that is a very good question! it has likely been called “heartburn” because it is often a burning pain that can be felt in the middle of the chest and under the breastbone. this is also the area where the heart lies. another name for heartburn is “pyrosis”. heartburn is often caused by acid reflux. acid reflux can occur when stomach acid washes up into the esophagus (the tube that connects the mouth and the stomach). the acid irritates the lining of the esophagus and can lead to heartburn. follow this link to a good series of slideshows that can help you understand heartburn a little better. <link>
why do doctors call it heartburn if it has nothing to do with the heart?