Abstract 16142: Aortic Flow Eccentricity and Wall Shear Stress in the Dilated Ascending Aorta With and Without Aortic Valve Stenosis and Regurgitation
Introduction: Ascending aortic (AAo) dilatation is associated with aortic valve stenosis (AS) and regurgitation (AR) but can also be present in patient with normal aortic valves. The understanding of the underlying changes in aortic hemodynamics associated with these different aortic dilatation phenotypes is lacking.
Purpose: To characterize differences in AAo flow eccentricity and wall shear stress (WSS) between patients with AS, AR, and neither AS nor AR (no AS/AR), all with dilated AAo, and healthy controls using 4D flow MRI.
Methods: A total of 96 subjects identified via IRB-approved retrospective chart review were comprised of moderate to severe AS (n=8, 72±9 years, mid AAo diameter [MAAd]: 41±2mm), moderate to severe AR (n=33, 62±14 years, MAAd: 44±5 mm), no AS/AR (n=30, 63±9 years, MAAd: 42±4 mm) and controls (n=25, 57±10 years, MAAd: 33±4 mm). All subjects underwent in-vivo 4D flow MRI. AAo flow eccentricity was evaluated by identifying regions with systolic peak velocities >1 m/s in 4 cross-sectional quadrants in the proximal, mid and distal AAo. Systolic peak WSS was calculated in 10 anatomic aortic segments (Fig .2).
Results: Increased flow eccentricity was observed in the patients with AS in the mid and distal AAo, with AR in any part of AAo, and with no AS/AR in the proximal AAo, while controls demonstrated more uniform flow profiles (Fig. 1). As summarized in Fig. 2, significantly elevated WSS was observed in the patients with AS from AAo to arch compared to those with AR, no AS/AR and controls, and in those with AR in outer curvature of proximal AAo, both curvatures of distal AAo and arch compared to those with no AS/AR. Significantly lowered WSS was found in the patients with no AS/AR in the inner curvature of distal AAo compared to controls.
Conclusions: Despite similar AAo dilatation severity, patients with AS and AR demonstrated elevated WSS and flow eccentricity compared to those with no AS/AR, indicating a different underlying flow physiology and disease phenotype.
Author Disclosures: K. Suwa: None. O.A. Rahman: None. E. Bollache: None. M.J. Rose: None. A.A. Rahsepar: None. H. Hayashi: None. J. Carr: None. J.D. Collins: None. A.J. Barker: None. M. Markl: None.
- © 2016 by American Heart Association, Inc.