The ex vivo heart perfusion device allows the donor heart to maintain full functionality during transfer between extraction and implantation surgeries. One of the current challenges include the mismatches in mechanical properties of synthetic tube materials compared to human aorta. This leads to frequent injuries to the soft and moving heart at the junction, which may result in the rejection of the donor heart for transplantation. In this study, we mimic the ‘J-shaped’ (rapidly strain-stiffening) and anisotropic stress-strain behaviour of human aorta by utilizing fabric-reinforced elastomers. Firstly, we measured the mechanical properties of human and porcine aorta to quantify anisotropic behaviour and a non-linear response. Fabric-reinforced elastomer composites (neo-aorta materials) were prepared from four different textiles to mimic aorta’s non-linear response to strain in three-layer sandwich design. The resulting composites exhibited the J-shaped strain-stiffening behaviour with anisotropicity that matches the properties of natural human and porcine aorta. Most notably, we developed analytical constitutive models based on Gent’s and Mooney-Rivlin’s constitutive law (to describe elastic matrix) combined with Holzapfel–Gasser–Ogden’s law (to represent the stiff fibers) to represent strain-stiffening behavior of natural aorta and confirm aorta-like behavior of fabric-reinforced composite. We anticipate the novel neo-aorta materials to be used in the ex vivo heart perfusion device to increase the number of successful heart transplants.

Mimicking ‘J-shaped’ and anisotropic stress-strain behavior of human aorta by fabric-reinforced elastomer composites

2019 Fall National Meeting

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