A prosthesis for implantation at a native semilunar valve includes a prosthetic distal valve, which includes a pliant material configured to collapse inwardly towards a longitudinal axis of the prosthesis during diastole, and to open outwardly during systole, and a distal fixation member configured to be positioned in a downstream artery of the subject. The apparatus also includes a proximal fixation member coupled to the distal fixation member, and configured to be positioned at least partially on a ventricular side of the native semilunar valve. The proximal fixation member is shaped so as to define a lattice that is shaped so as to define an intermediary portion that is coupled to the pliant material of the valve and diverges outwardly from the longitudinal axis, and a distal portion that is distal to the intermediary portion and diverges outwardly from the intermediary portion of the lattice. Other embodiments are also described.