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Congenital swallowing-induced symptomatic heart block: a case report of a probably hereditary disorder
Insights
A rare condition causes syncope (fainting) triggered by swallowing due to a strong vagal reflex. Genetic factors may play a role in this unusual cardiac response.
Area of Science:
- Cardiology
- Autonomic Nervous System Physiology
Background:
- Syncope, or fainting, can be triggered by various physiological events.
- The swallowing reflex involves complex autonomic nervous system (ANS) activity.
Observation:
- A 15-year-old female experienced recurrent syncope exclusively during food intake since infancy.
- Electrocardiogram (ECG) during eating revealed sinoatrial (SA) block with slow escape rhythms.
- No other cardiac or gastrointestinal abnormalities were identified.
Findings:
- The patient's syncope is attributed to an exaggerated vagal reflex during swallowing.
- This reflex significantly inhibited normal heart impulse formation and conduction.
- ECGs of relatives during food intake suggested a potential genetic predisposition.
Implications:
- Highlights the potential for severe autonomic dysregulation in response to common physiological stimuli.
- Suggests a possible genetic component influencing vagal reflex sensitivity.
- Underscores the importance of considering autonomic function in unexplained syncope cases.
Abstract:
A 15-year-old girl had had syncope induced by swallowing since infancy. An ECG recorded during food intake revealed SA block with very slow junctional and ventricular escape rhythms. No symptoms or signs of other cardiac disorders or gastrointestinal diseases were present. Activation of a strong vagal reflex, able to inhibit impulse formation and propagation in an otherwise normal heart, is the most likely explanation of the disorder in this patient. Furthermore, ECGs of her close relatives which were recorded during food intake as compared with the findings in a reference group (n = 20), indicated that a genetic factor could be involved.