Ex vivo and in vivo models for endoscopic submucosal dissection training

Auxetic solution for enhanced esophageal brachytherapy applicator

Purpose

In this study, a novel auxetic applicator equipped with four-channel catheters for esophageal brachytherapy was presented.

Material and methods

The applicator, made of a new biocompatible material, has an auxetic helical structure with four channels. Details of applicator modeling, construction, commissioning, and insertion were provided. Initial ex vivo trial conducted on a porcine model was outlined.

Results

Simulations and dose calculations closely matched experimental measurements, validating the modeling approach. This applicator achieved highly asymmetric dose distributions. Its unique auxetic helical design allowed smooth insertion, while mitigating sequential inter-fraction hot spot formation.

Conclusions

Ex vivo implementation of the applicator demonstrated feasibility, resulting in consistent and reproducible dose distributions. Initial outcomes showed promise for the applicator's efficacy and versatility in intra-luminal or intra-cavitary applications.

Intraoperative bleeding model for swine gastric endoscopic submucosal dissection via heparinization

Background and study aims: Live swine have a high degree of coagulation and aggregation and using them for training about how to manage intraoperative bleeding during endoscopic submucosal dissection (ESD) is unsatisfactory. This study aimed to identify the appropriate heparin dose in an intraoperative bleeding model and validate its applicability. Methods: First, we explored the dose of heparin required for a swine bleeding model in which the activated clotting time reached and maintained the upper limit of measurement (1500 s) after 10 minutes. Second, we compared intraoperative bleeding and hematoma frequency during ESD for 2-cm lesions between the heparinized bleeding model and control groups. Intraoperative bleeding was classified according to the Forrest classification. Results: The combination of a bolus (300 U/kg), continuous infusion (300 U/kg/h), and a bolus dose (150 U/kg) of heparin 10 minutes after the first infusion was identified as the dose for the bleeding model. Five ESDs were performed in each heparinized bleeding model and the control group. The median number of intraoperative bleeds was significantly higher in the heparinized model than in the control group (5 interquartile range [IQR] 4-7 vs. 3 [IQR 0-4, P = 0.028). All of the intraoperative bleeding events oozing (Forrest Ib) rather than spurting (Forrest Ia). The median number of hematomas was significantly higher in the heparinized model group than in the control group (3 [IQR 1-4] vs. 0 [IQR 0-1], P = 0.023). Conclusions: High doses of heparin significantly increased intraoperative bleeding and hematoma during swine ESD.

Novel quantitative assessment indicators for efficiency and precision of endoscopic submucosal dissection in animal training models by analyzing an electrical surgical unit

OBJECTIVES

Although endoscopic submucosal dissection (ESD) training is important, quantitative assessments have not been established. This study aimed to explore a novel quantitative assessment system by analyzing an electrical surgical unit (ESU).

METHODS

This was an ex vivo study. Step one: to identify the novel efficiency indicators, 20 endoscopists performed one ESD each, and we analyzed correlations between their resection speed and electrical status. Step two: to identify the novel precision indicators, three experts and three novices performed one ESD each, and we compared the stability of the electrical status. Step three: three novices in step two performed 19 additional ESDs, and we analyzed the learning curve using novel indicators.

RESULTS

Step one: the percentage of total activation time (AT) of ESU in the procedure time (β coefficient, 0.80; P < 0.01) and AT required for submucosal dissection (β coefficient, -0.57; P < 0.01) were significantly correlated with the resection speed. Step two: coefficient of variation of the AT per one pulse (0.16 [range, 0.13-0.17] vs. 0.26 [range, 0.20-0.41], P = 0.049) and coefficient of variation of the peak electric power per pulse during mucosal incision (0.14 [range, 0.080-0.15] vs. 0.25 [range, 0.24-0.28], P = 0.049) were significantly lower in the experts than in the novices. Regarding the learning curve, the percentage of total AT of ESU in the procedure time and AT required for submucosal dissection had a trend of improvement.

CONCLUSION

Novel indicators identified by analyzing ESU enable quantitative assessment for endoscopist's skill.

Usefulness of a new polyvinyl alcohol hydrogel (PVA-H)-based simulator for endoscopic submucosal dissection training: a pilot study

BACKGROUND/AIMS

We developed a new endoscopic submucosal dissection (ESD) simulator and evaluated its efficacy and realism for use training endoscopists.

METHODS

An ESD simulator was constructed using polyvinyl alcohol hydrogel sheets and compared to a previous ESD simulator. Between March 1, 2020, and December 30, 2021, eight expert endoscopists from three different centers analyzed the procedure-related factors of the simulator. Five trainees performed gastric ESD exercises under the guidance of these experts.

RESULTS

Although the two ESD simulators provided overall favorable outcomes in terms of ESD-related factors, the new simulator had several benefits, including better marking of the target lesion's limits (p<0.001) and overall handling (p<0.001). Trainees tested the usefulness of the new ESD simulator. The complete resection rate improved after 3 ESD training sessions (9 procedures), and the perforation rate decreased after 4 sessions (12 procedures).

CONCLUSION

We have developed a new ESD simulator that can help beginners achieve a high level of technical experience before performing real-time ESD procedures in patients.

The colonoscopic vacuum model-simulating biomechanical restrictions to provide a realistic colonoscopy training environment

INTRODUCTION

Practicing endoscopic procedures is fundamental for the education of clinicians and the benefit of patients. Despite a diverse variety of model types, there is no system simulating anatomical restrictions and variations in a flexible and atraumatic way. Our goal was to develop and validate a new modelling approach for adhesion forces between colon and abdominal wall.

METHODS

An inlay for a standard mechanical trainer was designed and 3D printed. Colon specimens were fixed to the inlay along colon ascendens (CA) and colon descendens (CD) by a vacuum. Our system, which we refer to as Colonoscopy Vacuum Model (CoVaMo), was validated with 11 test persons with varying level of expertise. Each performed one colonoscopy and one polypectomy in the CoVaMo and in the Endoscopic Laparoscopic Interdisciplinary Training Entity (ELITE). Achieved adhesion forces, times required to fulfill different tasks endoscopically and a questionnaire, assessing proximity to reality, were recorded.

RESULTS

Mean adhesion forces of 37 ± 7 N at the CA and 30 ± 15 N at the CD were achieved. Test subjects considered CoVaMo more realistic than ELITE concerning endoscope handling and the overall anatomy. Participants needed statistically significantly more time to maneuver from anus to flexura sinistra in CoVaMo (377 s ± 244 s) than in ELITE (58 s ± 49 s).

CONCLUSION

We developed a training environment enabling anatomically and procedural realistic colonoscopy training requiring participants to handle all endoscope features in parallel. Fixation forces compare to forces needed to tear pig colon off the mesentery. Workflow and inlay can be adapted to any arbitrary ex vivo simulator.

Simulator-based training method in gastrointestinal endoscopy training and currently available simulators

The apprenticeship-based training method (ABTM) is highly effective for gastrointestinal (GI) endoscopic training. However, the conventional ABTM has significant issues. Although many supplementary training methods (TMs) have been developed and utilized, they cannot entirely replace the ABTM, which remains the major TM strategy. Currently, new TM construction is crucial and necessary due to financial constraints, difficulty of obtaining sufficient training time due to patient safety-related regulations, and catastrophic damage caused by disasters such as the coronavirus disease 2019 pandemic. The simulator-based TM (SBTM) is widely accepted as an alternative to the ABTM, owing to the SBTM's advantages. Since the 1960s, many GI endoscopy training simulators have been developed and numerous studies have been published on their effectiveness. While previous studies have focused on the simulator's validity, this review focused on the accessibility of simulators that were introduced by the end of 2021. Although the current SBTM is effective in GI endoscopic education, extensive improvements are needed to replace the ABTM. Incorporating simulator-incorporated TMs into an improved ABTM is an attempt to overcome the incompleteness of the current SBTM. Until a new simulator is developed to replace the ABTM, it is desirable to operate a simulator-integrated and well-coordinated TM that is suitable for each country and institution.

A survey of physician training and credentialing in endoscopic submucosal dissection in the United States

BACKGROUND

Endoscopic submucosal dissection (ESD) is technically challenging, has a longer learning curve and a greater complication rate than most new endoscopic procedures. Formal training and credentialing guidelines for ESD are currently lacking in the United States (US).

AIM

To survey ESD experts across the US to determine their learning process and obtain their opinion on how training and credentialing for ESD should develop.

DESIGN

Anonymous electronic survey.

SUBJECTS

ASGE members who are practicing US endoscopists.

METHODS

The survey was developed by iterative revisions of questions administered to three investigators who have been performing ESD for > 5 years. The final survey was distributed electronically to US endoscopists who had previously attended ESD expert conferences.

RESULTS

Thirty-five (58.3%) of 60 practicing ESD experts responded to the survey. A majority (91%) were in university-based, community, or tertiary care hospitals. All practitioners practiced on porcine explants and observed live ESD procedures as part of the training. Out of the participants, 75.8% received formal supervised hands-on training on porcine explants and/or humans before performing ESD independently. Fifty percent indicated that their facility had written guidelines specifically for ESD credentialing. Four out of 5 felt that credentialing requirements should include attending weekend ESD courses, observing live procedures, practicing on explants, and advanced endoscopic training in interventional endoscopy such as an additional year of fellowship.

LIMITATIONS

Survey completion rate of 58.3%.

CONCLUSION

ESD training should include practicing on explants, observation of live procedures, training in interventional endoscopy, and attending educational courses. Credentialing guidelines for ESD based on expert opinion need to be developed in the US.

Comparison of sodium alginate-based and sodium hyaluronate-based submucosal injection materials based on rheological analysis

As a viscous high-performance submucosal injection material (SIM) used in endoscopic submucosal dissection (ESD), sodium alginate-based SIM (SA-SIM) was recently introduced as high-performance SIM equivalent to sodium hyaluronate-based SIM (HA-SIM) in Japan. However, a comprehensive, detailed comparison of SA and HA is yet to be performed. In this study, we precisely measured the viscoelastic properties, submucosal elevation height (SEH), and injection pressure (IP). Furthermore, we compared the outcomes of ESD using an ex vivo ESD model. There was no significant difference in SEHs between HA-SIM and SA-SIM at all post-injection times, and the IP of the SA-SIM injection was significantly higher than that of the HA-SIM injection in all conditions (P < 0.0001). The viscosity at high shear rates of SA-SIM was higher than that of HA-SIM; this result was consistent with SEH/IP measurement results. No significant difference was observed in ESD procedure time and total volume of injected SIM between HA-SIM and SA-SIM (18.1 ± 6.7 and 17.8 ± 6.0 min, P = 0.8987; 13.3 ± 5.3 and 11.6 ± 5.9 ml, P = 0.4658, respectively). Although SA-SIM was slightly more difficult to inject than HA-SIM, there was no significant difference in performance between the materials. Thus, this basic study demonstrated that SA-SIM can be used for endoscopic treatment as well as HA-SIM, and supported previous clinical research data.

Differences between two sodium hyaluronate-based submucosal injection materials currently used in Japan based on viscosity analysis

In Japan, two 0.4% sodium hyaluronate (HA)-based submucosal injection materials (SIMs) are currently used in endoscopic submucosal dissection (ESD): MucoUp (HA-Mc) and Ksmart (HA-Ks). HA-Mc and HA-Ks have the same concentration and are, thus, construed by most endoscopists to have no difference. Nevertheless, visual observation conveys the impression that HA-Ks have a higher viscosity than HA-Mc, suggesting that HA-Ks performs better than HA-Mc. This study aimed to examine the differences between HA-Mc and HA-Ks. HA-Ks exhibited higher viscosity due to greater weight-average molecular weight compared with HA-Mc. HA-Ks had significantly greater submucosal elevation height (SEH) than HA-Mc; the SEH of HA-Ks-80% (80% dilution of HA-Ks) was the same as that of HA-Mc. The ESD procedure time was significantly shorter with HA-Ks than with HA-Mc (15.2 ± 4.1 vs. 19.5 ± 5.9; P = 0.049). The total injection volume for HA-Ks was significantly lower than that for HA-Mc (10.8 ± 3.6 vs. 14.4 ± 4.6; P = 0.045). However, no significant difference in these items was observed between HA-Mc and HA-Ks-80%. HA-Mc and HA-Ks were considered to be almost the same. Nonetheless, HA-Ks exhibited higher viscosity and SIM performance than HA-Mc. HA-Ks-80% had almost the same performance as HA-Mc. Thus, understanding SIM performance and characteristics requires a focus on the viscosity of SIMs.

An innovative next-generation endoscopic submucosal injection material with a 2-step injection system (with video)

BACKGROUND AND AIMS

Next-generation submucosal injection materials (SIMs) with higher performance and flexibility than the current SIMs (eg, 0.4% sodium hyaluronate solution [HA]) are expected to improve the outcomes of endoscopic submucosal dissection (ESD) but are difficult to develop. We developed a next-generation SIM by devising a 2-solution-type SIM comprising 2.0% calcium chloride solution (Ca) and 0.4% sodium alginate solution (SA) and evaluated its performance.

METHODS

Viscoelasticity, submucosal elevation height, and injection pressure of HA, SA, and the next-generation SIM were measured. Outcomes of ESDs on pseudo-lesions in ex vivo porcine stomach/colon models were compared.

RESULTS

The dramatic increase in SA viscoelasticity with the addition of Ca facilitated the formation of highly viscous submucosal cushions that can be controlled by endoscopists. The submucosal elevation height of the next-generation SIM was significantly higher than that of HA or SA with the same injection pressure. The ESD procedure time using the next-generation SIM was significantly shorter than that using HA or SA (14.2 ± 6.1 vs 29.2 ± 9.1 minutes, P = .0004, or 14.2 ± 6.1 vs 29.1 ± 5.9 minutes, P <.0001). Furthermore, the total injection volume for the next-generation SIM was considerably lower than that for HA or SA (7.0 ± 0.9 vs 17.2 ± 3.4 mL, P <.0001, or 7.0 ± 0.9 vs 16.2 ± 2.9 mL, P <.0001).

CONCLUSIONS

We developed an ideal next-generation SIM that achieved high performance and high flexibility in ex vivo models. Our findings warrant further investigations in a patient population.

Current state of education and training for endoscopic submucosal dissection: Translating strategy and success to the USA

Endoscopic submucosal dissection (ESD) is a rigorous and technically sophisticated method for removal of lesions within the gastrointestinal tract. Despite having advantages of en-bloc resection of lesions, regardless of size, and widespread use in Japan and Asia, ESD has not become widely adopted in the USA for a variety of reasons. Based upon Japanese education and the master-apprentice model, modification to the education system and additional techniques designed to facilitate broader adoption are required for trainees in the USA. This article will review the current state of education and training for ESD in the USA.

Development of Sodium Polyacrylate-Based High-Performance Submucosal Injection Material with Pseudoplastic Fluid Characteristics

The development of high-performance submucosal injection materials (SIMs) has significantly contributed to the advancement of rapid and safe endoscopic submucosal dissection (ESD). A previous study authored by us described that pseudoplastic fluid was more suitable for high-performance SIMs than Newtonian fluid. Herein, a novel high-performance SIM is developed, which is primarily composed of sodium polyacrylate (SPA) and exhibits pseudoplastic fluid characteristics. As a representative of current high-performance SIMs with Newtonian fluid characteristics, 0.4% sodium hyaluronate (HA) was selected as the target for comparison. Further, viscoelasticity, submucosal elevation height (SEH), and injection pressure (IP) of HA and SPA were evaluated. The results obtained by ESD were compared using HA or SPA in an ex vivo model. According to the measured viscoelasticity, the concentration of SPA was adjusted to 0.07%; this was aimed at obtaining the IP of SPA, which is equal to that of 0.4% HA. Moreover, no significant difference was observed between the IP values (31.6 ± 1.7 vs 31.4 ± 3.1 psi). SEHs of 0.07% SPA were higher than those of 0.4% HA at all postinjection times (P < 0.001). The duration of the ESD procedure using 0.07% SPA was significantly shorter than that obtained using 0.4% HA (16.6 ± 3.7 vs 22.2 ± 2.9 min, P = 0.0276); further, the total volume of the injected 0.07% SPA was significantly less than that of 0.4% HA (9.0 ± 3.1 vs 15.7 ± 3.9 mL, P = 0.0165). Based on rheological analysis, a high-performance SIM (0.07% SPA) with pseudoplastic fluid characteristics was theoretically developed. It was observed that the SIM performance of 0.07% SPA was higher than that of 0.4% HA.

How to master endoscopic submucosal dissection in the USA

Endoscopic submucosal dissection (ESD) is an established technique for the endoscopic therapy of dysplastic and early cancerous lesions throughout the gastrointestinal tract. The procedure requires both a sophisticated knowledge for lesion characterization and high-level endoscopic skills. As a result, the learning curve is very steep and, in Japan, it takes years to gain proficiency under the traditional Master-Apprentice teaching model. At present, as a result of multiple limitations, this training model is not applicable to the USA. Nevertheless, a unique, multipronged, stepwise approach has emerged as a viable pathway to train US endoscopists in ESD. Although this approach deserves refinement, it has already led to the expansion of ESD in the USA, has contributed to the widening of the indications for ESD, and has further developed ESD techniques. Multiple challenges remain, but they can be overcome by active collaboration between Japanese and US endoscopists and professional societies. The robust interest in ESD in the USA has drawn industry attention with a few innovations already coming to fruition and many more in development.

A local structured training program with live pigs allows performing ESD along the gastrointestinal tract with results close to those of Japanese experts

BACKGROUND AND AIMS

The high specific skill needed by ESD limit its widespread use in Europe and animal training is recommended in Europe to improve the results of ESD that are far from Japanese at present. We create a local training program using live pigs as models, along with our human cases, to provide continuous exposure to the technique.

METHODS

Between February 2013 and December 2015, two young operators performed 55 pig gastric ESDs in parallel with 62 human cases for large superficial cancerous lesions. The number and training dates of pig cases were adapted to those of the human cases to achieve continuous exposure to ESD cases.

RESULTS

The en bloc, R0, and curative resection rates were 100%, 85.5% (53/62), and 77.5% (48/62), respectively with no recurrence observed during the one year follow up. There was no statistically significant difference in terms of the R0 or curative resection rates among ESDs performed during 2013-2015 (R0: 80% vs. 86.6% vs. 86.4%; Curative: 80% vs. 86.6% vs. 73%).

CONCLUSION

A local structured training program using live pig models was used to train endoscopists for ESD in humans with high safety and efficiency, similar to results published by Japanese experts.

Endoscopic submucosal dissection

ESD is an established effective treatment modality for premalignant and early-stage malignant lesions of the stomach, esophagus, and colorectum. Compared with EMR, ESD is generally associated with higher rates of en bloc, R0, and curative resections and a lower rate of local recurrence. Oncologic outcomes with ESD compare favorably with competing surgical interventions, and ESD also serves as an excellent T-staging tool to identify noncurative resections that will require further treatment. ESD is technically demanding and has a higher rate of adverse events than most endoscopic procedures including EMR. As such,sufficient training is critical to ensure safe conduct and high-quality resections. A standardized training model for Western endoscopists has not been clearly established,but will be self-directed and include courses, animal model training, and optimally an observership at an expert center.Numerous dedicated ESD devices are now available in the United States from different manufacturers. Although the use of ESD in the United States is increasing, issues related to technical difficulty, limited training opportunities and mentors, risk of adverse events, long procedure duration,and suboptimal reimbursement may limit ESD adoption in the United States to a modest number of academic referral centers for the foreseeable future.

Colorectal endoscopic submucosal dissection from a Western perspective: Today’s promises and future challenges

Over the last few years, endoscopic submucosal dissection (ESD) has shown to be effective in the management of early colorectal neoplasms, particularly in Asian countries where the technique was born. In the Western world, its implementation has been slow and laborious. In this paper, the indications for ESD, its learning model, the available methods to predict the presence of deep submucosal invasion before the procedure and the published outcomes from Asia and Europe will be reviewed. Since ESD has several limitations in terms of learning achievement in the West, and completion of the procedure for the first cases is difficult in our part of the world, a short review on colorectal assisted ESD has been included. Finally, other endoscopic and surgical treatment modalities that are in competition with colorectal ESD will be summarized.

Impact of formal training in endoscopic submucosal dissection for early gastrointestinal cancer: A systematic review and a meta-analysis

AIM: To summarize the clinical impact of a formal training for the effectiveness and safety of endoscopic submucosal dissection for gastrointestinal cancer.

METHODS: We searched databases including PubMed, EMBASE and the Cochrane Library and Science citation Index updated to August 2014 to include eligible articles. In the Meta-analysis, the main outcome measurements were en bloc resection rate, local recurrence rate (R0) and the incidence of procedure-related complications (perforation, bleeding).

RESULTS: En bloc resection was high for both, dissecting stomach tumors with an overall percentage of 93.2% (95%CI: 90.5-95.8) and dissecting colorectal tumors with an overall percentage of 89.4% (95%CI: 85.1-93.7). Although the number of studies reporting R0 resection (the dissected specimen was revealed free of tumor in both vertical and lateral margins) was small, the overall estimates for R0 resection were 81.4% (95%CI: 72-90.8) for stomach and 85.9% (95%CI: 77.5-95.5) for colorectal tumors, respectively. The analysis showed that the percentage of immediate perforation and bleeding were very low; 4.96 (95%CI: 3.6-6.3) and 1.4% (95%CI: 0.8-1.9) for colorectal tumors and 3.1% (95%CI: 2.0-4.1) and 4.8% (95%CI: 2.8-6.7) for stomach tumors, respectively.

CONCLUSION: In order to obtain the same rate of success of the analyzed studies it is a necessity to create training centers in the western countries during the “several years” of gastroenterology residence first only to teach EGC diagnose and second only to train endoscopic submucosal dissection.

New isolated bovine colon model dedicated to colonic ESD hands-on training: development and first evaluation

INTRODUCTION

ESD is the reference method to achieve en bloc resections for large digestive lesions. Nevertheless, it is a difficult and risky technique. Animal models exist to teach the initial skills, particularly in Japan, where pigs' stomachs are dedicated models to gastric ESD. In Europe, we have to develop different strategies of teaching with dedicated colon models. A pig colon is a good model but thinner and narrower than a human's. In this present work, we evaluated a bovine colon model to perform rectal ESD in retroflexion.

METHODS

First, we prepared six bowels to precise the preparation protocol. Then, two endoscopists unexperienced in ESD performed 64 procedures on eight models. Learning curves and factors of variation were studied.

RESULTS

A precise protocol to prepare the colon was defined. The two students achieved en bloc resection in 89.1 % of cases with a rate of 6.2 % of perforations. A large heterogeneity appeared between the speed and the success rate depending mainly on the age of the animal bowel. Using calf colons, the failure rates were higher (p = 0.002) and the speed was lower (p < 0.001) than for adult bovine ones. A learning curve appeared with, respectively, 0.49 and 0.59 cm(2)/min throughout the study. No significant difference appeared between measured and calculated specimen areas.

DISCUSSION

Bovine colon is a new model to teach ESD in colorectal conditions. The bovine age is important to homogenize the model. A learning curve existed with a time procedure decreasing throughout the study. Further studies are needed to evaluate the precise learning curve with more students.

CONCLUSION

A bovine colon model is a suitable model to teach colorectal ESD. Nevertheless, an adult bovine colon model is more homogeneous than a calf one.

Future perspective of gastric cancer endotherapy

Endoscopic resection of early gastric cancer (EGC) has proven safety and efficacy, and is the established standard of care in Japan. In the past decade, it is increasingly established worldwide. The endoscopic submucosal dissection (ESD) is superior to endoscopic mucosal resection (EMR) technique as it is designed to provide adequate staging and long-term curative therapy-based on the en bloc R0 specimen irrespective of the size and/or location of the tumor coupled with the reliable pathological specimen. However, ESD is still requiring skilled and experienced endoscopist to perform because of complex procedures, higher complication and causing long-time consuming. The learning and application of these relatively complex endoscopic techniques for EGC has been shown across the world. Thus, a standardized ESD training system is urgently needed to disseminate safe and effective ESD technique to practices with limited ESD experience. In recent years, several innovations providing solutions to easier and safer performance of ESD have emerged. Those increase control of surgical effectors manipulating the target tissue, and enhance performance in complex surgical tasks. Very recently, the use of the laparoscopic and endoscopic cooperative surgery (LECS) procedure is indicated for EGC that would be difficult to treat with ESD. As an ultimate gastric cancer endotherapy with a reasonable surgical time, LECS might be promising method at this stage. The indications for LECS for EGC could be expanded in the future, which could result in increasingly successful gastric cancer treatment.

Training methods and models for colonoscopic insertion, endoscopic mucosal resection, and endoscopic submucosal dissection

Colonoscopic examination is considered an effective examination for the detection of colorectal cancers. Additionally, early colorectal cancers can be resected using endoscopic techniques such as endoscopic mucosal resection and endoscopic submucosal dissection. However, those examinations and treatments need special techniques. Various training methods are practiced to acquire such endoscopic techniques throughout the world. In clinical cases, magnetic positioning devices help endoscopic insertion by less experienced endoscopists. There is a physical model made by polyvinyl chloride and a virtual simulator for training of colonoscopic insertion. Various techniques including a method to apply pressure to the abdomen and consideration for patient's pain can be trained using these models. In view of extensive training of endoscopic mucosal resection and endoscopic submucosal dissection, animal models are useful and actually used. Live animal models of minipig, which entails blood flow, are ideal and used frequently, but are cumbersome to prepare. On the other hand, ex vivo animal models using intestine of porcine and bovine are convenient for preparation and less expensive. Unique ex vivo animal models with blood flow have been developed recently and techniques for hemostasis can be practiced. With respect to a method of training for colorectal endoscopic submucosal dissection, a stepwise system has been adopted throughout the world. Thus, first they observe the expert's technique, then practice training of animal models, and finally, they perform clinical rectal cases. The system is useful for a safe and definite procedure. In this review, we reveal various training methods for colonoscopic examinations and treatments.

ESD around the world: United States

Endoscopic submucosal dissection (ESD) is a well-established advanced mucosal resection technique used in Japan, where it originated, and some other Asian countries. The technical difficulty and potentially higher rates of significant complications have been obstacles for its dissemination across the United States, on top of the lack of available equipment, candidate lesions in the gastrointestinal tract, and adequate training programs. Yet American physicians are becoming increasingly aware of the benefits of ESD. Simplification of technique, modification of tools and materials, and improved availability of training opportunities are essential in order to accelerate the adoption of ESD in the United States.

Gastric ESD: current status and future directions of devices and training

Endoscopic mucosal resection (EMR) of early gastric cancer, which has been proved to be safe and effective and is the established standard of care in Japan, has become increasingly established worldwide in the past decade. Endoscopic submucosal dissection (ESD) is superior to EMR, as it is designed to provide precise pathologic staging and long-term curative therapy based on an en bloc R0 specimen irrespective of the size and/or location of the tumor. However, ESD requires highly skilled and experienced endoscopists. The introduction of ESD to the Western world necessitates collaborations between Eastern and Western endoscopists, pathologists, and surgeons.

Colorectal ESD: current indications and latest technical advances

The number of medical facilities that perform colorectal endoscopic submucosal dissection (ESD) has been growing, and its effectiveness has been increasingly reported in recent years. Indications approved by the Japanese government's medical insurance system are early colorectal cancers with a maximum tumor size of 2-5 cm. ESD was an effective procedure for treating noninvasive colorectal tumors difficult to resect en bloc by conventional EMR, resulting in a higher en bloc resection rate that is less invasive than surgery. Based on the excellent clinical results of colorectal ESDs, the Japanese health care insurance system has approved colorectal ESD for coverage.

Gastric endoscopic submucosal dissection: From animal model to patient

AIM: To assess whether the use of porcine models is useful for learning endoscopic submucosal dissection (ESD), thus contributing to its subsequent application in human patients.

METHODS: This study/learning process was carried out in 3 phases: Phase I: Ex vivo animal; Phase II: In vivo animal; Phase III: Humans. One endoscopist performed 30 gastric ESDs in porcine models, and later 5 gastric ESDs in 5 patients. The ESD was done following the method practiced at the National Cancer Center in Tokyo, Japan. Technical aspects, size, time and speed of ESD, as well as complications were registered. In patients, their clinical, endoscopic and histologic evolution was additionally added.

RESULTS: Thirty en bloc ESDs were carried out in animal models. The mean ± SD size of the pieces was of 28.4 ± 1.2 mm, and the time of ESD was 41.7 ± 2.4 min. The time of ESD in the first 15 procedures was 43.0 ± 3.0 min whereas in the next 15 procedures, the time was 40.3 ± 3.9 min, P = 0.588. The speed in the first 15 ESDs was 1.25 ± 0.11 cm²/min vs 2.12 ± 0.36 cm²/min in the remaining 15, P = 0.028. There were no complications. In patients, 5 lesions were resected en bloc. The size of the pieces was 25.2 ± 5.1 mm and the time was 85.0 ± 25.6 min. Endoscopic and histological controls did not show evidence of residual neoplastic tissue.

CONCLUSION: A sequential ESD training program of a unique endoscopist, based on the practice in porcine models, contributed to learning ESD for its subsequent application in humans, yielding good results in efficacy and safety.

Endoscopic submucosal dissection training with ex vivo human gastric remnants

BACKGROUND

Endoscopic submucosal dissection (ESD) offers en bloc resection of early cancer or precancerous lesions, potentially saving patients from major organ resection, such as gastrectomy, colectomy, and esophagectomy. Japan now leads the world in ESD due to its high rate of gastric cancer. Western countries, with their lower gastric cancer rates, do not get as much experience with the technique. Training in ESD utilizing both in vivo and ex vivo porcine stomach has been shown to decrease rates of perforation and operative time. Both models can be prohibitively expensive or not generally available to the majority of endoscopists on a regular basis. This study describes the framework for using human gastric remnants from sleeve gastrectomy patients for ESD training.

METHODS

Patients undergoing sleeve gastrectomy for morbid obesity were consented for use of their gastric specimen before surgery. The specimen was weighed and measured by the pathologist and then used for ESD training. The specimen was mounted to a 15-mm laparoscopic port and secured using a pursestring suture. ESD was then performed through this port.

RESULTS

We were able to successfully use this model to resect multiple marked out lesions in an en bloc fashion. Training using this model has improved our dissection times from approximately 2 h to 30 min for a 2-cm simulated lesion.

CONCLUSIONS

ESD requires the endoscopist to perform a surgical dissection. Until now, development of these skills required intensive training on porcine models that are not widely available. We were able to create a method using the excised portion from sleeve gastrectomy patients, providing a more accessible and cost-effective model for ESD training and potentially other endoscopic therapeutic modalities.