Heartburn or pyrosis is a painful burning sensation in the esophagus, just below the breastbone. The pain often rises in the chest and may radiate to the neck or throat. Heartburn is also identified as one of the causes of asthma and chronic cough.
Pathophysiology
The sensation of heartburn is caused by exposure of the lower esophagus to the acidic contents of the stomach.
Normally, the lower esophageal sphincter (LES) separating the stomach from the esophagus is supposed to contract to prevent this situation. If the sphincter relaxes for any reason (as normally occurs during swallowing), stomach contents, mixed with gastric acid, can return into the esophagus. This return is also known as reflux, and may progress to gastroesophageal reflux disease (GERD) if it occurs frequently.
Peristalsis, the rhythmic wave of muscular contraction in the esophagus, normally moves food down and past the LES and is responsible for ultimately clearing refluxed stomach contents. In addition, gastric acid can be neutralized by buffers present in saliva.