Editor,A 38-year-old woman was referred to hospital for investigation following a three-year history of lightheadedness, dizziness and poor balance associated with eating. During this period, she had one episode of loss of consciousness. Symptoms were associated with flushing of the face which resolved spontaneously within 15 seconds. She reported that she could have up to fifteen episodes per week. She denied headaches and did not have any autonomic problems with her bladder or bowels. She had no significant past medical history. She did not take any regular medication and had no known allergies. them for a pioneering research in the field of the practical application of NIV.Blood pressure and heart rate were within normal ranges and she had no postural hypotension. A 12-lead ECG showed normal sinus rhythm with QTc interval within normal limits at 400ms.MRI brain and EEG were unremarkable. A 24-hour ambulatory ECG showed episodes of Mobitz Type 2 second degree atrioventricular block of which the patient was symptomatic, all occurring whilst she was eating (Figure 1 (a) and (b)). A diagnosis of swallow or deglutition syncope was made. Permanent pacemaker was implanted with complete resolution of symptoms.
Figure 1
Figures 1 (a) and (b) showing 2nd degree heart block. On both occasions, the patient had documented that she had been eating a meal.
DISCUSSION
Swallow syncope is a rare disorder thought to be due to a vagus nerve-mediated reflex. An increase in afferent vagal activity from the oesophageal plexus to the nucleus solitarius in the medulla is associated with swallowing food. Efferent parasympathetic fibres to trigger peristalsis have a cardioinhibitory effect and lead to bradycardia, hypotension and vasodilatation. Severe cardiac conduction disturbance may cause loss of consciousness 1. Over one hundred cases have been described in literature2, despite having been first reported3 in 1793.The management of swallow syncope should include the withdrawal of any medication that slows the rate of cardiac conduction or causes vasodepression. Anticholinergic medications such as atropine have been trialed with a view to prevent bradyarrhythmias by inhibiting vagal tone. However, results have been inconsistent, and many drugs have undesirable side effects and are therefore poorly tolerated 2.Eighty-five percent of reported cases of swallow syncope had either sinus bradycardia, sinus arrest, SA block or AV block. Implantation of a permanent pacemaker is increasingly used for patients with swallow syncope 4. Whilst permanent pacemaker implantation does not correct the cause of the condition, it has been demonstrated to be an effective treatment.
Figure 1