A prosthesis implanting system includes a delivery sheath for receiving the prosthesis and delivering it to the treatment site and an alignment device on the sheath visible to a user for indicating a rotational and an axial position of the sheath with respect to the treatment site. The alignment device is part of a delivery assembly slidably disposed in a handle. The delivery assembly has a hollow first lumen for slidably receiving therein a guidewire, a hollow second lumen slidably disposed about the first lumen, a hollow third lumen slidably disposed about the second lumen and having a distal end at which the sheath is connected and is disposed about the first and second lumen. The sheath holds the prosthesis therein prior to implantation and the alignment device is connected to the sheath. A relatively stiff outer lumen is slidably disposed about the third lumen and sheath.