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Familial symptomatic sinus bradycardia: autosomal dominant inheritance
A V Mehta1, B Chidambaram, A Garrett
1Department of Pediatrics, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37604, USA.
Pediatric Cardiology
|September 1, 1995
Summary
Familial sinus bradycardia, a heart rhythm disorder, can be inherited in an autosomal dominant pattern. This condition, often caused by vagotonia, necessitates pacemaker implantation for symptomatic individuals.
Area of Science:
- Cardiology
- Clinical Electrophysiology
- Genetics
Background:
- Symptomatic sinus bradycardia can manifest due to sick sinus syndrome or vagotonia.
- Familial occurrence suggests a potential genetic component in some bradycardia cases.
Observation:
- An 18-year-old male presented with palpitations and reduced exercise capacity due to severe sinus bradycardia (40 bpm).
- The patient exhibited prolonged sinus pauses (up to 6 seconds) during sleep.
- Diagnostic tests indicated vagotonia rather than intrinsic sinus node dysfunction.
Findings:
- The patient's father and cousin also had similar histories of syncope and severe sinus bradycardia.
- Autosomal dominant inheritance pattern was suggested for this familial bradycardia.
- Electrophysiologic studies and exercise testing helped differentiate vagal tone effects from intrinsic sinus node disease.
Implications:
- This case highlights the importance of considering familial inheritance in unexplained sinus bradycardia.
- Autosomal dominant vagotonia can cause significant symptomatic bradycardia requiring pacemaker implantation.
- Early diagnosis and genetic counseling may be beneficial for affected families.