Is the left bundle branch pacing a choice to conquer the right bundle branch block?—A case report

Figures

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  Figure 1. (a) Intrinsic RBBB pattern with a QRS width of 141 ms showed in 12‐lead ECG. Intracardiac electrogram recorded by the lead tip at the atrial side of the AV septum showed the sharp His‐bundle potential (arrow) and atrial and ventricular potentials with the almost equal amplitudes. (b) Intracardiac electrogram recorded by the lead tip at the ventricular side of the AV septum showed the small atrial signals and multiphasic fragmented His‐bundle potential (arrow). (c and d) Pacing map of the ventricular side of AV septum before screwing‐in the lead. (c) During pacing at the lower output (<5.0 V/1.0 ms), there was a notch at the downslope of the QS pattern in V1 (paced QRS width = 128 ms), indicating high RV septal pacing and predicting future LBB capture after typical evolvement of the notch with fixation of the lead. When pacing at the high output (≥5.0 V/1.0 ms), the abrupt narrower QRS (paced QRS width = 106 ms) indicated the capture of His‐bundle and correction of RBBB pattern. Recording speed was 100 mm/s

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  Figure 2. Comparisons of 12‐lead ECG showed the RBBB pattern at baseline and after the fixation of the lead with different outputs. (a) baseline intrinsic rhythm showed a typical RBBB pattern with the QRS width of 141 ms; (b) unipolar pacing at 0.75 V/0.4 ms captured the intra‐Hisian LBB with the resultant qR pattern in V1 (red oval dashed circle) but significantly narrower QRS of 109 ms. The iso‐electrical interval between the pacing spike and the onset of the QRS indicated selective capture of the LBB. (c) With bipolar pacing or increasing output unipolar pacing, the qR pattern remained in V1 (blue oval dashed circle), but iso‐electrical intervals fainted (suggesting nonselective LBB capture), and finally, R wave disappeared in V1 (red oval dashed circle) and narrow QRS of 106 ms indicated His‐bundle captured with RBB recruitment. The recording speed was 25 mm/s. Schematic representation of the site of RBBB and capture of intra‐Hisian LBB and His‐bundle are shown at the sides of the ECG. The intra‐Hisian LBB capture might activate the RBB by transverse interconnections and result in a similar later activation manner as in HBP. (d) Final lead locations showed in fluoroscopic images.…