A clinical feasibility study of atrial and ventricular electromechanical wave imaging

Abstract

Background Cardiac Resynchronization Therapy (CRT) and atrial ablation currently lack a noninvasive imaging modality for reliable treatment planning and monitoring. Electromechanical Wave Imaging (EWI) is an ultrasound-based method that has previously been shown to be capable of noninvasively and transmurally mapping the activation sequence of the heart in animal studies by estimating and imaging the electromechanical wave, i.e., the transient strains occurring in response to the electrical activation, at both very high temporal and spatial resolution. Objective Demonstrate the feasibility of noninvasive transthoracic EWI for mapping the activation sequence during different cardiac rhythms in humans. Methods EWI was performed in CRT patients with a left bundle-branch block (LBBB), during sinus rhythm, left-ventricular pacing, and right-ventricular pacing and in atrial flutter (AFL) patients before intervention and correlated with results from invasive intracardiac electrical mapping studies during intervention. Additionally, the feasibility of single-heartbeat EWI at 2000 frames/s, is demonstrated in humans for the first time in a subject with both AFL and right bundle-branch-block. Results The electromechanical activation maps demonstrated the capability of EWI to localize the pacing sites and characterize the LBBB activation sequence transmurally in CRT patients. In AFL patients, the propagation patterns obtained with EWI were in agreement with results obtained from invasive intracardiac mapping studies. Conclusion Our findings demonstrate the potential capability of EWI to aid in monitoring and follow-up of patients undergoing CRT pacing therapy and atrial ablation with preliminary validation in vivo.

Assessing the atrial electromechanical coupling during atrial focal tachycardia, flutter, and fibrillation using electromechanical wave imaging in humans

“…EWI was performed during sinus rhythm and during pre-ventricular contraction. The EWI isochrones obtained during sinus rhythm show propagation from the RA, into the LA and then into the ventricles, similar to the normal cases published previously (Provost et al, 2013, 2011b). When this patient underwent premature ventricular complex, the region that was activated early in the ventricle during sinus rhythm triggered the entire electromechanical activation sequence, i.e., from the ventricles to the atria.…”

“…Such high frame rates allow unprecedented temporal resolution, and, perhaps most importantly, a five-fold improvement in the signal-to-noise ratio of cardiac motion and deformation mapping (Provost et al, 2012). Using such techniques, we have recently shown that mapping the transient strains occurring in response to the electrical activation, i.e., the electromechanical wave, can be used to map the transmural activation sequence of the normal and abnormal heart (Provost et al, 2011a, 2011b, 2010) and to locate pacing sites in patients undergoing cardiac resynchronization therapy (Provost et al, 2013). …”

High-contrast ultrafast imaging of the heart

“…The electromechanical activation has been imaged at typical frame rates of 800-2000 images/s using single diverging waves [35], [36]. Using 5 waves, we have shown in vivo in the human heart a strong improvement of both the B-mode and the velocity estimation quality compared to one diverging wave imaging.…”

Phase-Sensitive 2D Motion Estimators Using Frequency Spectra of Ultrasonic Echoes

“…After the development of shear wave elastography by Tanter, et al [11], which was the first practical application of high-frame-rate ultrasound, various studies have been conducted for cardiovascular applications, such as vascular strain and blood flow imaging [12][13][14], pulse wave imaging [15,16], and cardiac strain and blood flow imaging [17][18][19][20][21]. In addition, various studies for improvement of the image quality in high-frame-rate ultrasound have been conducted [22][23][24][25][26].…”