PROSTHETIC HEART VALVE MECHANICS

Strain in commercial grade bovine pericardium leaflets under diastolic pressure of 120 mmHg, as a function of collagen fibre patterns. Material properties calibrated from uniaxial and fatigue bulge loading.

Non-destructive optical analysis of commercial-grade bovine pericardium using in-house small angle light scattering (SALS). Contour plot shows heterogenous collagen fibre structure across patch, with alignment ranging from low to high (0.5 – 0.9). 

Additional to improving materials currently used in bioprosthetic heart valves, we are also developing new material solutions for minimally invasive devices using additive manufacturing. By integrating techniques like melt electrowriting with silicone moulding, we hope to create prosthetic valve leaflets with material properties and structure inspired by healthy, native aortic valve leaflets. Informed by native leaflet material properties and structure (obtained from mechanical testing and imaging), we can use finite element modelling to assess various designs and material pairings for ideal bioinspired, polymer prosthetic valve leaflets.  

Reference: Hughes, C., Johnston, R., Whelan, A., O’Reilly, D., Campbell, E., Lally, C. (2023) ‘Using Finite Element Modelling to Inform Fibre Reinforcement in Polymer Heart Valve Leaflets’ in Bioengineering in Ireland Conference. Enfield, Ireland.  

Publications

[1] Gaul, R., Nolan, D. and Lally, C., 2017. Collagen fibre characterisation in arterial tissue under load using SALS. Journal of the Mechanical Behavior of Biomedical Materials, 75, pp.359-368. Available: 10.1016/j.jmbbm.2017.07.036

[2] Whelan, A., Williams, E., Nolan, D., Murphy, B., Gunning, P., O’Reilly, D. and Lally, C., 2021. Bovine Pericardium of High Fibre Dispersion Has High Fatigue Life and Increased Collagen Content; Potentially an Untapped Source of Heart Valve Leaflet Tissue. Annals of Biomedical Engineering, 49(3), pp.1022-1032. Available: 10.1007/s10439-020-02644-4

[3] Whelan, A., Williams, E., Fitzpatrick, E., Murphy, B. P., Gunning, P. S., O'Reilly, D., & Lally, C. 2021. Collagen fibre-mediated mechanical damage increases calcification of bovine pericardium for use in bioprosthetic heart valves. Acta Biomaterialia, 128, 384-392. doi:10.1016/j.actbio.2021.04.046

[4] Whelan, A., Duffy, J., Gaul, R., O’Reilly, D., Nolan, D., Gunning, P, Lally, C, Murphy, B. 2019. Collagen fibre orientation and dispersion govern ultimate tensile strength, stiffness and the fatigue performance of bovine pericardium. Journal of the Mechanical Behavior of Biomedical Materials, 90, 54-60. doi:10.1016/j.jmbbm.2018.09.038

[5]  Campion, G., Hershberger, K., Whelan, A., Conroy, J., Lally, C., & Murphy, B. P. 2021. A biomechanical and microstructural analysis of bovine and porcine pericardium for use in bioprosthetic heart valves. Structural Heart, 5(5), 486-496. doi:10.1080/24748706.2021.1938317

[6]  Whelan, A., O'Brien, G., Szagdaj, A., O'Reilly, D., & Lally, C. 2021. Investigation into early stage fatigue-damage accumulation in glutaraldehyde-fixed bovine pericardium using a novel equibiaxial bulge inflation system. Journal of the Mechanical Behavior of Biomedical Materials, 121, 104588. doi:10.1016/j.jmbbm.2021.104588