Abstract: Disclosed herein is a catheter device for use in a biological conduit having an encoder structure for indicating linear movement of the work element. The work element includes an ultrasonic transducer along a linear axis of the catheter. The catheter has a housing for insertion in the biological conduit. The transducer transmits ultrasonic pulses and receives echoes in response thereto for imaging an inside wall of the conduit. The housing has a window formed therein to image the conduit inside wall. An encoder structure adjacent an area of the window determines distal movement and travel direction of the transducer through the window area along a linear axis of the catheter housing.

Abstract: A flexible composite drive shaft used with a flexible vascular atherectomy catheter for connecting a proximal rotating drive member and a distal rotatable working member. The flexible composite drive shaft includes a core of specially selected highly elastic shape memory alloy surrounded by a flexible torsional reinforcing helical wound member and a covering of a smooth polymeric material penetrating the interstices between the wound member and the outer surface of the core. The material of the core, the relative winding direction of the reinforcing member and the direction of angular offset between the reinforcing member and the core are selected to optimize the consistency of the rotational characteristics of the drive shaft in use.