Regional analysis of dynamic deformation characteristics of native aortic valve leaflets.

BACKGROUND: The mechanical environment of the aortic valve (AV) has a significant impact on valve cellular biology and disease progression, but the regional variation in stretch across the AV leaflet is not well understood. This study, therefore, sought to quantify the regional variation in dynamic deformation characteristics of AV leaflets in the native mechanical environment in order to link leaflet stretch variation to reported AV calcification patterns.
METHODS: Whole porcine AVs (n=6) were sutured into a physiological left heart simulator and subjected to pulsatile and physiologically normal hemodynamic conditions. A grid of ink dots was marked on the entire ventricular surface of the AV leaflet. Dual camera stereo photogrammetry was used to determine the stretch magnitudes across the entire ventricular surface over the entire diastolic duration.
RESULTS: Elevated stretch magnitudes were observed along the leaflet base and coaptation line consistent with previously reported calcification patterns suggesting the higher mechanical stretch experienced by the leaflets in these regions may contribute to increased disease propensity. Transient stretch overloads were observed during diastolic closing, predominantly along the leaflet base, indicating the presence of a dynamic fluid hammer effect resulting from retrograde blood flow impacting the leaflet. We speculate the function of the leaflet base to act in cooperation with the sinuses of Valsalva to dampen the fluid hammer effect and reduce stress levels imparted on the rest of the leaflet.