What is "intraoperative mapping atrial tachycardia"?

EP procedure. This is generally done in a cath lab using wires similar or pacemaker electrodes. They are inserted through blood vessels in the leg, and place into the heart. There they "read" electrical activity to determine where the abnormal conduction is taking place. Then the offending circuit can be severed using radio-frequency ablation.
Investigate further. Get a multifunction cardiogram! http://en.M.Wikipedia.Org/wiki/multifunction_cardiogram.