A device and method for removing atheroma. An expandable atherectomy device comprises a rotatably motor-driven flexible hollow shaft that is slidable over a guidewire introducible through a flexible catheter tube and is coaxial with the longitudinal axis of the guidewire, an expandable cutting unit connected to a distal end of the hollow shaft, and an actuator which is operable to induce selective expansion of the cutting unit. The cutting unit, when expanded, is eccentrically rotatable about the longitudinal axis to cut and remove atheromous material from a blood vessel. In one embodiment, the method also includes the step of drilling an occlusion present in the lumen of a blood vessel by a drill unit connected to the cutting unit.