The disclosure relates to a variety of systems and methods for sensing electrical events about a selected annulus region of the heart and for treating tissue in the selected annulus region. Wherein the system includes a first catheter that has an expandable member, an ablation element, and a lumen configured to allow a second catheter therethrough. The second catheter includes a distal section in a ring shape and a plurality of electrodes coupled around the ring. Optionally a second lumen can be included through the first catheter that allows for contrast media to be delivered to the distal end of the system.