Catheter system

An injection electrode comprising:

• a flexible, metallic coil comprising coil windings, an insulated proximal end, an uninsulated distal end, and a lumen extending therealong;
• a metallic guide rod disposed within the lumen of the metallic coil;
• an injection port configured such that fluid injected into the port flows through the lumen of the metallic coil;
• a connector in electrical communication with the metallic coil and configured to energize the uninsulated distal end;
• a thermocouple in electrical communication with the metallic coil and configured to measure temperature at the uninsulated distal end;
• wherein electrical conductors of the connector, the thermocouple, or both, extend within the lumen of the metallic coil;
• and
• wherein a portion of the uninsulated distal end comprises a plurality of the coil windings spaced apart to allow the fluid injected through the lumen to flow out therebetween around a full exterior circumference of the lumen of the metallic coil.