There is provided a prosthetic aortic conduit comprising a replacement valve locating means. The replacement valve locating means can be, for example, a biocompatible radio-opaque marker, for example a tantalum marker. Optionally the replacement valve locating means comprises three radio-opaque markers, conveniently equi-distally spaced around the circumference of the conduit. The replacement valve locating means identifies the location of the aortic valve and facilitates later insertion of a replacement aortic valve by catheter. Methods of treatment are also described.