Type of aortic valve replacement influences ascending aortic flow characteristics - a pilot study using 4D flow MRI

Knobelsdorff-Brenkenhoff et al. Journal of Cardiovascular Magnetic Resonance Type of aortic valve replacement influences ascending aortic flow characteristics - a pilot study using 4D flow MRI Florian von Knobelsdorff-Brenkenhoff 0 Ralf F Trauzeddel 0 Alex J Barker 2 Henriette Gruettner 0 Michael Markl 1 2 Jeanette Schulz-Menger 0 From th Annual SCMR Scientific Sessions San Francisco CA USA. January - 1 February 0 Working Group Cardiovascular MRI, Experimental and Clinical Research Center (Charite Medical Faculty and MDC) and HELIOS Clinics Berlin , Berlin , Germany 1 Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University , Chicago, IL , USA 2 Department of Radiology, Feinberg School of Medicine, Northwestern University , Chicago, IL , USA - Background Prosthesis-related alterations of blood flow in the ascending aorta after aortic valve replacement (AVR) may influence aortic remodeling. The study aimed at analyzing ascending aortic flow characteristics after various types of AVR. Methods Flow-sensitive four-dimensional magnetic resonance imaging (4D-flow) was acquired in 38 AVR patients (n=9 mechanical, n=8 stentless bioprosthesis, n=14 stented bioprosthesis, n=7 autograft) and 9 healthy controls. Analysis included grading of vortex and helix flow (0-3 point scale), assessment of systolic flow eccentricity (1-3 point scale), and quantification of the segmental distribution of peak systolic wall shear stress (WSSpeak) in the ascending aorta. Results Compared to controls, mechanical prostheses showed the most distinct vorticity (2.70.5 vs. 0.70.7; p<0.001), while stented bioprostheses exhibited most distinct helicity (2.60.7 vs. 1.60.5; p=0.002) (Figures 1 and 2). Figure 2 Evaluation of vorticity, helicity and eccentricity of blood flow: The upper row shows the frequency of each score for the various AVR groups and controls. The lower row depicts the mean SD scoring results. Please note that the order of the groups varies between the three columns. (* p<0.05 vs. stentless, autografts and controls; p<0.05 vs. stentless, autografts and controls; <0.05 vs. controls; $ p<0.05 vs. stented, autografts, controls; | |p<0.05 vs. stentless, mechanical, autografts and controls). Instead of a physiologic central flow, all stented, stentless and mechanical prostheses showed eccentric flow jets mainly directed towards the right-anterior aortic wall. Stented and stentless prostheses showed an asymmetric distribution of WSSpeak along the aortic circumference, with significantly increased local WSSpeak where the flow jet impinged on the aortic wall. Local WSSpeak was higher in stented (1.40.7N/m2) and stentless (1.3 0.7N/m2) compared to autografts (0.60.2N/m2; p=0.005 and p=0.008) and controls (0.70.1N/m2; p=0.017 and p=0.027). Autografts exhibited lower absolute WSSpeak than controls (0.40.1N/m2 vs. 0.70.2N/ m2; p=0.003). Funding FvKB is supported by the Else Krner-Fresenius Stiftung (Bad Homburg, Germany). AJB is funded by the Whitaker Postdoctoral and Fulbright Grants (New York, USA). MM is supported by the NMH Excellence in Academic Medicine (EAM) Program Advanced Cardiovascular MRI Research Center (Chicago, USA). (...truncated)