An ablation apparatus is provided which ablates at least a portion of an interior of a body structure while reducing a swelling response in the body structure. The apparatus provides a catheter including a catheter tissue interface surface and a port formed in the catheter tissue interface surface. An electrode is at least partially positioned in the interior of the catheter and configured to be advanced and retracted in and out of the port. The electrode includes an electrode electromagmetic energy delivery surface. A cooling element includes a cooling medium inlet conduit and a cooling medium exit conduit, both extending through an interior of the catheter forming at least a partial cooled catheter tissue interface surface. The electrode electromagnetic energy delivery surface is thermally isolated from the cooling element. An electrode advancement and retraction device is at least partially positioned in the interior of the catheter. A cable is coupled to the electrode.