Detailed Analysis of the Relation Between Bipolar Electrode Spacing and Far- and Near-Field Electrograms

OBJECTIVESThis study sought to evaluate the relation between bipolar electrode spacing and far- and near-fieldelectrograms.BACKGROUNDThe detailed effects of bipolar spacing on electrograms (EGMs) is not well described.METHODSWith a HD-Grid catheter, EGMs from different bipole pairs could be created in each acquisition. This studyanalyzed the effect of bipolar spacing on EGMs in 7 infarcted sheep. A segment was defined as a 2-mm center-to-centerbipole. In total, 4,768 segments (2,020 healthy, 1,542 scar, and 1,206 in border areas, as defined by magnetic resonanceimaging [MRI]) were covered with an electrode pair of spacing of 2 mm (Bi-2), 4 mm (Bi-4), and 8 mm (Bi-8).RESULTSA total of 3,591 segments in Bi-2 were free from local abnormal ventricular activities (LAVAs); 1,630 segmentswere within the MRI-defined scar and/or border area. Among them, 172 (10.6%) segments in Bi-4 and 219 (13.4%)segments in Bi-8 showed LAVAs. In contrast, LAVAs were identified in 1,177 segments in Bi-2; 1,118 segments were withinthe MRI-defined scar and/or border area. Among them, LAVAs were missed in 161 (14.4%) segments in Bi-4 and in 409(36.6%) segments in Bi-8. In segments with LAVAs, median far-field voltage increased from 0.09 mV (25th to 75thpercentile: 0.06 to 0.14 mV) in Bi-2, to 0.16 mV (25th to 75th percentile: 0.10 to 0.24 mV) in Bi-4, and to 0.28 mV (25thto 75th percentile: 0.20 to 0.42 mV) in Bi-8 (p<0.0001). Median near-field voltage increased from 0.14 mV (25th to75th percentile: 0.08 to 0.25 mV) in Bi-2, to 0.21 mV (25th to 75th percentile: 0.12 to 0.35 mV) in Bi-4, and to 0.32 mV(25th to 75th percentile: 0.17 to 0.48 mV) in Bi-8 (p<0.0001). The median near-/far-field voltage ratio decreased from1.67 in Bi-2, to 1.43 in Bi-4, and 1.23 in Bi-8 (p<0.0001).CONCLUSIONSCloser spacing better discriminates surviving tissue from dead scar area. Although far-field voltagesystematically increases with spacing, near-field voltages were more variable, depending on local surviving muscularbundles. Near-field EGMs are more easily observed with smaller spacing, largely due to the reduction of the far-field effect.(J Am Coll Cardiol EP 2019;5:66–77) © 2019 by the American College of Cardiology Foundation.

Masateru Takigawa, Jatin Relan, Ruairidh Martin, Steven Kim, Takeshi Kitamura, et al.. Detailed Analysis of the Relation Between Bipolar Electrode Spacing and Far- and Near-Field Electrograms. JACC: Clinical Electrophysiology, 2019, 5 (1), pp.66-77. ⟨10.1016/j.jacep.2018.08.022⟩ (lien externe). ⟨hal-02369809⟩ (lien externe)