The congenital bicuspid aortic valve (BAV) is associated with increased leaflet calcification, ascending aortic dilatation, aortic stenosis (AS) and regurgitation (AR). Although underlying genetic factors have been primarily implicated for these complications, the altered mechanical environment of BAVs could potentially accelerate these pathologies. The objective of the current study is to characterize BAV hemodynamics in an in vitro system. Two BAV models of varying stenosis and jet eccentricity and a trileaflet AV (TAV) were constructed from excised porcine AVs. Particle Image Velocimetry (PIV) experiments were conducted at physiological flow and pressure conditions to characterize fluid velocity fields in the aorta and sinus regions, and ensemble averaged Reynolds shear stress and 2D turbulent kinetic energy were calculated for all models. The dynamics of the BAV and TAV models matched the characteristics of these valves which are observed clinically. The eccentric and stenotic BAV showed the strongest systolic jet (V = 4.2 m/s), which impinged on the aortic wall on the non-fused leaflet side, causing a strong vortex in the non-fused leaflet sinus. The magnitudes of TKE and Reynolds stresses in both BAV models were almost twice as large as comparable values for TAV, and these maximum values were primarily concentrated around the central jet through the valve orifice. The in vitro model described here enables detailed characterization of BAV flow characteristics, which is currently challenging in clinical practice. This model can prove to be useful in studying the effects of altered BAV geometry on fluid dynamics in the valve and ascending aorta. These altered flows can be potentially linked to increased calcific responses from the valve endothelium in stenotic and eccentric BAVs, independent of concomitant genetic factors.
This erratum is to correct for a normalization factor that was not applied in the contour plots in Figure 10(b) of the published paper. The viscous shear stress (VSS) values were not normalized by the number of vector fields utilized for ensemble averaging (N = 50), hence the correct magnitudes of the VSS for all three valves should be smaller by a factor of 50 than the images presented in the original manuscript. However, the trends observed from the VSS, which are presented in the Results and Discussion sections of the paper, are not affected due to this error, since results from all three valve models are scaled by the same number of images (N = 50).The corrected version of Fig. 10 is presented here. As such, all other figures in the original manuscript were verified to be correct. FIGURE 10. (a) Out-of-plane vorticity and (b) VSS for all valve models.
In about 1–2% of all live births, the human aortic valve only consists of two anomalous leaflets and is known as the bicuspid aortic valve (BAV). BAVs are the most common congenital cardiac anomaly, and are associated with significant valvular dysfunction, including calcific aortic stenosis (AS) and aortic regurgitation (AR), as well as aortic wall abnormalities including coarctation of the aorta, ascending aortic dilatation and aneurysms [1]. Many studies have proposed a common underlying genetic defect in progression of complications with BAVs [2]. However, other recent studies have also suggested that the altered hemodynamic environment associated with BAVs could also be responsible for accelerated disease progression in these patients [3, 4]. A recent in vitro study showed elevated levels of turbulence associated with BAVs, and indicated that fluid flow patterns in the aortic sinuses are also affected due to the altered valve morphology [5]. The present work seeks to compare the levels of turbulence in BAVs to pure trileaflet aortic stenosis models.
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