Figure 13 - Representative recording of esophageal motility from a patient with an isolated abnormality of lower esophageal sphincter (LES) relaxation.

Basal LES pressure is relatively high. Although LES relaxation clearly occurs with swallowing, there is an abnormally high nadir pressure. This results in an increased pressure "ramp" in the distal esophagus cause by increased resistance to the flow of the bolus across the incompletely relaxed LES. Peristalsis is preserved, thereby effectively excluding achalasia. A similar effect can be seen after fundoplication.