Rotating element catheters and catheter assemblies employ clutch assemblies for preventing rotational energy from being transmitted from a motor drive unit to the catheter element under defined circumstances. The catheter assembly includes an elongate member in which there is disposed a rotatable catheter...http://www.google.co.uk/patents/US20020151799?utm_source=gb-gplus-sharePatent US20020151799 - Catheter drive shaft clutch
