Omnipolarity applied to equi-spaced electrode array for ventricular tachycardia substrate mapping

AIMS : Bipolar electrogram (Bi(EGM))-based substrate maps are heavily influenced by direction of a wavefront to the mapping bipole. In this study, we evaluate high-resolution, orientation-independent peak-to-peak voltage (Vpp) maps obtained with an equi-spaced electrode array and omnipolar EGMs (OT(EGMs)), measure its beat-to-beat consistency, and assess its ability to delineate diseased areas within the myocardium compared against traditional Bi(EGMs) on two orientations: along (AL) and across (AC) array splines. METHODS AND RESULTS: The endocardium of the left ventricle of 10 pigs (three healthy and seven infarcted) were each mapped using an Advisor™ HD grid with a research EnSite Precision™ system. Cardiac magnetic resonance images with late gadolinium enhancement were registered with electroanatomical maps and were used for gross scar delineation. Over healthy areas, OT(EGM) Vpp values are larger than AL bipoles by 27% and AC bipoles by 26%, and over infarcted areas OT(EGM) Vpp values are 23% larger than AL bipoles and 27% larger than AC bipoles (P < 0.05). Omnipolar EGM voltage maps were 37% denser than Bi(EGM) maps. In addition, OT(EGM) Vpp values are more consistent than bipolar Vpps showing less beat-by-beat variation than Bi(EGM) by 39% and 47% over both infarcted and healthy areas, respectively (P < 0.01). Omnipolar EGM better delineate infarcted areas than traditional Bi(EGMs) from both orientations. CONCLUSION: An equi-spaced electrode grid when combined with omnipolar methodology yielded the largest detectable bipolar-like voltage and is void of directional influences, providing reliable voltage assessment within infarcted and non-infarcted regions of the heart.