A hollow anatomical structure therapy system comprising: a heat delivery device suitable for insertion into a blood vessel； a power source in communication with said heat delivery device, said power source being programmed to: (a) deliver power to said heat delivery device during a temperature ramp-up phase； (b) measure time elapsing during power delivery； (c) monitor operation of said heat delivery device； and (d) if said operation of said heat delivery device either during or shortly after said temperature ramp-up phase is acceptable, deliver a generally decreasing amount of power to said heat delivery device after said temperature ramp-up phase and maintain a temperature of said heat delivery device within a constant temperature range.
