Abstract: An intravenous surgical instrument comprises an inner shaft or post and an outer sheath. At a distal end of the inner post a spring-tail or whip-like electrode is disposed substantially in a sagittal plane, or one perpendicular to a longitudinal axis of the shaft. Following an insertion into a human vein or other circulatory vessel the distal end of the shaft is protruded from the sheath; thereafter sheath, post and electrode are simultaneously withdrawn from the vein, with a relative rotatory motion being imparted to the electrode. A current flow is preferably simultaneously imposed across the electrode into an inner surface of the surrounding vessel, facilitating a damaging of the vessel inner surface and a collapse of the vessel.