A prosthesis (10) 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 comprises an expandable frame (20) configured to radially expand and contract for deployment within the body cavity and an annular flap (50) positioned around and secured to an exterior of the expandable frame, the annular flap having a distal edge secured at or near the distal end (14) of the frame and extending to a proximal edge secured at an intermediate location on the frame between the proximal (12) and distal (14) ends. The prosthesis also comprises a valve body positioned within an interior of the expandable frame, wherein the valve body comprises: an inner skirt (62) secured to the interior of the expandable frame (20)； and a plurality of leaflets (64) configured to allow flow in a first direction and prevent flow in a second opposite direction. An opening is defined at or near the distal end of the frame between the annular flap and the valve body to provide access for fluid to flow into a space (59) between the annular flap and the valve body, and wherein fluid flow into the space causes the annular flap to move from a first configuration wherein the flap is closer to the frame to a second configuration wherein the flap is spaced further away from the frame to increase the surface area of the prosthesis and create a barrier to fluid flow exterior to the frame when deployed within the body cavity.L'invention concerne une prothèse (10) qui peut être configurée pour saisir un tissu intraluminal lorsqu'il est déployé à l'intérieur d'une cavité corporelle, et empêcher un écoulement axial de fluide autour de l'extérieur de la prothèse. La prothèse comprend un cadre extensible (20) configuré pour s'étendre et se contracter radialement pour un déploiement à l'intérieur de la cavité corporelle, et un rabat annulaire (50) positionné autour de l'extérieur du cadre extensible et fixé à
