1. A method of treating cardiac arrhythmias, which comprises the steps of: (a) positioning the distal tip of each of one or more catheters at a site adjacent to or within a patient's heart; (b) sensing location information at the site; (c) sensing local information concerning the heart's electrical activity at the site; (d) processing sensed information from steps (b) and (c) to create one or more data points; (e) repeating steps (a) , (b) , (c) and (d) one or more times to create sufficient data points for a map of the heart's electrical pathways; and (f) ablating a portion of the heart whose electrical pathways cause said arrhythmias.