Computational fluid dynamics technique shows potential to benefit the design of prosthetic heart valves

Posted: September 13, 2022
Schematic of leaflets used in the study
Schematic of leaflets used in the study: (a) baseline - without VGs, (b) with co-rotating VGs, (c) with counter-rotating VGs , (d) VG configurations and arrangements

Patients in need of a replacement aortic heart valve face the risk of blood damage caused by prosthetic heart valves, but a recent study led by an MAE researcher sought to find a solution.

Dr. Zhenyu Wang, an assistant research professor in the MAE department and Simulation Innovation and Modeling Center who specializes in computational fluid dynamics (CFD), investigated whether the use of vortex generators on bi-leaflet mechanical aortic heart valves could reduce the risk of blood clotting and red blood cell damage caused by high turbulence as a result of traditional valve designs. His research was published in the Biomedical Engineering Society’s Annals of Biomedical Engineering.

Graph of blood damage with co-rotating configuration being the lowest
Fraction of blood damage for various configurations

By demonstrating that the use of vortex generators on mechanical heart valves has significant potential to reduce the risk of blood damage, Dr. Wang’s study has substantial implications for the safety of patients in need of a replacement.

“The wide impact is that younger patients are possible to receive a replacement heart valve that will serve them for the rest of their lives without the need for additional operations or strong blood thinner therapy,” Wang said.

The goal of this study was to investigate if vortex generators applied on mechanical heart valves could reduce the risk of blood damage when comparing to the traditional replacement heart valves in use today. With traditional valves, high turbulence and Reynold’s Shear Stress are a large contributing factor to blood damage and decay of prosthetic heart valves.

The CFD model, including the mechanical heart valves and vortex generators, was created and simulated in STAR-CCM+ via the high-performance computational clusters from Ohio Supercomputer Center. This research was conducted using the computational method and validated by the experimental data from a collaborator from Georgia Tech.

Comparison of time-averaged vorticity contour of the co-rotating and counter-rotating mechanical heart valves in the central plane
Comparison of time-averaged vorticity contour of the co-rotating and counter-rotating mechanical heart valves in the central plane (z=0) between the (a) Experiment_Co-rotating VG; (b) Experiment_Counter-rotating VG; (c) Simulation_Co-rotating VG; (d) Simulation_Counter-rotating VG

Wang set up a simulation of three different leaflet schematics: a baseline without any vortex generators, a leaflet with co-rotating vortex generators and a leaflet with counter-rotating vortex generators.

CFD simulations provide a visual representation of the flow field for each configuration. The flow characteristics obtained in the simulations showed that the test configurations with vortex generators considerably reduced blood flow turbulence compared to the control simulation with no vortex generator.

Reynolds shear stress (Pa) contours in the central plane: (a) control - without VGs, (b) with co-rotating VGs, (c) with counter-rotating VGs
Reynolds shear stress (Pa) contours in the central plane: (a) control - without VGs, (b) with co-rotating VGs, (c) with counter-rotating VGs

“We found that in these configurations, the co-rotating VG configuration resulted in the lowest turbulence,” he said, “hypothetically making it the most effective at preventing blood clots and red blood cell damage.”

Computational fluid dynamics simulations are extremely valuable in situations like these where obtaining detailed flow characteristic that are nearly impossible to be accessed by experimental measurement.

 

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