Non-invasive Characterization of Focal Arrhythmia with Electromechanical Wave Imaging in Vivo

Abstract

There is currently no established method for the non-invasive characterization of arrhythmia and differentiation between endocardial and epicardial triggers at the point of care. Electromechanical wave imaging (EWI) is a novel ultrasound-based imaging technique based on time-domain transient strain estimation that can map and characterize electromechanical activation in the heart in vivo. The objectives of this initial feasibility study were to determine that EWI is capable of differentiating between endocardial and epicardial sources of focal rhythm and, as a proof-of-concept, that EWI could characterize focal arrhythmia in one patient with premature ventricular contractions (PVCs) before radiofrequency (RF) ablation treatment. First, validation of EWI for differentiation of surface of origin was performed in seven (n = 7) adult dogs using four epicardial and four endocardial pacing protocols. Second, one (n = 1) adult patient diagnosed with PVC was imaged with EWI before the scheduled RF ablation procedure, and EWI results were compared with mapping procedure results. In dogs, EWI was capable of detecting whether pacing was of endocardial or epicardial origin in six of seven cases (86% success rate). In the PVC patient, EWI correctly identified both regions and surface of origin, as confirmed by results from the electrical mapping obtained from the RF ablation procedure. These results reveal that EWI can map the electromechanical activation across the myocardium and indicate that EWI could serve as a valuable pre-treatment planning tool in the clinic.

Detection of Regional Mechanical Activation of the Left Ventricular Myocardium Using High Frame Rate Ultrasound Imaging

“…This is a time consuming and invasive procedure as the generation of the map requires measurement of many spatial points. Thus, quick and non-invasive methods for activation mapping are needed, as abnormal activation patterns could be a clinical indicator of scar tissue, fibrosis and arrhythmias [14,15].…”

“…In 2012, Provost et al performed the first clinical evaluation of electromechanical wave imaging (EWI) in patients [38] using a single heartbeat approach [39]. Later on, the same research group has used the EWI method to investigate ischemic hearts [40] and atrial [41] and ventricular [14] arrhythmias [7,42,43], as well as expanding the method to 3D [15].…”

Noninvasive localization of cardiac arrhythmias using electromechanical wave imaging

“…The isochrone generation process does not depend on patient cardiac geometry, and there is no anatomical assumption of longitudinal symmetry when rendering the activation maps. EWI has also been used to differentiate epicardial from endocardial ventricular origins in focally paced canine ventricles (28). Other echocardiography strain-based methods have previously been investigated for identification of arrhythmia such as AP localization (29)(30)(31).…”

Localization of Accessory Pathways in Pediatric Patients With Wolff-Parkinson-White Syndrome Using 3D-Rendered Electromechanical Wave Imaging

“…(16,17) Moreover, EWI has been shown capable of accurately determining the origin of activation during ventricular pacing from different endocardial and epicardial sites in paced canine hearts in vivo. (18) In this study, EWI is used for the first time in a pediatric population. Our aim was to investigate the feasibility of using this transthoracic ultrasound technique for the localization of accessory pathways in pediatric patients with WPW.…”