Severe aortic stenosis generated highly skewed jet velocities up to 8.0 m/s and maximum turbulent shear stresses of 2,500 Pa, compared to 260 Pa in mild AS and 490 Pa in moderate AS.
How do blood flow dynamics and shear stresses change across mild, moderate, and severe aortic stenosis models?
Severe aortic stenosis generates extremely high peak velocities (up to 8 m/s) and turbulent shear stresses (up to 2,500 Pa), providing a biomechanical link to hemostatic abnormalities like acquired von Willebrand syndrome.
Supraphysiologic high shear stresses created in calcific aortic stenosis (AS) are known to cause hemostatic abnormalities, however, the relationship between the complex blood flows over the severity of AS and hemostatic abnormalities still remains unclear. This study systematically characterized the blood flow in mild, moderate, and severe AS. A series of large eddy simulations (LES) validated by particle image velocimetry were performed on physiologically representative AS models with a peak physiologic flow condition of 18 liter per minute. Time-accurate velocity fields, transvalvular pressure gradient, and laminar viscous-and turbulent (or Reynolds) shear stresses (RSSmax) were evaluated for each degree of severity. The peak velocities of mild, moderate, and severe AS were on the order of 2.0, 4.0, and 8.0 m/s, respectively. Jet velocity in severe AS was highly skewed with extremely high velocity (as high as 8 m/s) and mainly traveled through the posterior aortic wall up to the aortic arch while still carrying a relatively high velocity, that is, >4 m/s. The mean laminar viscous wall shear stresses (WSS) for mild, moderate, and severe AS were on the order of 40, 100, and 180 Pa, respectively. The RSSmax were on the order of 260, 490, and 2,500 Pa for mild, moderate, and severe AS, respectively. This study may provide a link between altered flows in AS and hemostatic abnormalities such as acquired von Willebrand syndrome and hemolysis, thus, help diagnosing and timing of the treatment.
Jhun et al. (2020) studied Aortic Stenosis. Aortic stenosis severity (mild, moderate, severe) was evaluated on Blood flow characteristics (peak velocity, laminar viscous wall shear stress, turbulent shear stress). Severe aortic stenosis generated highly skewed jet velocities up to 8.0 m/s and maximum turbulent shear stresses of 2,500 Pa, compared to 260 Pa in mild AS and 490 Pa in moderate AS.