Apparatus for use with at least one leaflet-engaging element, the apparatus including a delivery tool which includes an inner shaft, a surrounding shaft, and at least one leaflet-engaging element holder coupled to a portion of the surrounding shaft, the leaflet-engaging-element holder being shaped to define at least one coupling site for reversibly coupling the leaflet-engaging element to the tool. The surrounding shaft surrounds a portion of the inner shaft and is slidable along the inner shaft so as to position the leaflet-engaging holder in a vicinity of at least one leaflet of an atrioventricular valve of a patient. A distal end of the inner shaft is advanceable between leaflets of the atrioventricular valve and toward a tissue site of a ventricle of the patient. Other applications are also described.