Aortic wall shear stress in Marfan syndrome

Abstract

The aim of this study was to quantify changes in thoracic aortic wall shear stress (WSS) in asymptomatic patients with Marfan syndrome (MFS) compared with healthy controls. WSS in the thoracic aorta was quantified based on time-resolved 3D phase contrast MRI with three-directional velocity encoding (4D flow MRI, temporal resolution ∼44 ms, spatial resolution ∼2.5 mm) in 24 patients with confirmed MFS (age = 18 ± 12 years) and in 12 older healthy volunteers (age = 25 ± 3 years). Diameters of the thoracic aorta normalized to body surface area were similar for both groups. Peak systolic velocity, absolute WSS, time-averaged WSS, circumferential WSS, peak systolic WSS, and WSS eccentricity were calculated in eight analysis planes distributed along the thoracic aorta. Plane-wise comparison revealed significant differences between MFS patients and volunteers in the proximal ascending aorta for peak systolic velocities (1.11 ± 0.23 m/s vs. 1.34 ± 0.18 m/s, P = 0.004) and circumferential WSS (0.14 ± 0.03 N/m(2) vs. 0.11 ± 0.02 N/m(2), P = 0.007). WSS eccentricity was altered in most of the ascending aorta and proximal arch (P = 0.009-0.020). MFS patients demonstrated segmental differences in peak systolic WSS with a significantly higher WSS at the inner curvature in the proximal ascending aorta and at the anterior part in the more distal ascending aorta (P < 0.01). These findings indicate differences in WSS associated with MFS despite similar aortic dimensions compared to controls.

Greater asymmetric wall shear stress in Sievers' type 1/LR compared with 0/LAT bicuspid aortic valves after valve-sparing aortic root replacement

“…18 To determine the degree of rotation, particle traces released at the Abbreviations and Acronyms BAV ¼ bicuspid aortic valve CT ¼ computed tomography Type 0/LAT ¼ type 0 valve without the presence of a raphe, and with the 2 commissures oriented right-anterior-to-leftposterior Type 1/LR ¼ type 1 valve with fusion of the left and right cusps with 1 raphe Type 1/RN ¼ type 1 valve with fusion of the right and noncoronary cusps with 1 raphe V-SARR ¼ valve-sparing aortic root replacement WSS ¼ wall shear stress 4D flow MRI ¼ time-resolved 3-dimensional phase contrast magnetic resonance imaging beginning of systole were visualized qualitatively to determine the degree of helical flow. Additionally, the percentage of the vessel lumen containing helical flow was quantified based on axial vector fields at multiple planes through the ascending aorta.…”

Altered aortic 3D hemodynamics and geometry in pediatric Marfan syndrome patients

“…Independent associations between hemodynamic markers and aortopathy have been presented in cardiovascular magnetic resonance (CMR) imaging studies [7–10]. These studies employed time-resolved 3D phase-contrast CMR with three-directional velocity encoding (4D flow CMR) to enable a comprehensive, non-invasive in-vivo investigation of cardiac and aortic hemodynamics.…”

Advanced flow MRI: emerging techniques and applications

“…A number of investigators have exploited these advantages of multi-dimensional flow imaging to derive new physiological and pathophysiological haemodynamic parameters, such as wall shear stress (WSS) vectors 21,22,84-89 , pulse wave velocity (PWV) 29,30 , 3D pressure difference maps 25,26,28,90-92 , or energy loss 13,31,32,93 . These advanced haemodynamic measures can provide quantitative information on the impact of vascular disease on aortic or pulmonary blood flow patterns.…”