Method for ablating with needle electrode

A method for ablating tissue in or around the heart comprising:

• introducing into the heart the distal end of a catheter, wherein the catheter includes a needle electrode at its distal end, the needle electrode being in a retracted position within the distal end of the catheter;
• introducing a distal end of the needle electrode into the tissue, including moving the needle electrode from its retracted position within the distal end of the catheter to an extended position outside the distal end of the catheter;
• infusing into the tissue an electrically-conductive fluid through the needle electrode while in the extended position;
• and
• ablating the tissue after and/or during introduction of the fluid into the tissue, whereby the fluid conducts ablation energy within the tissue to create a larger lesion than would be created without the introduction of the fluid.