Methods and devices for augmenting an atrioventricular valve leaflet is disclosed. A method according to an exemplary embodiment includes piercing a leaflet of the valve to at least a portion of the leaflet's thickness to form a pierced section; and extending the leaflet using said pierced section. A device according to an exemplary embodiment of the invention includes a catheter comprising: a longitudinal tube having a lumen; and a cutting element extendable from the lumen. The cutting element is adapted for forming a limited cut in an atrioventricular valve. A device according to another exemplary embodiment of the invention includes a catheter comprising a longitudinal tube having a lumen; a cutting element extendable from the lumen and adapted for forming a cut in a leaflet of an atrioventricular valve; and a frame, configured to attach to the leaflet and stay attached to the leaflet when the heart beats.