 [ Symptoms ] what is heartburn [ Disease ] heartburn also called acid indigestion is a symptom of gastroesophageal reflux disease often referred to as gerd it can occur when acid or other contents from your stomach back up into the esophagus that is the tube food passes through going from your mouth to your stomach the problem stems from a muscle that may be weak or may relax at inappropriate times it is called the lower esophageal sphincter or les and it is located between your stomach and your esophagus if it does not close quickly enough it can not prevent the acid backwash that results in heartburn when acid reflux is frequent you may have a condition called gerd or gastroesophageal reflux disease food sensitivities are often the culprit iif there is shortness of breath palpitations and sweating the problem may be heart related