Uncommon output-dependent paced QRS morphology transition during left bundle branch pacing.
Yoji Iida1, Nobuyuki Makishima1
1Department of Cardiology, Kobari General Hospital, Noda, Chiba, Japan.
Pacing and Clinical Electrophysiology : PACE
|May 22, 2022
Summary
Left bundle branch pacing (LBBP) can be challenging. A case study shows that a change in QRS morphology does not always confirm selective LBBP; high-output pacing assessment is crucial.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Device Technology
Background:
- Intermittent complete heart block necessitates pacing interventions.
- Left bundle branch pacing (LBBP) is an advanced pacing technique aiming for physiological ventricular activation.
- Achieving selective LBBP is critical for optimal pacing outcomes.
Observation:
- A patient undergoing LBBP exhibited a QRS morphology shift from nonselective to selective pacing during unipolar stimulation.
- This morphological transition was paradoxically associated with prolonged stimulus-to-left ventricular activation time (Stim-LVAT).
- Further lead manipulation resulted in selective LBBP with a significantly reduced and stable Stim-LVAT.
Findings:
- A QRS morphology transition from nonselective to selective pacing does not reliably confirm successful selective LBBP.
- Stimulus-to-left ventricular activation time (Stim-LVAT) is a key indicator of pacing success and efficiency.
- High-output pacing assessment is mandatory to confirm true selective LBBP.
Implications:
- Clinical interpretation of paced QRS morphology requires careful consideration of other electrophysiological parameters.
- Accurate assessment of pacing lead placement and capture is vital for effective LBBP.
- This case highlights the importance of comprehensive evaluation beyond simple morphological changes in pacing procedures.
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