The prosthesis has a body (1) in which right and left ventricles are arranged. A fixing unit formed of transverse groove (16) and transverse axle (25), fixes an end of a bezel (2) on a bezel (3), where the unit permits to fold the bezel (2) on the bezel (3). A guiding unit formed of longitudinal surfaces (10, 11, 20, 21) and a front surface (22) guides the bezels with respect to each other before and during the fixing of bezel. A latching unit formed of pin (19) and hooks (26) latches the bezel (2) on the bezel (3) in an operation position corresponding to an end of folding of the bezel (2).