A method of securing a prosthesis atraumatically to body tissue can include one or more of the following steps. A prosthesis can be delivered into a patient. The prosthesis may include an expandable frame. The frame can be expanded within a body cavity of the patient. Expansion of the frame can causes respective ends of both proximal prongs and distal prongs to draw closer together to grasp native tissue between the respective ends of the proximal prongs and distal prongs.