What is the anatomy involved in Heller's myotomy?

Anatomy of Heller's Myotomy

Heller's myotomy is a surgical procedure that involves cutting the muscle fibers of the lower esophageal sphincter (LES) to relieve obstruction caused by achalasia or other esophageal motility disorders. The procedure targets specific anatomical structures to improve esophageal emptying while minimizing complications such as reflux.

Key Anatomical Structures

Esophageal Layers

• Mucosa: Innermost layer that remains intact during myotomy
• Submucosa: Contains blood vessels, lymphatics, and nerve plexuses
• Muscularis propria: Target of myotomy, consisting of:
  • Inner circular muscle layer - primary target for cutting
  • Outer longitudinal muscle layer - may also be cut depending on technique
• Adventitia: Outermost layer

Lower Esophageal Sphincter (LES)

• Located at the esophagogastric junction (EGJ)
• Consists of thickened circular muscle fibers
• Primary target of myotomy
• Extends approximately 2-4 cm onto the gastric cardia 1

Surrounding Structures

• Phrenoesophageal ligament: Connects esophagus to diaphragm
• Short gastric vessels: Support the angle of His
• Vagus nerves: Run alongside the esophagus
• Diaphragmatic hiatus: Opening where esophagus passes through diaphragm

Anatomical Approach in Laparoscopic Heller Myotomy

1. Surgical Access:

   • Typically performed via laparoscopic approach through abdominal incisions
   • Alternative thoracoscopic approach possible but associated with longer recovery 2

2. Surgical Dissection:

   • Isolation of the EGJ requires division of:
     • Phrenoesophageal ligament
     • Short gastric vessels
     • These structures help maintain the angle of His (an anti-reflux mechanism) 1

3. Myotomy Procedure:

   • Extramucosal incision of both longitudinal and circular muscle layers
   • Extends from distal esophageal body to 2-4 cm onto gastric cardia
   • Careful preservation of the mucosa to prevent perforation 3
   • Intraoperative endoscopy often used to guide extent of myotomy 4

4. Fundoplication Component:

   • Typically combined with partial fundoplication:
     • Anterior (Dor) or posterior (Toupet) fundoplication
     • Helps prevent post-procedure reflux
     • Toupet fundoplication may provide better symptom relief compared to Dor 2

Anatomical Approach in Per-Oral Endoscopic Myotomy (POEM)

1. Mucosal Entry:

   • Mucosal incision created 10-15 cm proximal to LES 1

2. Submucosal Tunnel:

   • Created between mucosa and circular muscle layer
   • Extends distally 2-4 cm onto gastric cardia 1

3. Myotomy:

   • Selective circular muscle myotomy performed within submucosal tunnel
   • Begins 2-3 cm distal to mucosal entry point
   • Extends to distal point of cardia dissection 1
   • Preserves longitudinal muscle layer and anti-reflux mechanisms

4. Anatomical Advantages:

   • Avoids division of phrenoesophageal ligament and short gastric vessels
   • Preserves angle of His
   • Allows for longer myotomy if needed (especially beneficial for type III achalasia) 5
   • Avoids potential vagal nerve injury 1

Anatomical Considerations Based on Achalasia Subtype

• Type I (Classic) Achalasia:

  • Negligible pressurization within esophagus
  • Standard myotomy length usually sufficient

• Type II Achalasia:

  • Panesophageal pressurization
  • Standard myotomy length usually sufficient

• Type III (Spastic) Achalasia:

  • Premature contractions with rapid propagation
  • Benefits from longer myotomy extending into esophageal body
  • POEM particularly advantageous due to ability to perform extended myotomy 5

Anatomical Considerations in Special Cases

• Extreme Megaesophagus (>10 cm diameter):

  • Standard myotomy approach can still be effective
  • May relieve compression of heart and lungs caused by severely dilated esophagus 6

• Previous Failed Treatments:

  • Laparoscopic Heller myotomy effective even after failed dilation or Botox therapy 7
  • POEM shows good results for patients with prior PD or LHM 1

Anatomical Pitfalls and Complications

• Esophageal Perforation:

  • Most common serious complication (reported in 7.7% of cases) 4
  • Careful identification of mucosal layer essential

• Post-Procedure Reflux:

  • Higher risk with POEM due to preservation of EGJ anatomy without fundoplication 5
  • Fundoplication reduces reflux risk in laparoscopic approach

• Incomplete Myotomy:

  • Inadequate extension onto gastric cardia can lead to persistent symptoms
  • Intraoperative endoscopy helps confirm adequate myotomy 4

Understanding these anatomical considerations is crucial for successful performance of Heller's myotomy and optimal patient outcomes with minimal complications.