enhanced by techniques and structures which separate heart cycle signals originating from differing chambers and or regions of the heart tissue application_number US 85045904 A description while the following description is largely directed to localization and or treatment of focal atrial fibrillation the methods devices and systems of the present invention may be used for a variety of arrhythmias including both focal and re entrant arrhythmias such as those resulting from scars when used for treatment of re entrant arrhythmia treatment may be directed at or near an exit site or insertion point of a pathway the invention is well suited for use with pulmonary vein isolation therapies now being developed in which linear circumferential and or perimeter lesions may isolate one or more pulmonary veins to inhibit propagation from triggers or exit sites in or near the veins by allowing selection of target veins and or indicating whether vein isolation should be utilized the invention is particularly useful for localizing paroxysmal afib but may also find application for persistent and chronic afib localizing an insertion point of a concealed accessory pathway and the like referring now to fig1 a the techniques of the present invention will generally make use of an array 10 of sensors 12 distributed across anterior and posterior.