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[Localization of the conduction defect in complete A-V block by means of His bundle electrograms (author's transl)]
Insights
Complete atrio-ventricular (A-V) block is often misdiagnosed. His bundle electrograms reveal most cases involve bilateral bundle branch block, not A-V junctional issues.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Diagnostics
Context:
- Traditional electrocardiography (ECG) provides indirect and unreliable localization of conduction defects in complete atrio-ventricular (A-V) block.
- The atrio-ventricular junction, including the A-V node and bundle of His, or the bundle branches can be implicated.
- QRS complex analysis in ECG is particularly unreliable in bundle branch block cases.
Purpose:
- To differentiate the precise localization of conduction defects in complete A-V block.
- To assess the diagnostic utility of His bundle electrograms in complete A-V block.
- To determine the prevalence of different types of conduction defects in complete A-V block.
Summary:
- His bundle electrograms enable accurate differentiation of conduction defects in complete A-V block.
- Analysis of 162 cases (11 personal, 151 literature) showed 63% of complete A-V block cases are due to bilateral bundle branch block.
- The remaining 37% presented as A-V junctional block, further classifiable into A-V nodal block or His bundle block via His bundle electrograms.
Impact:
- His bundle electrography significantly improves diagnostic accuracy for complete A-V block.
- Findings suggest bilateral bundle branch block is a more common cause of complete A-V block than previously recognized.
- This diagnostic capability allows for more precise patient stratification and potentially tailored therapeutic strategies.
Abstract:
The localization of the conduction defect in so-called complete A-V block can be established by electrocardiography only indirectly and unreliably. In principle the region of the atrio-ventricular junction, i.e. the A-V node and the bundle of His, may be involved just as well as the two branches. Analysis of the configuration of the QRS complex in the electrocardiogram is unreliable, particularly in cases with bundle branch block, because any pattern can arise from the appropriate site of a tertiary focus of stimulation in one of the two ventricles. Recording His bundle potentials (His bundle electrogram) enables differentiation. In eleven personal observations and 151 cases collected from the literature of complete A-V block the analysis with this method showed that the so-called A-V block in the majority of cases (63%) is actually due to bilateral bundle branch block. In the other 37% an A-V junctional block was present. This type of block could be differentiated by means of His bundle electrograms into an A-V nodal block and His bundle block.