49-06: Using electromechanical wave imaging, a novel non-invasive ultrasound imaging tool to detect endocardial versus epicardial arrhythmia origins

Abstract

Introduction: Ventricular tachycardia (VT) may have an endocardial or epicardial ventricular origin. Currently there is no non-invasive way to differentiate between endocardial or epicardial trigger. We have used electromechanical wave imaging (EWI) a direct ultrasound imaging technique to map transmural activation in all four chambers in vivo and we demonstrate EWI can differentiate between epicardial and endocardial pacing origins. Methods: EWI was performed in 5 open-chest canines (N= 5) while pacing (EP-4 Stimulator, St Jude Medical, NJ, USA) from locations in the LV, both endocardially and epicardially. A Verasonics ultrasound system (Redmond, WA) with a 2.5-MHz phased array and an unfocused beam sequence at 2000 frames/s, and electromechanical strains and activation maps were estimated using high-precision, RF-based speckle tracking. Results: Activation maps from endocardial pacing showed early regions of activation in the endocardium, whereas maps from epicardial pacing showed early regions of activation on the epicardium. Transmural activation was 60 ± 5 ms for endocardial pacing (n = 3) and 65± 25 ms for epicardial pacing (n = 3).