Short‐term and intermediate‐term performance and safety of left bundle branch pacing

Figures

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  Figure 1. Electrophysiological characteristics of LBBP. Surface and intracardiac electrograms were taken from patients under LBBP. In the first patient (a), a LBB potential was recorded with the PVI being 20 ms, and the potential to LVAT duration was equal to 67 ms (a1). There was consistency among LVAT at low output (a2, 0.5 V@ 0.4 ms), high output (a3, 5 V@ 0.4 ms) and intrinsic activation. In another patient who underwent LBBP (b), the intrinsic QRS complex presented LBBB morphology, no LBB potential was recorded and the intrinsic LVAT was 116 ms (b1). The paced QRS wave presented “rSR” morphology in V1 with an isoelectric line before the onset of QRS wave which was deemed as selective LBB capture under capture threshold (0.3 V@ 0.4 ms, b2). As the output increased, the isoelectric line disappeared with the “R” wave of V1 decreased and the S wave of V5, V6 shallowed which was deemed as nonselective LBB capture (b3 and b4). The stim‐LVAT was 68 ms and consistent during high and low output which was shorter than intrinsic LVAT. LBB, left bundle branch; LBBB, left bundle branch block; LVAT, left ventricular activation time; PVI, potential to ventricular interval; stim‐LVAT, stimulus to…

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  Figure 2. Dynamic changes of stim‐LVAT and potential amplitude during LBBP procedure. In one patient, a small LBB potential was recorded with a PVI of 22 ms (a1) and a LVAT of 72 ms under intrinsic conduction (a2). The paced QRS complex presented QR morphology and the stim‐LVAT was 108 ms under high output (5 V@ 0.4 ms, a3). The amplitude of LBB potential increased as the lead was slightly screwed in (b1). Under the high output, the R‐wave in V1 enlarged and a s wave presented in V5 and V6. In addition, there was a consistency between high output (5 V@ 0.4 ms) and intrinsic activation on LVAT (b2). An abrupt change of stim‐LVAT was convinced under low (1 V@ 0.4 ms) and high outputs (b2 and b3). A high‐frequency signal (black arrow) was recorded on IEGM under low output, and the duration from the signal to the peak of R‐wave in lead V5 was consistent with LVAT under high output or intrinsic conduction (b3). The lead depth in the septum was showed in a4 and b4. LBB, left bundle branch; LVAT, left ventricular activation time; PVI, potential to ventricular interval; stim‐LVAT, stimulus to left ventricular activation time

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  Figure 3. Lead parameters during follow‐up. The pacing impedance decreased significantly at 3 days after operation compared with that during operation. The capture threshold, R‐wave amplitude and impedance remained stable throughout the whole observation period

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  Figure 4. Transventricular septal method for LBBP. A transventricular septal method was applied during the LBBP procedure. Via echo, the tip of active lead was observed to protrude toward the LV cavity while just beneath the endocardium at 3 days after operation. A, Short axis view; B, apical four‐chamber view. LBBP, left bundle branch pacing; LV, left ventricular

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  Figure 5. Septum remodeling after LBBP. In a patient complicated with DCM who underwent LBBP for resynchronization therapy, the phenomenon of “lead protruding” toward the LV cavity disappeared after remodeling of the ventricular septum during follow‐ups. The patient's IVSd increased from 7.8 mm to 10.2 mm. A, Three days after operation; B, 1 year after operation. DCM, dilated cardiomyopathy; IVSd, interventricular septal thickness; LBBP, left bundle branch pacing; LV, left ventricular