In one embodiment, the present invention relates to a mechanically releasabledelivery system. More specifically,this embodiment includes an implantable device secured by tether at a distalend of the delivery system. The tether is fixed to theimplantable device and looped around a selectively slidable mandrel. When themandrel is retracted to expose its distal end, thelooped 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 theslidable mandrel. Preferably, movement of the mandrelis controlled by an actuation control on the handle of the delivery system,allowing the user to selectively release the implantabledevice during a medical procedure.