Key result
Aortic stenosis caused a 125% increase in total shear stress in the bulk flow during late systole compared to healthy flow, accompanied by a shift to left-handed helical structures.
Why the study?
Aortic stenosis causes altered supra-valvular flow patterns that can increase red blood cell membrane damage, but patient-specific flow patterns and their reversal remain to be investigated.
Does 4D Flow MRI-based CFD modeling identify altered hemodynamic bulk flow patterns in patients with severe aortic stenosis?
Does 4D Flow MRI-based CFD modeling identify altered hemodynamic bulk flow patterns in patients with severe aortic stenosis?
Patient-specific 4D Flow MRI-based CFD modeling demonstrates that severe aortic stenosis causes a 125% increase in bulk flow shear stress and alters helical flow patterns, potentially explaining increased red blood cell damage.
May link elevated shear to RBC damage in aortic stenosis; leaves open translation to human 4D Flow MRI CFD.
Aortic stenosis (AS) leads to alterations of supra-valvular flow patterns which can cause increased damage of red blood cell (RBC) membranes. We investigated these patient specific patterns of a severe AS patient and their reversal in healthy flow through a 4D Flow MRI-based CFD methodology. Computational models of subject-specific aortic geometries were created using in-vivo medical imaging data. Temporally and spatially resolved boundary conditions derived from 4D Flow MRI were implemented for an AS patient and a healthy subject. After validation of the in-silico results with in-vivo data, a healthy inflow profile was set for the AS patient in the CFD model. Pathological versus healthy flow fields were compared regarding their blood flow characteristics, i.e., shear stresses on RBCs and helicity. The accuracy of the 4D Flow MRI-based CFD model was proven with excellent agreement between in-vivo and in-silico velocity fields and R² = 0.9. A pathological high shear stress region in the bulk flow was present during late systole with an increase of 125% compared to both healthy flow. The physiological bihelical structure with predominantly right-handed helices vanished for the pathological state. Instead, a left-handed helix appeared, accompanied by an overall increase in turbulent kinetic energy in areas of accumulated left-handed helicity. The validated 4D Flow MRI-based CFD model identified marked differences between AS and healthy flow. It suggests that altered turbulent and helical structures in the bulk flow are the cause for increased, potentially damaging forces acting upon RBCs in AS.
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Wang et al. (2025) studied Aortic stenosis (n=2). Aortic stenosis flow vs. Healthy flow was evaluated on Total shear stress in bulk flow (125% increase). Aortic stenosis caused a 125% increase in total shear stress in the bulk flow during late systole compared to healthy flow, accompanied by a shift to left-handed helical structures.
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