Apparatus and methods are described, including one or more valve support guide members that are delivered to one or more commissures of a native atrioventricular valve of a patient. A prosthetic valve support is advanced toward the native valve along the one or more valve support guide members and placed at the native valve. A prosthetic valve is coupled to the valve support. One or more sealing elements facilitate sealing of an interface between the prosthetic valve support and the native valve. Other applications are also described.