What is most common Gerd mechanism
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GERD pathophysiology mechanism lower esophageal sphincter
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The most common mechanism of GERD is transient lower esophageal sphincter relaxations (TLESRs).
GERD Mechanisms — Overview
The pathophysiology of GERD centers on a dysfunctional esophagogastric junction (EGJ), which acts as the antireflux barrier. This barrier is composed of two components working together:
- Lower esophageal sphincter (LES) — the intrinsic smooth muscle sphincter
- Crural diaphragm — the external skeletal muscle component
Most Common Mechanism: Transient LES Relaxations (TLESRs)
TLESRs account for the majority of reflux episodes — approximately ~80–90% in patients without hiatal hernia. These are:
- Spontaneous, prolonged relaxations of the LES not triggered by swallowing
- Mediated by a vagovagal reflex originating from gastric distension (especially postprandial)
- The crural diaphragm also simultaneously inhibits, eliminating both components of the antireflux barrier
- Allow large volumes of gastric content (liquid and gas) to reflux
Other Contributing Mechanisms
| Mechanism | Relative Contribution | Notes |
|---|---|---|
| TLESRs | Most common (~80%) | Primary mechanism in non-erosive and mild GERD |
| Low basal LES pressure | Less common alone | More relevant in severe/erosive esophagitis |
| Hiatal hernia | Significant | Disrupts crural diaphragm support, impairs LES; associated with more severe GERD |
| Impaired esophageal clearance | Amplifying factor | Prolongs mucosal acid exposure after reflux |
| Delayed gastric emptying | Contributing factor | Increases gastric distension, promotes TLESRs |
| Decreased salivary production | Contributing factor | Reduces acid neutralization and clearance |
Why TLESRs Dominate
Gastric distension after meals triggers stretch receptors in the gastric cardia/fundus, activating a vagally mediated reflex that causes the LES to relax for 10–45 seconds (vs. the 6–8 seconds during a normal swallow-induced relaxation). This prolonged window allows reflux to occur.
In patients with hiatal hernia, the additional loss of crural diaphragm support shifts the mechanism more toward low resting LES pressure and anatomic displacement of the EGJ above the diaphragm, compounding reflux.
(Source: Diagnosis and Management of Gastroesophageal Reflux Disease, p. 2)
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