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His bundle electrography (HBE) helps localize atrioventricular (AV) block sites. Accurate HBE analysis guides appropriate therapy for AV block patients, reducing unnecessary pacemaker implantations.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Atrioventricular (AV) block diagnosis and management rely on precise localization of the block site.
- His bundle electrography (HBE) is a key diagnostic tool in evaluating AV conduction abnormalities.
Observation:
- This study analyzed 61 AV block patients using HBE, classifying them into P(A)-H block, BH block, H-V block, and mixed block groups.
- P(A)-H block cases rarely required permanent pacemakers.
- BH block cases showed a 33% pacemaker implantation rate, with some exhibiting split H block phenomena during right atrial pacing.
- All H-V block patients required permanent pacemakers, though precise block localization within the His-Purkinje system was challenging.
Findings:
- HBE effectively differentiates various types of AV block based on the block's anatomical location.
- The study observed that P(A)-H block generally has a favorable prognosis regarding pacemaker necessity.
- Right atrial pacing can unmask or exacerbate conduction abnormalities in certain AV block subtypes, supporting the longitudinal dissociation theory.
Implications:
- Accurate HBE interpretation is crucial for determining the exact site of AV block.
- This precise localization aids in selecting the most suitable therapeutic strategy for AV block patients.
- HBE can potentially prevent unnecessary permanent pacemaker implantations by clarifying block etiology and level.
Abstract:
In this report, 61 A-V block patients were analysed using HBE. According to the site of the block, these cases were classified into P(A)-H block, BH block H V block and mixed block. In P(A) H block group (23 cases), the permanent pacemaker implantation was not needed except for one patient with persistent heart failure due to marked bradycardia. Postmortem histology of this patient was well coincident to the results of HBE. In BH block group (18 cases), moderate number of patients were needed to have permanent pacemakers implanted (33%). RA pacing induced split H block with H-V prolongation and varied H and QRS configuration in two cases of this group. These phenomena may be well explained by the longitudinal dissociation theory. In H-V block patients, permanent pacemakers were implanted in all patients (12 cases). In this group, it is difficult to decide the exact location of block, either distal His, bifurcation or bundles, because of the difficulty to record the left or right bundle potentials in clinical practise. Finally, it is important to record the HBE in order to decide the exact site of block, and to choose the suitable therapy for A-V block patients.