What are the recommendations for LAMS (Lumen-Apposing Metal Stent) placement in a pancreatic collection with minimal or increased vascularity and what is the ideal wall thickness for a safe procedure?

LAMS Placement in Pancreatic Collections with Vascularity and Wall Thickness Considerations

For pancreatic collections with minimal or increased vascularity, LAMS placement should be avoided due to high risk of bleeding complications, and the ideal wall thickness for safe LAMS placement should be at least 10 mm but not exceeding 15 mm. 1, 2

Vascularity Considerations for LAMS Placement

Risk Assessment for Collections with Vascularity

• Increased vascularity = increased bleeding risk: Collections with significant vascularity pose substantial bleeding risks when using LAMS
• Bleeding complications: Literature review shows 3.8% overall bleeding events with LAMS, with 46.2% of these events occurring within the first week of placement 3
• Contraindication: The presence of significant vascularity in the collection or along the puncture tract should be considered a relative contraindication for LAMS placement

Management Recommendations for Vascular Collections

• Pre-procedure imaging: Cross-sectional imaging (MRCP or CT) is essential to assess vascularity before attempting LAMS placement 4
• Alternative approaches for collections with significant vascularity:
  • Consider plastic double pigtail stents which have shown technical and clinical success rates over 90% with better safety profile 1
  • Surgical drainage may be preferred for highly vascular collections
  • Consider interventional radiology consultation for embolization of visible vessels prior to drainage if LAMS is deemed necessary

Wall Thickness Requirements for LAMS Placement

Optimal Wall Thickness

• Minimum wall thickness: At least 10 mm wall thickness is required for safe LAMS placement 2
• Maximum effective range: The novel 15-mm-long LAMS can safely accommodate collections with walls up to 14 mm from the luminal surface 2
• Technical considerations:
  • Standard LAMS are designed for collections <10 mm from the luminal wall
  • The 15-mm-long LAMS should be used for collections located 10-14 mm from the gastric/duodenal wall 2

Safety Considerations Based on Wall Thickness

• Too thin (<10 mm): Insufficient wall thickness increases risk of stent migration, leakage, and peritonitis
• Too thick (>15 mm): Excessive distance may prevent proper deployment of even the longest available LAMS
• Technical success rates: 97% technical success reported with appropriate wall thickness (10-14 mm) using the 15-mm LAMS 2

Procedural Recommendations

Pre-procedure Assessment

• Perform cross-sectional imaging to:
  • Assess vascularity of the collection and surrounding tissue
  • Measure exact wall thickness between collection and gastrointestinal lumen
  • Evaluate for presence of interposed vessels in the puncture tract

Stent Selection Algorithm

1. For collections with minimal vascularity:

   • Wall thickness 10-14 mm: Use 15-mm LAMS
   • Wall thickness <10 mm: Standard LAMS appropriate
   • Wall thickness >15 mm: Consider alternative approaches (plastic stents or surgery)

2. For collections with significant vascularity:

   • Avoid LAMS placement due to bleeding risk
   • Consider plastic double pigtail stents 1
   • Consider surgical drainage for highly vascular collections

Post-procedure Monitoring

• Early LAMS removal protocol (within 4 weeks for pseudocysts, within 6 weeks for walled-off necrosis) helps prevent delayed bleeding complications 3
• Multidisciplinary support including interventional radiologists, surgeons, and anesthesiologists should be available to manage potential complications 1, 4

By carefully assessing vascularity and ensuring appropriate wall thickness, LAMS placement can achieve high technical and clinical success rates (97%) while minimizing complications 2.