Simulating the Transmural Mechanical Response of Functionally Graded Arterial Grafts

With coronary artery disease remaining the leading cause of mortality worldwide, the design and manufacture of clinically viable synthetic coronary artery grafts remains a fundamental healthcare challenge. It is widely accepted that vascular mimicking materials (VMMs) should emulate the heterogeneous biomechanical and biological functions of the multilayered artery wall to ensure long-term patency postimplantation. However, few VMMs can adequately meet these complex design requirements. Poly(vinyl alcohol) (PVA)/gelatin cryogels are prospective VMMs due to their combined mechanical (PVA) and biointegrative (gelatin) features, but their development thus far has been limited to homogeneous constructs. The aim of this research is to assess the mechanical response of biomimetically designed multilayered grafts, simulated using Finite Element Analysis. The impact of a sinusoidal interface on circumferential stress distribution and graft compliance, was explored. Using qualitative insight from research on hydrogel based functionally graded biomaterials, and in the context of subzero extrusion additive manufacturing, rough (infinite) friction was used to model the contact between the layer. It was found that transmural stress patterns were continuously graded (phased) as a function of interface amplitude and frequency. In contrast to laminated models, which displayed a discontinuity in transmural stress between layers. This design methodology illustrates a novel approach to achieving functionally graded synthetic grafts through interface design.