off a long thin portion of this plaque while doing so the cutting wheel 106 will typically have a diameter of about 1 14 mm and may have a straight edge a beveled edge which allows removal of plaque without damaging the underlying artery lumen or a fluted edge depending upon the needs of the specific application usually the cutting wheel will be mounted on a shuttle or cam mechanism to allow the operator to adjust the protrusion of the wheel from the window or alternatively the angle of the wheel or even the location of the wheel relative to the window opening causing the window to be open partially closed or fully closed by the wheel the cutting wheel will typically rotate at speeds appreciably faster than 100 rotations per minute rpm preferably about 8 000 rotations per minute rpm the cutting edge of the blades may be optionally hardened by an appropriate coating such as me 92 tungsten carbide or other suitable materials as taught by u s pat nos 4 771 774 5 242 460 5 312 425 5 431 673 and 5 674 232 the contents of which are incorporated herein by reference as previously discussed the action of blade can be facilitated by ultrasonic vibration laser cutting radio frequency electrodes and the like if this option is elected appropriate mechanisms i e a piezoelectric ultrasonic vibrator laser diode or optical fiber electrodes etc may also be provided in the catheter head to drive the blade as needed if the action of the ultrasonic laser or electrode cutter is sufficiently.