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Swallow syncope is a neurally mediated situational syncope associated with vagal over activity due to oesophageal stimulation. Diagnosis requires the demonstration of temporal relationship between swallowing and syncope. Provocative testing with various types of solid and liquid foods, particularly trigger foods, under electrocardiogram (ECG) monitoring can help to confirm the diagnosis.
A 71-year-old man presented with recurrent episodes of loss of consciousness lasting for couple of seconds when swallowing solid foods or fluids, mainly Coca-Cola, one of his favourite beverages. The episodes started a day after he underwent fundoplication for severe gastro-oesophageal reflux disease. There were no cardiac symptoms or indicators to suggest a seizure disorder. He had no relevant medical or family history. He had started to reluctantly avoid Coca-Cola, which led to reduction in the number of syncopal episodes. Physical examination was unremarkable. Routine 12 lead electrocardiogram (ECG) was normal. As the episodes were mainly precipitated by Coca-Cola, provocative testing was undertaken by asking the patient to drink Coca-Cola under ECG monitoring. He immediately became symptomatic with transient syncope lasting for 10 s. ECG revealed sinus arrest lasting for 9 s (Figure 1a). There was prompt recovery with no post-episode confusion. This was reproducible and the episode was associated with marked drop in blood pressure (Figure 1b). Implantation of permanent pacemaker led to complete resolution of his symptoms.
Swallow or deglutition syncope is a relatively rare, neurally mediated situational syncope associated with vagal over activity due to oesophageal stimulation.1 –3 The condition is more common in adult males.1,2 Most cases are associated with underlying oesophageal or cardiac disorder; however some cases have no underlying cause.1,2 Underlying oesophageal disorders include oesophageal spasm, oesophageal stricture, achalasia, oesophageal diverticula, oesophageal cancer and hiatus hernia.1,2 Cardiac disorders include acute myocardial infarction, digoxin use and rheumatic carditis. Other reported associations include ascending aortic aneurysm, thoracic surgery, advanced lung cancer and transient hypoxia.1,2
Patients present with sudden onset of symptoms during swallowing, ranging from transient episodes of dizziness or light-headedness to actual loss of consciousness.1 –4 Symptoms occur during or immediately after swallowing and are reasonably reproducible. The intake of solid foods or fluids can cause syncope but carbonated beverages have been commonly implicated, presumably due to gaseous distension of the oesophagus.4
The pathophysiology of swallow syncope is not completely understood, and is probably multifactorial including intense vagal afferent activation due to oesophageal stimulation and direct mechanical compression of the cardiac chambers by a huge hiatus hernia.1,2 The symptoms result from sudden and transient reduction in cardiac output due to arrhythmias induced by increase in vagal tone.1,2
Diagnosis of deglutition syncope requires the demonstration of temporal relationship between swallowing and symptoms of light-headedness and syncope.1 –4 Provocative testing with various types of solid and liquid foods, particularly trigger foods, under ECG monitoring can help to confirm the diagnosis.1,2,4 Appropriate investigations to rule out an underlying oesophageal or cardiac illness should be undertaken. Management includes avoidance of the precipitating stimulus, treatment of underlying condition or, if uncontrolled, permanent dual-chamber pacing in cases with bradyarrhythmias.1,2,4
The cause of swallow syncope in our case remains unclear. Although he had severe gastro-oesophageal reflux disease, the temporal association with fundoplication is of interest and has not been reported previously in the literature. This case demonstrates the importance of meticulous history taking and focussed investigations in diagnosing uncommon conditions like swallow syncope.
Conflict of interest: None declared.