Non-invasive Electromechanical Wave Imaging of atrial, supraventricular and ventricular cardiac conduction disorders in canines and humans

Abstract

Electromechanical Wave Imaging (EWI) is a novel ultrasound-based imaging modality for the mapping of the electromechanical wave (EW), i.e., the transient deformations occurring in immediate response to the electrical activation. The correlation between the EW and the electrical activation has been established in canines in previous studies. However, the methods used previously to map the EW required the reconstruction of images over multiple cardiac cycles, precluding the application of EWI for non-periodic arrhythmia such as fibrillation. In this study, we present a new unfocused sequences based on flash emissions to image the entire heart at very high frame rates (2000 fps) during free breathing in a single heartbeat and compare it to the automatic composite technique (ACT), which is based on acquisition spanning multiple heart cycles and is used to image normal human subjects during sinus rhythm. Feasibility of flash-beam sequences is assessed by imaging the atria and ventricles of closed-chest, conscious canines during sinus rhythm and during right-ventricular pacing following atrioventricular dissociation, i.e., a non-periodic rhythm and during ventricular fibrillation in one open-chest canine. These results indicate that EWI can be used for the characterization of non-periodic arrhythmia in conditions close to the clinical setting, in a single heartbeat, and during free-breathing.

Spatiotemporal matrix image formation for programmable ultrasound scanners

“…Over the last few years, the emergence of programmable ultrasound imaging (Tanter and Fink, 2014) has bred a number of novel clinical applications such as, the functional imaging of the brain (Mace et al, 2011), the mapping of the electromechanical wave in the heart (Provost et al, 2013(Provost et al, , 2012(Provost et al, , 2011 and the quantitative characterization of tumors (Bercoff et al, 2004). For instance, Ultrafast Ultrasound Imaging (UUI) is based on the transmission of a small number of defocused waves such as plane (Montaldo et al, 2009), circular (Couade et al, 2009;Lockwood et al, 1998;Nikolov and Jensen, 2003;Papadacci et al, 2014;Provost et al, 2012), or spherical diverging waves (Provost et al, 2014) to insonify the entire field of view (FOV) at each emission. This enables frame rates approximately 100 times faster than standard ultrasound sequences, even in three dimensions (Provost et al, 2014).…”