A delivery device for positioning and deploying an implantable device within a lumen is provided. The device includes a longitudinal outer tube having proximal and distal ends, wherein the implantable device is positioned proximate to the distal end of the outer tube. The device also includes a longitudinal inner tube slidably disposed within the outer tube and having proximal and distal ends, wherein at least a portion of the distal end of the inner tube is configured to underlie at least a portion of a proximal end of the implantable device. The distal end of the inner tube is located proximally of the distal end of the outer tube to define a gap for accommodating at least a portion of the implantable device. A mechanism is coupled to the inner and/or outer tubes and is operable to deploy the implantable device within the lumen.