While mechanical, homograft and bio-prosthetic valves have been used in patients for many decades and have made significant improvements in patient morbidity, there is still a distinct need to overcome their limitations. Recently, emerging elastomer heart valves have been shown to be able to better re-create the flow physics of native heart valves, resulting in preferable hemodynamic responses. Unfortunately, elastomers such as silicone are prone to structural failure, which drastically limits their applicability towards the development of valve prosthesis. In order to produce a mechanically more robust silicone substrate, we reinforced it with graphene nanoplatelets (GNPs). Cytotoxicity and hemocompatibility tests revealed that the incorporation of GNPs did not adversely affect cell proliferation or augment adhesion of platelets on the surface of the composite materials. The ECM valves showed good hydrodynamic properties and favorable acute performance compared to a commercially available valve. We conclude that both the Graphene reinforce silicone and the ECM is useful and warrants further evaluation as aortic valve substitutes.