Ultrasound ablation catheter and method for its use

A catheter comprising:

• an elongated catheter body having proximal and distal ends and an irrigation lumen extending therethrough;
• a tip electrode fixedly and non-rotationally mounted at the distal end of the catheter body and comprising an irrigation passage;
• an infusion tube extending through the irrigation lumen in the catheter body into the irrigation passage in the tip electrode, the infusion tube being in fluid communication with the irrigation passage in the tip electrode;
• an ultrasound transducer mounted on a surface of the tip electrode, the transducer having a front surface and an opposing back surface, wherein the back surface of the transducer is mounted to the distal end of the catheter body such that the transducer is positioned to transmit ultrasound energy toward tissue facing the front surface but not toward tissue facing the back surface;
• a sensor mounted within the catheter near the ultrasound transducer for sensing a location and an orientation of the ultrasound transducer within a patient.