A mitral hook instrument for use particularly in heart valve operations. The mitral hook is used in particular for grasping or hooking secondary chords for lysis procedures. The interior surface of the hook has a groove or channel to facilitate use of a scalpel to cut a chord or other member which has been grasped and exposed by the hook. Also, markings are preferably provided on the distal end of the mitral hook instrument in order to assist the surgeon.