Catheter-based ablation systems and methods of ablation

An endovascular catheter system for ablation of the left atrial appendage (LAA) or other cardiovascular tissue, comprising:

• an outer catheter;
• a multi-lumen body, the multi-lumen body including:
• a first lumen for delivery of fluid under pressure, the first lumen having a proximal open end and a distal closed end, the first lumen including spray openings disposed proximate to the distal closed end of the first lumen, and
• a second lumen for suctioning fluid under vacuum, the second lumen having a proximal open end and a distal closed end, the second lumen being located inside the first lumen so that the second lumen has a diameter equal to a fraction of a diameter of the first lumen, the second lumen extending beyond the distal closed end of the first lumen, the second lumen including suction openings disposed beyond the distal closed end of the first lumen toward the distal closed end of the second lumen;
• a first balloon fixed to the outside of the outer catheter;
• and
• a first inflation tube connecting a proximal end of the outer catheter and the first balloon.