Computational Fluid Dynamics Analysis of Artificial Aortic Valves: Impact of Tilted Implantation on Haemodynamics

Prosthesis-patient mismatch (PPM) and tilted implantation in aortic valve replacement can significantly affect haemodynamics, increasing wall shear stress (WSS) and thrombosis risk. This study uses computational fluid dynamics (CFD) to assess the impact of valve size and implantation angle on blood flow in Medtronic Avalus heart valves.

Computational fluid dynamics (CFD) simulations were conducted using Ansys Fluent to evaluate 3 Medtronic Avalus valve sizes (23 mm, 25 mm, 27 mm) under 2 leaflet-opening configurations. The simulations incorporated physiological boundary conditions, including a steady inlet velocity of 0.3 m/s and a no-slip wall condition. Wall shear stress (WSS) and general shear stress (SS) thresholds were analysed to assess thrombosis risk.

The 25 mm valve reduced the WSS-affected area by 20.83% and the shear stress-affected area by 7.64% compared to the 23 mm valve, demonstrating improved haemodynamics. In contrast, the 27 mm valve increased the WSS-affected area by 41.25% and the shear stress-affected area by 11.26%, with elevated turbulence and recirculation zones near the aortic wall, increasing thrombosis risk.

Moderate upsizing to a 25 mm valve improves haemodynamic performance without introducing adverse flow effects, while further upsizing to 27 mm increases stress and turbulence, raising thrombosis risk.