A prosthetic heart valve having a plurality of leaflets each having an upstream end , wherein each leaflet is synthetic and has a modulus of elasticity in the range of 10-45 MegaPascals (MPa); and a support structure wherein the prosthetic heart valve has a closed position and an open position and the plurality of leaflets and the support structure moves between the closed position and the open position comprising: a plurality of projections having a downstream end and coupled with the plurality of leaflets ; and an annular base about the periphery of the support structure integral with the plurality of leaflets upstream of the plurality of projections , wherein the plurality of projections and the base are elastic, and the support structure has a modulus of elasticity between 3000 and 5000 MPa and the upstream base has an upstream edge that is sinusoidally-shaped in the closed positions and a reversed-profile sinusoidally shaped in the open position and wherein the upstream edge has a first location directly upstream from each downstream end of the plurality of projections such that a plurality of first locations are present on the upstream edge ; and a second location directly upstream from each upstream end of the plurality of leaflets such that a plurality of second locations are present on the upstream edge , wherein, at a first time during movement of the support structure from the closed position to the open position, each first location moves in a upstream direction and each second location moves in an downstream direction; wherein the prosthetic heart valve is configured to permit fluid flow in an upstream to downstream direction when a transvalve fluid pressure is positive, and configured such that the plurality of leaflets are in a coapted state when the transvalve fluid pressure is a peak negative pressure. a plurality of projections having a downstream end and coupled with the plurality of leaflets ; and an annular base about the periphery of the support structure integral with the plurality of leaflets upstream of the plurality of projections , wherein the plurality of projections and the base are elastic, and the support structure has a modulus of elasticity between 3000 and 5000 MPa and the upstream base has an upstream edge that is sinusoidally-shaped in the closed positions and a reversed-profile sinusoidally shaped in the open position and wherein the upstream edge has a first location directly upstream from each downstream end of the plurality of projections such that a plurality of first locations are present on the upstream edge ; and a second location directly upstream from each upstream end of the plurality of leaflets such that a plurality of second locations are present on the upstream edge , wherein, at a first time during movement of the support structure from the closed position to the open position, each first location moves in a upstream direction and each second location moves in an downstream direction; a second location directly upstream from each upstream end of the plurality of leaflets such that a plurality of second locations are present on the upstream edge , wherein, at a first time during movement of the support structure from the closed position to the open position, each first location moves in a upstream direction and each second location moves in an downstream direction; wherein the prosthetic heart valve is configured to permit fluid flow in an upstream to downstream direction when a transvalve fluid pressure is positive, and configured such that the plurality of leaflets are in a coapted state when the transvalve fluid pressure is a peak negative pressure. <EOS>