A prosthesis retaining assembly for securing an implantable prosthesis to a catheter assembly can include a first member including a prosthesis retaining slot configured to retain a portion of the prosthesis. The retaining slot can have a first portion with a first width and a second portion with a second width. The first portion can be distal to the second portion. The second width can be larger than the first width, and the retaining slot can have an opening at a first surface of the first member. The prosthesis retaining assembly can also include a second member configured to be move relative to the first member. The second member can be configured to move to a position that obstructs a portion of the opening of the retaining slot.
