Abstract: A valve prosthesis for controlling the flow of blood through a cardiac opening in which a stent (b) is adapted to be permanently secured to the cardiac tissue around a cardiac opening (a) and the stent (b) forms a cylindrical opening having a preset inside diameter not less than the diameter of the cardiac opening (a) or is slightly larger than the diameter of the cardiac opening (a). A valve member (c) is releasably connected to stent (b) to control the flow of blood through the cardiac opening (a). The valve member (c) may be releasably connected to the stent (b) by means of a set of teeth (3) that are wedged into an inside circumferential groove (2) extending around the stent ring (b') or a thread set (3) can engage a thread (2) on the stent ring (b').