An atherectomy catheter having an inner drive shaft which rotates a distal rotary tissue borer with a helical cutting surface which enables the catheter to cut through and cross a CTO. Additionally, the atherectomy catheter has a distal cutting element rotated by an outer drive shaft configured to cut material from the wall of a vessel at a treatment site as the catheter is pushed distally through the treatment site. The atherectomy catheter includes a collection chamber positioned proximally of the cutting element and rotary tissue borer. The atherectomy catheter may include means to direct material cut from the treatment site into the collection chamber, means to break down larger portions of material that may block or clog the collection chamber and means of transporting the material collected from the treatment site to a proximal opening in the atherectomy catheter.