Determinants of Heartburn

Most people with heartburn have a normal-appearing esophageal mucosa. Even if a biopsy is examined under the microscope, it too would likely be normal. However, some would have microscopic changes such as epithelial damage, inflammation, and increased basal cell activity. A few patients with heartburn will have overt tissue damage. Conversely, and inexplicably, some people with very severe esophagitis have no heartburn. Since GERD is responsible for both heartburn and esophagitis, these facts are difficult to reconcile.

When heartburn occurs, it usually does so in concert with LES relaxation and reflux, as demonstrated by 24-hour recording of intraesophageal pressure and acidity. However, most refluxes - in most people most of the time - are unaccompanied by heartburn. No doubt, luminal and cellular factors protect the esophagus, but the truth is that we do not know how the sensation of heartburn occurs. There are no superficial nerve endings to detect acid reflux and send the heartburn message to the brain. Probably, acid and other irritating materials penetrate through the tissue barrier deep into the mucosa, where nerve endings do exist. In some people, the esophageal mucosa seems hypersensitive to normal refluxes. In other cases, severe esophagitis or Barrett's esophagus destroy these nerve endings, which might explain why some people with esophagitis have no heartburn.

Psychological Considerations
We are becoming aware of the importance of the enteric nervous system and the brain itself in the perception of pain in gastrointestinal disease. Normally, messages from the gut to the brain are suppressed. This suppression may be lessened by stress or emotion. This may be the means by which emotional upset can produce heartburn. Also, anxiety, stress, and lack of social support increase esophageal sensitively. Some people perceive heartburn at an esophageal pH of 6, while others feel nothing at a pH of 2.