Lumen Opposing Metal Stents, A New Frontier in Therapeutic Endoscopy. Primary Author Dr. Shyam Thakkar. Aslam Syed, nothing to disclose. Neel Carlton, nothing to disclose. Gurneet Bedi, nothing to disclose. Grissimran Kochar, nothing to disclose. Harshith Khera, nothing to disclose. Shivangi Kothari, nothing to disclose. Shyam Thakkar, nothing to disclose. The learning objectives of this video include the application of endoscopic lumen opposing metal stent in pancreatic disease, describing LAMS interventions for non-pancreatic gastrointestinal conditions, highlights of the safety and efficacy of LAMS in patients who are not surgical candidates, overview of complications associated with LAMS, and the resulting management. Lumen opposing metal stents were initially developed to manage various types of pancreatic fluid collections. These are dumbbell-shaped stents with the end diameters of the stent being twice the size of the central saddle section. This allows for a decreased risk of migration and leakage. They are deployed under endoscopic ultrasound guidance, commonly with electrocautery. They are currently available in 10, 15, and 20 millimeter inner diameter. When looking at the pancreatic interventions using LAMS, reported technical success ranges from 93% to 100% for the management of pancreatic pseudocysts and 82% to 100% for walled-off necrosis. Clinical success ranges from 86% to 100% for pancreatic pseudocysts and 64% to 91% for walled-off necrosis management. Minimal adverse events are reported as summarized in the several studies below. Additionally, when compared to surgical intervention, Bang and colleagues performed a randomized control trial comparing endoscopic therapy to surgical necrosectomy for walled-off necrosis. In their study, endoscopic therapy, which included luminoposing metal stents, demonstrated better outcomes in terms of major complications, lowered costs, and increased quality of life. The surgery arm had significantly longer procedure time, higher disease-related adverse events, procedures at 72 hours, longer intensive care unit stay, and had a higher mean total cost of over $40,000. In preparation for deployment of a LAMS, we identify an area of walled-off necrosis with endoscopic ultrasound. Passage of the electrocautery enhanced tip is shown here, followed by the deployment of the distal flange of the LAMS under EUS visualization. The proximal flange is deployed under direct visualization. To gain endoscopic access into the walled-off necrosis, balloon dilation is performed to expand the saddle regions of the stent. Successful dilation reveals a necrotic material within the cyst. Necrosectomy is performed with clearance of almost all necrotic material using a snare. Other accessories, such as baskets and balloons, may also be utilized to assist in removing the necrotic material. After adequate removal, the result is a clean cyst wall. Because of the ease of deployment and access, the use of lumen-opposing metal stents has expanded to non-pancreatic pathologies, including inoperable cholecystitis, with and without abscess formation, afferent loop syndrome, malignant gastric outlet obstruction, altered anatomy access, refractory luminal, and benign anastomotic strictures. Lumen-opposing metal stents may help reduce the complexity associated with challenging conditions such as these. Our first case presents a 68-year-old man with a medical history of duodenal adenocarcinoma, status post Whipple's procedure, and adjuvant chemotherapy. He had recurrence with metastasis of his adenocarcinoma, complicated by a gastrojejunal stricture causing a gastric outlet obstruction, status post endoscopic stenting. A 22 by 90 millimeter enteral stent was placed across the gastrojejunal anastomosis into the efferent limb. He presented one week later with elevated liver enzymes. CT imaging showed dilated loops in the afferent limb concerning for an afferent loop syndrome. This was felt to be the etiology for the patient's jaundice and elevated liver enzymes. Also seen is the enteral stent in good position in the efferent limb, with loops of the efferent limb in close proximity to the loops of the dilated afferent limb. The patient was deemed a poor surgical candidate due to advanced malignant disease. The afferent limb could not be accessed endoscopically due to obstruction in a previously placed stent. Decision was made to attempt endoscopic ultrasound-guided jejunal-jejunal anastomosis across the previous enteral stent from the efferent limb to the afferent limb. First, an adult gastroscope is introduced that demonstrates the stent in good position with complete obstruction for access of the afferent limb. A wire is placed deep into the efferent limb to help safely guide the endoscopic ultrasound scope for the purpose of performing a jejunal-jejunostomy. Following placement of the wire, the therapeutic linear echoendoscope is successfully introduced across the stent. Three loops of bowel are identified, and needle aspiration confirms bilious fluid. An electrocautery-enhanced lumen-opposing metal stent is advanced, and the distal flange is deployed initially, followed by the proximal flange. Fluoroscopic imaging will demonstrate placement as well. The lumen is then dilated to 15 mm. Following dilation, an adult gastroscope is exchanged, and the LAMs can be seen just distal to the enteral stent. The adult gastroscope can be introduced to the afferent limb for the purpose of performing ERCP should liver enzymes in jaundice not improve. The patient's jaundice resolved following the LAMs placement, and the patient did not require any further intervention at three-month follow-up. A lumen-opposing metal stent was used via EUS guidance across a previously placed enteral stent to safely and effectively perform an enteroenterostomy as an alternative to high-risk surgery. This novel approach offers an increased efficiency and safety profile when compared to the surgical and other endoscopic alternatives. Such procedures may be performed in both benign and malignant causes of obstruction, and the technical and clinical success that has been seen to date is favorable for the use of EUS-guided bypass interventions. Literature review shows data limited to case reports and small case series. However, all have demonstrated favorable technical and clinical success in the management of afferent loop syndrome with lumen-opposing metal stent decompression. Prospective multicenter randomized control studies are needed for further validation of this application. Our second case describes an 82-year-old female who presented with acute calculus cholecystitis. She was deemed to be a poor surgical candidate due to decompensated cirrhosis with ascites and encephalopathy and high-risk cardiac disease. A decision was made for a palliative, permanent internal gallbladder drainage using a lumen-opposing metal stent. Here, a linear endoscopic ultrasound shows a thickened gallbladder wall. An EUS-guided transgastric gallbladder puncture is made using a 19-gauge needle. A contrast injection reveals distended gallbladder and gallstones under fluoroscopy. A 15-millimeter LAMS is deployed under EUS guidance. The LAMS is then dilated. Pus can be seen extruding around the balloon. Now we see pus evacuation and gallstone extraction after a lavage. We further expand the utility of a lumen-opposing metal stent for gallbladder drainage through describing our experience managing a case of complicated cholecystitis with perforation and abscess formation in the liver. A 61-year-old female with unresectable pancreatic adenocarcinoma arising from the head of the pancreas presented with symptoms of right upper quadrant discomfort and nausea without fevers or rigors. She underwent placement of partially covered metal stent through the common bile duct four months prior and was undergoing chemotherapy at the time of presentation. A contrast-enhanced CT of the abdomen was obtained, which subsequently revealed a perforated gallbladder and resultant intraparenchymal abscess formation within the liver. Here on EUS imaging, we can see the previously placed metal biliary stent in good position. Next, a distended gallbladder is seen measuring up to 16 millimeters. Septated hyperechoic material was seen concerning for infection. Here the abscess cavity is located. The posterior gallbladder perforation in communication to the abscess cavity can also be seen using endoscopic ultrasound. Under EUS visualization, a 15-millimeter luminoposing metal stent with an attached electrocautery device is punctured with a transduodenal approach. The distal flange is first deployed under ultrasound. The proximal flange is then deployed under endoscopic visualization. Initial images show pus rapidly evacuating through the stent. Following dilation of the stent waste with a 15-millimeter balloon, the gallbladder may be entered using an adult therapeutic scope, and the site of perforation can easily be identified endoscopically. A catheter is then introduced to lavage the gallbladder and abscess cavity. Following clearance of the purulent material, a 7 French by 5 centimeter double pigtail plastic stent was placed transluminally to maintain drainage, patency, and future access if necessary. Post-procedure, the patient did well, completing a course of oral antibiotics and continuing palliative chemotherapy. EUS-guided transmural gallbladder drainage is a safe and effective method of treating patients who are high risk for cholecystectomy. Surgical and clinical success has been shown to be favorable with low adverse event profile. Observationally, the transgastric approach appears to be the favored method as opposed to a transduodenal approach due to the ability to take down a transgastric cholecystic fistula should the patient become a surgical candidate in the future. Our next use of lumen opposing metal stent describes a 64-year-old female with a history of Roux-en-Y gastric bypass presenting with recurrent biliary pancreatitis. She was a poor surgical candidate for laparoscopic assisted ERCP due to her history of multiple abdominal surgeries. An EUS-directed transgastric ERCP procedure, commonly known as the EDGE procedure, was pursued using a lumen opposing metal stent. Initial EGD demonstrates Roux-en-Y gastric bypass anatomy. Following identification of the pouch, the excluded stomach is seen under EUS guidance and a 19-gauge needle is used to puncture the excluded stomach. This is then filled with a mixture of contrast and saline. The distention of the excluded stomach aids in deployment of the LAMs from the gastric pouch to the excluded stomach. Following deployment, the stent is then dilated using a 15-millimeter balloon so that a standard ERCP scope can be advanced into the excluded stomach. Once advanced, ERCP can be performed to treat the patients with underlying biliary pancreatitis. Small single-center studies have recently shown the success of EDGE utilizing LAMs. A case series of 19 patients that underwent EDGE procedure was reported in 2018 by Barron. Technical and clinical success reached 100%. Another case series of 16 patients that underwent EDGE was described by Kahali in 2017. Results were very favorable, achieving a technical and clinical success of 100% and 90% respectively. The EDGE procedure is a novel alternative to LAP-assisted ERCP in patients of the Roux-en-Y gastric bypass. Potential adverse effects include stent dislodgement and peritonitis. However, we have not encountered this in our experience. There is also a potential risk for temporary weight gain due to the gastrogastric or enterogastric fistula. This should be kept in mind and may be managed endoscopically. Our next use describes management of anastomotic strictures. A 70-year-old male with a past medical history of esophageal cancer, status post-esophagectomy with colonic interposition presented with an anastomotic stricture. The patient had undergone multiple Bougie dilations, through-the-scope balloon dilations with and without steroid injections and incisional therapies. Unfortunately, the patient continued to have recurrent strictures and a plan was to place a lumen-opposing metal stent. The narrowed lumen can be seen to the left of the screen. A long wire is passed through the anastomotic stricture under fluoroscopic guidance. A biliary balloon is passed over the wire with contrast injection in the distal lumen to assess the length of the stenosis. Fluoroscopic view shows a 10 mm long stenosis. A 15 mm lumen-opposing metal stent was deployed under endoscopic and fluoroscopic guidance. The LAMS was then dilated with a 12-15mm wire guided CRE balloon to a maximum diameter of 15mm. The efferent limb is now successfully accessible. Luminoposing metal stents can also be used for complications related to treating strictures such as dilation-induced perforations. We describe a case of a 22-year-old female with the Roux-en-Y gastric bypass complicated by gastrojejunal anastomotic stenosis. She was referred for endoscopic dilation. A stenosis was noted at the GJ with an inability to traverse the endoscope. A through-the-scope esophageal balloon dilator was introduced and the stricture was dilated using a balloon. A resulting perforation was noted at the anastomosis. This defect was successfully stented with a 15mm luminoposing metal stent. Post-procedure, the patient was asymptomatic. The patient underwent an upper GI series, which showed no evidence of extravasation. The patient returned three months later for repeat endoscopy and removal of the luminoposing metal stent. Luminoposing metal stent removal showed an improvement in the previously noted GJ stenosis. The patient remained asymptomatic and was tolerating a normal diet. Advantages of luminoposing metal stents for anastomotic strictures. Anastomotic guided LAMs placement is a safe and effective alternative to dilation, traditional stents and cryotherapy ablation of short benign strictures. Self-expandable metal stents pose a high risk for migration. We see decreased rates of migration using the double flanged ends of a luminoposing metal stent. Luminoposing metal stents have also been used for benign gastrointestinal strictures. Irani et al. presented a study with 25 patients who underwent luminoposing metal stent placement for short benign GI strictures, including the following, esophagogastric anastomoses, gastrojejunal anastomoses, pylorus, vertical banded gastroplasty, and ileoclonic anastomoses. Technical and clinical success was observed in 100% and 60% of patients respectively. Other examples of non-pancreatic interventions using luminoposing metal stents are the use in patients with pancreatic ductal adenocarcinoma that may lead to obstructive jaundice. Luminoposing metal stents may be placed for palliative biliary drainage where standard ERCP and surgery is not feasible. A 65-year-old female presented with locally advanced pancreatic adenocarcinoma complicated by duodenal obstruction secondary to a pancreatic mass. Multiple attempts were made to perform ERCP for biliary stenting prior to enteral stent placement, however, this was unsuccessful. A duodenal enteral stent was placed for palliative purposes and a plan was made to follow the patient's clinical course. Two weeks later, the patient was noted to be jaundiced with elevated liver enzymes concerning for worsening biliary obstruction. A decision was then made to perform EUS guided biliary decompression. The common bile duct was noted to be dilated to 20 mm on EUS examination. The common bile duct was punctured using a 19 gauge needle with a transduodenal approach with bilious return. A clandiogram was obtained showing a distal biliary stricture in relation to the pancreatic mass. A wire was passed through the puncture site and a 15 mm luminoposing metal stent was then deployed over the wire. The waist of the luminoposing metal stent was dilated to 12 mm and a single plastic pigtail stent was placed through the luminoposing metal stent into the left hepatic duct to maintain access and prevent migration. Although luminoposing metal stents have been shown to achieve very high technical and clinical success rates, complications have been reported. A review article by SINGLE describes complications including perforation, abdominal pain, stent migration, and bleeding at minimal rates with majority managed endoscopically. Bang et al. also reported delayed bleeding in 3 out of 62 patients after LAMS placement for Waldorf necrosis. Two of the three patients required blood transfusions in the intensive care unit five weeks after post-LAMS placement. Endoscopic view revealed bleeding in the LAMS shown in figure A. Interlacing vessels were visualized within the distal flange of the LAMS shown in figure B on EUS. CT angiogram confirmed pseudoaneurysms in all three patients. They were successfully managed by embolization seen in figure C. These types of complications may result from collapse of the pseudocyst wall with erosion of the LAMS into the collaterals associated with pseudocyst or pancreatitis. The development of this complication may be minimized by placing 1-2 double pigtail plastic stents through the LAMS at deployment and by removing LAMS from Waldorf necrosis interventions prior to five weeks. Our institutional practice is to place 2 double pigtail stents through the LAMS and image at four weeks. If the collection has resolved, then we remove all stents within that week. Tissue overgrowth can be a problematic complication, leading to an inability for stent removal and migration. We describe a case at our institution of a 48-year-old male with a pancreatic pseudocyst status post cyst gastrostomy with lumen opposing metal stent placement in the gastric antrum. The picture on the left depicts the proximal flange in the correct location. The picture on the right shows a pigtail catheter placement through the lumen opposing metal stent. Immediate endoscopy on follow-up for removal of the lumen opposing metal stent showed tissue overgrowth and displacement of two indwelling pigtail catheters. A small opening through the mucosa was still present. We attempted to use a CRE balloon to dilate the opening, however, due to the pseudocyst being collapsed, there was not enough room to negotiate the balloon into the stent without hitting and puncturing the back wall of the cyst. The balloon tip was cut to decrease the risk of puncture and was then inserted into the stent and dilated, allowing careful removal of the lumen opposing metal stent with rat tooth forceps. In the case series by Irani et al., the suspected cause of buried lumen opposing metal stents included increased motility in the gastric antrum resulting in traction on the stent, inducing a hypertrophic response leading to tissue overgrowth. Tissue overgrowth and buried lambs complications have not been seen in deployment of lambs in other common locations such as the gastric body or duodenal bulb. Transluminal plastic pigtail stents are typically placed to maintain patency and position of the lambs. Other endoscopic rescue maneuvers for removal of buried lambs include APC tissue destruction and or needle knife cautery. Complications associated with non-pancreatic uses for lumen opposing metal stents have also been reported. Edge-specific complications have also been reported by Barron and Kahale reporting small case series. Adverse events include stent malposition, persistent fistula, perforation, and stent dislodgement. Endoscopic management was successfully utilized to manage all of these complications. Additional non-pancreatic intervention related complications have been reported. Dahlhoff conducted a case series of patients undergoing EUS guided gallbladder drainage using a lambs. Migration of the stent and recurrent cholecystitis were reported in a small percentage of patients. In our experience, the risk of recurrent cholecystitis from stent obstruction may be minimized by placement of a double pigtail stent through the lambs. A low risk of stent migration may also occur when lambs is utilized for benign strictures. This again may be managed endoscopically. In conclusion, lumen-opposing metal stent is an effective technology for pancreatic fluid collections and Waldorf necrosis. Alternative uses for non-pancreatic interventions in patients that are poor surgical candidates are described with favorable technical and clinical success. The successful utilization of this technology effectively provides applications of transluminal surgery through natural orifice endoscopy. Lumen-opposing metal stents have been approved for peripancreatic fluid drainage. Their non-pancreatic interventions are broadening the application of this technology and advancing the therapeutic frontier of the endoscopist.

LAMS

therapeutic endoscopy

pancreatic pseudocysts

complications

cost

quality of life