Patient Education

Heart Health Library

Our Health Library does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn more about their heart health. Our providers may not see and/or treat all topics found herein.

Our Health Library information does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn more about their health. Our providers may not see and/or treat all topics found herein.

Lower esophageal sphincter (LES)

The lower esophageal sphincter (LES) is a ring of muscle that forms a valve at the lower end of the esophagus where it joins the stomach.

The LES stays closed except during swallowing, when it allows food to pass from the esophagus into the stomach. When the LES is closed, it prevents the backflow (reflux) of stomach acid into the esophagus. If the LES does not close tightly enough, stomach acid backs up into the esophagus, causing heartburn. A weak lower esophageal sphincter is a major cause of gastroesophageal reflux disease (GERD).