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Hereditary bundle branch defect: right bundle branch blocks of different causes have different morphologic
E Stéphan1, A de Meeus, P Bouvagnet
1Faculté de Médecine, Université Saint Joseph, Beirut, Lebanon.
American Heart Journal
|February 1, 1997
Summary
Hereditary bundle branch defect, an autosomal dominant disease, shows varied conduction blocks and potential sudden death. Early signs and specific ECG patterns, like the "r' pattern," indicate mutation carriers, with males more affected.
Area of Science:
- Genetics
- Cardiology
- Molecular Biology
Background:
- Hereditary bundle branch defect is an autosomal dominant disorder affecting cardiac electrical conduction.
- Previous studies mapped the disease locus to chromosome 19q in a Lebanese family.
- The condition presents with diverse conduction abnormalities, including bundle branch blocks and atrioventricular blocks.
Purpose of the Study:
- To further characterize hereditary bundle branch defect through a two-decade follow-up.
- To analyze electrocardiographic features and their correlation with mutation-carrier status.
- To investigate the disease's progression, penetrance, and prevalence.
Main Methods:
- Longitudinal follow-up of affected individuals and mutation carriers over 20 years.
- Detailed electrocardiographic analysis, focusing on QRS morphology and conduction abnormalities.
- Genotyping to determine mutation-carrier status.
Main Results:
- Conduction blocks can manifest early and worsen in 5-15% of cases, potentially leading to complete atrioventricular block and sudden death.
- An "r' pattern" in right precordial leads was observed in 53% of mutation carriers, with 19% progressing to complete fascicular block.
- Mutation carriers with a normal ECG remained normal; males showed conduction blocks more frequently (75%) than females (50%).
Conclusions:
- The "r' pattern" on ECG is a significant indicator of mutation carrier status in hereditary bundle branch defect.
- Incomplete penetrance and slow disease evolution suggest the condition is likely underdiagnosed.
- Understanding ECG patterns and carrier status is crucial for managing this genetic cardiac disorder.
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