Key result
Left bundle branch pacing at different outputs resulted in different left ventricular activation times, likely due to longitudinal dissociation of the His-Purkinje system.
Why the study?
Although interest in conduction system pacing is increasing, data on longitudinal dissociation in the literature remain limited.
What is the mechanism of QRS morphology transition during threshold testing of left bundle branch pacing in a patient with sick sinus syndrome and AV block?
Case Report (n=1)
What is the mechanism of QRS morphology transition during threshold testing of left bundle branch pacing in a patient with sick sinus syndrome and AV block?
Threshold testing during left bundle branch pacing can reveal different left ventricular activation times at different outputs, likely due to longitudinal dissociation of the His-Purkinje system.
Threshold testing in LBBP may yield output-dependent LV activation; this single case leaves open mechanistic confirmation of His-Purkinje dissociation.
BACKGROUND: Although the interest in conduction system pacing is increasing, the data on longitudinal dissociation in the literature is still limited. METHODS AND RESULTS: We performed left bundle branch (LBB) pacing on a patient with sick sinus syndrome and atrioventricular block. The transition of QRS morphology can be observed during the threshold testing. The main findings were different left ventricular activation times when selective LBB capture was performed at different outputs. CONCLUSIONS: This phenomenon may be due to the anatomical basis of longitudinal dissociation of the His-Purkinje system, which allows pacing stimulation at different thresholds to excite different portions of the conduction system.
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Shen et al. (2022) conducted a case report in Sick sinus syndrome and atrioventricular block (n=1). Left bundle branch (LBB) pacing was evaluated on Transition of QRS morphology and left ventricular activation times during threshold testing. Left bundle branch pacing at different outputs resulted in different left ventricular activation times, likely due to longitudinal dissociation of the His-Purkinje system.
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