Achalasia, also known as esophageal achalasia, achalasia cardiae, cardiospasm, and esophageal aperistalsis,'s an esophageal motility disorder: The smooth muscle layer of the esophagus loses normal peristalsis (muscular ability to move food down the esophagus), and the lower esophageal sphincter (LES) fails to relax properly in response to swallowing. Achalasia's characterized by difficulty swallowing, regurgitation, and sometimes chest pain. Diagnosis's reached with esophageal manometry and ba… (More on Achalasia)