AXIOS Lumen Apposing Metal Stent for Walled Off Necrosis Drainage IDE Study

Inclusion Criteria: * Age between 22 and 75 years old * Severe or moderately severe acute necrotizing pancreatitis, defined per the 2012 Revised Atlanta Classification. * WON resulting from necrotizing pancreatitis per contrast-enhanced CT with the following characteristics, per the 2012 Revised Atlanta Classification: * Heterogeneous with liquid and non-liquid density with varying degrees of loculations (some may appear homogeneous) * Well defined wall * Location-intrapancreatic and/or extrapancreatic * Infected WON or symptomatic sterile WON Note: WON-related symptoms may include: pain, fever, leukocytosis, failure to thrive or deterioration of overall heath score, gastric outlet obstruction (GOO), weight loss, biliary obstructive symptoms, systemic inflammatory response syndrome (SIRS), deteriorating organ function, chronic nausea, lethargy, and inability to eat or gain weight * Imaging suggestive of greater than 30% necrotic material * WON ≥ 6cm in size * Eligible for endoscopic intervention * Acceptable candidate for endoscopic transluminal drainage * Patient understands the study requirements and the treatment procedures and provides written Informed Consent * Patient is willing to comply with all specified follow-up evaluations, including willingness to undergo a pre/post imaging study Exclusion Criteria: * Pseudocyst * Cystic neoplasm * Untreated Pseudoaneurysm \> 1cm within the WON * More than one WON clearly separated and requiring drainage * WONs that require dual modality interventions (endoscopic and percutaneous) from the beginning (i.e. deep paracolic space involvement that is inaccessible through the central drainage access) * Prior surgical, interventional radiology or endoscopic procedures for the treatment of the WON * Abnormal coagulation: * INR \> 1.5 and not correctable * presence of a bleeding disorder * platelets \< 50,000/mm3 * Intervening gastric varices or unavoidable blood vessels within the access tract (visible using endoscopy or endoscopic ultrasound) * WON that poorly approximates the GI lumen (≥1cm away) * Pericolic gutter necrosis * Pelvic necrosis * Prior true anaphylactic reaction to contrast agents, nitinol (nickel titanium), silicone or any other materials contacting the patient * Female of childbearing potential with a positive pregnancy test prior to the procedure or intends to become pregnant during the study * Currently participating in another investigational drug or device study that has not completed the primary endpoint or that clinically interferes with the endpoints of this study