ECG-based evaluation of ventricular synchrony in left bundle branch area pacing through characterization of the activation sequence

Figures

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  Fig. 1. (A) V1-V6 LF-QRS in black. Blue points indicate the ATl Dash blue line represents the activation sequence constructed by linking AT1-6. AT5 and AT1, in red, are the first and last lead activated, respectively. pAD is the time difference between both shown with dash red lines. (B) V4 LF-QRS construction. On the left, V4 ECG signal and different band frequencies envelopes filtered. Grey solid lines correspond to QRS fiducial point. Grey dash lines correspond to start and end QRS window. On the right, median filtered QRS envelope. The normalized average of those generates V4 LF-QRS. LF-QRS: low-frequency QRS. ATl: activation time of ECG lead l.

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  Fig. 2. Calculation of the ECG depolarization descriptors. Upper row shows a representative narrow QRS patient example and bottom row a RBBB patient example. (A) QRSd is computed from QRS onset and end delineated in the 12-lead standard ECG. Dash black lines represent QRS onset and QRS end. (B) V1-V6 LF-QRSs and each lead activation time as a circle mark. V1-V6 line-linking showing the first and last lead activated in red and pAD value. (C) Calculation of QRSa from individuals X, Y and Z orthogonal leads positive and negative areas of the delineated QRS. (D) First three components of the SVD of the QRS and the norm of these components. QRS60 is the temporal interval between the two blue crosses. RBBB: Right bundle branch block: QRSd: QRS duration; LF-QRS: Low-frequency QRS; QRSa: QRS area; SVD: Singular value decomposition.

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  Fig. 3. Median, 25th, and 75th percentiles of ventricular activation sequences at baseline (in grey), LBBAP (in blue) and RVP (in red) and corresponding pAD median, 25th and 75th percentiles values in baseline (A) narrow QRS (B) RBBB and (C) LBBB population. LBBAP: left bundle branch area pacing; RVP: right ventricular pacing; LBBB: left bundle branch block; RBBB: right bundle branch block.

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  Fig. 4. Median, 25th and 75th percentiles of QRSd, QRSa, and QRS60 markers computed in baseline (A) narrow QRS, (B) RBBB and (C) LBBB patients. QRSd: QRS duration; QRSa: QRS area; LBBB: left bundle branch block; RBBB: right bundle branch block.

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  Fig. 5. (A) Narrow baseline-QRS in black and after LBBAP in blue and corresponding ventricular activation sequences and pAD values. Ventricular activation sequences showed progressive activation from V1 to V6 at baseline (black) with pAD value of 7 ms while paced-QRS displayed delayed V1 activation (blue) with pAD value of − 11 ms. (B) Linear correlation analysis \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{AT}}_{6,\text{s}}$$\end{document} with V6 RWPT and (C) global RWPT. QRSd: QRS duration; QRSa: QRS area; pAD: precordial activation delay, RWPT: R-wave peak time.