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1. Endoscopic Step-up Approach for Walled-off Necrosis (WON)
2. Endoscopic Tools
3. Complex Collections, Complications, and Procedural Challenges
4. Ask the Experts
5. Case Discussions

1. Endoscopic Step-up Approach for Walled-off Necrosis (WON)

When do you decide to intervene for Walled-off Necrosis?

• Acute Necrotic Collection <4 weeks
  • Infection
• Walled Off Necrosis 4+ Weeks
  • Infection
  • Enlarging Collection
  • Unrelenting Pain
  • Feeding Intolerance
  • Obstruction of stomach/intestines or bile duct

Intervention

Step 1:

Endoscopic transluminal drainage of WON. If drainage does not lead to clinical improvement or is impossible, proceed to Step 2.

Step 2:

Direct Endoscopic Necrosectomy (DEN) of necrotic debris.

Step 3:

Assess patients for clinical improvement, repeat DEN if improvement is not seen.

Predicting the Need for Necrosectomy:

The study shows that: “Individuals with PFCs (size of the collection) > 10 cm in size, paracolic extension, or > 30% solid necrosis are more likely to require step-up therapy and should be considered for early endoscopic reintervention”

Immediate vs Delayed Necrosectomy:

Research shows that: “Direct Endoscopic Necrosectomy DEN at the time of initial transmural stent placement reduces the number of necrosectomy sessions required for successful clinical resolution of complex walled off pancreatic necrosis”

When do you typically decide to perform your initial endoscopic necrosectomy?

How long do you wait between placing a LAMS (lumen-apposing metal stent) and performing your first necrosectomy?

For inpatients usually the waiting time is 2-5 days after placing the LAMS.

For outpatients usually the waiting time is 1 week after placing the LAMS.

For an outpatient should an imaging for the necrosectomy be performed after the waiting time?

No, it is not important. The first imaging is still valid.

How long do you wait between interventions?

• It depends on clinical symptoms such as fever, abdominal pain, obstruction, and if they are an in- or outpatient.
• For inpatients usually the waiting time is 3-5 days at most 1 week before the next necrosectomy is performed.

2. Endoscopic Tools

What are your preferred tools for necrosectomy?

The most preferred tools for necrosectomy are EndoRotor and Snare.

Necrotic Debridement Challenges

• Blind grasping: increased risk of bleeding and perforation.
• Firm and ddherent necrosis.
• Liquefactive or fat necrosis.
• Repeated scope/device withdrawal from collection: Risk of stent dislodgement and time consuming.
• Scope and device manipulation.
• Gas embolism. It is imperative to use CO2 during necrosectomies.

Current endoscopic tools

• Conventional Devices (most are not FDA cleared; depends from the thickness of the material):
  • Rat tooth Forceps. (Removes limited amount of necrosis)
  • Snares (Removes large materials, but extraction can be a problem)
  • Baskets (Problems with opening)
  • Nets. (Problems with extracting the material)
  • Tripod Grasper (Can catch the LAMS and cause its displacement)
• EndoRotor System (FDA-cleared):
  • EndoRotor-Powered Endoscopic Debridement (PED) (stable scope position, works within the necrotic material itself, help to directly visualize the necrotic material, very advanced device that has successfully solved the most challenges faced on conventional devices)

Conventional Necrosectomy Devices

• Based on a systematic review: “Endoscopic Transmural Necrosectomy offers the advantage of minimally invasive endoscopic treatment without transabdominal surgery; however better techniques and equipment are still needed to improve procedural efficiency.”
• Avg numbers of procedures for clearance: 4.09
• Avg Patient length of stay: 32.85 days
• Procedural complication rate: 21.33%
• Surgery required (In case of irresolution or complications): 12.98%

The Risk of Blind Grasping

• Blind Grasping with snare:
• The loss of imaging of the cutting wire of the snare.
• Risk of blood vessels rupture.

Innovative Necrosectomy Device

• EndoRotor (Powered Endoscopic Debridement-PED)
  • First dedicated solution for endoscopic necrosectomy.
  • Flexible 3.2 mm catheter with dedicated vacuum.
  • Fixed outer cannula with inner cutting blade cannula.
  • Catheter debrides by suctioning necrosis into cutting window, dissecting with blade and collecting in suction bag.
  • 360° rotation.
• Median numbers of procedures for clearance: 1.5
• Median Patient length of stay: 10 days
• Procedural complication rate: 10%
• Surgery required (In case of irresolution or complications): 0.0%

Innovative Necrosectomy Device

• NecroMax 6.0
  • Available December 2021
  • Outer diameter 5.omm (versus 3.omm first gen catheter)
  • Up to 8x greater throughput
  • 3x larger cutting window
  • For use through Olympus TQ-160 “clot Buster” scope (6.omm working channel)
  • EndoRotor CATHGUIDE; accessory channel required for users without “Clot Buster” and can be attached to standard or therapeutic gastroscopes.
• NecroMax (Video):
  • Can clear a large necrotic area with ease.
  • Should be cautious to not damage large blood vessels because it is quite aggressive.
  • With caution can clear large necrotic areas quite quickly.

3. Complex Collections, Complications, and Procedural Challenges

Complex Collections

• What makes a WON/WOPN collection complex?
  • Infection
  • Disconnected Pancreatic Duct
  • Collection requiring intervention before 4 weeks.
  • Extension of collection to paracolic gutters.
  • Vessels - known and unknown.

Case Discussion - WON Extension to Pelvis:

• 33-year-old woman with obesity (BMI 38) and EtOH abuse but no other PMH presents with 2 days of severe upper abdominal pain nausea and vomiting.
• VS: BP 153/103, HR 90, RR 24
• Labs: WBC 13k, Lipase 1186, LFTs normal, blood urea nitrogen 24, creatinine 1,2; Calcium 5.3;
• CT (initial): Peripancreatic fat stranding and diffuse hypoattenuation of pancreas. Gallbladder normal.
• 7 days later developed fever and WBC 16.6K
• CT (Repeated/Day 10): Worsening peripancreatic inflammatory changes with collection extending to bilateral pararenal space and left paracolic gutter, pelvis and cul-de-sac. Fluid collection compresses superior mesenteric vein and displaces stomach, duodenum, jejunum, and urinary bladder. With Low grade pain and leukocytosis.
• CT (Day 30): A much more controlled collection, still extensive heading down to the left colic gutter.
• First DEN occluded LAMS: After placing the LAMS a few days later it is completely occluded with coagulation necrosis and using a snare it is not very effective. It was decided to use the EndoRotor. It is seen to be very effective against coagulation and pancreatic necrosis and later on fat necrosis. Stents were put to prevent the pelvis walled off necrosis and to maintain the access. Through this access it was entered down to the pelvis with the EndoRotor and soft fat necrosis was removed very effectively in a single session.
• Follow-up (Cleared Collection): It cleared up all the paracolic gutter, something not possible with the conventional endoscopic tools.

Risk of Bleeding

• Biggest risk factor for endoscopic necrosectomy.
• The study shows:
  • Transmural Endoscopic necrosectomy after acute pancreatitis
  • Complications: 26%
  • Bleeding: 13%
  • Bleeding requiring surgery: 3
  • Death from bleeding complications: 1

Vessels - Known and Unknown

• Study shows:
  • Incidence of bleeding-All Procedures: 5.2%
  • Incidence of bleeding-All Patients 11.9%
• Risk of bleeding significantly increased in patients with cirrhosis, Thrombocytopenia and classification of vessels within the WON cavity.

How Do You Manage Vessels in a Collection?

• Steps to avoid vessels disruption:
  • Radiologic evaluation (CT; MRI; etc.)
  • Take note of large vessels during LAMS placement
  • Sampling with needle aspiration, if it is blood than proceed to embolization
  • Direct embolization
  • Direct visualization
  • Removal of LAMS when concerned about collection collapse
• Case study shows: “After two DEN sessions, without any complications, only minimal debris remained in the area proximal to the superior mesenteric artery. In our case, the EndoRotor catheter performed DEN under constant endoscopic visualization, allowing successful treatment despite the presence of the SMA inside the collection.”
• If the patient has arterial bleeding during the direct endoscopic necrosectomy or LAMS placing or stent removal, it should go immediately for arterial embolization.
• To perform a better necrosectomy you can remove the LAMS and it depends a lot on the angles of which the stent can inhibit the direction of the necrosectomy. It is not recommended but, if necessary, it can be removed.
• Naso-cystic drain is used less often than before, usually a lavage with diluted H2O2 (oxygen peroxide) every couple of days is performed. It’s used before LAMS were common and now with LAMS, it is less necessary to use the naso-cystic drain.
• For the pelvis and the paracolic gutter, the majority should be maintained with the percutaneous drain and then a LAMS in the lesser sack space to get that collection cleared up.

Complications & Treatments

• Procedural Complications:
  • Bleeding:
    • Epinephrine
    • Coagrasper forceps
    • Hemostatic clip
    • Interventional Radiology intervention
  • Wall perforation (Pneumoperitoneum)
    • Antibiotics
    • Endoscopic closure (Anterior Vs Posterior)
    • Surgery
  • LAMS Dislodgement
    • Endoscopic retrieval
    • Re-establishment of cystogastrostomy tract
    • Treatment of bleeding (In-grown stent)
• WON Complications:
  • Infection
    • Endoscopic, percutaneous, surgical intervention
  • Compression of Surrounding Structures (Biliary stricture)
    • Biliary stent placement (LAMS, off-label metal stent)
  • Disconnected pancreatic duct syndrome (Imaging check before stent removal)
    • Plastic stent placement
    • Surgery

Interdisciplinary Approach

• Who to include:
  • Gastroenterologists, Surgeons, Critical care specialists, Interventional radiologists.
• Expertise Consideration:
  • In situations where clinical expertise may be limited, consideration should be given to transferring patients with significant pancreatic necrosis to an appropriate tertiary-care center.
• Benefits:
  • Final diagnosis and treatment plan is confirmed by consensus
  • Strengths of each specialist are used to ensure the best outcome for the patient.

4. Ask the Experts

What do you consider an endpoint for a successful necrosectomy?

• When a patient resolves the clinical symptoms, it is often seen a resolution in size on the CT scan with near collapse or complete resolution and when gone endoscopically, minimal necrosis is seen to remain. It is not a particular endpoint but obviously if an endpoint should be picked up, it would be the resolution of the clinical symptoms.
• The EndoRotor makes the thing easier because through it a much greater percent of necrosectomy can be done in one or two sessions and the patient will resolve much quicker.
• Also, with the EndoRotor, a better visualization of the cavity can be achieved.

How long do you leave the LAMS in and when is the earliest time that you can remove the LAMS?

• Usually, the LAMS are removed within a week or a maximum of 10 days until the first necrosectomy. A concern would be the separation of the wall, the collection and the stomach with premature removal and subsequent perforation. But to avoid all the complications, it should not be left in more than 6 days.

Which one of the LAMS is preferred to be used 15 mm or 20 mm?

• 20 mm LAMS is preferred, allowing easier access especially if using the 6 mm EndoRotor. The 15 mm LAMS is too small to maneuver.
• One downside of the larger LAMS is that if you have 20 mm Axios, and you put a double pigtail it will fall out. But if we have a 15 mm diameter axios, double pigtail stent can be put and they will not fall out.

Do you use H2O2 in the lavage in the treatment of the Walled Off Pancreatic Necrosis?

• H2O2 has been used pretty regularly, and every necrosectomy was ended with a H2O2 lavage in the past. It is used 1,5% H2O2 because 3% H2O2 can cause mucosal injury particularly small bowel mucosal injury which in times can be symptomatic. In addition, hydrogen peoxide has been associated with air embolims and is not approved for use in cavities in many countries in the World, particularly Europe.
• Entire cavity lavage as a last step to a necrosectomy because it makes the necrosis more consolidated and also debrides the necrosis away from the wall so that the necrosum is much easier when coming back. It is important when using snare because the entire necrosis can be removed as a single entity. But this was performed in the past with conventional tools.
• Now that EndoRotor is used more, the necrosum needs to be kept as liquid as possible and remove as much as possible in the first experience with the patient. For soft necrosis it works very well. When the necrosis gets a bit firmer, the EndoRotor still works but it takes time.
• For this reason, H2O2 is not used if EndoRotor is used exclusively.
• But if it is decided to use the H2O2, having a pump for the H2O2 through the smaller channel and then the necrosectomy device through the therapeutic channel allows us to do both.
• If the H2O2 is done, because of the effervescent reaction, it is harder to see with all the chemical debridement and it is better to leave that in the end.

Is this procedure a solo interventionist at a time or multiple members event following an attending?

• This can be done by yourself. The EndoRotor is a very nice convenient device, it is rotatable so it's all self-contained. No other additional assistant is needed. The fellows love doing it so they want to get in and try it. That's a noble and gratifying procedure so they enjoy it.
• This is easier than any other method tried before.

What is the total time for each session?

• As long as progress is made, we keep going. But usually, it takes 60-90 min.
• This is a really big difference between the EndoRotor and conventional devices, because it reduces the total procedural time.
• With conventional devices it takes more than 2 hours. This also depends on the size of the cavity.

Is the necrosectomy frequently done on the index cystenterostomy?

• It is performed but not frequently, usually through a laparoscopic assisted trans gastric cystenterostomy in a multidisciplinary team by the surgeons.

What CPT code is being used?

• Frequently it is used the UNLISTED Pancreas for a 999, because it is an unlisted procedure and the way of reimbursing is going to depend on the institution and the negotiations with the payer.
• 48105 is the code for a surgical necrosectomy and you have to write a comment if it is performed endoscopically. Some procedures are done in assistance with a surgeon and if they do an incision on the skin and a VAR (video assisted retroperitoneal dissection), then it would be a more combined billing.

Antibiotics & Necrosectomy

• Given initially during the LAMS placement at the time you are crossing transmurally, but later as the collection is open, it should be ok to not add antibiotics. If the LAMS gets clogged then there would be symptoms to trigger the patient to come back and evaluate the need of antibiotics.

PPI & Necrosectomy

• The patient must hold the PPI for 1 week.
• The study shows that taking off PPI reduces the number of sessions required to remove the WON.
• Lower PH acts as an antimicrobial effect.

Do you place pigtails on the index procedure after completion/removal of the stent?

• Yes, absolutely. After the procedure, even though the cavity is largely collapsed, fluid can still accumulate there so we don't want to close it too prematurely. So, it is usually left there with a couple of pigtails for at least 3 months.
• Then after everything is resolved, we can pull them out.
• If the Axios stent is too large, there is a risk of pigtail stent falling off.
• The pigtail prevents the stand to not get clogged.

Big Thanks go to:

Ali Ahmad, MD (Associate Professor of Medicine; University of Alabama at Birmingham)

Joo Ha Hwang, MD (Professor of Medicine and Surgery; Stanford University)

Amrita Sethi, MD (Associate Professor of Medicine; Columbia University)

Thomas Kowalski, MD (Associate Professor of Medicine; Thomas Jefferson University)

Summary of “Improving your Next Necrosectomy”

The honorable presenters of this presentation are Ali Ahmad, MD; Joo Ha Hwang, MD; Amrita Sethi, MD; Thomas Kowalski, MD.

At first the step-up approach to a walled off necrosis was discussed, including

• when the right time to intervene for a walled off necrosis was,
• intervention steps,
• predicting the need for necrosectomy,
• deciding between the immediate or the delayed necrosectomy,
• when do we typically decide to perform our initial endoscopic necrosectomy and,
•  how long do we need to wait between interventions.

Then the discussion focused on the endoscopic tools, the most preferred tools and the challenges we need to tackle with these tools. The conventional Devices and the EndoRotor, the risk of blind grasping and how the Innovative Necrosectomy Devices have changed the game.

After that the discussion continued on how to manage complex collections, complications and the procedural challenges. Which factors make this WON/WOPN complex, the risks of bleeding, the vessels prone to bleeding and their correct management. Which are all the complications and treatments and the benefits of an interdisciplinary approach.

At the end the participants answered a lot of questions from the great audience that was watching the presentation. The questions had a broad spectrum and had at the center of their concerns the benefits of the EndoRotor, reduction of compliances and the time of sessions of a WON.

Summarizing, it is decided to intervene for a walled off necrosis based on the clinical evaluation and clinical condition of the necrosis. The intervention is performed in steps which usually are three. Based on a study, the need for necrosectomy is more frequent in individuals with PFCs (size of the collection) > 10 cm in size, paracolic extension, or > 30% solid necrosis. Another research shows that the DEN direct endoscopic necrosectomy and the time of transmural stent placement reduces the number of necrosectomy sessions required.  When placing LAMS, the waiting time should be 2-5 days, for an inpatient and 1 week for the outpatients. Then necrosectomy is performed. Between interventions we usually wait 3-5 days, max 1 week.

Currently, the most preferred tools for necrosectomy are EndoRotor and snare. A lot of necrotic debridement challenges are still faced, including blind grasping, firm and adherent necrosis, liquefactive or fat necrosis etc. The conventional necrosectomy devices based on systematic reviews are less effective, and associated with more complications like the risk of blind grasping. On the other hand, innovative devices like the Endo Rotor, NecroMax 6.0 appear quite effective and seem to have a very low percentage of complications. Also, the time of recovery and the number of necrosectomy sessions is reduced dramatically.

Some of the walled off necrosis can get infected, can cause disconnected pancreatic ducts, can extend in the paracolic gutters and have within known or unknown vessels. These are complexes that increase the When addressing complications the discussion focused on risk of f bleeding especially if there are known or unknown vessels. We need to manage carefully the vessels in the collection and avoid with all cost the disruption. Other than bleeding there are other procedural complications like wall perforation, LAMS dislodgement or walled off necrosis complications like infection, compression of surrounding structures, disconnected pancreatic duct syndrome. These complications are very important and in various situations may need an interdisciplinary approach which can include gastroenterologists, surgeons, critical care specialists and interventional radiologists.

The professors were asked a lot of questions by the audience and they gave some brilliant answers which cleared up a lot of misconceptions about the walled off necrosis and the necrosectomy, helping to improve the work of many other doctors. They were asked for the best endpoint of successful necrosectomy, the appropriate amount of time to leave a LAMS in and the most appropriate time to take it out. Which LAMS is better, the 15 or 20 mm. Also, the audience needed to know the best use of H2O2 (hydrogen peroxide) lavage and if it is still done when using the EndoRotor. Which is the total time of a necrosectomy session and if it is done frequently in the index cystenterostomy. A very interesting question was about the pigtail stents and their use. The CPT code is associated with an endoscopic necrosectomy and the use and effect of drugs like antibiotics and PPI on a successful necrosectomy.

This is a brief summary of all that happened in the presentation. Big thanks go to the professors for their knowledge and invaluable experience which they brought forward to offer better solutions on the patient lives. Also, big thanks go to the audience for attending the presentation and providing some great questions.

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