A prosthesis delivery system for implanting a heart valve prosthesis, comprising: a handle assembly comprising: a housing; and a control element; and a delivery catheter extending from the handle assembly comprising: an outer sheath slidably controlled by the control element; and an inner shaft (116, 516) slidably controlled by the control element, the inner shaft (116, 516) having a valve retainer (132, 532), wherein the control element comprises a thumbwheel, wherein the thumbwheel comprises an exterior surface having a plurality of protrusions located on the exterior surface, and wherein the system further comprises: a track having an exterior surface and a plurality of protrusions located on at least a portion of the exterior surface; an outer sheath carrier connected to the track and the outer sheath; an inner shaft carrier, having an exterior surface and a plurality of protrusions located on at least a portion of the exterior surface, connected to the inner shaft (116, 516); and a secondary gear having an exterior surface and a plurality of protrusions located on the exterior surface, wherein the protrusions on the thumbwheel interface with the protrusions on the track, the protrusions on the track interface with the protrusions on the secondary gear, and the protrusions on the secondary gear also interface with the protrusions on the inner shaft carrier, wherein rotation of the thumbwheel causes the track to move in a first direction and the inner shaft carrier to move in an opposite direction. a handle assembly comprising: a housing; and a control element; and a delivery catheter extending from the handle assembly comprising: an outer sheath slidably controlled by the control element; and an inner shaft (116, 516) slidably controlled by the control element, the inner shaft (116, 516) having a valve retainer (132, 532), wherein the control element comprises a thumbwheel, wherein the thumbwheel comprises an exterior surface having a plurality of protrusions located on the exterior surface, and wherein the system further comprises: a track having an exterior surface and a plurality of protrusions located on at least a portion of the exterior surface; an outer sheath carrier connected to the track and the outer sheath; an inner shaft carrier, having an exterior surface and a plurality of protrusions located on at least a portion of the exterior surface, connected to the inner shaft (116, 516); and a secondary gear having an exterior surface and a plurality of protrusions located on the exterior surface, a track having an exterior surface and a plurality of protrusions located on at least a portion of the exterior surface; an outer sheath carrier connected to the track and the outer sheath; an inner shaft carrier, having an exterior surface and a plurality of protrusions located on at least a portion of the exterior surface, connected to the inner shaft (116, 516); and a secondary gear having an exterior surface and a plurality of protrusions located on the exterior surface, wherein the protrusions on the thumbwheel interface with the protrusions on the track, the protrusions on the track interface with the protrusions on the secondary gear, and the protrusions on the secondary gear also interface with the protrusions on the inner shaft carrier, wherein rotation of the thumbwheel causes the track to move in a first direction and the inner shaft carrier to move in an opposite direction.