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Atrioventricular Conduction: Physiology and Autonomic Influences.
Eric N Prystowsky1, Jasen L Gilge2
1Cardiac Arrhythmia Service, St. Vincent Hospital, 8333 Naab Road, Indianapolis, IN 46260, USA; Duke University Medical Center, Durham, NC, USA.
Cardiology Clinics
|June 15, 2023
Summary
Sudden heart block often indicates increased vagal tone affecting the atrioventricular node. However, heart block with activity suggests the His-Purkinje system is involved, influenced by autonomic tone changes.
Area of Science:
- Cardiology
- Electrophysiology
- Autonomic Nervous System
Background:
- Atrioventricular (AV) nodal conduction exhibits decremental properties and is sensitive to autonomic tone.
- His-Purkinje system (HPS) conduction relies on fast-channel tissue, making it less susceptible to autonomic influence.
Purpose of the Study:
- To differentiate the location of heart block based on autonomic tone alterations.
- To understand the role of autonomic perturbations in AV nodal and His-Purkinje system conduction.
Main Methods:
- Analysis of electrophysiological principles governing AV nodal and HPS conduction.
- Correlation of heart block patterns with changes in sinus rate and autonomic tone.
Main Results:
- Sudden heart block during stable sinus rate, preceded by slowing, typically implicates the AV node due to increased vagal tone.
- Heart block accompanied by activity suggests a block within the His-Purkinje system.
- Enhanced sympathetic and reduced vagal tone can promote AV and atrioventricular node reentry.
Conclusions:
- Autonomic tone significantly impacts AV nodal conduction, often causing block.
- Heart block location can be inferred from its relationship with sinus rate and autonomic state.
- Understanding these principles aids in diagnosing the origin of heart block.
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