflet tips and commissures, and shifted valve orifice area with maximum geometric orifice area achieved at 70% belly curve shift in HH40 chick embryo valves.
A parametric finite element analysis of chick embryo aortic valves demonstrates that while altering the belly curve to a linear profile reduces average tissue stress, it causes stress concentration at the tips and commissures, highlighting a biomechanical trade-off during valve development.
The anatomy and mechanical strength of aortic valve leaflets are critical determinants of their biomechanical behavior and long-term structural integrity. The embryonic developmental period, when valves are forming, is critical to establish baseline leaflet properties. However, fetal stages of valve development, when valve leaflets are still forming and remodeling, are not well understood. The goal of this study is to investigate the biomechanical stress and deformation modes of developing valve leaflets during systole, and how leaflet biomechanics are affected by anatomy and material properties. To this end, the study employs a parametric approach to model the leaflet anatomy of an HH40 chick embryo, used here as a model of fetal cardiac development. To perform biomechanical analysis, a pressure profile derived from in ovo Doppler ultrasound measurements was applied, and an Ogden hyperelastic material model was employed following a sensitivity analysis. To determine the effect of valve anatomy on leaflet tissue deformation and stresses, we changed the leaflet midline curve (belly curve) from its native curvature to a linear profile and quantified biomechanical responses. Our analysis revealed a strong decrease in average leaflet effective stress as the belly curvature was shifted towards a linear profile. However, this reduction in average stress was at the expense of a biomechanical trade-off. The shift induced a progressive localization of stress concentration at the leaflet tips and commissures, and a distinct bending deformation mode at the tip under peak load. Our findings demonstrate that while the belly curve of the leaflet modulates tissue stress during valve opening, a low-stress anatomy does not align with hemodynamic performance. This work characterizes competing leaflet biomechanical responses (stress reduction versus failure modes) that shape valve leaflet formation, providing fundamental insights into developmental valve biomechanics.
Mutlu et al. (Fri,) conducted a other in Developing aortic valve leaflets of HH40 stage chick embryos (approx. 14 days incubation) used as a model of fetal cardiac valve development. Parametric finite element modeling of aortic valve leaflet biomechanics with varied leaflet midline belly curve geometry vs. Native (0% shift) belly curve leaflet geometry was evaluated on Valve leaflet effective stress distribution and valve orifice area during systole (peak pressure time point 0.08 seconds). Shifting the aortic valve leaflet belly curve from native to a linear profile progressively decreased average leaflet effective stress but localized maximum stress to leaflet tips and commissures, and shifted valve orifice area with maximum geometric orifice area achieved at 70% belly curve shift in HH40 chick embryo valves.