Investigating valve and sinus geometery in polymeric valves for a Total Artificial Heart

Introduction

Team Bath Heart is developing a Total Artificial Heart with a polymeric aortic valve and sinus designed for recirculation and regurgitation prevention. Inappropriate valve geometry disrupts the balance between biocompatibility and structural integrity, leading to blood trauma and long-term adverse effects. This project investigates how valve and sinus geometrical parameters influence performance and aims to optimise the design using Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD).

Methods

Transient FEA was used to simulate the valve leaflet using a Mooney–Rivlin hyperelastic material model. Physiological transvalvular pressure loads were used to analyse stress distributions and leaflet coaptation during the cardiac cycle. Steady CFD models were developed to study flow dynamics of the valve and sinus under peak systolic pressure. Optimisation used Gaussian Process Regression and Bayesian Regularized Artificial Neural Network surrogate models trained on 56 FEA and CFD simulations of varying leaflet lengths, thicknesses, and sinus radii, generated by Latin hypercube sampling. Genetic algorithms were used to explore the design space and minimise blood trauma indicators.

Results

FEA revealed stress concentration at commissure locations, while leaflet thickness was identified as critical for valve flexure and movement. Coaptation analysis confirmed robust sealing throughout the cardiac cycle, strongest at the onset of diastole. CFD simulations showed central jet reattachment on the downstream aortic wall, generating sinus vortex formation. High wall shear and haemolysis risk were observed at commissure tips, motivating further parameterisation. Optimisation and flow analysis indicated that middle-length leaflets promoted central jet reattachment at downstream aortic wall, promoting recirculation vortexes for washout. A smaller sinus radius strengthens and enhances vortex stability throughout the cycle.

Discussion

The combined FEA/CFD framework and surrogate-based optimisation successfully identified key geometric trade-offs in valve and sinus design, highlighting the importance of balancing shear reduction, vortex facilitation, and washout to minimise blood trauma, providing a critical foundation for further refinement of polymer total artificial heart valves.