Microwave ablation catheter system with impedance matching tuner and method

A power supply for use in a medical microwave ablation catheter system that includes an ablation catheter having a coaxial transmission waveguide and an antenna coupled to the coaxial transmission waveguide for radiating microwave energy, the coaxial transmission waveguide being coupled to the power supply by a connector arrangement, the power supply comprising:

• a microwave generator for generating electromagnetic energy having a frequency in the microwave range, the microwave energy generator being coupled to the coaxial transmission waveguide through a coaxial power supply transmission line and said connector;
• means for monitoring the amount of power that is transmitted to and reflected from the catheter during use, the monitoring means including,
• a first directional coupler in communication with the transmission line for diverting a small portion of the power that is reflected frown the catheter during use,
• a first power sensor for detecting the magnitude of the power diverted by the first directional coupler and outputting a first signal indicative of the magnitude of the power that is reflected from the catheter during use,
• a second directional coupler in communication with the transmission line for diverting a small portion of the power that is transmitted to the catheter during use,
• a second power sensor for detecting the magnitude of the power diverted by the second directional coupler and outputting a second signal indicative of the magnitude of the power that is transmitted to the catheter during use;
• means for detecting the temperature in the vicinity of the antenna portion of the ablation catheter;
• tuner means arranged to automatically match the impedance of a power generator side portion of the catheter system with the impedance of a catheter side portion of the catheter system, the tuning means including,
• a tuner controller that receives said first and second signals and generates a control signal based at least in part on the magnitude of the reflected power, and
• a stub tuning mechanism coupled to the transmission line for adjusting the impedance of the transmission line, the stub tuning mechanism being responsive to said control signal, and
• whereby the tuning means is arranged to match the impedance of the power generator side portion of the catheter system with the impedance of the catheter side portion of the catheter system at least in part by using the stub tuning mechanism to alter tile effective impedance of the transmission line;
• and
• an interlock system for automatically shutting off the microwave generator when certain predefined safety hazards are detected, the predetermined safety hazards including when no catheter is plugged into the power supply and when an over temperature condition is detected the interlock system being in communication with the temperature detecting means.