Bicuspid aortic valve disease is associated with abnormal wall shear stress, viscous energy loss, and pressure drop within the ascending thoracic aorta

Figure 1. The illustrated definitions of (i) axial, circumferential, and magnitude WSS sub-vectors (left) and (ii) the 2 methods of measuring these WSS sub-vectors at aortic locations. Ao, aorta; BAV, bicuspid aortic valve; WSS, wall shear stress; WSSA, axial wall shear stress; WSSC, circumferential wall shear stress; WSSM, magnitude wall shear stress; WSSavg, circumference-averaged WSS; WSSmax, localized maximum WSS.

Figure 2. Workflow diagram of study methods. AAo, ascending aorta; AA1, proximal to first aortic branch; BAV, bicuspid aortic valve; DAo, descending aorta; EL, viscous energy loss; LVOT, left ventricular outflow tract; MAA, mid-ascending aorta; PD, pressure drop; SOV, sinuses of Valsalva; WSS, wall shear stress.

Figure 3. Hemodynamic contrasts between controls and BAV cohorts. Each color-coded value represents the mean value of its respective cohort. BAV, bicuspid aortic valve; ELindex, peak systolic viscous energy loss normalized to LVOT net flow; ELsys, peak systolic viscous energy loss; LVOT, left ventricular outflow tract; PDsys, peak systolic pressure drop; WSSA,avg, circumference-averaged axial wall shear stress; WSSC,avg, circumference-averaged circumferential wall shear stress; WSSM,avg, circumference-averaged magnitude wall shear stress. ∗∗P < 0.01.

Figure 4. Visualized examples of localized maximum WSSM values at each aortic location in a healthy control and a BAV patient. AA1, proximal to first aortic branch; BAV, bicuspid aortic valve; LVOT, left ventricular outflow tract; MAA, mid-ascending aorta; SOV, sinuses of Valsalva; WSS, wall shear stress; WSSM, magnitude wall shear stress; yrs, years old.

Figure 5. Correlations between indexed diameter and several 4D-Flow parameters at each aortic location separately. AA1, proximal to first aortic branch; ELindex, peak systolic viscous energy loss indexed to left ventricular outflow tract net flow; MAA, mid-ascending aorta; PDsys, peak systolic pressure drop; R, correlation coefficient; SOV, sinuses of Valsalva; WSSavg, circumference-averaged wall shear stress. ∗P < 0.05, ∗∗P < 0.01.

Figure 6. Correlations between indexed diameter and several 4D-Flow parameters at all aortic locations collectively. AA1, proximal to first aortic branch; ELindex, peak systolic viscous energy loss indexed to left ventricular outflow tract net flow; MAA, mid-ascending aorta; PDsys, peak systolic pressure drop; R, correlation coefficient; SOV, sinuses of Valsalva; WSSavg, circumference-averaged wall shear stress. ∗P < 0.05, ∗∗P < 0.01.