Patent ID: 7037271

Claim:
A medical device for use within a body, the medical device comprising: an elongate, flexible tubular body adapted to enter the body; an elongate, flexible drive shaft adapted to be translatable within the tubular body, wherein the flexible drive shaft includes an outer coil and an inner coil, which are wound in opposite helical directions and are connected at their ends such that when the coils are turned in one direction, the outer coil diameter decreases and the inner coil diameter increases, wherein each coil is formed by at least four circular cross-sectional wires, wherein the distal end of the drive shaft is configured for dynamic frictional drag during use, and wherein the coils are pre-twisted relative to one another with the distal ends of the coils locked together in a pre-loaded assembly; an imaging device coupled to the drive shaft, the drive shaft enabling the imaging device to rotate, the imaging device to transmit energy for forming images of tissue within the body; a fluid-confining sheath adapted to receive the imaging device; and an energy-transmissive portion of the sheath located at or near the imaging device, the energy-transmissive portion to permit energy from the imaging device to substantially pass through the energy-transmissive portion.