A system for cardiac implantation of a valve prosthesis, comprising: - a catheter; and - a radially expandable valve prosthesis comprising: -- an expandable annular support frame adapted to be initially crimped in a narrow configuration for catheterization through a body duct to a target location, the annular support frame comprising a plurality of longitudinally rigid support beams of fixed length each provided with a plurality of bores, the expandable support frame configured to be expanded to an expanded configuration in the target location; and -- a tricuspid leafed-valve assembly comprising a conduit having an inlet end and an outlet, made of pliant material arranged so as to present collapsible walls at the outlet, wherein the valve assembly is made of pericardium, and wherein the attachment of the valve assembly to the frame is facilitated by the support beams to which the valve assembly is stitched with thread or fiber through the bores of the support beams; -- wherein when flow is allowed to pass through the valve prosthesis from an inlet to an outlet the valve assembly is kept in an open position, whereas a reverse flow is prevented as the collapsible walls of the valve assembly collapse inwardly for providing blockage to the reverse flow. - a catheter; and - a radially expandable valve prosthesis comprising: -- an expandable annular support frame adapted to be initially crimped in a narrow configuration for catheterization through a body duct to a target location, the annular support frame comprising a plurality of longitudinally rigid support beams of fixed length each provided with a plurality of bores, the expandable support frame configured to be expanded to an expanded configuration in the target location; and -- a tricuspid leafed-valve assembly comprising a conduit having an inlet end and an outlet, made of pliant material arranged so as to present collapsible walls at the outlet, wherein the valve assembly is made of pericardium, and wherein the attachment of the valve assembly to the frame is facilitated by the support beams to which the valve assembly is stitched with thread or fiber through the bores of the support beams; -- wherein when flow is allowed to pass through the valve prosthesis from an inlet to an outlet the valve assembly is kept in an open position, whereas a reverse flow is prevented as the collapsible walls of the valve assembly collapse inwardly for providing blockage to the reverse flow. -- an expandable annular support frame adapted to be initially crimped in a narrow configuration for catheterization through a body duct to a target location, the annular support frame comprising a plurality of longitudinally rigid support beams of fixed length each provided with a plurality of bores, the expandable support frame configured to be expanded to an expanded configuration in the target location; and -- a tricuspid leafed-valve assembly comprising a conduit having an inlet end and an outlet, made of pliant material arranged so as to present collapsible walls at the outlet, wherein the valve assembly is made of pericardium, and wherein the attachment of the valve assembly to the frame is facilitated by the support beams to which the valve assembly is stitched with thread or fiber through the bores of the support beams; -- wherein when flow is allowed to pass through the valve prosthesis from an inlet to an outlet the valve assembly is kept in an open position, whereas a reverse flow is prevented as the collapsible walls of the valve assembly collapse inwardly for providing blockage to the reverse flow.