ROTATIONAL ATHERECTOMY DEVICE WITH FRICTIONAL CLUTCH HAVING MAGNETIC NORMAL FORCE

摘要

An atherectomy device is disclosed, with a clutch between the motor and the drive shaft. The clutch includes two plates that rely on frictional to transmit torque from one plate to the other. The clutch has an attractive magnetic normal force that holds the plates together. For relatively low torques, as is the case during normal use, a static frictional torque holds the plates together, and the plates spin together without slipping. For relatively high torques, as occurs when the distal end of the drive shaft encounters an obstacle and stops abruptly, the high torque exceeds the maximum possible static frictional torque, and the plates slip. When slipping, the plates transmit a kinetic frictional torque that is low enough to avoid damage to the patient or to the atherectomy device. In some cases, the torque levels associated with a stoppage of the drive shaft distal end are chosen to mimic those of a known atherectomy device, in which a gas-driven turbine is clutchlessly attached to the drive shaft.