What is the cause and pathophysiology of Acute Necrotizing Esophagitis (ANEC)?

Causes and Pathophysiology of Acute Necrotizing Esophagitis (ANEC)

Acute Necrotizing Esophagitis (ANEC) is primarily caused by significant ischemia to the esophageal mucosa, resulting from a combination of hemodynamic compromise, reduced esophageal perfusion, and compromised mucosal defense mechanisms.

Primary Pathophysiological Mechanisms

1. Ischemic Injury

• Hypoperfusion: The most important causative factor is severe hypoperfusion and hypovolemic shock, which leads to decreased blood flow to the esophageal mucosa 1
• Vascular Anatomy: The distal esophagus is particularly vulnerable due to its relatively poor vascularization compared to other segments of the gastrointestinal tract
• Watershed Area: The distal esophagus represents a watershed area with limited collateral blood supply, making it susceptible to ischemic injury during systemic hypoperfusion 2

2. Contributing Clinical Conditions

• Hemodynamic Compromise:

  • Diabetic ketoacidosis (DKA) - frequently associated with ANEC 3, 4
  • Shock states (hypovolemic, cardiogenic, septic)
  • Cardiac dysfunction, particularly right ventricular failure 5

• Comorbidities:

  • Diabetes mellitus (present in a significant percentage of cases)
  • Advanced age (mean age 75.24 years in large case series) 2
  • Multiple comorbid conditions (present in 83% of patients) 2

3. Secondary Aggravating Factors

• Acid Reflux: Gastric acid reflux exacerbates the initial ischemic injury
• Impaired Mucosal Defense: Reduced ability to neutralize acid and repair mucosal damage
• Infection: Secondary bacterial invasion of damaged tissue may worsen necrosis

Clinical Presentation and Distribution

• Presentation: Most commonly presents with upper gastrointestinal bleeding (85% of cases) 1
• Location: Predominantly affects the lower two-thirds of the esophagus (59% of cases) 2
• Appearance: Characteristic circumferential black mucosal discoloration that typically spares the gastroesophageal junction 3

Disease Progression and Complications

• Acute Phase: Mucosal necrosis with potential for full-thickness involvement
• Healing Phase: With appropriate treatment, mucosal healing typically occurs
• Complications:
  • Stricture formation (most common long-term complication) 3
  • Perforation (rare but life-threatening)
  • Mediastinitis
  • Persistent dysphagia

Mortality and Prognosis

• Mortality Rate: Approximately 30% of patients die either during hospitalization or follow-up 1
• Prognosis Factors: Mortality is more related to underlying comorbidities than to the esophageal lesions themselves 2
• Recovery: With appropriate supportive care, esophageal lesions typically resolve in surviving patients 2

Key Points for Clinicians

• ANEC should be considered in the differential diagnosis of upper gastrointestinal bleeding, particularly in elderly patients with multiple comorbidities
• Early recognition and treatment of the underlying hemodynamic compromise is essential
• Proton pump inhibitors and mucosal protectants form the cornerstone of management
• Vigilance for stricture formation during recovery is important, as this may require endoscopic intervention