Increased rotational flow in the proximal aortic arch is associated with its dilation in bicuspid aortic valve disease

Abstract

Aims Aortic dilation in bicuspid aortic valve (BAV) might extend to the proximal arch. Arch flow dynamics and their relationship with this segment dilation are still unexplored. Using 4D-flow cardiovascular magnetic resonance, we analysed flow dynamics in the arch for each BAV morphotype and their association with this segment dilation. Methods and results One hundred and eleven BAV patients (aortic diameters ≤55 mm, non-severe valvular disease), 21 age-matched tricuspid aortic valve (TAV) patients with dilated arch and 24 healthy volunteers (HV) underwent 4D-flow. BAV were classified per fusion morphotype: 75% right-left (RL-BAV), and per arch dilation: 57% dilated, mainly affecting the right-noncoronary (RN) BAV (86% dilated vs. 47% in RL-BAV). Peak velocity, jet angle, normalized displacement, in-plane rotational flow (IRF), wall shear stress, and systolic flow reversal ratio (SFRR) were calculated along the thoracic aorta. ANCOVA and multivariate linear regression analyses were used to identify correlates of arch dilation. BAV had higher rotational flow and eccentricity than TAV in the proximal arch. Dilated compared with non-dilated BAV had higher IRF being more pronounced in the RN-morphotype. RN-BAV, IRF, and SFRR were independently associated with arch dilation. Aortic stenosis and male sex were independently associated with arch dilation in RL-BAV. Flow parameters associated with dilation converged to the values found in HV in the distal arch. Conclusion Increased rotational flow could explain dilation of the proximal arch in RN-BAV and in RL-BAV patients of male sex and with valvular stenosis. These patients may benefit from a closer follow-up with cardiac magnetic resonance or computed tomography.

Measuring the Interaction Between the Macro- and Micro-Vasculature

“…Indeed, since they do not require a specific measurement location or velocity encoding direction, 4D-flow MRI is free of angle-dependent errors (velocity errors ensuing from the misalignment between velocity encoding and blood velocity). Another key result of encoding in three directions is the possibility to quantify complex flow patterns, which are related to local dilation (31, 35, 124, 125) and arterial wall disruption (126).…”

Fluid–structure interaction simulations outperform computational fluid dynamics in the description of thoracic aorta haemodynamics and in the differentiation of progressive dilation in Marfan syndrome patients

“…In this section, results from CFD and FSI simulations are compared with respect to their capacity to stratify aneurysm progression in MFS patients. Considering our prior experience in the association between circumferential WSS and aneurysm as well as the well-known relationship between axial WSS and local diameter [11,35,47], the SSR, a WSS-based marker normalizing circumferential WSS for axial WSS was chosen for the test. Differences between stable and dilating patients were higher in FSI compared to CFD simulations.…”

4D flow CMR analysis comparing patients with anatomically shaped aortic sinus prostheses, tube prostheses and healthy subjects introducing the wall shear stress gradient: a case control study

“…2. It seems straightforward that these altered hemodynamic conditions directly influence mechanical forces acting on the vessel wall and it has been hypothesized, that secondary flow patterns are not only a consequence of altered aortic geometry, but also induce its development [28]. The correlations between WSS parameters and a previously introduced semiquantitative grading system of secondary flow patterns [8] provide evidence that an increased number of secondary flow patterns can potentially lead to postoperative aneurysm growth and therefore affect postoperative morbidity.…”