Because conventional physicians are becoming more skilled at diagnosing and treating heartburn, a condition in which stomach acid splashes upward into the esophagus, this common problem is undergoing some name changes. Strictly speaking, when you used to feel as though Mount St. Helens was erupting beneath your breastbone, it was called “heartburn.” After doctors developed gastroscopes to actually see the irritated esophagus, your heartburn grew into the more respectable “reflux esophagitis,” or “reflux” for short.