A leaflet for a prosthetic valve formed of at least one layer that includes acomposite material containing at least one expanded fluoropolymer membranehavingserpentine fibrils and an elastomer is provided. The fluoropolymer may bepolytetrafluoroethylene.In at least one embodiment, the elastic properties are present in an axialdirection the leaflet. The leaflets may be single layered or multi-layered.The leaflets maybe coupled to a support structure and movable between open and closedconfigurationsrelative to the support structure to form a heart valve. The elasticity withinthe leafletspermits, among other things, the leaflets to bend with a reduced occurrence ofwrinklesas the valve opens and closes. The elastic properties of the leaflet also,among otherthings, improve bending properties and reduce closure stresses, therebyextending thelife of the leaflet.
