Patent ID: 8491520

Claim:
A method for delivering radiofrequency (RF) energy to living tissue, which comprises: extending a guidewire to a tissue treatment site in a body; providing a controllable stiffness catheter having: a shaft having a distal end, a stiffness sheath, and an access lumen; a stiffness device disposed at the stiffness sheath, having non-metallic properties, and being in a relatively stiff state at or below a first temperature and being in a relatively soft state at or above a second temperature, the relatively soft state being entered in response to a change in the non-metallic properties of the stiffness device; a temperature-changing device in thermal contact with the stiffness device, the temperature-changing device changing a temperature of the stiffness device at least below the first temperature and above the second temperature; a power controller electrically connected to the stiffness device and selectively supplying power to the temperature-changing device to change a stiffness of the stiffness device between the stiff state and the soft state; and an RF energy supply device having at least a portion thereof disposed at the distal end of the shaft for selectively supplying RF energy from the distal end; while supplying power to the temperature-changing device, threading the controllable stiffness catheter along the guidewire up to the treatment site; removing power from the temperature-changing device to alter the non-metallic properties of the stiffness device directly resulting in a change of stiffness of the stiffness device to the stiff state without straightening the catheter; physically contacting the RF energy supply device with the treatment site; and delivering RF energy to the treatment site from the RF energy supply device.