A technique for removing plaque from blood vessel includes passing a wire saw-catheter assembly through an artery to a location adjacent an area of plaque buildup. The wire saw is then moved out of the end of the catheter into engagement with the plaque buildup. The wire saw is reciprocated through a stroke of 0.01-4 millimeters at a rate of between 3,000-30,000 cycles per second. In one embodiment, the wire saw is straight while a second embodiment of the wire saw includes a a curved end. In both embodiments, a triangularly shaped cutting element is helically wound about the tube end. The cutting element reciprocates against and comminutes the relatively hard plaque without damaging the relatively soft blood vessel. The debris produced by the action of the wire saw is removed by a variety of techniques causing liquid flow back through the catheter including: (1) delivering a quantity of liquid through the end of the cutting tool, (2) applying suction to the catheter, and (3) blocking flow in the artery at an effective location. The technique also disintegrates and removes other hard, relatively immobile deposits from ducts, such as gall or kidney stones.