Abstract
A 21 year old man presented with multiple, recurrent episodes of complete atrioventricular (AV) block associated with swallowing. Electrophysiological study revealed an AV block with swallowing of carbonated beverages and balloon inflation in the lower oesophagus. Evaluation did not demonstrate any underlying oesophageal or cardiac disease, and the AV block was not induced after intravenous atropine administration. The AV block was probably caused by a hypersensitive vagotonic reflex triggered by mechanical receptors in the lower oesophagus, resulting in suppression of the AV node. Head up tilt test revealed an increase in the high frequency spectrum of heart rate variability before the onset of the syncope. These findings suggest that the amplitude of the continual fluctuations in response to a variety of stimuli and derangement from both intrinsic and extrinsic environments was greater in this patient than in normal subjects. Swallow syncope is an unusual but treatable disorder. These reflexes that become exaggerated to the point of causing illness are poorly understood. Keywords: swallow syncope; AV block; electrophysiological study; head up tilt test
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Figure 1 .
ECG during swallowing carbonated beverage. (A) Swallowing is followed by three seconds of complete AV block. (B) After the intravenous administration of 2 mg of atropine, the AV block is completely blocked.
Figure 2 .
Intracardiac ECG during swallowing carbonated beverage. The AH intervals were prolonged transiently immediately after swallowing.
Figure 3 .
Sequential changes in heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), amplitude of high frequency (HF), and ratio of low frequency (LF) amplitude to HF amplitude (LF/HF). The spectral component at 0.25 Hz was defined as the HF component, whereas at 0.03 to 0.15 Hz it was defined as the LF component.