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.