Non-Newtonian blood models alter wall shear stress predictions by 15-30% in stenotic and stented flows, review finds

The review synthesizes constitutive models ranging from generalized Newtonian to full TEVP frameworks and evaluates them against steady and pulsatile flows in stenoses, bifurcations, and aneurysms. Mechanisms such as red-cell aggregation and deformability produce shear-thinning and viscoelastic effects that reduce wall shear stress gradients and extend residence times near prosthetic valves and stents. These changes directly influence thrombosis thresholds and device-induced hemolysis rates.

Existing hemodynamic simulations in regulatory submissions still default to Newtonian viscosity, underestimating flow stagnation by up to 25% in low-shear regions according to cited benchmark studies. Sasmal connects this gap to clinical observations of higher thrombosis in certain stent geometries where Newtonian codes predicted safe flow. The analysis highlights that viscoelastic normal stresses can stabilize or destabilize recirculation depending on heart-rate frequency.

Future device design will require TEVP implementations in patient-specific CFD to set hemolysis and thrombosis risk thresholds. Validation against high-resolution particle-image velocimetry in pulsatile loops remains the critical missing step before these models enter FDA review pathways.

Supporting work on viscoelastic blood in mechanical heart valves (Vlastos et al., J Biomech 2022) and thixotropic effects in aneurysms (Morbiducci et al., Ann Biomed Eng 2023) confirms the magnitude of deviation reported here.