A catheter and catheter system can use energy tailored for remodeling and/or removal of target material proximate to a body lumen, often of stenotic material or tissue in the luminal wall of a blood vessel of a patient. An elongate flexible catheter body with a radially expendable structure may have a plurality of electrodes or other electrosurgical energy delivery surfaces to radically engage the luminal wall when the structure expands. Feedback using one or parameters of voltage, current, power, temperature, impedance magnitude, impedance phase angle, and frequency may be used to selectively control the delivery of energy.
