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His-Purkinje system longitudinal dissociation: From bench to bedside. A case of output-dependent fascicular capture
Leonardo Marinaccio1, Francesco Vetta2, Barbara Ignatiuk3
1Department of Cardiology, Immacolata Concezione Hospital, Piove di Sacco, Padua, Italy.
Insights
This study shows selective His bundle (HB) pacing can correct heart rhythm delays. Pacing different HB compartments reveals distinct electrical conduction pathways.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Anatomy
Background:
- Histological studies reveal the His bundle (HB) is anatomically partitioned by collagen fibers, suggesting potential for longitudinal dissociation.
- Direct His bundle pacing can normalize QRS duration and axis in patients with proximal HB lesions causing bundle branch block.
- Evidence for selective pacing of specific His bundle partitions remains limited.
Observation:
- A case of intra-Hisian left bundle branch block was observed.
- Permanent distal His bundle pacing was performed in this patient.
- Pacing resulted in correction of left ventricular delay and varied QRS morphology with different voltage outputs.
Findings:
- The observed varied QRS morphology suggests recruitment of distinct His bundle compartments.
- This demonstrates the functional relevance of His bundle longitudinal dissociation.
- Selective His bundle pacing can modulate ventricular activation patterns.
Implications:
- This case provides further evidence supporting the concept of His bundle longitudinal dissociation.
- Findings may inform novel pacing strategies for cardiac conduction disorders.
- Further research into selective His bundle compartment pacing is warranted.
Introduction:
Histological studies reported that the His bundle (HB) is partitioned into narrow cords by collagen running in its long axis, providing the anatomical setting necessary for its longitudinal dissociation. Further confirmations came from the demonstration that direct HB pacing normalizes the QRS axis and duration in subjects with proximal HB lesions causing bundle branch block. However, there is no evidence of the possibility of selective HB partitions pacing destined to the composition of branches and fascicles.
Methods And Results:
We describe a case of intra-Hisian left bundle branch block in which permanent distal HB pacing corrects left ventricular delay and produces different QRS morphology at different voltage outputs, as an expression of different selective HB compartments recruitment.
Conclusion:
This case would strengthen the limited data in the literature about HB longitudinal dissociation.
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