Novel automated “score mapping” of diaphragmatic compound motor action potential for the early detection of phrenic nerve injury during cryoablation

Abstract

The proximity of phrenic nerve to right sided pulmonary veins (PV) make it susceptible to injury during cryoballoon ablation (CBA) for atrial fibrillation (AF). Monitoring of diaphragmatic compound motor action potentials (CMAP) obtained from lead aVF or modified surface ECG leads placed along the diaphragm have been used for early detection of phrenic nerve injury (PNI). 1 Schaerli N. Badertscher P. Spies F. et al. A Simplified Method to Detect Phrenic Nerve Injury During Cryoballoon Ablation of Atrial Fibrillation Using Lead aVF of the Surface ECG. Circ Arrhythm Electrophysiol. 2021 Aug; 14e009986https://doi.org/10.1161/CIRCEP.121.009986 Crossref Scopus (0) Google Scholar Thirty percent drop in CMAP amplitude has been shown in studies as the threshold for prevention of PNI. 2 Miyazaki S. Hachiya H. Taniguchi H. et al. Prospective Evaluation of Bilateral Diaphragmatic Electromyograms During Cryoballoon Ablation of Atrial Fibrillation. JCE. 2015; 26: 622-628 Google Scholar However, CMAP signals may be susceptible to respiratory variations, catheter movement, inadequate baseline amplitude making it difficult to monitor the change in CMAP. 3 Sharma P.S. Padala S.K. Thompson J.J. Gunda S. Koneru J.N. Ellenbogen K.A. Factors Influencing Diaphragmatic Compound Motor Action Potentials During Cryoballoon Ablation for Atrial Fibrillation. JCE. 2016; 7: 1384-1389 Google Scholar Score-map of the CMAP using template matching with 3D electroanatomic mapping system can be used to automate the monitoring of CMAP. The aims of this study were to assess the relationship of change in CMAP amplitude with change in score-map and then use the automated score-map prospectively for early detection of PNI during CBA.