A prosthesis can be configured to grasp intralumenal tissue when deployed within a body cavity and prevent axial flow of fluid around an exterior of the prosthesis. The prosthesis can include an expandable frame configured to radially expand and contract for deployment within the body cavity, and an annular flap positioned around an exterior of the expandable frame. In some embodiments, the annular flap can extend outward from the frame and have a collapsed configuration and an expanded configuration.
