Abstract:The presence of the sinus of valsalva plays an essential part in the closing mechanism of the aortic valve. High-energy vortices are initiated at the upper limit of each sinus or supraaortic crest, and last during the whole valve closing time. An attempt was made to prove this hypothesis in vivo by intermittent augmentation of each supraaortic ridge. In a series of five dogs without cardiopulmonary bypass, pledgeted sutures were placed at the level of each crest and passed through tourniquets. In a series of t… Show more
“…Previoius authors have suggested that the presence of the sinuses of Valsalva are to assist in cushioning early diastolic transvalvular pressures (Beck et al, 2001; Duran et al, 1990; Sacks et al, 2009). Simulations have shown that the absence of the sinuses results in additional stresses on the leaflets , as does a reduction in the sinus wall compliance (Beck et al, 2001).…”
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 is 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.
“…Previoius authors have suggested that the presence of the sinuses of Valsalva are to assist in cushioning early diastolic transvalvular pressures (Beck et al, 2001; Duran et al, 1990; Sacks et al, 2009). Simulations have shown that the absence of the sinuses results in additional stresses on the leaflets , as does a reduction in the sinus wall compliance (Beck et al, 2001).…”
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 is 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.
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