05372602 is referenced by 292 patents and cites 13 patents.

The invention provides a motor drive unit for use in conjunction with an atherectomy device which limits the torque exerted on a drive cable for rotating a cutting blade in the device. In a preferred embodiment, a motor drive unit includes a motor having a shaft coupled to the drive cable for rotating the cutting blade, a power supply coupled to the motor and a switch for selectively connecting the power supply to the motor. A torque control circuit connected to the power supply and the motor controls the torque exerted by the motor when the switch is closed, whereby the current to the motor is continuously increased from zero to a start-up level, the start-up level being the minimum current sufficient to turn the cutting blade. Usually, the torque control circuit will include a resistor and a capacitor connected to a power supply in parallel with the motor, wherein a gradually decreasing portion of current from the battery is diverted through the RC circuit to charge the capacitor such that the current to the motor is at the start-up level when the capacitor is charged. The motor drive unit further includes a power MOSFET for discharging the capacitor when the switch is opened to reset the circuit.

Method of removing plaque using catheter cutter with torque control
Application Number
Publication Number
Application Date
November 30, 1992
Publication Date
December 13, 1994
Phillip C Burke
Townsend and Townsend Khourie and Crew
Device for Vascular Intervention
A61B 17/20
View Original Source