Understanding Heartburn -- the Basics What Is Heartburn? Despite
its name, heartburn has nothing to do with the heart. Some of
the symptoms, however, are similar to those of a heart attack or
heart disease. Heartburn is an irritation of the esophagus that
is caused by stomach acid. This can create a burning discomfort
in the upper abdomen or below the breast bone. With gravity's
help, a muscular valve called the lower esophageal sphincter, or
LES, keeps stomach acid in the stomach. The LES is located where
the esophagus meets the stomach -- below the rib cage and
slightly left of center. Normally it opens to allow food into
the stomach or to permit belching; then it closes again. But if
the LES opens too often or does not close tight enough, stomach
acid can reflux, or seep, into the esophagus and cause the
burning sensation. Occasional heartburn isn't dangerous, but
chronic heartburn or gastroesophageal reflux disease (GERD) can
sometimes lead to serious problems. Heartburn is a weekly
occurrence for about 2