Safety and effectiveness of endobiliary radiofrequency ablation according to the different power and target temperature in a 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).

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.

Consensus statements on endoscopic radiofrequency ablation for malignant biliary strictures

Endoscopy-guided endobiliary radiofrequency ablation has emerged as a novel treatment for malignant biliary strictures in recent years. When combined with biliary stenting and systemic chemotherapy, it can effectively postpone local tumor progression, improve patient's quality of life, and prolong their survival, which is mainly indicated for patients with inoperable extrahepatic cholangiocarcinoma and ampullary cancer. Based on the existing clinical evidence, the Digestive Endoscopology Branch of Chinese Medical Association, the Digestive Endoscopy Professional Committee, Endoscopic Physicians Branch of Chinese Medical Doctor Association, and the National Clinical Research Center for Digestive Diseases (Shanghai) organized relevant experts to discuss the indications, contraindications, technical operation specifications, and prevention and treatment of the complications during endoscopy-guided endobiliary radiofrequency ablation. Consensus statements were established, trying to provide references for standard treatment of malignant biliary tumors in clinical practice.

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.

Feasibility of in vivo swine models using guide wire-assisted intraductal radiofrequency ablation for benign biliary stricture

Several in vivo swine models of benign biliary stenosis (BBS) have been recently reported for preclinical studies of novel endoscopic techniques and devices. The aim of this study was to evaluate the efficacy and feasibility of large animal models of BBS by using intraductal radiofrequency ablation (RFA) assisted by guide wire. Six in vivo swine models were made by using an intraductal RFA for cauterization at 10 W, 80 °C, 90 s in the common bile duct (CBD). Endoscopic retrograde cholangiopancreatography (ERCP) was performed with cholangiography and histologic evaluation was done for the common bile duct. Blood tests were examined before, after, and at the final follow-up. Guide wire assisted RFA electrode produced BBS in all (6/6, 100%) animal models without severe complications. Fluoroscopy findings at 2 weeks after intraductal RFA in every model revealed BBS in the common bile duct. In histologic evaluations, fibrosis and chronic inflammatory changes were noted. After the procedure, ALP, GGT, and CRP were elevated and decreased after an appropriate drain. A swine model of BBS is developed by inducing intraductal thermal injury using intraductal RFA assisted by guide wire. This novel technique for inducing BBS in swine is effective and feasible.

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.

Endobiliary and Pancreatic Radiofrequency Ablations

Radio frequency ablation (RFA) involves use of thermal energy to perform ablation of tissues. It has a wide range of application in gastrointestinal tract. Over the last few years, several studies have reported successful and safe application in the biliary and pancreatic tissues. It is particularly beneficial in patients with biliary malignancies in whom it has shown to improve survival. Additionally, it can be applied in occluded metal stents secondary to tumor ingrowth to prolong the patency of stents. In pancreas, RFA can successfully ablate cystic lesions and neuroendocrine tumors. It has also been applied in unresectable pancreatic cancers. This review discusses the application of endobiliary and pancreatic RFAs.

Impact of endobiliary radiofrequency ablation on biliary drainage in patients with malignant biliary strictures treated with uncovered self-expandable metal stents: a randomized controlled multicenter trial

BACKGROUND AND AIMS

Endobiliary radiofrequency ablation (RFA), usually combined with endoscopic stent insertion, is a simple procedure with the potential to improve stent patency and patient survival for malignant biliary obstruction. We conducted this randomized multicenter trial to evaluate the impact of RFA on stent patency.

METHODS

Eighty-six patients with malignant biliary obstruction and nonresectable tumors (pancreatic carcinoma, cholangiocarcinoma, or metastases) were included and randomly assigned to receive a self-expandable metal stent (SEMS) only (n = 44) or RFA followed by SEMS insertion (RFA+SEMS, n = 42). The primary outcome measure was stent patency after 3 and 6 months; secondary outcome measures were patient survival and early adverse events within 30 days.

RESULTS

Technical success rates for RFA and stent insertion were 100% and 98.8%, respectively. Stent patency after 3 and 6 months did not differ significantly between groups (RFA+SEMS group, 73.1% and 33.3%, respectively; SEMS-only group, 81.8% and 52.4%, respectively; P = .6). Similarly, the addition of RFA did not impact overall survival (hazard ratio, .72; P = .389 for RFA+SEMS). The adverse event rate in the RFA+SEMS group was 10.5% compared with 2.3% in the SEMS-only group, without a statistically significant difference (P = .18).

CONCLUSIONS

RFA as an addition to SEMS implantation had no positive impact on patency rate or survival. (Clinical trial registration number: DRKS00018993.).

Stent-based electrode for radiofrequency ablation in the rat esophagus: a preliminary study

Endoluminal radiofrequency (RF) ablation has been widely used as a safe and effective treatment for Barrett's esophagus. However, inadequate RF ablation may occur due to insufficient contact between the electrode and target tissues. Herein, a stent-based monopolar RF electrode (SE) was developed to evenly deliver RF energy to the inner wall of the rat esophagus. The optimal RF parameters were evaluated in the exposed rat esophagus. The temperature in the rat esophagus reached 70 ℃ in 89 s at 30 W, 59 s at 40 W, and 34 s at 50 W. The technical feasibility and efficacy of RF ablation using SE were evaluated based on changes in histological transformation and immunohistochemical parameters of tissues compared at immediately, 1 and 2 weeks after the procedure. The degrees of inflammatory cell infiltration, fibrotic changes, TUNEL, and HSP70 in the RF-ablated rat esophagus were significantly higher than compared with sham control (all p < 0.05). TUNEL-positive deposition gradually decreased, but HSP 70-positive deposition maintained a similar level for 2 weeks. The stent-based RF ablation was technically feasible and effective in evenly inducing thermal damages to the rat esophagus. The RF ablation system using the SE may represent a promising treatment for endoluminal malignancies.

Efficacy and safety of percutaneous endobilliary radiofrequency ablation with a novel temperature-controlled catheter in malignant biliary strictures

Purpose

The purpose of this study is to evaluate the efficacy and safety of temperature-controlled endobilliary radio-frequency ablation (EB-RFA) followed by metal stent placement for nonresectable malignant biliary strictures.

Material and methods

From May 2017 to March 2021, 18 patients with malignant biliary obstruction who had undergone percutaneous EB-RFA and stent placement (n = 9) or stent placement only (n = 9) were included in this retrospective study. Outcomes were stent patency, technical and clinical success, overall survival, and 30-day complication rate. Kaplan-Meier and Cox regression analyses were performed to examine the relationship of EB-RFA with stent patency and overall survival.

Results

The clinical and technical success rate for each group was 100%. The median stent patency was 128 days (95% CI: 122.2-133.8) in the EB-RFA group and 86 days (95% CI: 1.2-170.7) in the control group. It was significantly longer in the study group (p = 0.012). The mean overall survival was 267.7 ± 68.5 days (95% CI: 133.3-402.2) in the study group and 239.6 ± 33.9 days (95% CI: 173.1-306.2) in the control group. Log-rank test showed there was not a statistically significant difference in overall survival rates (p = 0.302). There were no major complications and no statistically significant difference in cholangitis rates (p = 0.620).

Conclusions

Percutaneous temperature-controlled EB-RFA combined with biliary stent placement for malignant biliary obstruction can be safe and feasible, and effectively increase stent patency.

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.

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.

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.

[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.

Effect of endoscopic radiofrequency ablation on the survival of patients with inoperable malignant biliary strictures: A large cohort study

BACKGROUND AND AIMS

Endoscopic radiofrequency ablation (RFA) is an emerging technique for the palliation of inoperable malignant biliary strictures (MBSs). We aimed to systemically investigate the long-term outcome of RFA in a large cohort of patients.

METHODS

We recruited 883 patients with various MBSs who underwent endoscopic interventions at two large-volume centers; 124 patients underwent RFA and stenting, whereas 759 underwent stenting alone. To overcome selection bias, we performed 1:4 propensity score matching (PSM). The main outcome was overall survival (OS).

RESULTS

Following PSM, patients in the RFA group showed significantly longer OS (9.5 months; 95% CI: 7.7-11.3 months) than those in the stenting alone group (6.1 months; 95% CI: 5.6-6.6 months; P < .001). In stratified analyses, the improved OS was only demonstrated in the subgroup of extrahepatic cholangiocarcinoma (11.3 months 95% CI: 10.2-12.4 vs 6.9 months 95% CI: 6.0-7.8; P < .001), but not in the subgroups of gallbladder cancer, hepatocellular carcinoma, intrahepatic cholangiocarcinoma, pancreatic cancer, and other metastatic cancers (all P > .05). The survival benefits were noted only in the patients with non-metastatic cholangiocarcinoma (11.5 vs 7.4 months, P < .001).

CONCLUSIONS

The survival benefits of endoscopic RFA appear to be limited to patients with extrahepatic cholangiocarcinoma without distant metastasis.

[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.

Feasibility and Safety of Endoluminal Radiofrequency Ablation as a Rescue Treatment for Bilateral Metal Stent Obstruction Due to Tumor Ingrowth in the Hilum: A Pilot Study

Background. Radiofrequency ablation (RFA) is a palliative method known for its application in the endoscopic treatment of malignant bile duct obstruction. It may be a useful rescue method for metal stent malfunction caused by tumor ingrowth. This study aimed to examine the feasibility and safety of endoluminal RFA for occluded bilateral hilar metal stents due to tumor ingrowth in patients with malignant hilar bile duct obstruction. Methods: From March 2016 to June 2018, 11 patients with unresectable malignant hilar bile duct stricture with occluded bilateral hilar metal stents due to tumor ingrowth were enrolled. Endoluminal RFA was performed through a novel temperature-controlled catheter at a setting of 7 W power for 120 s with a target temperature of 80 °C via endoscopic retrograde cholangiopancreatography (ERCP). The patients’ demographics, clinical outcomes, and adverse events were investigated. Results: The median age was 64 (interquartile range, 54–72) years. All RFA procedures were successful. Clinical success was achieved in eight patients (72.7%). During the follow-up, eight patients (72.7%) showed stent dysfunction, and the median patency after RFA was 50 days (95% confidence interval (CI): 34–not available (NA)). All stent dysfunctions were successfully managed with ERCP. Ten patients died, and the median overall survival was 289 days (95% CI, 107–NA) from RFA to death. There was one case of mild abdominal pain after the procedure without serious adverse events. Conclusions: As a rescue therapy for occluded bilateral hilar metal stents due to tumor ingrowth, endoluminal RFA seemed to be safe and useful in selected patients.

Role of Intraductal RFA: A Novel Tool in the Palliative Care of Perihilar Cholangiocarcinoma

Background

Patients with irresectable perihilar cholangiocarcinoma (PHC) have a limited prognosis with median survival times still less than 1 year. In addition to the current standard first-line systemic chemotherapy (gemcitabine and a platinum derivate), endoscopic treatment aims to ensure adequate drainage of the biliary system by placing biliary plastic or metal stents. Local ablative procedures like intraluminal biliary brachytherapy (ILBT) or photodynamic therapy (PDT) are used to improve local tumor control and to optimize the stent patency.

Summary

Intraductal radiofrequency ablation (RFA) is another promising tool in the therapeutic armamentarium for the endoscopic management and tumor ablation of extrahepatic cholangiocarcinoma (eCCA). By applying thermal energy to the tissue through high-frequency alternating current, RFA induces coagulative necrosis and causes local destruction of the tumor. It is established as a first line percutaneous treatment of solid liver tumors, and since 2011 an endoscopic catheter is available that allows intraductal RFA in the biliary or pancreatic ducts. While the first pilot studies primarily evaluated this new method in patients with distal eCCA, there is now evidence accumulating also for PHC. Two retrospective and two prospective studies demonstrated a significantly improved overall survival and a longer stent patency with intraductal RFA, which overall had a favorable safety profile and was not associated with a significant increase in adverse events. However, prospective studies comparing the efficacy and safety of intraductal RFA, PDT, and/or ILBT are lacking.

Key Messages

Recent studies suggest that intraductal RFA is an effective and well-tolerated additional treatment option with regard to stent patency but also overall survival. Since RFA has fewer systemic side effects and requires less logistical effort when compared to ILBT and PDT, intraductal RFA should be considered as another safe and feasible adjuvant method for the palliative care of patients with advanced PHC. Since comparative studies are lacking, the choice of the local ablative method remains in each case an individual decision.

Thermal Processes in Bile Ducts During Laparoscopic Cholecystectomy with Monopolar Instruments. Experimental Study Using Real-Time Intraluminal and Surface Thermography

Introduction. A significant rate of complications during laparoscopic cholecystectomy (LC) occurs due to thermal injury caused by monopolar electrosurgery (MES) equipment. Most of them manifest weeks and months after surgery with the common bile duct (CBD) and large duodenal papilla strictures, some in the early postoperative period with bile leaks. Objective. To study thermal processes occurring in the lumen and on the surface of the bile ducts during monopolar coagulation in a porcine model of LC. Methods. The temperature of the bile ducts was measured using instrumentation consisted of biliary stent with temperature sensors, which was inserted in the porcine CBD, signal amplifier, and current sense transformer. Surface temperature was measured with a scientific grade thermal camera. Cholecystectomy was performed using a standard "critical view of safety" (CVS) approach with 5 mm monopolar laparoscopic instruments. Results. Application of MES caused significant tissue heating. Lateral thermal spread and the rate of tissue heating depended on the duration of energy application and the initial tissue temperature. In 5 out of 6 experiments, the intraluminal temperature rose up to the critical threshold, and the exposure time ranged from 54 to 560 seconds. A sensor positioned at the papilla site was heated in all the experiments but still below the cell damage inducing threshold. The analysis of thermographic charts revealed the presence of the "current channeling" effect and the pedicle effect. Conclusion. There is a possibility of a direct and delayed thermal injury to the bile ducts during LC.

Palliative Measures with Ethanol Gallbladder Ablation and Endobiliary Radiofrequency Ablation Followed by Endoscopic Biliary Stent Placement in an Advanced Case of Common Bile Duct Cancer: A Case Report

Endobiliary radiofrequency ablation (RFA) is a procedure performed widely to induce locoregional tumor control by the transfer of thermal energy to the lesion and subsequent tumor necrosis. A 72-year-old male with a prior history of acute calculous cholangitis and perforated cholecystitis was admitted to the Kyungpook National University Hospital complaining of fever and nausea. He had an indwelling percutaneous transhepatic gallbladder drainage (PTGBD) catheter from the previous episode of perforated cholecystitis. An abdominal CT scan showed marked dilation of both the intrahepatic and extrahepatic bile ducts. Common bile duct cancer was confirmed histologically after an endobiliary biopsy. A surgical resection was considered to be the initial treatment option. During open surgery, multiple metastatic nodules were present in the small bowel mesentery and anterior abdominal wall. Resection of the tumor was not feasible, so endobiliary RFA was performed prior to biliary stenting. Cholecystectomy was required for the removal of the PTGBD catheter, but the surgical procedure could not be performed due to a cystic ductal invasion of the tumor. Instead, chemical ablation of the gallbladder (GB) with pure ethanol was performed to breakdown the GB mucosa. Palliative treatment for a biliary obstruction was achieved successfully using these procedures. In addition, a PTGBD catheter was removed successfully without significant side effects. As a result, an improvement in the patient's quality of life was accomplished.

Novel balloon catheter-based endobiliary radiofrequency ablation system: Ex-vivo experimental study

BACKGROUND

Endobiliary radiofrequency ablation (RFA) is a promising treatment option for malignant biliary obstruction, but conventional catheter RFA (Conventional-RFA) has several limitations. We examined the feasibility of a novel approach to balloon-based RFA (Balloon-RFA) with an automatic temperature control system in freshly resected pig livers.

METHODS

Balloon-RFA application was performed in a step-by-step manner at target temperatures of 50°C, 60°C, and 70°C. The temperatures were maintained for 60 s. As a control, Conventional-RFA was performed at 7 W of power for 90 s, 7 W 120 s, 10 W 90 s, and 10 W 120 s. The ablation areas were measured and compared between Balloon-RFA and Conventional-RFA.

RESULTS

The maximum ablation depths in Balloon-RFA were 1.86 ± 0.53, 2.29 ± 0.31, and 3.19 ± 0.47 mm at target temperatures of 50, 60, and 70°C, respectively. The maximum ablation depths in Conventional-RFA were 2.81 ± 0.46, 4.09 ± 0.45, 3.41 ± 0.58, and 4.27 ± 0.29 mm at 7 W 90 s, 7 W 120 s, 10 W 90 s, and 10 W 120 s, respectively. Differences between the minimum and maximum depths were significantly smaller in Balloon-RFA (0.73 ± 0.31 mm) than in Conventional-RFA (2.00 ± 0.62 mm; P < 0.001). Excessive ablation occurred only in Conventional-RFA (0% vs. 67%; P = 0.005).

CONCLUSIONS

The novel balloon-based RFA system allows ablation to be finely tuned in order to successfully obtain consistent ablation depths and avoid excessive ablation.

Usefulness of intraductal RFA in patients with malignant biliary obstruction

BACKGROUND/AIMS

Intraductal radiofrequency ablation (ID-RFA) is a novel therapy for unresectable malignant biliary obstructions. ID-RFA for perihilar lesions is associated with a high risk of adverse events. We aimed to evaluate the feasibility and efficacy of temperature-controlled ID-RFA for perihilar malignant biliary obstruction.

METHODS

Sixteen patients with pathologically proven perihilar cholangiocarcinoma were prospectively enrolled to evaluate the feasibility of hilar ID-RFA. Clinical efficacy and outcomes were subsequently evaluated in a multicenter retrospective cohort.

RESULTS

Nine of the 16 patients in the prospective cohort had Bismuth type IV and 7 had type IIIA perihilar cholangiocarcinoma. The median length of stricture was 34.5 mm. The median number of ID-RFA sessions was three, and all sessions were technically and functionally successful without severe adverse events. Clinical outcomes were assessed using a multicenter hilar ID-RFA cohort of 21 patients; the median stent patency and overall survival were 90 days (range: 35-483 days) and 147 days (range: 92-487 days), respectively. An approximate 16-month patency of the bile duct was maintained in one patient who had an intraductal growth pattern. In a comparison of the self-expandable metallic stent (SEMS) and plastic stent (PS) after hilar ID-RFA, no differences in stent patency (89 vs 90.5 days, respectively; P = .912) and adverse events (20.0% vs 10%, respectively; P = .739) were observed.

CONCLUSIONS

ID-RFA at 7 W for 120 seconds is safe and feasible in patients with advanced perihilar cholangiocarcinoma. After ID-RFA, SEMS and PS placement showed comparable patency and survival rates.

TRIAL REGISTRATION NUMBER

KCT0003223.

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.

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.

Endoscopic Radiofrequency Ablation Prolongs Survival of Patients with Unresectable Hilar Cholangiocellular Carcinoma - A Case-Control Study

The life expectancy of unresectable hilar cholangiocellular carcinomas (CCCs) is very limited and endoscopic radiofrequency ablation (ERFA) of the biliary tract may prolong survival. Our single-center-study retrospectively analysed all CCC cases, in whom ERFAs of the biliary tract were performed between 2012 and 2017 and compared these to historical control cases who received the standard treatment of sole stent application. ERFA was performed in 32 patients with malignant biliary strictures that were mainly caused by Bismuth III and IV hilar CCCs (66%). 14 of these patients received repeated ERFAs, for an overall performance of 54 ERFAs. Stents were applied after examination of all patients (100%). Adverse events occurred in 18.5% of examinations. Case-control analysis revealed that the survival time of cases with unresectable Bismuth type III and IV hilar CCCs (n = 20) treated with combined ERFA and stent application significantly increased compared to controls (n = 22) treated with sole stent application (342 +/- 57 vs. 221 +/- 26 days; p = 0.046). In conclusion, ERFA therapy significantly prolonged survival in patients with unresectable Bismuth type III and IV hilar CCC. As an effective and safe method, ERFA should be considered as a palliative treatment for all these patients.

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.

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

BACKGROUND AND AIMS

Endobiliary radiofrequency ablation (EB-RFA) is a new adjunctive method for biliary drainage restoration. However, a concern remains about long-term adverse events of this procedure, such as biliary stricture, perforation, and hemorrhage. Therefore, we aimed to assess the long-term effects of in vivo EB-RFA in a swine model.

METHODS

Six mini-pigs were divided into 2 groups: 10-W/33-mm EB-RFA and 7-W/18-mm EB-RFA. Endoscopic retrograde cholangiography-guided temperature controlled EB-RFA (80°C, 7-10 W, 120 seconds) was performed. After 28 days all mini-pigs underwent follow-up ERC and were killed to assess the long-term effects of EB-RFA.

RESULTS

All mini-pigs developed biliary stricture (median length, 10.5 mm; range, 6-15) with jaundice (total bilirubin, 5.84 mg/dL; range, 4.3-9.2) and purulent bile at 1 month after EB-RFA. A significant difference was found in the length of stricture on cholangiogram between the 10 W/33-mm and 7 W/18-mm EB-RFA groups (median, 14 vs 6 mm; P = .034); however, no differences were found in the width of the stricture and laboratory findings. Histologic examination revealed marked thickening of bile duct with severe damage of whole layers replaced with reactive myofibroblastic proliferation, dense collagen laydown, chronic and acute inflammation, and fat necrosis. However, long-term adverse events, such as perforation or hemorrhage, were not found.

CONCLUSIONS

As a long-term result of EB-RFA, segmental biliary stricture with cholangitis develops in proportion to the power/length of the RFA electrode. Therefore, biliary stents should be placed to maintain biliary drainage after EB-RFA.

Safety and effect on ablation size of hydrochloric acid-perfused radiofrequency ablation in animal livers

PURPOSE

Our objective was to determine the safety and ablation size of hydrochloric acid-perfused radiofrequency ablation (HCl-RFA) in liver tissues, prospectively using in vivo rabbit and ex vivo porcine liver models.

MATERIALS AND METHODS

The livers in 30 rabbits were treated in vivo with perfusions of normal saline (controls) and HCl concentrations of 5%, 10%, 15%, and 20%, during RFA at 103 °C and 30 W for 3 min. For each experimental setting, six ablations were created. Safety was assessed by comparing baseline weight and selected laboratory values with those at 2, 7, and 14 days' post-ablation, and by histopathological analysis. The livers in 25 pigs were treated ex vivo with the same five perfusions during RFA at 103 °C, at both 30 W and 60 W, for 30 min. Ablation diameters and volumes were measured by two examiners.

RESULTS

Rabbit weights and selected laboratory values did not differ significantly from baseline to 7 and 14 days' post-ablation, liver tissues outside the ablation zones were normal histologically, and adjacent organs showed no macroscopic damage. The mean ablation volumes in the porcine livers treated with HCl-RFA were all larger than those treated with normal saline perfusion during RFA (NS-RFA), at both 30 W and 60 W (p < 0.001). The largest ablation volume and transverse diameter were observed in the porcine livers during 10% HCl-RFA at 60 W, measuring 179.22 (SD = 24.79) cm³ and 6.84 (SD = 0.36) cm, respectively.

CONCLUSIONS

Based on our experiments, HCl-RFA in the liver appears to be as safe as NS-RFA while also resulting in larger ablation zones.

Bile Duct Patency Maintained after Intraductal Radiofrequency Ablation in a Case of Hepatocellular Cholangiocarcinoma with Bile Duct Invasion

Combined hepatocellular-cholangiocarcinoma (HCC-CC) with bile duct invasion (BDI) is rare. In unresectable cases, biliary stent placement and photodynamic therapy (PDT) are used for resolving obstructive jaundice. However, stent occlusion remains problematic, and PDT is expensive and time-consuming. Intraductal radiofrequency ablation (RFA) is an emerging procedure for palliation in these patients. It has potential benefits including less expense, lower rates of severe complication, longer maintenance of ductal patency, and easier technique compared with PDT or stenting alone. We report a 67-year-old man who underwent repeated intraductal RFA for HCC-CC and HCC with BDI, for whom bile duct patency was maintained without additional biliary procedures.