An expandable atherectomy catheter device includes an expandable cutting head consisting of deformable cutting members to remove an atheroma or blood clot from a blood vessel. The cutting members, consisting of wires or blades, extend parallel to each other and are supported at the distal end of a rotatable catheter. A retraction member is slidingly disposed within the rotatable catheter and is coupled at its distal end to the cutting members; the retraction member can be manipulated from the proximal end thereof to adjust compression of the cutting members, and hence, the diameter of the cutting head. A motor is coupled to the proximal end of the rotatable catheter for rotating the cutting head to remove the atheromatous plaque or blood clot. A non-rotatable delivery catheter is inserted percutaneously within the blood vessel, and the distal end thereof is positioned proximate the site of the obstruction. The rotatable catheter extends within the delivery catheter, and the cutting head of the rotatable catheter is expanded upon being advanced to the site of the obstruction. Apparatus for aspirating the removed plaque or blood clot is also provided.