A vascular device is provided having a catheter body and a rotatable cutter assembly located at the distal end of the catheter body. The cutter assembly has at least one helical cutting surface within a housing that is coupled by a torque shaft to a drive mechanism. A conveyor mechanism helically wound about the torque shaft conveys occlusive material conveyed into the housing by the helical cutting blade further proximally along the catheter body for discharge without supplement of a vacuum pump. The catheter body is manipulated to insert the distal end of the catheter body within a body lumen and advance the distal end of the catheter body toward the occlusive material. The drive mechanism is operated to rotate the helical cutting surface to cut and convey the occlusive material from the body lumen proximally into the housing and to convey the occlusive material conveyed into the housing by the helical cutting surface further proximally along the catheter body by the conveyor mechanism for discharge without supplement of a vacuum pump. The distal end of the catheter body is deflected and rotated to sweep the cutter assembly in an arc about the center axis of the catheter body to cut occlusive material in a region larger than the outside diameter of the cutter assembly.
