Impact of Aortic Valve Replacement on Flow Profiles in the Ascending Aorta

Objectives: Complex flow profiles in the ascending aorta have been associated with progression in aortic dilation, which affects morbidity and mortality of patients. We aimed to compare blood flow profiles in the ascending aorta in patients before and after aortic valve replacement (AVR) with 4D VEC-MRI. Computational Fluid Dynamics (CFD) virtually assessed the effect of modified surgical technique on flow profiles in the ascending aorta.

Methods: Thirty-four patients underwent 4D VEC-MRI before and after AVR (n = 27, biological AVR (BAVR); n = 7, mechanical AVR [MAVR]). Seven healthy volunteers served as controls. Assessment of helical, vortical, and eccentric flow in the ascending aorta was performed to calculate an “eccentricity score” (ES) and “complex flow

Results: Before AVR, all patients showed a higher degree of complex flow profiles than healthy volunteers (ES: 2.5 vs. 1, p < 0.0001; CFS: 4.7 vs. 1, p < 0.0001). After BAVR, the degree of complex flow profiles fell only moderately (ES: 2.7 vs. 2.3, p < 0.001; CFS: 4.7 vs. 4.3, p < 0.0001) and remained altered compared with healthy volunteers (ES: 2.3 vs. 1, p < 0.0001; CFS 4.3 vs. 1, p < 0.0001). After MAVR, the degree of complex flow profiles fell strongly (ES: 2.3 vs. 1, p = 0.02; CFS: 4.3 vs. 1, p = 0.02) and did not show a significant difference to healthy volunteers (p = 0.5 and p = 0.7, respectively). A subsequent CFD analysis in 4 cases suggested that changes in the rotational position of the MAVR or changes in size and angulation of the BAVR could improve flow profiles.

Conclusion: AVR using biological valves did not restore normal blood flow profiles in the ascending aorta. Mechanical valves, however, showed flow profiles that were more comparable to healthy volunteers. The use of CFD might be helpful to adapt the surgical technique for optimized flow profiles in the ascending aorta.