Webinar #1: Electromechanical Wave Imaging - Prof. Elisa Konofagou

Title: Electromechanical Wave Imaging for Noninvasive and Direct Mapping of Arrhythmias in 3D

Abstract: Arrhythmias refer to the disruption of the natural heart rhythm. This irregular heart rhythm causes the heart to suddenly stop pumping blood. Arrhythmias increase the risk of heart attack, cardiac arrest and stroke. Reliable mapping of the arrhythmic chamber stands to significantly improve these currently low treatment success rates by localizing arrhythmic foci before the procedure starts and following progression throughout. To this end, our group has pioneered Electromechanical Wave Imaging (EWI) that characterizes the electromechanical function throughout all four cardiac chambers. The heart is an electrically driven mechanical pump that adapts its mechanical and electrical properties to compensate for loss of normal mechanical and electrical function as a result of disease. During contraction, the electrical activation, or depolarization, wave propagates throughout all four chambers causing mechanical deformation in the form of the electromechanical wave. This deformation is extremely rapid and completes within 15-20 ms following depolarization. Therefore, fast acquisition and precise estimation is extremely important in order to properly map and identify the transient and minute mechanical events that occur during depolarization. Activation maps are generated based on the zero crossing of strain variation in the transition from end-diastole to systole. Our group has demonstrated that EWI yields 1) high precision electromechanical activation maps that include transmural propagation, 2) imaging of transient cardiac events (electromechanical strains within ~0.2-1 ms). Our studies have shown the EWI capable of capability atrial fibrillation and atrial flutter, transmural atrial pacing, RF ablation lesions while more recently it has been shown more robust that 12-lead EKG in characterizing focal arrhythmias such as the Wolf-Parkinson-White (WPW) and Pre-ventricular Contraction (PVC) as well as macro-reentrant arrhythmias in patients.. In the last part of the lecture, two machine learning aspects will be described. The first entails the use of ML techniques to automate the zero crossing estimates in the generation of the EWI activation maps by using Logistic Regression and Random Forest methods. The second ML application will include EWI mapping at lower imaging framerates used so far (less than 500 Hz) in order to determine what percentage of the activation maps can be reconstructed based on unsupervised training data at higher framerates. The quality of performance of EWI can be further enhanced by ML methodologies.

Bio: Elisa E. Konofagou is the Robert and Margaret Hariri Professor of Biomedical Engineering and Professor Radiology as well as Director of the Ultrasound and Elasticity Imaging Laboratory at Columbia University in New York City. Her main interests are in the development of novel elasticity imaging techniques and therapeutic ultrasound methods and more notably focused ultrasound in the brain for drug delivery and stimulation, myocardial elastography, electromechanical and pulse wave imaging, harmonic motion imaging with several clinical collaborations in the Columbia Presbyterian Medical Center and elsewhere. Elisa is an Elected Fellow of the American Institute of Biological and Medical Engineering, a member of the IEEE in Engineering in Medicine and Biology, IEEE in Ultrasonics, Ferroelectrics and Frequency Control Society, the Acoustical Society of America and the American Institute of Ultrasound in Medicine. She has co-authored over 225 published articles in the aforementioned fields. Prof. Konofagou is also a technical committee member of the Acoustical Society of America, the International Society of Therapeutic Ultrasound, the IEEE Engineering in Medicine and Biology conference (EMBC), the IEEE International Ultrasonics Symposium and the American Association of Physicists in Medicine (AAPM). Elisa serves as Associate Editor in the journals of IEEE Transactions in Ultrasonics, Ferroelectrics and Frequency Control, Ultrasonic Imaging and Medical Physics, and is recipient of awards such as the CAREER award by the National Science Foundation (NSF), the Nagy award by the National Institutes of Health (NIH) and the IEEE-EMBS Technological Achievement Award as well as additional recognitions by the American Heart Association, the Acoustical Society of America, the American Institute of Ultrasound in Medicine, the American Association of Physicists in Medicine, the Wallace H. Coulter foundation, the Bodossaki foundation, the Society of Photo-optical Instrumentation Engineers (SPIE) and the Radiological Society of North America (RSNA).