Long-term results of temperature-controlled endobiliary radiofrequency ablation in a normal swine model

Impact of temperature-controlled endobiliary radiofrequency ablation for inoperable hilar cholangiocarcinoma: A propensity score-matched analysis

Background and study aims Endobiliary radiofrequency ablation (RFA) can be an effective palliative treatment, but few studies have evaluated its outcomes for malignant obstruction in the hilar bile duct, which has a thin wall and complex duct-vascular contacts. We evaluated the efficacy and safety of temperature-controlled endobiliary RFA, which can reduce the risk of unintentional thermal injury by maintaining the temperature of the ablation segment, in the treatment of inoperable hilar cholangiocarcinoma (CCA). Patients and methods After propensity score matching, 64 patients with inoperable hilar CCA were categorized to the RFA + stent group (endobiliary RFA with stenting; n=32) or stent-only group (stenting only; n=32). The evaluated outcomes were the median time to recurrent biliary obstruction (RBO), overall survival (OS), and adverse events (AEs). Results Technical success was achieved in all patients. The clinical success rate was 93.8% in the RFA + stent group and 87.5% in the stent-only group ( P =0.672). The median time to RBO was 242 days in the RFA + stent group and 168 days in the stent-only group ( P =0.031). The median OS showed a non-significant tendency to be higher in the RFA + stent group (337 versus 296 days; P =0.260). Overall AE rates were comparable between the two groups (12.5% vs 9.4%, P =1.000). Conclusions Temperature-controlled endobiliary RFA resulted in favorable stent patency without increasing the rate of AEs but it did not significantly increase OS in patients with inoperable hilar CCA (Clinical trial registration number: KCT0008576).

Anti-fibrotic and anti-stricture effects of biodegradable biliary stents braided with dexamethasone-impregnated sheath/core structured monofilaments

Endoscopic biliary stent insertion has been widely used for the treatment of benign biliary stricture (BBS). Thus, the development of stent materials in the perspectives of structure, mechanical properties, and biocompatibility has been also studied. However, conventional metal and plastic stents have several disadvantages, such as repeated procedures to remove or exchange them, dislodgment, restenosis, biocompatibility, and poor mechanical properties. Sustainable effectiveness, attenuation and prevention of fibrosis, and biocompatibility are key factors for the clinical application of stents to BBS treatment. In addition, loading drugs could show synergistic effects with stents' own performance. We developed a dexamethasone-eluting biodegradable stent (DBS) consisting of a sheath/core structure with outstanding mechanical properties and sustained release of dexamethasone, which maintained its functions in a BBS duct over 12 weeks in a swine model. The insertion of our DBS not only expanded BBS areas but also healed secondary ulcers as a result of the attenuation of fibrosis. After 16 weeks from the insertion, BBS areas were totally improved, and the DBS was degraded and thoroughly disappeared without re-intervention for stent removal. Our DBS would be an effective clinical tool for non-vascular diseases. STATEMENT OF SIGNIFICANCE: This study describes the insertion of a drug-eluting biodegradable stent (DBS) into the bile duct. The sheath/core structure of DBS confers substantial durability and a sustained drug release profile. Drug released from the DBS exhibited anti-fibrotic effects without inflammatory responses in both in vitro and in vivo experiments. The DBS maintained its function over 12 weeks after insertion into the common bile duct, expanding benign biliary stricture (BBS) and reducing inflammation to heal secondary ulcers in a swine BBS model. After 16 weeks from the DBS insertion, the DBS thoroughly disappeared without re-intervention for stent removal, resulting in totally improved BBS areas. Our findings not only spotlight the understanding of the sheath/core structure of the biodegradable stent, but also pave the way for the further application for non-vascular diseases.

Ablation Therapy of the Biliary Tree: Status and Comprehensive Review

Malignant biliary obstruction is typically referred to endoscopists for palliation. A curative resection is indeed rarely an option in this condition. Photodynamic therapy and radiofrequency ablation are 2 modalities that can be offered in those patients. Many studies have demonstrated improved stent patency and survival after ablation. Photodynamic therapy is unfortunately very expensive and is associated with photosensitivity; however, it transmits to the entire biliary tree. Radiofrequency ablation is more affordable and easier to apply but requires contact with the tumor to be efficient. This review explores both modalities in terms of their safety and efficacy for bile duct cancer palliation.

The Impact of Radiofrequency Ablation on Survival Outcomes and Stent Patency in Patients with Unresectable Cholangiocarcinoma: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Endoluminal biliary radiofrequency ablation (RFA) has been proposed as a palliative treatment for patients with malignant biliary obstruction (MBO) in order to improve stent patency and survival. However, the existing data on patients with inoperable extrahepatic cholangiocarcinoma (eCCA) are conflicting. We performed a meta-analysis of randomized trials comparing RFA plus stenting versus stenting alone in patients with inoperable eCCA. We searched for trials published in the PubMed/MEDLINE, Scopus, and Cochrane databases up to November 2023. Data extraction was conducted from published studies, and a quality assessment was carried out in accordance with the guidelines recommended by the Cochrane Collaboration. Hazard ratios (HRs) with 95% CI were estimated from the trials. The primary endpoints of interest were overall survival and stent patency. Out of 275 results, 5 randomized trials and 370 patients were included. While overall survival was not different between the groups (HR 0.62; 95% CI 0.36-1.07; p = 0.09; I2 = 80%;), the subgroup analysis of studies employing plastic stents showed a trend toward better survival in the RFA-treated group (HR 0.42; 95% CI 0.22-0.80; p = 0.009; I2 = 72%). Stent patency was improved in patients receiving RFA (HR 0.64; 95% CI 0.45-0.90; p = 0.01; I2 = 23%). Adverse events were not different between the groups (OR 1.21; 95% CI 0.69-2.12; p = 0.50; I2 = 0%). Despite the promising results, high heterogeneity and potential biases in the included studies suggest the need for further high-quality randomized trials to explore the potential cumulative effects of RFA on CCA treatment outcomes.

Long-term disease control by endobiliary radiofrequency ablation in localized extrahepatic cholangiocarcinoma: a first case report

An 84-year-old woman with cerebrovascular disease, dementia, and chronic kidney disease developed jaundice because of localized extrahepatic cholangiocarcinoma (eCCA) at the lower bile duct. Aggressive treatment, including surgery and chemotherapy, was difficult because of the underlying disease; therefore, only metal stent placement with endobiliary radiofrequency ablation (RFA) was performed. Subsequently, six additional RFA sessions were performed 12, 16, 24, 27, 33, and 36 months after the initial RFA using the same settings as the first RFA session. All these procedures were performed for tumor ingrowth. Computed tomography performed 42 months after the initial procedure revealed no stent with stricture resolution and no other metastatic lesion. Thereafter, no recurrence or adverse events have been observed with persisting stent-free status until the reporting of this study (72 months after the initial procedure). This is the first report of a stent-free status and long-term survival in a patient with localized eCCA that was achieved using only endobiliary RFA without any other anti-tumor treatment. Although several problems and issues associated with endobiliary RFA remain unelucidated, it may be a useful therapeutic option for early and localized eCCA in poor surgical candidates.

Long-term Outcomes of Endoscopic Intraductal Radiofrequency Ablation for Ampullary Adenoma with Intraductal Extension after Endoscopic Snare Papillectomy

Background/Aims

There are limitations in treating ampullary adenomas with intraductal extension using conventional endoscopic modalities. Endoscopic intraductal radiofrequency ablation (ID-RFA) may be useful for treating intraductal (common bile duct [CBD] and/or pancreatic duct [PD]) extensions of ampullary adenomas, but long-term data are lacking. We thus evaluated the long-term outcomes of endoscopic ID-RFA for managing ampullary adenomas with intraductal extension.

Methods

Prospectively collected endoscopic ID-RFA database at Asan Medical Center was reviewed to identify consecutive patients with ampullary adenoma who underwent ID-RFA for intraductal extension between January 2018 and August 2021. Technical success, short-term and long-term clinical success, and adverse events were evaluated.

Results

A total of 29 patients (14 CBD, 1 PD, and 14 CBD and PD) were analyzed. All patients had undergone endoscopic snare papillectomy prior to ID-RFA. A median of one session of ID-RFA (range, 1 to 3) for residual or relapsed intraductal extension of ampullary adenoma were successfully performed (technical success=100%). Both biliary and pancreatic stenting were routinely performed after ID-RFA to prevent ductal stricture. After a median follow-up of 776 days (interquartile range, 470 to 984 days), the short-term and long-term clinical success rates were 93% and 76%, respectively. Seven patients experienced procedural adverse events and three patients developed ductal strictures.

Conclusions

Endoscopic ID-RFA showed good long-term outcomes in treating residual or relapsed ampullary adenomas with intraductal extension. Repeated ID-RFA may be considered as an option for managing recurrence. Further studies are needed to standardize the procedure.

Impact of endobiliary radiofrequency ablation on survival of patients with unresectable cholangiocarcinoma: a narrative review

Cholangiocarcinoma (CCA) is a rare cancer originating from the biliary epithelium and accounts for about 3% of all gastrointestinal malignancies. Unfortunately, the majority of patients are not eligible for surgical resection at the time of diagnosis, because of the locally advanced stage or metastatic disease. The overall survival time of unresectable CCA is generally less than 1 year, despite current chemotherapy regimens. Biliary drainage is often required as a palliative treatment for patients with unresectable CCA. Recurrent jaundice and cholangitis tend to occur because of reobstruction of the biliary stents. This not only jeopardizes the efficacy of chemotherapy, but also causes significant morbidity and mortality. Effective control of tumor growth is crucial for prolonging stent patency and consequently patient survival. Recently, endobiliary radiofrequency ablation (ERFA) has been experimented as a treatment modality to reduce tumor mass, and delay tumor growth, extending stent patency. Ablation is accomplished by means of high-frequency alternating current which is released from the active electrode of an endobiliary probe placed in a biliary stricture. It has been shown that tumor necrosis releases intracellular particles which are highly immunogenic and activate antigen-presenting cells, enhancing local immunity directed against the tumor. This immunogenic response could potentially enhance tumor suppression and be responsible for improved survival of patients with unresectable CCA who undergo ERFA. Several studies have demonstrated that ERFA is associated with an increased median survival of approximately 6 months in patients with unresectable CCA. Furthermore, recent data support the hypothesis that ERFA could ameliorate the efficacy of chemotherapy administered to patients with unresectable CCA, without increasing the risk of complications. This narrative review discusses the results of the studies published in recent years and focuses on the impact that ERFA could have on overall survival of patients with unresectable cholangiocarcinoma.

In-stent radiofrequency ablation with uncovered metal stent placement for tumor ingrowth/overgrowth causing self-expandable metal stent occlusion in distal malignant biliary obstruction: multicenter propensity score-matched study

BACKGROUND AND AIMS

In patients with unresectable malignant biliary obstruction (MBO), endoscopic drainage with a self-expandable metal stent (SEMS) is a well-established treatment, but stent patency is limited. This study aimed to evaluate the efficacy of in-stent radiofrequency ablation (IS-RFA) followed by uncovered SEMS placement for the management of occluded SEMSs.

METHODS

From 2016 to 2020, 48 patients with recurrent biliary obstruction due to tumor ingrowth or overgrowth after SEMS placement for pancreatobiliary cancer in 3 tertiary hospitals were analyzed. For distal MBO, patients in the RFA group were treated with IS-RFA and uncovered SEMS placement, and those in the control group were treated with uncovered SEMS placement alone. Patients in both groups were matched on the basis of propensity scores in a 1:1 ratio.

RESULTS

The median time to recurrent biliary obstruction (TRBO) was 117 days in the RFA group and 82.5 days in the control group (P = .029). No significant differences in median overall survival were detected between the 2 groups (170 days vs 72 days; P = .902). No significant adverse events were reported after the second SEMS placement in either group, but 2 cases of mild cholangitis were reported in the control group. Ablation was interrupted in 5 patients (35.7%) of the RFA group owing to in-stent contact, but sufficient ablative energy was delivered in the majority of the patients (92.9%) after IS-RFA was repeated in the same session.

CONCLUSIONS

IS-RFA followed by an uncovered SEMS is safe and feasible and may improve TRBO as a stent revision for occluded SEMSs in pancreatobiliary cancer.

Endoscopic radiofrequency ablation for ingrowth occlusion after bilateral metal stent placement for malignant hilar biliary obstruction: a prospective pilot study

BACKGROUND AND AIMS

Endoscopic biliary radiofrequency ablation (RFA) may be an option for the treatment of ingrowth occlusion after self-expandable metal stent (SEMS) deployment; however, its utility remains uncertain. This study aimed to examine the feasibility of RFA for the palliation of ingrowth after bilateral SEMS placement in patients with malignant hilar biliary obstruction.

METHODS

This prospective, single-center, pilot study enrolled 30 patients who met the eligibility criteria between April 2020 and March 2022. Study outcomes were technical success, clinical success, recurrent biliary obstruction (RBO), and adverse events (AEs) besides RBO associated with RFA for ingrowth occlusion. Furthermore, factors predictive of clinical success were evaluated.

RESULTS

Technical and clinical success rates were 93.3% (28/30) and 71.4% (20/28), respectively. The rates of early and late AEs were 6.7% (2/30) and 10.0% (2/20), respectively. The incidence rate of RBO after RFA was 45.0% (9/20), and the median time to RBO was 163 days. Multivariate analysis of the factors affecting clinical success revealed a positive association between the recanalization diameter on the ingrown part within the SEMS (odds ratio, 1.13; 95% confidence interval, 1.01-1.26; P = .038). The calculated optimal cutoff for the ratio of the recanalization diameter to the SEMS diameter for predicting clinical success was 51.1%.

CONCLUSIONS

Endoscopic biliary RFA elicited promising results, with good long-term stent patency and without the requirement of any additional stent placement, for the palliation of ingrowth occlusion after bilateral SEMS placement. However, the clinical success rate was insufficient, necessitating improvements in the future. (Clinical trial registration number: UMIN000040154.).

Endoscopic management of benign and malignant hilar stricture

Management of hilar strictures pose a significant challenge for endoscopists. Several strategies have been demonstrated in the last decade beyond decompression, however, there remains controversy and minimal consensus in the literature. This review seeks to summarize the current literature and discuss emerging therapies, such as photodynamic therapy and radiofrequency ablation.

Optimal reproduction of a porcine benign biliary stricture model using endobiliary radiofrequency ablation

The use of endobiliary radiofrequency ablation (RFA) to generate a benign biliary stricture (BBS) model has a significant reproducibility problem. The aims of this animal study were to create an optimal BBS model using endobiliary RFA and determine the best way to develop it. The first step was performed on the common bile duct (CBD) of 10 miniature pigs using endoscopic RFA with a target temperature-controlled mode (80 ℃, 7 W for 90 s). The second step was performed on the CBD of five miniature pigs to understand more about the time-dependent changes in BBS development and the causes of adverse events. Using the conditions and techniques identified in the previous steps, the third step was conducted to create an optimal BBS model in 12 miniature pigs. In the first trial, four out of 10 animals died (40%) after the procedure due to cholangitis-induced sepsis. Based on this, biliary obstruction was prevented in further steps by placing a biliary plastic stent after RFA application. Histologic examinations over time showed that a severe abscess developed at the RFA application site on the fifth day, followed by fibrosis on the tenth day, and completion on the twentieth day. In the third trial, 11 animals survived (91.7%), the average BBS fibrotic wall thickness was 1107.9 µm (763.1–1864.6 µm), and the degree of upstream biliary dilation was 14.4 mm (11.05–20.7 mm). In conclusion, endobiliary RFA combined with a biliary plastic stent resulted in a safe and reproducible BBS animal model.

Comparative efficacy and safety of local palliative therapeutics for unresectable malignant biliary obstruction: a Bayesian network meta-analysis

BACKGROUND

Both radiofrequency ablation (RFA), photodynamic therapy (PDT), and biliary stent alone are common local palliative therapies for unresectable malignant biliary obstruction (MBO), but the best modality is uncertain.

RESEARCH DESIGN AND METHODS

Embase, Cochrane Library, PubMed, and Web of Science were systematically searched up to 30 January 2022, for eligible studies that compared either two or all modalities in unresectable MBO.

RESULTS

Thirty-three studies with 2974 patients were included in this study. The PDT+Stent and RFA+Stent groups had better overall survival and longer mean survival time than Stent alone (all P < 0.05). Moreover, patients with RFA+Stent demonstrated better mean duration of stent patency (MD: 2.0, 95%CI,1.1 to 2.8, P < 0.05) than Stent alone. The three modalities had similar postoperative mild bleeding, cholangitis, and pancreatitis (all P ≥ 0.05). According to network ranking, PDT+Stent was most likely to provide better survival, RFA+Stent was most likely to maintain stent patency.

CONCLUSIONS

RFA or PDT plus biliary stent is effective and safe local palliative therapy for unresectable MBO, but the current studies cannot absolutely determine which modality is the best. We should offer patients the most appropriate treatment according to the advantage of each therapy and the patient's performance status.

Preclinical evaluation of endoscopic placement of a steroid-eluting metal stent in an in vivo porcine benign biliary stricture model

Treatment of benign biliary strictures (BBS) using fully covered self-expandable metal stents (FCSEMS) has a high success rate, but recurrence can occur. Corticosteroids may be useful based on their anti-fibrotic and anti-inflammatory effects. We investigated the safety and efficacy of corticosteroid-eluting FCSEMS in an animal model. BBSs were created by radiofrequency ablation in 12 mini-pigs. Four weeks later, FCSEMS coated with 0 mg (control), 15 mg (steroid 1 × group), or 30 mg (steroid 2 × group) triamcinolone were inserted endoscopically. The in vitro drug release assay revealed that the optimal stent had 15 mg of triamcinolone and a hydrophilic membrane. No transmural necrosis or perforation occurred in any animal. Fibrous wall thickness tended to decrease macroscopically and microscopically in a triamcinolone dose-dependent manner (control vs. steroid 2 × group: 773.1 vs. 468.5 µm, P = 0.037). Thickness also decreased over time in the steroid 2 × group (3 days vs. 4 weeks: 907.9 vs. 468.5 µm, P = 0.025). Blood parameters tended to improve after stent insertion. In a porcine BBS model, steroid-eluting FCSEMS showed potential as a safe and effective treatment modality to reduce fibrotic tissue. Studies are required to confirm their safety and efficacy in humans with refractory BBS.

Development and validation of a novel porcine bile duct dilation model for EUS training

Background and study aims  Image-guided minimally invasive techniques have transformed the management of malignant and benign bile duct obstructions. These evolving techniques are being widely adopted and applied and hands-on training using high quality models is required to improve the proficiency of practitioners. This experimental study aimed to validate an in vivo porcine model created to simulate bile duct dilation for interventional endoscopic ultrasound (EUS) hands-on training curriculums. Materials and methods  Thirty-six porcine models were involved and the procedures were performed in an experimental hybrid operating room under general anesthesia. Animals underwent endoscopic duodenal papilla clipping with several hemostatic metallic clips. After a survival period of 24 to 48 hours, the models with effective intrahepatic and extrahepatic bile duct dilatation were included in the hands-on training. Trainees and faculty were given structured evaluations of the model realism and usefulness. Results  Extrahepatic bile duct and gallbladder dilation was achieved in all 36 of the models, and in 11 of the 36 models, a treatable intrahepatic duct dilatation was achieved. During the hands-on training, EUS-guided biliary drainage, EUS-guided transgastric gallbladder drainage, and EUS through-the-needle microbiopsy forceps procedures were feasible. Overall, 75 % of the experts and trainees evaluated the training as excellent. Conclusions  We present a minimally invasive, reliable and time- effective model of extrahepatic dilation suitable for interventions. The model was less effective for intrahepatic ducts, which should be considered if intrahepatic biliary dilation is required for training.

Local palliative therapies for unresectable malignant biliary obstruction: radiofrequency ablation combined with stent or biliary stent alone? An updated meta-analysis of nineteen trials

BACKGROUND

Recently, there has been a burgeoning interest in radiofrequency ablation combined with stent (RFA + Stent) for unresectable malignant biliary obstruction (MBO). This study aimed to perform a meta-analysis to evaluate the efficacy and safety of RFA + Stent compared with biliary stent alone.

METHODS

We searched PubMed, Cochrane Library, Embase, and Web of Science databases from their inception dates to June 20, 2021, for studies that compared RFA + Stent and stent alone for unresectable MBO. The main outcomes were survival, patency, and adverse effects. All meta-analyses were calculated using the random-effects model.

RESULTS

A total of 19 studies involving 1946 patients were included in this study. Compared with stent alone, RFA + Stent was significantly associated with better overall survival (HR 0.55; 95% CI 0.48, 0.63; P < 0.00001), longer mean survival time (SMD 2.20; 95% CI 1.17, 3.22; P < 0.0001), longer mean stent patency time (SMD 1.37; 95% CI 0.47, 2.26; P = 0.003), higher stent patency at 6 months (OR 2.82; 95% CI 1.54, 5.18; P = 0.0008). The two interventions had similar incidence of postoperative abdominal pain (OR 1.29; 95% CI 0.94, 1.78; P = 0.11), mild bleeding (OR 1.28; 95% CI 0.65, 2.54; P = 0.48), cholangitis (OR 1.09; 95% CI 0.76, 1.55; P = 0.65), pancreatitis (OR 1.39; 95% CI 0.82, 2.38; P = 0.22). Furthermore, the serum bilirubin levels and stricture diameter after operations were significantly alleviated than before operations, but the degree of alleviation between the two groups were not significantly different (all P > 0.05).

CONCLUSION

Although the alleviation of serum bilirubin and stricture diameter did not differ between the two interventions, RFA + Stent can significantly improve the survival and stent patency with comparable procedure-related adverse events than stent alone. Thus, RFA + Stent should be recommended as an attractive alternative to biliary stent alone for patients with unresectable MBO.

Updated evidence on the clinical impact of endoscopic radiofrequency ablation in the treatment of malignant biliary obstruction

Endoscopic biliary radiofrequency ablation (RFA) was recently developed as a novel adjunctive procedure and a promising therapeutic option in patients with malignant biliary obstruction (MBO). RFA can achieve local tumor control, resulting in improved biliary stent patency and a potential survival benefit. However, the efficacy of biliary RFA remains controversial, and previous studies have shown conflicting results. At present, extrahepatic cholangiocarcinoma is considered the condition most effectively treated by biliary RFA, but there is limited research even on this point. Further, limitations of RFA associated with the devices used during the procedure are an important subject of discussion. In addition to further well-designed clinical trials, development of innovative devices is warranted to investigate and conclusively establish the usefulness of biliary RFA. In this review we summarize the updated evidence regarding the use of endoscopic biliary RFA for MBO and discuss issues that should be addressed in future studies.

Mechanical properties and degradation process of biliary self-expandable biodegradable stents

OBJECTIVES

The clinical outcomes and prevalence of adverse events associated with biliary biodegradable stents (BS) can differ according to degradation process and time. The aim of this study was to observe the degradation process and time of different BS prototypes, and to evaluate sequential changes in their mechanical properties.

METHODS

Using an in vitro bile flow phantom model, we compared degradation time, radial force changes, and morphologic changes among four different BS prototypes: polydioxanone (PDO) BS, polyglycolide (PGA) BS, polydioxanone/poly-l-lactic acid (PDO/PLLA) sheath-core BS, and polydioxaone/magnesium (PDO/Mg) sheath-core BS. Using an in vivo swine bile duct dilation model, we performed a direct peroral cholangioscopy (DPOC) examination to observe the biodegradation process and related adverse events at regular intervals.

RESULTS

In the bile flow phantom model, the PGA BS and PDO/Mg BS prototypes showed rapid radial force reduction and morphological changes and complete degradation within six weeks. PDO/PLLA BS maintained high radial force and kept their original shape for longer than the PDO BS, up to 16 weeks. A total of 24 BS were inserted into the dilated bile ducts of 12 swine. In this animal model, DPOC examination revealed that PDO BS and PDO/PLLA BS maintained their original shapes for approximately 12 weeks, but PDO BS showed a greater degree of fragmentation and induced biliary stones and bile duct obstruction.

CONCLUSION

Our results showed that PDO/PLLA BS maintained their original shape and radial force for a relatively long time and minimized adverse events.

[Recent Updates on Endoscopic Retrograde Cholangiography-guided Intraductal Radiofrequency Ablation for Malignant Biliary Stricture]

Malignant biliary strictures are caused by pancreatobiliary cancer and other metastatic malignancies. Most of them are unresectable at diagnosis with a dismal prognosis. Various new ablation methods have been introduced. Of them, ERCP-guided intraductal radiofrequency ablation (ID-RFA) appears to be the most promising minimally invasive endoscopic treatment by delivering a high-frequency alternating current to the target tissue, leading to coagulative necrosis. Thus far, many studies have provided evidence that ERCP-guided ID-RFA is a safe, feasible, and effective treatment modality for stent patency and overall survival. Compared to other ablation treatments, ERCP-guided ID-RFA has several advantages, including ease of delivery, controlled application of thermal energy, low cost, and fewer systemic side effects with an acceptable safety profile. Therefore, ERCP-guided ID-RFA can be considered an adjunctive treatment for the palliation of unresectable malignant biliary strictures. On the other hand, the decision of local ablation treatment should be individualized by multidisciplinary team support due to the lack of comparative studies.

Percutaneous endobiliary ablation of malignant biliary strictures with a novel temperature-controlled radiofrequency ablation device

PURPOSE

We aimed to determine the safety and effectiveness of percutaneous endobiliary radiofrequency ablation of malignant biliary obstructions with a temperature-controlled radiofrequency ablation device.

METHODS

In this single center retrospective study, a total of 62 consecutive patients with malignant biliary obstruction were evaluated. Thirty patients who underwent endobiliary radiofrequency ablation with metallic stent placement were in the study group and 32 patients who underwent only metallic stenting were in the control group. Outcomes of this study were technical success, complications related to the procedure, stent patency, and overall survival.

RESULTS

All procedures were technically successful in both groups. There was no procedure-related mortality in either group. Procedural complication rates were similar between the groups. Although statistically not significant, the only two major complications (hemobilia requiring endovascular treatment) were in the control group. Median primary stent patency was significantly longer in the study group than in the control group (223 days vs. 158 days; P = 0.016). Median survival rates were also longer in the study group (246 days vs. 198 days; P = 0.004).

CONCLUSION

Percutaneous endobiliary radiofrequency ablation is safe and feasible with this novel radiofrequency ablation device in patients with malignant biliary obstruction. Percutaneous endobiliary radiofrequency ablation has a potential to improve both stent patency and survival.

Radiofrequency ablation for intraductal extension of ampullary adenomatous lesions: proposal for a standardized protocol

Background and study aims  Intraductal extension of ampullary adenoma represents a challenging endoscopic issue. Intraductal radiofrequency ablation (RFA) has been recently suggested, but evidence and standardization of this technique are still lacking. This study aimed to provide a long-term evaluation of clinical efficacy and safety of intraductal RFA ablation with a standardized algorithm of treatment. Patients and methods  Data were prospectively collected from consecutive patients with intraductal extension of adenomatous ampullary lesions from January 2016 to November 2018. Endpoints of the study were clinical success evaluated on histology results at the last follow-up, technical success, and adverse events assessment. Results  Nine patients with intraductal (biliary ± pancreatic) extension of ampullary adenomas were treated with RFA during the study period. Histology on the papillectomy specimen confirmed intraductal involvement with low-grade dysplasia (LGD) in five cases (56 %), high-grade dysplasia (HGD) in three (33 %), and HGD with intramucosal adenocarcinoma in one patient (11 %). Additional argon plasma coagulation to ablate the adenoma on the duodenal mucosa was applied in five patients (56 %). Technical success was 100 %. One patient (11 %) with failed pancreatic stenting, developing acute pancreatitis after RFA, recovered with medical therapy. After a median follow-up of 21 months (IQR 20-31), six patients (67 %) achieved clinical success being free of recurrence, whereas one was diagnosed with persistence of adenocarcinoma, one with recurrent HGD, and one with recurrent LGD. Conclusions  In our experience, intraductal RFA achieved acceptable results after a 2-year follow-up. Further studies are required to confirm our results and to select those patients most likely to respond.

[Large Animal Models in Pancreas and Biliary Disease]

Rodent models, which have played important roles in preclinical research of pancreas and biliary diseases, have some limitations to translating data from rodent models to human diseases. Large animal models have recently been developed to overcome these limitations and perform translational research of medical devices and drugs in pancreas and biliary diseases. Preclinical studies using large animal models are necessary before clinical application, especially for the research and development of equipment, instrumentation, and techniques in pancreato-biliary diseases. As long as the endoscope used in humans can enter an organ, there appears to be no limitation in terms of species or organ for endoscopic experiments of large animal models. Investigators have mainly used swine for pancreas and biliary endoscopic experiments. Until now, unique swine models that investigators have been established include the normal bile duct model, bile duct dilation model, bile duct dilation+direct peroral cholangioscopy model, benign biliary stricture model, hilar biliary obstruction model, and acute pancreatitis (post-ERCP pancreatitis) model. Many preclinical studies have been performed using these established endoscopy-based large animal models to develop novel medical devices. Furthermore, porcine pancreatic cancer models induced by a transgenic or orthotopic method are currently under development. These models appear to be available for general use in the future and will have multiple potential preclinical and clinical applications.

The Safety of Radiofrequency Ablation Using a Novel Temperature-Controlled Probe for the Treatment of Residual Intraductal Lesions after Endoscopic Papillectomy

Background/Aims

Treatment of residual intraductal lesions after endoscopic papillectomy for ampullary adenomas is relatively difficult. Few studies have been conducted using intraductal radiofrequency ablation (RFA) in the treatment of such lesions, and no study has aimed to reduce the side effects of excessive heat caused by RFA. Recently, a temperature-controlled RFA probe was developed to avoid excessive heat. This study aimed to investigate the safety of this new RFA probe in the treatment of intraductal lesions of ampullary adenoma.

Methods

Patients who received RFA for residual intraductal lesions after endoscopic papillectomy between November 2017 and June 2019 were retrospectively reviewed. A novel temperature- controlled probe (ELRA) was used for intraductal RFA, and clinical data including adverse events were collected.

Results

Ten patients were included in this study. Intraductal adenomas showed low-grade dysplasia in eight patients and high-grade dysplasia in two patients. The median diameter of intraductal adenomas was 9 mm (range, 5 to 10 mm) in the common bile duct and 5 mm (range, 4 to 11 mm) in the pancreatic duct. Adverse events occurred in three patients (30.0%), of which two were mild pancreatitis and one was asymptomatic biliary stricture. Over a median follow-up period of 253 days, only one patient underwent additional surgery, as the remainder showed no adenomatous lesions on follow-up biopsies.

Conclusions

The new temperature-controlled RFA probe can be used with acceptable safety for the treatment of residual intraductal lesions after endoscopic papillectomy. Further evaluation through future prospective studies is needed.

Acute and subacute effects of irreversible electroporation on normal common bile ducts in a rabbit model

BACKGROUND/PURPOSE

This study aimed to evaluate the acute and subacute effects of irreversible electroporation (IRE) on normal common bile ducts (CBDs).

METHODS

Cell susceptibility to IRE was assessed in vitro with cholangiocarcinoma and normal cell lines. The electric field and temperature distributions were evaluated with a two-dimensional simulation model of bile duct. In vivo bile duct IRE was performed in 28 adult rabbits.

RESULTS

Different cells showed different susceptibility to the effect of IRE, cancer cell line HUCC-T1 was the least sensitive to IRE. Simulations predicted the distributions of electric field and temperature during the IRE process, and the maximum temperature of tissue was below 43℃. Complications were observed in 8/28 animals (biliary dilatation, n = 4; biliary stricture, n = 4) by postoperative days 7, 14, and 28. Histopathological analyses revealed complete cell death with bile duct wall integrity. Bile duct epithelial recovery was completed between post-IRE days 14-28.

CONCLUSIONS

The normal CBD retains the lumen wall integrity following IRE with immediate periductal placement of the electrode. However, the risk of biliary dilatation and stricture is a reminder that the parameters of IRE need to be determined more precisely to ensure the treatment efficacy and reduce the risk of collateral damage.

Efficacy and safety of palliative endobiliary radiofrequency ablation using a novel temperature-controlled catheter for malignant biliary stricture: a single-center prospective randomized phase II TRIAL

BACKGROUND

Endobiliary radiofrequency ablation (EB-RFA) has emerged as a palliative treatment for malignant biliary strictures (MBSs); however, concerns about complications related to thermal injury remain. In this study, we evaluated the efficacy and safety of EB-RFA with a novel catheter for MBS.

METHODS

Patients with inoperable cancer causing MBS were randomly assigned to either the radiofrequency ablation (RFA) group or the non-RFA group. The RFA group underwent EB-RFA at the stricture site with a temperature-controlled catheter (ELRA™; STARmed Co., Goyang, Korea) followed by deployment of a self-expanding metal stent (SEMS). For the non-RFA group, only SEMS placement was performed. The duration of stent patency, overall survival (OS), and 30-day complication rate were evaluated. This trial was registered at ClinicalTrials.gov (number NCT02646514).

RESULTS

A total of 48 patients were enrolled (24 in each group). During a median follow-up period of 135.0 days (RFA group) and 119.5 days (non-RFA group), the 90-day stent patency rate, median duration of stent patency, and median OS were not different between the groups (58.3% vs. 45.8% [P = 0.386], 132.0 days vs. 116.0 days [P = 0.440], and 244.0 days vs. 180.0 days [P = 0.281], respectively). In the RFA group, procedure-related complications including thermal injury-related complications, such as bile duct perforation or hemobilia, were not reported. The early complication (< 7 days) rates were not different between the groups (4.2% vs. 12.5%, P = 0.609), and there were no late complications (7-30 days) in both groups.

CONCLUSION

EB-RFA with a temperature-controlled catheter followed by SEMS placement for patients with inoperable MBS can be safe and feasible with acceptable biliary patency.

Novel swine biliary dilatation model with temperature-controlled endobiliary radiofrequency ablation: An effective tool for training in EUS-guided biliary drainage

Background and Objectives:

EUS-guided biliary drainage (EUS-BD) is used as a rescue method after failed endoscopic retrograde cholangiography. However, it is considered a technically challenging procedure. Phantoms and ex vivo biliary dilatation models have been used to enhance the learning of EUS-BD, but they provide a limited level of realism. The aim of this study was to develop a swine biliary dilatation model that uses temperature-controlled endobiliary radiofrequency ablation (EB-RFA) for training in EUS-BD.

Materials and Methods:

Target temperature-controlled (80°C at 7 or 10 W for 60–120 s) EB-RFA was performed on seven pigs. Two weeks after the EB-RFA, EUS examination was performed to confirm biliary dilatation, and EUS-BD was then attempted by performing a hepaticogastrostomy (HGS) or cholecystogastrostomy (CGS).

Results:

Twelve sessions of EB-RFA (11 at the distal common bile duct [CBD] and one at the proximal CBD) were successfully performed on the seven pigs. There were no immediate postprocedural adverse events. Two weeks after the procedures, clinical signs of jaundice were observed in all the pigs. EUS examination revealed massive intrahepatic and extrahepatic biliary dilatations in all the pigs, and EUS-BD was attempted in the same session. HGS was performed on six pigs. Technical success was achieved in five of the six pigs (83.3%). Technical failure in HGS occurred during the stent deployment, and CGS was successfully performed on one pig.

Conclusions:

Our study shows that EB-RFA is an effective minimally invasive method for creating biliary dilatation models. It may be considered suitable for training in EUS-BD.

Intraductal temperature-controlled radiofrequency ablation in malignant hilar obstruction: a preliminary study in animals and initial human experience

Background and study aims  Intraductal radiofrequency ablation (ID-RFA) is a recently developed method widely used for treatment of malignant extrahepatic biliary tract obstructions. However, its safety in hilar application has yet to be clearly demonstrated. The aim of this study was to evaluate the safety of ID-RFA in the treatment of malignant hilar obstruction. Patients and methods  Endoscopic retrograde cholangiography followed by temperature-controlled ID-RFA at the hilar area using different probe lengths (11, 18, and 22 mm) and settings (7 or 10 W for 60 - 120 s) was performed in six mini-pigs. In addition, patients with malignant hilar obstruction who underwent palliative ID-RFA were retrospectively evaluated. Results  In the animal study using different ID-RFA settings , post-ID-RFA fluoroscopic radiocontrast leakage and microscopic bile duct perforation with hepatic abscess were observed in four of the six mini-pigs. Only two of the them, in which an 11-mm ID-RFA probe at a target temperature of 80 °C, power of 7 W, and duration of 60 s was used, underwent successful ID-RFA without any immediate adverse events (AEs). Clinically, ID-RFA was performed using the 11-mm probe with the setting of 80 °C, 7 W, and 60 - 120 s for malignant hilar obstruction, and total of 11 patients underwent successful ID-RFA without AEs. Conclusions  Our study suggests that ID-RFA performed using a short-length probe with settings of 80 °C, 7 W and 60 - 120 s is a safe and feasible palliative treatment for malignant hilar obstruction.

The safety of newly developed automatic temperature-controlled endobiliary radiofrequency ablation system for malignant biliary strictures: A prospective multicenter study

BACKGROUND AND AIMS

Catheter-based endobiliary radiofrequency ablation (RFA) is an endoscopic local treatment for patients with malignant biliary stricture (MBS). However, excessive heating of the bile duct by the current RFA system can induce serious complications. Recently, a new RFA system with automatic temperature control was developed. In the present study, we examined the safety of the new RFA system in patients undergoing endobiliary RFA for extrahepatic MBS.

METHODS

This prospective, multicenter study enrolled patients with unresectable or inoperable extrahepatic (> 2 cm from the hilum) MBS. Endobiliary RFA was performed using a newly developed RFA catheter (ELRA™, STARmed, Goyang, Korea) at a setting of 7 or 10 W for 120 s and with a target temperature of 80°C. A self-expandable metallic stent was inserted after endobiliary RFA. The rate of procedure-related adverse events was assessed.

RESULTS

The 30 patients were enrolled in this study. Cholangiocarcinoma was diagnosed in 19 patients, pancreatic cancer was found in 9, and gallbladder cancers were recorded in 2. The mean stricture length was 22.1 ± 6.6 mm. Post-procedural adverse events occurred in three patients (10.0%; 2 mild pancreatitis and 1 cholangitis) without hemobilia and bile duct perforation. The pancreatitis and cholangitis resolved with conservative treatment. The cumulative duration of stent patency and survival were 236 and 383 days, respectively.

CONCLUSIONS

Automatic temperature-controlled endobiliary RFA using a newly developed catheter was safely applied in patents with extrahepatic MBS. Further prospective studies are needed to confirm the efficacy of endobiliary RFA for MBS.

Endobiliary radiofrequency ablation for distal extrahepatic cholangiocarcinoma: A clinicopathological study

BACKGROUND

Most patients with distal extrahepatic cholangiocarcinoma have developed jaundice or cholangitis at the time of initial diagnosis, which can delay surgery. We aim to evaluate the actual EB-RFA ablation volume and validated the clinical feasibility of preoperative endobiliary radiofrequency ablation (EB-RFA) for resectable distal extrahepatic cholangiocarcinoma.

METHODS

The medical records of patients who underwent EB-RFA from July 2016 to June 2017 at a single tertiary academic medical center were reviewed. Inclusion criteria were patients with resectable distal extrahepatic cholangiocarcinoma who required preoperative biliary decompression. Clinical outcomes of EB-RFA were reviewed retrospectively and the surgical specimens were reevaluated.

RESULTS

Of the eight patients who required a delayed operation, preoperative EB-RFA was successfully performed without serious complications including peritonitis, hemobilia, or perforation. Although curative resection was attempted in all patients, one patient underwent open and closure due to hepatic metastasis. Seven patients underwent curative surgical resection and the histology revealed that median maximal ablation depth was 4.0 mm (range, 1-6) and median effective ablation length (histological ablation length/fluorosocopic ablation length) was 72.0% (range, 42.1-95.3).

CONCLUSIONS

EB-RFA partially ablated human cancer tissue and preoperative EB-RFA might be a safe and feasible in patients with distal extrahepatic cholangiocarcinoma who require a delayed operation. Ablation of the target lesion longer than the estimated length by fluoroscopy may improve the efficacy of EB-RFA.