: A condition where symptoms persist despite a normal endoscopy and even when acid suppression therapy fails. It is often linked to esophageal hypersensitivity , where the nerves in the esophagus are overly sensitive to even physiological (normal) levels of acid. Distinguishing Heartburn from Heart Attacks Heartburn or heart attack: When to worry - Mayo Clinic

: Normally, the lower esophageal sphincter (LES) acts as a seal. If this muscle becomes loose or relaxes inappropriately, acid can leak through.

Heartburn is a painful, burning sensation in the chest or throat, typically caused by stomach acid backing up into the esophagus. This "deep" dive into the condition covers its physiological mechanisms, variations, and critical distinctions from more serious health issues. Physiological Mechanisms

The primary cause is gastroesophageal reflux (GER), where stomach contents regurgitate into the esophagus.

: Unlike the stomach, the esophagus lacks a protective lining against acid and pepsin. Chronic exposure damages the mucosa and submucosa, triggering pain through deep-seated sensory nerves.

: Brain imaging shows that perceived heartburn involves activated cortical regions in the sensory, motor, and prefrontal areas, with GERD patients showing more rapid and intense brain activity than healthy individuals. Functional vs. Erosive Heartburn Not all heartburn is caused by visible physical damage.

: Patients have typical symptoms but no visible esophageal damage during an endoscopy.