The invention provides an implantable fixation element for anchoring an elongate, for instance essentially cylindraical, element, particularly an electrical lead for a pacemaker in human or animal tissue, comprising a pair of first gripper beaks, movable to and from each other to enclose this element and, interconnected therewith, a pair of second fixation gripper beaks which, together with the first pair can hinge around a common point of rotation for a simultaneous opening and closing thereof, and having an open configuration with opposite ends, of which said second gripper beaks, the ends during the closing thereof, are adapted to penetrate the tissue, the beaks being provided with means to lock them together in the closed state. The invention also provides a sleeve to be used in combination with such a fixation element and an applicator, particularly intended to fix, by means of such a fixation element, the lead of a pacemaker to human or animal tissue.