In one embodiment, the present invention relates to a mechanically releasable delivery system. More specifically, this embodiment includes an implantable device secured by tether at a distal end of the delivery system. The tether is fixed to the implantable device and looped around a selectively slidable mandrel. When the mandrel is retracted to expose its distal end, the looped tether slides off the mandrel, freeing the implantable device. Alternately, the tether can be fixed to the delivery system, wrapped around a portion of the implantable device and looped on to the slidable mandrel. Preferably, movement of the mandrel is controlled by an actuation control on the handle of the delivery system, allowing the user to selectively release the implantable device during a medical procedure.