Distinct intracardiac electrogram waveforms with perforation during left bundle branch area pacing implantation

Figures

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  Figure 1. Macroperforation with complete loss of capture during continuous unipolar pacing at 5 V/0.5 ms. Note the fall in current of injury (COI), initially measured at 4.2 mV (double-sided arrow), falling to 0.8 mV just before loss of capture. Note that the COI falls to a lesser extent during repolarization (i.e. during the T-wave, annotated by *) than during depolarization (i.e. during the QRS complex, where the measurement was consistently taken in all patients). This patient was being implanted with a 3830 lead, with interruption of rotations, while the paced COI was approximately 12 mV. The perforation occurred spontaneously over the following 30 s (possibly due to release of torque build-up within the delivery catheter). Sweep speed is 25 mm/s. CSP UF = unfiltered conduction system pacing channel; CSP F = filtered conduction system pacing channel.

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  Figure 2. Typical waveforms in a patient with narrow QRS during (A) Microperforation with pacing and sensing. During sensing, note the deep and wide QS wave (62 ms, 12.2 mV) and low COI (3.1 mV) in the unfiltered channel and no high-frequency multiphasic component in the filtered channel. (B) Sensed waveform during gradual pullback of the perforated lead. Note the sudden change in electrogram waveform from a QS to an R pattern and thereafter a gradual increase in COI amplitude. (C) Final lead position with pacing and sensing. During sensing, note the tall R-wave (13.5 mV) and high COI amplitude (21.3 mV) with the high-frequency components in the filtered electrogram, timed at QRS onset (arrow). Sweep speed is shown in mm/s in the top left of each panel. CSP UF = unfiltered conduction system pacing channel. CSP F = filtered conduction system pacing channel.

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  Figure 3. Patient with left bundle branch block. (A) Microperforation with electrogram during pacing (left) with a QS waveform and during sensing (right) with a broad RS waveform in the unfiltered channel. Note the sharp high-frequency component in the filtered channel, timed late after QRS onset (arrow). (B) Final lead position with electrogram during pacing and sensing. Sweep speed is 100 mm/s. CSP UF = unfiltered conduction system pacing channel (scale 32x); CSP F = filtered conduction system pacing channel (scale 128x).

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  Figure 4. Microperforation during pacing (left) and during sensing (right) of right ventricular paced rhythm. Note the QS iEGM morphology during pacing and the broad R waveform during sensing of the backup paced rhythm. Sweep speed is 100 mm/s. CSP UF = unfiltered conduction system pacing channel (scale 32x); CSP F = filtered conduction system pacing channel (scale 128x).

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  Figure 5. Example of lead in its final position with a small q-wave (QR morphology of the waveform), with a myocardial current of injury amplitude of 21 mV. Note the small fascicular potential in the filtered channel (asterisk) with a visible current of injury in the unfiltered channel (arrow). Multiphasic sharp high-frequency potentials are visible in the filtered channel at the onset of the QRS complex. Sweep speed is 100 mm/s. CSP UF = unfiltered conduction system pacing channel (scale 32x); CSP F = filtered conduction system pacing channel (scale 128x).

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  Figure 6. Post-pause QRS narrowing in a patient with underlying left bundle branch block with microperforation. Note the deep and wide QS waveform during sensing of the narrow cycle, with broad RS morphology during resumption of left bundle branch block. Sweep speed is 50 mm/s. CSP UF = unfiltered conduction system pacing channel; CSP F = filtered conduction system pacing channel.

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  Figure 7. Plot of difference between current of injury amplitude (COI) and the negative component of the waveform (Q or S wave). Negative values indicate greater Q or S amplitude compared to COI. The datasets are separated according to baseline QRS (normal or non-LBBB vs. LBBB/paced), during perforation, and at final position.

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  Figure 8. Intracardiac unipolar LBBAP unfiltered sensed electrogram waveforms at different lead depths and with different QRS morphologies. In patients with a normal QRS/non-LBBB, the interventricular septum is activated from left to right. With a sub-endocardial LBBAP lead, the wavefront is initially directed towards the lead tip, resulting in an R wave. With micro- and macro-perforation, the wavefront is directed away from the lead tip, resulting in a predominantly negative and broad (Q or S) waveform, possibly also due to the fall in COI amplitude, which has a lesser counteracting effect. In patients with LBBB and RVP, septal activation is from right to left, resulting in a predominantly positive R/RS waveform at all lead depths. COI = current of injury; LBBAP = left bundle branch area pacing; LBBB = left bundle branch block; RVP = right ventricular pacing.