Two-phase technique to restore artery patency and a catheter temperature control system in atherectomy

A method of two-phase atherectomy for removal of plaque within an artery forming a stenosis, the method comprising:

• a first phase of rotational drilling by exerting a rotational force on a cutter to form a channel within the plaque having a diameter substantially equal to a diameter of the cutter, the cutter being rotated at a first rotational speed sufficient to maintain rotation of the cutter about a rotational axis, wherein the rotational axis is stationary during the first phase;
• and
• a second phase of orbital impact by exerting a rotational force on the cutter to result in radial orbital motion of the cutter within the channel resulting in periodic impact of the cutter upon the plaque to form micro-fractures within the plaque and enlarge the diameter of the channel to a diameter substantially greater than the diameter of the cutter, the cutter being rotated at a second rotational speed sufficient to result in the radial orbital motion of the cutter such that the rotational axis of the cutter generally orbits an orbital axis, the rotational axis being offset from the orbital axis.