An improved valvulectome (10) is adapted for use in selectively excising the leaflets of a venous valve. The apparatus includes an elongated probe (11) having one tip end portion (12) adapted to be inserted generally longitudinally into a vein. An actuating rod (55) may be moved relative to the probe to selectively move a pair of blade members (45,46) between their respective fully-retracted positions, at which the blade cutting edges (51,51') will be concealed within the transverse profile or outline of the probe, and their outwardly-extending ready-to-cut positions. The probe has a lumen (38) for sensing the fluid pressure proximate the probe tip. The probe also has a piezoelectric sensor (29) for sensing and measuring the velocity of blood proximate the probe tip. In use, the probe is inserted into a vein, and pushed through a valve with the blades retracted. The blades are then extended radially, and the probe is pulled rearwardly to excise portions of the valve leaflets.