A system for replacing a native heart valve, the system comprising: an expansible helical anchor formed as multiple coils adapted to support a heart valve prosthesis, at least one of the coils being normally being at a first diameter, and being expandable to a second, larger diameter upon application of radial outward force from within the helical anchor; an expansible heart valve prosthesis capable of being delivered into the helical anchor and expanded inside the multiple coils into engagement with the at least one coil to move the at least one coil from the first diameter to the second diameter while securing the helical anchor and the heart valve prosthesis together, wherein the expansible heart valve prosthesis includes a blood inflow end and a blood outflow end, characterized in that the system further comprises: a seal (84, 90) on the expansible heart valve prosthesis configured to engage the helical anchor and prevent blood leakage past the heart valve prosthesis after implantation of the heart valve prosthesis in the helical anchor, wherein the blood outflow end of the heart valve prosthesis includes a bumper for preventing damage to tissue structure in the heart after implantation, the bumper comprising an internal layer covered by a sealing layer (84, 90), the sealing layer (84, 90) covering an outflow portion of the expansible heart valve prosthesis. an expansible helical anchor formed as multiple coils adapted to support a heart valve prosthesis, at least one of the coils being normally being at a first diameter, and being expandable to a second, larger diameter upon application of radial outward force from within the helical anchor; an expansible heart valve prosthesis capable of being delivered into the helical anchor and expanded inside the multiple coils into engagement with the at least one coil to move the at least one coil from the first diameter to the second diameter while securing the helical anchor and the heart valve prosthesis together, wherein the expansible heart valve prosthesis includes a blood inflow end and a blood outflow end, characterized in that the system further comprises: a seal (84, 90) on the expansible heart valve prosthesis configured to engage the helical anchor and prevent blood leakage past the heart valve prosthesis after implantation of the heart valve prosthesis in the helical anchor, wherein the blood outflow end of the heart valve prosthesis includes a bumper for preventing damage to tissue structure in the heart after implantation, the bumper comprising an internal layer covered by a sealing layer (84, 90), the sealing layer (84, 90) covering an outflow portion of the expansible heart valve prosthesis. a seal (84, 90) on the expansible heart valve prosthesis configured to engage the helical anchor and prevent blood leakage past the heart valve prosthesis after implantation of the heart valve prosthesis in the helical anchor, wherein the blood outflow end of the heart valve prosthesis includes a bumper for preventing damage to tissue structure in the heart after implantation, the bumper comprising an internal layer covered by a sealing layer (84, 90), the sealing layer (84, 90) covering an outflow portion of the expansible heart valve prosthesis.