Mucosal ablation devices

Non-Contact Irreversible Electroporation in the Esophagus With a Wet Electrode Approach

Our objective was to develop a technique for performing irreversible electroporation (IRE) of esophageal tumors while mitigating thermal damage to the healthy lumen wall. We investigated noncontact IRE using a wet electrode approach for tumor ablation in a human esophagus with finite element models for electric field distribution, joule heating, thermal flux, and metabolic heat generation. Simulation results indicated the feasibility of tumor ablation in the esophagus using an catheter mounted electrode immersed in diluted saline. The ablation size was clinically relevant, with substantially lesser thermal damage to the healthy esophageal wall when compared to IRE performed by placing a monopolar electrode directly into the tumor. Additional simulations were used to estimate ablation size and penetration during noncontact wet-electrode IRE (wIRE) in the healthy swine esophagus. A novel catheter electrode was manufactured and wIRE evaluated in seven pigs. wIRE was performed by securing the device in the esophagus and using diluted saline to isolate the electrode from the esophageal wall while providing electric contact. Computed tomography and fluoroscopy were performed post-treatment to document acute lumen patency. Animals were sacrificed within four hours following treatment for histologic analysis of the treated esophagus. The procedure was safely completed in all animals; post-treatment imaging revealed intact esophageal lumen. The ablations were visually distinct on gross pathology, demonstrating full thickness, circumferential regions of cell death (3.52 ± 0.89 mm depth). Acute histologic changes were not evident in nerves or extracellular matrix architecture within the treatment site. Catheter directed noncontact IRE is feasible for performing penetrative ablations in the esophagus while avoiding thermal damage.

Radiofrequency ablation compared with argon plasma coagulation after endoscopic resection of high-grade dysplasia or stage T1 adenocarcinoma in Barrett's esophagus: a randomized pilot study (BRIDE)

BACKGROUND AND AIMS

Endoscopic resection (ER) is safe and effective for Barrett's esophagus (BE) containing high-grade dysplasia (HGD) or mucosal adenocarcinoma (T1A). The risk of metachronous neoplasia is reduced by ablation of residual BE by using radiofrequency ablation (RFA) or argon plasma coagulation (APC). These have not been compared directly. We aimed to recruit up to 100 patients with BE and HGD or T1A confirmed by ER over 1 year in 6 centers in a randomized pilot study.

METHODS

Randomization was 1:1 to RFA or APC (4 treatments allowed at 2-month intervals). Recruitment, retention, dysplasia clearance, clearance of benign BE, adverse events, healthcare costs, and quality of life by using EQ-5D, EORTC QLQ-C30, or OES18 were assessed up to the end of the trial at 12 months.

RESULTS

Of 171 patients screened, 76 were randomized to RFA (n = 36) or APC (n = 40). The mean age was 69.7 years, and 82% were male. BE was <5 cm (n = 27), 5 to 10 cm (n = 45), and >10 cm (n = 4). Sixty-five patients completed the trial. At 12 months, dysplasia clearance was RFA 79.4% and APC 83.8% (odds ratio [OR] 0.7; 95% confidence interval [CI], 0.2-2.6); BE clearance was RFA 55.8%, and APC 48.3% (OR 1.4; 95% CI, 0.5-3.6). A total of 6.1% (RFA) and 13.3% (APC) had buried BE glands. Adverse events (including stricture rate after starting RFA 3/36 [8.3%] and APC 3/37 [8.1%]) and quality of life scores were similar, but RFA cost $27491 more per case than APC.

CONCLUSION

This pilot study suggests similar efficacy and safety but a cost difference favoring APC. A fully powered non-inferiority trial is appropriate to confirm these findings. (Clinical trial registration number: NCT01733719.).

Insights into the management of gastric antral vascular ectasia (watermelon stomach)

Gastric antral vascular ectasia (GAVE) is an uncommon but important cause of chronic gastrointestinal bleeding. It is often associated with systemic diseases such as autoimmune diseases, liver cirrhosis, chronic renal insufficiency and cardiovascular disease. The etiology of GAVE has not been fully explored and remains controversial. Diagnosis is mainly based on endoscopic presentation with flat or raised erythematous stripes radiating from the pylorus to the antrum and resembles a watermelon. Clinical presentation may range from iron-deficiency anemia secondary to occult blood loss, melena to hematemesis. In past decades, many therapeutic modalities including medical, endoscopic and surgical intervention have been introduced for GAVE treatment with variable efficacy. Herein, we review the efficacy and safety of these treatment options for GAVE.

Radiofrequency ablation of symptomatic cervical inlet patch using a through-the-scope device: a pilot study

BACKGROUND AND AIMS

The cervical inlet patch (CIP) is an area of heterotopic gastric mucosa at the proximal esophagus, which can secrete both acid and mucus. Attributable symptoms include chronic globus sensation and sore throat. Previous studies have demonstrated improvement in symptoms after ablation using argon plasma coagulation. Our aim was to assess a through-the-scope radiofrequency ablation (RFA) catheter for ablation of symptomatic CIP.

METHODS

Ten patients with endoscopically and histologically proven CIP and symptoms of globus or sore throat were included in the study. An ablation protocol of 3 ablations at 12 J/cm², without removal of coagulated tissue between ablations, was used. A maximum of 2 RFA sessions, 3 months apart, was allowed. A visual analog score was completed at baseline, 6 weeks (on proton pump inhibitor), 3 months (off proton pump inhibitor), and 12 months after treatment.

RESULTS

Mean patient age was 56 years (±3 years, standard error of the mean), 60% were men, and 80% were white. Barrett's esophagus was present in 50%. The mean number of CIPs was 2 (range, 1-4) with a median surface area of 2 cm² (range, .5-14). After a median of 2 treatments, 80% achieved complete endoscopic and histologic resolution, with a mean follow-up of 14 months (range, 12-17). Globus, sore throat, and cough significantly improved from baseline (P < .05). No strictures or buried glands were identified.

CONCLUSIONS

This prospective pilot study demonstrates that RFA using a through-the-scope device is safe and effective for treating patients with symptomatic CIP. One-year follow-up data suggest the effect is durable.

Chronic radiation proctopathy: A practical review of endoscopic treatment

Chronic radiation proctopathy (CRP) is a troublesome complication of pelvic radiotherapy. The most common presentation is rectal bleeding. CRP symptoms interfere with daily activities and decrease quality of life. Rectal bleeding management in patients with CRP represents a conundrum for practitioners. Medical therapy is ineffective in general and surgical approach has a high morbid-mortality. Endoscopy has a role in the diagnosis, staging and treatment of this disease. Currently available endoscopic modalities are formalin, potassium titanyl phosphate laser, neodymium:yttrium-aluminum-garnet laser, argon laser, bipolar electrocoagulation (BiCAP), heater probe, band ligation, cryotherapy, radiofrequency ablation and argon plasma coagulation (APC). Among these options, APC is the most promising.

Endoscopic assessment and management of early esophageal adenocarcinoma

Esophageal carcinoma affects more than 450000 people worldwide and the incidence is rapidly increasing. In the United States and Europe, esophageal adenocarcinoma has superseded esophageal squamous cell carcinoma in its incidence. Esophageal cancer has a high mortality rates secondary to the late presentation of most patients at advanced stages. Endoscopic screening is recommended for patients with multiple risk factors for cancer in Barrett’s esophagus. These risk factors include chronic gastroesophageal reflux disease, hiatal hernia, advanced age, male sex, white race, cigarette smoking, and obesity. The annual risk of esophageal cancer is approximately 0.25% for patients without dysplasia and 6% for patients with high-grade dysplasia. Twenty percent of all esophageal adenocarcinoma in the United States is early stage with disease confined to the mucosa or submucosa. The significant morbidity and mortality of esophagectomy make endoscopic treatment an attractive option. The American Gastroenterological Association recommends endoscopic eradication therapy for patients with high-grade dysplasia. Endoscopic modalities for treatment of early esophageal adenocarcinoma include endoscopic resection techniques and endoscopic ablative techniques such as radiofrequency ablation, photodynamic therapy and cryoablation. Endoscopic therapy should be precluded to patients with no evidence of lymphovascular invasion. Local tumor recurrence is low after endoscopic therapy and is predicted by poor differentiation of tumor, positive lymph node and submucosal invasion. Surgical resection should be offered to patients with deep submucosal invasion.

Gastric antral vascular ectasia: the evolution of therapeutic modalities

Gastric Antral Vascular Ectasia (GAVE) may be an enigmatic source of non-variceal upper GI bleeding associated with various systemic diseases such as connective tissue disorders, liver disease, and chronic renal failure. Successful treatment of GAVE continues to be a challenge and has evolved through the years. Currently, given the rapid response, safety, and efficacy, endoscopic ablative modalities have largely usurped medical treatments as first-line therapy, particularly using argon plasma coagulation. However, other newer ablative modalities such as radiofrequency ablation, cryotherapy, and band ligations are promising. This paper is an overview of GAVE and its various endoscopic and medical therapies.

Efficacy of argon plasma coagulation in the treatment of radiation-induced hemorrhagic gastroduodenal vascular ectasia

OBJECTIVE

Radiation-induced hemorrhagic gastroduodenal vascular ectasia (GDVE) is rare but difficult to manage. Argon plasma coagulation (APC) has not yet been evaluated in the treatment of radiation-induced hemorrhagic GDVE. The efficacy of APC in patients with radiation-induced hemorrhagic GDVE has been investigated in this article.

MATERIAL AND METHODS

Eighteen patients with upper gastrointestinal (GI) bleeding caused by radiation-induced GDVE, including 13 with hepatocellular carcinoma, 3 with pancreatic cancer, and 2 with cholangiocarcinoma, were treated with APC. The efficacy of APC was retrospectively evaluated, based on cessation of macroscopic GI bleeding, resolution or stabilization of anemia and transfusion dependence, endoscopic ablation of almost all vascular lesions, complications, and recurrence.

RESULTS

Mean patient age was 59 years (range 42-80 years). The median time from radiation to GDVE diagnosis was 4.6 months (range 3.3-21.5 months). The median number of APC sessions per patient was 2.4 (range 1-4). All 18 patients showed an endoscopic response to APC treatment, with sustained increases in mean hemoglobin level, from 6.6 g/dL (range 2.9-9.5 g/dL) to 9.7 g/dL (range 7.1-12.7 g/dL) (p < 0.001), and decreased dependence on transfusion, from 9.1 (range 0-30) to 4.1 (range 0-15) units of packed red blood cells per patient (p = 0.038) after last endoscopic eradication by APC treatment. There were no major procedure-related adverse events or deaths. At a median follow up of 4.7 months (range 0.6-24.5 months), none of the patients experienced recurrence of GDVE.

CONCLUSIONS

APC showed short-term effectiveness and safety in the treatment of radiation-induced hemorrhagic GDVE.

Dose-dependent depth of tissue injury with carbon dioxide cryotherapy in porcine GI tract

BACKGROUND

Cryotherapy is a method of endoscopic mucosal ablation that involves delivery of a cryogen to result in tissue destruction by extreme low temperature. Its effects are influenced by the dosage of cryogen and thawing of ice. There are limited data on the tissue effects of multiple freeze and thaw cycles of carbon dioxide (CO(2)) cryotherapy on GI tissues.

OBJECTIVE

To investigate the extent of tissue injury due to escalating doses of CO(2) cryotherapy on the esophagus, stomach, and colon of pigs.

DESIGN

Animal experiment.

INTERVENTION

Varying doses of CO(2) cryotherapy with increasing number of freeze-thaw cycles were applied to each site. The animals were allowed to survive for 48 hours.

MAIN OUTCOME MEASUREMENTS

Depth of tissue injury assessed in blinded fashion by varying doses of cryotherapy on a defined area of porcine esophagus, stomach, and colon.

RESULTS

There was a dose-dependent relationship of CO(2) cryogen and depth of injury (P = .0001 and P = .002, respectively). In the stomach, the dose-response relationship was significant (P = .007), but the average grades of injury across the various doses were lower when compared with the esophagus at comparable cryogen doses (P = .0004). The estimated depth of tissue injury from the mucosal surface in the porcine esophagus and colon tissue ranged from 1.2 to 2.5 mm and 1.3 to 2.5 mm, respectively.

LIMITATIONS

The study was performed in a normal porcine model.

CONCLUSION

There was a dose-dependent relationship between the dose of CO(2) cryotherapy and the depth of tissue injury in the porcine esophagus, stomach, and colon.

Endoscopic ablation therapy for gastrointestinal superficial neoplasia

AIM

  In Japan, endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have been widely accepted and standardized for the treatment of gastrointestinal superficial neoplasia.

METHODS

  In contrast, mucosal ablation techniques are more common in Western countries and a variety of endoscopic ablation modalities, including argon plasma coagulation (APC), photodynamic therapy (PDT) and lasers, are used.

RESULTS

  Recently developed modalities such as radiofrequency ablation (RFA) and cryotherapy are also available for the treatment of superficial lesions such as dysplasia of Barrett's esophagus.

CONCLUSION

  Although we should understand that the completeness of destruction of neoplastic tissue can only be judged at follow up, endoscopic ablation is a viable alternative to endoscopic resection for dysplasia and early-stage malignancies, especially for poor candidates of surgery or endoscopic resection.

Assessment on the potential role of applying cryoprobe for tissue ablation

Background/Aims

Cryotherapy is the therapeutic application for tissue ablation. Clinical applications of cryotherpy such as in pulmonology have increased. Until now, its development in gastroenterology has been insignificant. But, as clinical application such as mucosal ablation on Barrett's esophagus became possible, various applications have been developed. Therefore, it is important to make standards of tissue injury's extent in cryotherapy prior to clinical trial. We evaluated the tissue injury according to the application of cryoprobe with a pig model.

Methods

Cryoprobe was applied to several different segments of the esophagus and stomach for various lengths of time using various number of probe's contact in a pig model. After 48 hours, esophagus and stomach were harvested and histological tissue injury was assessed. The extent of tissue injury was decided by the injury of the deepest layer.

Results

Endoscopic application of cryoprobe on esophagus and stomach resulted in a dose-dependent injury: esophageal necrosis was limited to the submucosa after 10 seconds of cryotherapy, and extended to involve the transmural necrosis after over 15 seconds. Necrosis on stomach was extended to involve the transmural necrosis after over 20 seconds.

Conclusions

Positive relationship was seen between the duration and frequency of cryoprobe application and the extent of tissue injury.

Changes in screening, prognosis and therapy for esophageal adenocarcinoma in Barrett's esophagus

PURPOSE OF REVIEW

Significant changes in concepts of managing Barrett's esophagus have led to change in the recommendations concerning screening, surveillance, biomarkers, and therapies in this condition over the past several years. We summarize the important changes in this regard.

RECENT FINDINGS

Narrow band imaging and esophageal capsule endoscopy are alternative methods to screen for Barrett's esophagus. Narrow band imaging provides clear visualization of the mucosal pit patterns and vascular patterns, which improve the diagnostic value for specialized intestinal mataplasia. Esophageal capsule endoscopy is a new potential tool that allows a direct noninvasive visualization of esophagus. Research efforts are currently directed towards risk stratification of patients and biomarkers have been developed to predict development of esophageal adenocarcinoma. Recent studies have reported that frequent loss of heterozygosity (LOH) as well as allelic imbalances in chromosomes in esophageal adenocarcinoma. Fluorescent in-situ hybridization technique, which uses fluorescently labeled DNA probes to detect chromosomal alterations in cells, obtained from cytology specimens has been developed. It showed more sensitive and specific for abnormalities than PCR based techniques. Currently, many studies support the concept of endoscopic elimination of dysplastic lesions in the esophagus by a mucosal ablation therapy. Photodynamic therapy and radiofrequency ablation are recently developed, emerging techniques.

SUMMARY

Recent advances in screening; prognostication and therapy for esophageal adenocarcinoma in Barrett's esophagus have brought a significant new insight in clinical practices and will eventually ensure better patients outcomes.