There is disclosed herein a valve prosthesis comprising: a valve body； and a frame including a first tubular portion connected to the valve body, and a second tubular portion configured to contact and conform to a native valve annulus in situ, the frame having a delivery configuration in which the first tubular portion is positioned in series with the second tubular portion along a longitudinal axis of the frame and the first tubular portion is longitudinally adjacent to the second tubular portion, and an expanded configuration in which the first tubular portion is positioned within an interior area of the second tubular portion, such that the second tubular portion surrounds the first tubular portion and both of the first tubular portion and the second tubular portion extend parallel to the longitudinal axis of the frame.
