You said that the swallowing triggers a vagal reflex? What is the vagus nerve?
The vagus nerve is a nerve that generally slows the heart beat, reduces blood pressure and, in general, opposes the sympathetic nerves, the characteristic "fight or flight" reaction [aka stress response]. The vagus is important in the GI [gastrointestinal] tract to increase motility [movement]. Ordinarily, when you swallow a message is sent to the brain, [which then sends] a swallowing message to the esophagus saying to increase esophageal motility. For some reason, this message from the brain is also going to the heart and telling it to slow. And why that cross wiring happens, I don't know.
What is happening in the heart when it receives this slowing message from the brain?
The electrical signal doesn't make it [from the heart's top chambers] to the bottom [ones]; it's called heart block…. Heart block occurs because the vagus sends its impulse to the AV node [the atrioventricular node, a specialized section of tissue that relays electrical signals through the heart], causing it to block conduction from the top chamber to the bottom chambers. … Or, the vagal impulse can stop the normal pacemaker in the heart called the sinus node.
Why would this reflex be triggered by certain foods and not others?
It may take greater distension [expansion] of the esophagus [to stimulate the response, which may occur] with bulk food rather than liquids.
How common is the condition? Do women get it more than men?
It's uncommon but not unheard of. There have been many isolated reports. … It can [also] occur with coughing—it is probably a similarly induced vagal mechanism. … It's so infrequent that I don't know if there is a preference [for women or men].
For several years, doctors could not get the correct diagnosis for this woman. How do you explain that?
All you need to do is to record an electrocardiogram while she's swallowing and you'll get the answer. [Referring to the electrocardiogram results published in The Lancet, Zipes pointed to a large gap between spikes on the top line of the diagram. This gap indicates a pause in the heartbeat lasting 2.129 seconds. The line below represents the woman's heart rhythm after cardiologists gave her an artificial pacemaker to maintain a steady beat].