A stent and catheter for implanting or removing a helical-shaped stent within a body passageway; the catheter having an elongate sheath with a socket or means for securing one end of the stent at a distal region of the sheath and an inner member extending from the sheath, and also having a socket or means at a distal region of the inner member for securing the other end of the stent. The inner member is rotatable relative to the sheath to transmit torque to the stent to permit unwinding of the helical stent at its limiting strain to expand the stent. Also discussed are methods for performing procedures for implanting or removing a helical stent from a body passageway.