Computational simulation of oxygen diffusion in aortic valve leaflet for tissue engineering applications.

BACKGROUND AND AIM OF THE STUDY

Tissue thickness plays an important role in oxygen and nutrient transport and supply of tissue-engineered aortic valves. The study aim was to investigate the effect of tissue thickness and thickness variation on oxygen diffusion in a three-dimensional (3D) aortic valve leaflet model.

METHODS

Replicas of fresh porcine aortic valve cusps were cast using synthetic rubber, and the corresponding thickness profiles measured using contacting profilometry. Subsequently, the profiles were used for 3D oxygen diffusion modeling. Histological characterization of the trilaminar structure for the valve tissue was carried out to determine the ratios of each individual layer to the total tissue thickness. Computational simulations were carried out based on the native aortic cusp geometry obtained by the 3D thickness profiles, employing the finite difference numerical approach.

RESULTS

Excellent agreement in predicted oxygen pressure was achieved between the numerical solution, under both steady-state and transient conditions, and the analytical solution of the steady-state case. Oxygen distribution in the aortic leaflet model was predicted and compared to that of the two-dimensional (along the radial direction and cusp thickness) and one-dimensional (along the cusp thickness) models. Finally, the variation of predicted hypoxic areas with increasing mean cusp thickness was investigated.

CONCLUSION

The study results showed that the finite difference method can provide an accurate estimate of oxygen distribution within the leaflet. They also showed that both tissue thickness and thickness variation determined the minimum oxygen tension in the center of the leaflet, indicating that a 3D model is necessary in order to accurately predict oxygen distribution within the native leaflet.