Combined intra-Hisian block and A-V nodal bypass
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Insights
This study details a patient with complex heart block, revealing concealed intra-Hisian block and a masked atrio-ventricular (A-V) bypass tract. Electrophysiological studies were crucial for diagnosing these hidden cardiac conduction abnormalities.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Electrophysiology
Background:
- Atrio-ventricular (A-V) block and left bundle branch block can indicate complex conduction system disease.
- His bundle electrography is a key diagnostic tool for evaluating heart rhythm disorders.
Observation:
- A patient presented with first and second-degree A-V block and left bundle branch block.
- Electrophysiological study revealed both intra-His bundle branch block and an A-V nodal bypass tract.
- The intra-Hisian block was not apparent on the resting His bundle electrogram but emerged during atrial pacing.
Findings:
- A concealed intra-Hisian block was identified, becoming evident only with increased heart rate.
- An A-V nodal bypass tract was present but masked by the severe A-V conduction defect on surface ECG.
- The combination of infra-Hisian block and bypass tract presented a complex electrophysiological profile.
Implications:
- His bundle electrocardiography is essential for diagnosing concealed conduction abnormalities.
- Understanding combined infra-Hisian block and bypass tracts is critical for patient management.
- This case highlights the diagnostic limitations of surface ECG in complex arrhythmias.
Abstract:
A patient with first and second degree atrio-ventricular (A-V) block and left bundle branch block was shown on electrophysiological study to have an intra and infra-His bundle branch block. In addition, this patient also had an A-V nodal bypass tract. The intra-Hisian block was concealed on the resting His bundle electrogram and became evident only during atrial pacing. The A-V nodal bypass was masked on the surface electrocardiogram (ECG) by the associated A-V conduction defect. The clinical significance of A-V bypass and combined block below the A-V node is discussed. The diagnostic value of His bundle electrocardiography in a patient with complex electrophysiological abnormalities is stressed.