PO-03-097 DEFINING ELECTRODE CONFIGURATION FOR MAPPING MICROANATOMIC REENTRIES SUSTAINING ATRIAL FIBRILLATION

Abstract

A major challenge in mapping atrial fibrillation (AF) to guide ablation is that it is unclear what resolution is required to map potential regions of interest such as those microanatomic reentries revealed by optical mapping of ex-vivo human hearts (fig. A). The goal of the study was to define the electrode configurations that can identify potential ablation targets as specific EGM traces generated during the conduction through the common path of AF microanatomic reentry. We simulated a microanatomic reentry sustaining AF in anisotropic 3D model of atrial tissue of 40x40x3 mm with an endocardial pectinate muscle of 3x3x15 mm (0.25 mm resolution, fig. B), using Koivumäki-cellular model of human atrial action potential. The simulation also included recordings of endocardial unipolar and bipolar electrodes (3 mm inter-electrode distance, 1 mm length, 2 mm diameter) with different distances and orientations from the pectinate muscle (fig. B). Local activation time map (fig. C) of the simulation showed sub-endocardial microanatomic reentry, with the common path through the pectinate muscle with a cycle length of 110 ms. The electrical activation through the pectinate muscle and atrial wall below the electrodes (Fig. D) was compared to the simulated EGM traces at different distances from the common path (fig. E). On EGMs close to the pectinate muscle (<2mm) electrical activity of reentrant common path can be identified in both unipolar and bipolar EGM signals by peak with amplitude similar or larger than the main atrial wall activation (figs E-F). When bipolar electrodes were perpendicular to the pectinate muscle, the peak amplitude of the common path activity was lower than 25% of the atrial wall peak amplitude. Our simulation suggested that inter-electrode distance to detect sub-endocardial microanatomic reentries sustaining AF should be < 4mm. Mapping was more reproducible for unipolar than for bipolar mapping, as bipolar electrodes were highly sensitive to orientation relative to the common path conduction.