The lower esophageal sphincter. Physiologic and clinical aspects

Area of Science:

• Gastroenterology
• Physiology

Background:

• The lower esophageal sphincter (LES) plays a crucial role in preventing gastroesophageal reflux.
• Understanding its physiology and pathophysiology is essential for managing related disorders.

Purpose of the Study:

• To review current concepts regarding the LES mechanism.
• To identify factors influencing LES function and clinical syndromes of dysfunction.

Main Methods:

• Review of current literature on LES physiology and pathophysiology.
• Incorporation of data from in-vivo human manometric studies and in-vitro/in-vivo animal studies.

Main Results:

• Identified three key components of LES control: specialized smooth muscle, autonomic nervous system, and gastrointestinal hormones (e.g., gastrin).
• Recognized clinical syndromes linked to these control elements.
• Identified foods and drugs (anticholinergics, fatty foods, chocolate, alcohol, smoking) that can adversely affect LES pressure.
• Supported clinical effectiveness of antacids and bethanechol for heartburn therapy through controlled trials.

Conclusions:

• LES function is complex, involving muscle, neural, and hormonal regulation.
• Specific lifestyle factors and medications can impair LES function, contributing to heartburn.
• Therapeutic strategies like antacids and bethanechol show efficacy, with ongoing research into other pressure-increasing medications.