In an embodiment, the invention provides a catheter suitable for use in performing a procedure within a vessel, lumen or organ of a living having a distal end which is steerable, such as upon the application of compression. The catheter may be of the over the wire type, or alternatively may be a rapid exchange catheter. The catheter may provide for a rotating element which may be used to open a clogged vessel, or alternatively to provide information about adjacent tissues, such as may be generated by imaging or guiding arrangements using tissue detection systems known in the art, e.g., ultrasound, optical coherence reflectometry, etc. For rapid exchange catheters having a rotating element, there is provided an offset drive assembly to allow the rotary force to be directed from alongside the guidewire to a location coaxial to and over the guidewire.