Dilation of high-grade pancreatic and biliary ductal strictures with small-caliber angioplasty balloons

Comparison of time-to-event machine learning models in predicting biliary complication and mortality rate in liver transplant patients

Post-Liver transplantation (LT) survival rates stagnate, with biliary complications (BC) as a major cause of death. We analyzed longitudinal data with a median 19-month follow-up. BC was diagnosed with ultrasounds and MRCP. Missing data was imputed using mean and median. Data preprocessing involved feature scaling and one-hot encoding. Survival analysis used filter (Cox-P, Cox-c) and embedded (RSF, LASSO) feature selection methods. Seven survival machine learning algorithms were used: LASSO, Ridge, RSF, E-NET, GBS, C-GBS, and FS-SVM. Model development employed 5-fold cross-validation, random oversampling, and hyperparameter tuning. Random oversampling addressed data imbalance. Optimal hyperparameters were determined based on average C-index. Features importance was assessed using standardized regression coefficients and permutation importance for top models. Stability was evaluated using 5-fold cross-validation standard deviation. Finally, 1799 observations with 40 outcome predictors were included. RSF with Ridge achieved the highest performance (C-index: 0.699) for BC prediction, while RSF with RSF had the highest performance (C-index: 0.784) for mortality prediction. Top BC predictors were LT graft types, IBD in recipients, recipient's BMI, recipient's history of PVT, and previous LT history. For mortality, they were post-transplant AST, creatinine, recipient's age, post-transplant ALT, and tacrolimus consumption. We identified BC and mortality risk factors, improving decision-making and outcomes.

Impact of residual air trap in balloon on laser treatment of tubular tissue

OBJECTIVES

Tubular tissue, such as the bile duct and esophagus, often suffers from stenosis due to chronic inflammation or excessive contraction of smooth muscle. Laser treatment using a balloon catheter has been used to treat tubular tissue stenosis by mechanically expanding the tissue and irradiating laser light circumferentially on the tissue lumen. As the balloon is inflated with saline, the residual air in a delivery channel is often accumulated in the inflated balloon. Thus, the air trap may cause physical discontinuities at air-saline interface, leading to unpredictable and nonuniform photothermal interactions. The aim of the current study was to evaluate the optical-thermal effects of the air trap in the balloon on laser treatment of the tubular tissue by means of numerical simulations and experimental validations.

MATERIALS AND METHODS

A balloon-assisted diffusing applicator (BDA) was developed to inflate a balloon and deliver uniform and circumferential laser light. Before the balloon inflation, various numbers of deflations (0, 1, 2, 3, and 4) were applied to estimate the average amount of the air removed from the balloon. Ex vivo experiments using porcine liver duct were conducted with two deflation conditions (D0: no deflation for air trap and D3: three deflations for no air trap). The balloon was horizontally situated during laser irradiation to maintain the air trap at the same position in the balloon by minimizing gravity effect. Upon balloon inflation, 532 nm laser light was delivered through the BDA to the tissue (irradiance = 4 W/cm² ) at 10 W for 45 seconds to assess the optical-thermal effects of the air trap on the ductal tissue.

RESULTS

The size of the air trap was noticeably reduced with the number of deflations. The air trap volume in the balloon decreased to 0.5% of the total balloon volume after D3. Ex vivo results demonstrated that thicker coagulative necrosis (CN) for D0 near the air trap region in the tissue than bottom region that contact with saline, representing an asymmetric profile of CN in the tissue. D0 generated 17% thicker and nonuniform CN (overall CN thickness = 1.4 ± 0.7 mm), compared with D3 with no air trap (overall CN thickness = 1.2 ± 0.2 mm; p < 0.05). A threefold larger eccentricity (E) was found in D0 (49 ± 31%) than D3 (15 ± 13%; p < 0.001).

CONCLUSION

Both numerical simulations and experiments validated the effect of the air trap in a balloon on the distribution of CN in a tubular tissue during BDA-assisted laser treatment. Further in vivo studies will assess the current findings on the air trap for clinical translations of BDA-assisted laser treatment of tubular tissue stenosis.

Post-liver transplant biliary complications: Current knowledge and therapeutic advances

Liver transplantation is the current standard of care for end-stage liver disease and an accepted therapeutic option for acute liver failure and primary liver tumors. Despite the remarkable advances in the surgical techniques and immunosuppressive therapy, the postoperative morbidity and mortality still remain high and the leading causes are biliary complications, which affect up to one quarter of recipients. The most common biliary complications are anastomotic and non-anastomotic biliary strictures, leaks, bile duct stones, sludge and casts. Despite the absence of a recommended treatment algorithm many options are available, such as surgery, percutaneous techniques and interventional endoscopy. In the last few years, endoscopic techniques have widely replaced the more aggressive percutaneous and surgical approaches. Endoscopic retrograde cholangiography is the preferred technique when duct-to-duct anastomosis has been performed. Recently, new devices and techniques have been developed and this has led to a remarkable increase in the success rate of minimally invasive procedures. Understanding the mechanisms of biliary complications helps in their early recognition which is the prerequisite for successful treatment. Aggressive endoscopic therapy is essential for the reduction of morbidity and mortality in these cases. This article focuses on the common post-transplant biliary complications and the available interventional treatment modalities.

Endoscopic ultrasound-guided pancreatic duct intervention and pancreaticogastrostomy using a novel cross-platform technique with small-caliber devices

Background and study aims  Endoscopic ultrasound (EUS)-guided pancreaticogastrostomy (PG) has been used as an alternative to surgery to drain pancreatic ducts for treatment of disconnected pancreatic duct syndrome (DPDS). Previous techniques involved using needle-knife cautery, bougie dilation or a stent extraction screw to allow stent passage through the gastric wall and pancreatic parenchyma, with potential for severe complications including duct leak, especially if drainage fails. A novel technique employing EUS guided puncture of the main pancreatic duct (MPD) with a 19- or a 22-gauge needle, passage of an 0.018-guidewire, dilation of the tract with a small-diameter (4 F) angioplasty balloon and placement of 3F plastic stents with the pigtail curled inside the duct as an anchor. Methods  This is a retrospective case series at a single tertiary center. EUS-guided PG was considered when conventional endoscopic pancreatic duct drainage failed. Main outcomes included technical and clinic success and complications. Results  Eight patients underwent PG. Indications were DPDS (n = 4), stenotic pancreaticoenteral anastomosis after Whipple procedure (n = 3) and chronic pancreatitis with dilated MPD (n = 1). Median MPD diameter was 6.75 mm [IQR 2.8 - 7.6]. Technical success was achieved in seven of eight cases (88 %); angioplasty balloon passed into the pancreatic duct in all accessed ducts. There was one asymptomatic duct leak, and no major or delayed complications, with clinical improvement (complete or partial) in five of eight (71 %). Conclusions  EUS-guided PG using a small-caliber guidewire, 4F angioplasty balloon, and reverse 3F single pigtail stents offers a safe and atraumatic alternative without use of cautery.

A novel approach with holmium laser ablation for endoscopic management of intrahepatic biliary stricture

BACKGROUND

Hepatolithiasis, featuring high incidence, severe symptoms, and common recurrence, poses a heavy disease burden. Endoscopic management provides an opportunity to cure hepatolithiasis, but fails to properly resolve biliary stricture without additional interventional techniques. An innovative approach towards endoscopic management of biliary stricture is required.

METHODS

Holmium laser ablation was applied to biliary strictures via endoscopic access. Patients' demographic, operative, and follow-up data after receiving holmium laser ablation were retrospectively collected for analysis.

RESULTS

A total of 15 patients (4 males and 11 females) underwent stricture ablation by holmium laser via cholangioscopy. All the patients successfully received holmium laser ablation, indicating a technical success rate of 100%. No postoperative mortality or no major perioperative complication was observed. During the follow-up period, the recurrence-free rate was 73% at 2 years and 67% at 5 years.

CONCLUSIONS

We successfully developed a novel technique of biliary stricture removal by cholangioscopic holmium laser ablation with satisfying clinical outcomes.

Severe Primary Sclerosing Cholangitis Biliary Stricture Managed With a Small-Caliber Cardiac Angioplasty Balloon: Looking Outside the Endoscopic Retrograde Cholangiopancreatography Toolbox

Primary sclerosing cholangitis leads to biliary obstruction through a dominant biliary stricture. Endoscopic management of biliary strictures with balloon dilation is preferred over percutaneous radiological or surgical interventions. High-grade biliary strictures can be challenging to manage endoscopically because the traditional endoscopic retrograde cholangiopancreatography accessories fail to traverse these severely stenotic strictures. We describe a case of endoscopic management of a severe primary sclerosing cholangitis-related distal biliary stricture managed with a cardiac angioplasty balloon after failed attempts using the standard endoscopic retrograde cholangiopancreatography accessories and percutaneous radiological intervention.

Endoscopic treatment for biliary stricture after adult living donor liver transplantation

Endoscopic intervention is considered to be the primary treatment for biliary stricture after adult living donor liver transplantation (LDLT) with duct-to-duct biliary reconstruction. The aim of this study was to investigate the risk factors of biliary stricture and the clinical outcomes and predictors of failure after endoscopic retrograde cholangiography with balloon dilation (ERC-D). We enrolled 239 adult patients who underwent LDLT between 2000 and 2006. Sixty-eight patients (28.4%) developed biliary stricture. Twenty-nine patients with anastomotic biliary stricture were treated with ERC-D and stenting. We retrospectively analyzed the risk factors of biliary stricture and the clinical outcomes of ERC-D. The median follow-up period was 31 months. The risk factors of biliary stricture on multiple logistic regression analysis were a graft with multiple bile ducts, a previous history of bile leakage, and hepatic artery stenosis. The overall success rate of ERC-D was 64.5%. On simple logistic regression, the failure of primary ERC-D was associated with late biliary stricture over 24 weeks and more than 8 weeks between a 2-fold increase of serum alkaline phosphatase from the stable level and ERC-D, even though these were not statistically significant on multiple logistic regression. The relapse rate of stricture after successful ERC-D was 30%. The duration of stenting in the recurrence group was shorter than that in the nonrecurrence group (11.8 +/- 5.03 versus 29.0 +/- 11.6 weeks, P = 0.004). ERC-D is effective for the management of anastomotic biliary stricture. However, the failure rate of primary ERC-D may be high in patients with late onset and delayed diagnosis of biliary stricture. The recurrence seems to occur frequently in patients with a short duration of stenting.

Benign biliary strictures related to chronic pancreatitis: Balloons, stents, or surgery

Benign biliary strictures are seen in a subset of patients with chronic pancreatitis. Most patients are asymptomatic and require no intervention. In some patients, benign strictures can become symptomatic. In these patients, the aim of biliary drainage is to prevent long-term complications such as recurrent cholangitis and secondary biliary cirrhosis. The possibility of a malignant stricture should always be excluded. Successful endoscopic drainage of biliary obstruction has no influence on pain pattern in patients with chronic pancreatitis. At the first diagnosis of a symptomatic biliary stricture due to chronic pancreatitis, a polyethylene stent can be inserted endoscopically. If the stricture is still present despite stent exchange with serial insertion of multiple stents every 3 months for 1 year, surgery is indicated as definitive treatment. The role of self-expandable metal stents in the management of benign biliary strictures due to chronic pancreatitis is unclear, but they may be useful for nonoperative candidates and a select group of patients in whom surgery is planned. The aim of surgical therapy is to definitively treat the benign biliary stricture, especially in younger patients, who presumably have a longer lifespan.

Endoscopic therapy of benign biliary strictures

Benign biliary strictures are being increasingly treated with endoscopic techniques. The benign nature of the stricture should be first confirmed in order to ensure appropriate therapy. Surgery has been the traditional treatment, but there is increasing desire for minimally invasive endoscopic therapy. At present, endoscopy has become the first line approach for the therapy of post-liver transplant anastomotic strictures and distal (Bismuth Iand II) post-operative strictures. Strictures related to chronic pancreatitis have proven more difficult to treat, and endoscopic therapy is reserved for patients who are not surgical candidates. The preferred endoscopic approach is aggressive treatment with gradual dilation of the stricture and insertion of multiple plastic stents. The use of uncovered self expandable metal stents should be discouraged due to poor long-term results. Treatment with covered metal stents or bioabsorbable stents warrants further evaluation. This area of therapeutic endoscopy provides an ongoing opportunity for fresh research and innovation.

Endoscopic management of biliary disease

Therapeutic biliary endoscopy continues to evolve. Key articles this year primarily involve biliary stenting and biliary stone removal, the two important maneuvers available to the biliary endoscopist. The issues addressed in this review include follow-up after the use of multiple stents for benign strictures, unilateral versus bilateral stenting for Klatskin tumors, stent types and placement positions, the timing and approach to choledocholithiasis in the context of anticipated cholecystectomy, and resistant biliary duct stones.