Contact Impedance Mapping: A New Tool to Differentiate Focal From Macroreentrant Atrial Arrhythmias

Abstract

The aim was to evaluate a newly developed technique of active impedance mapping in differentiating arrhythmic mechanism. Differentiating focal atrial tachycardia (AT) from macroreentrant atrial flutter can sometimes be difficult, despite the use of pacing maneuvers and three-dimensional electroanatomical mapping. The variation in activation patterns which occur with focal and macroreentrant arrhythmias may be reflected in different patterns of tissue impedance. Patients undergoing supraventricular tachycardia ablation for AT or atrial flutter were included. All patients underwent a standardized electrophysiologic study and ablation procedure utilizing three-dimensional electroanatomical mapping. Impedance data were simultaneously collected. Offline analysis of impedance data was then performed. A total of 50 patients evenly split between AT and flutter were analyzed. Patients with AT were found to have a contiguous low impedance area (CLIA) in proximity to the area of successful ablation. Patients with atrial flutter had a more uniform impedance pattern with no CLIA. A subgroup of 14 patients with both AT and flutter found either during the same procedure or during subsequent procedures demonstrated a CLIA during the atrial tachycardia and uniform impedance without a CLIA during atrial flutter. Impedance mapping during atrial arrhythmias can differentiate macroreentrant atrial flutter from AT and can help localize the site of origin of an AT.