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Suture pulley countertraction method reduces procedure time and technical demand of endoscopic submucosal dissection among novice endoscopists learning endoscopic submucosal dissection: a prospective randomized ex vivo study
ORIGINAL ARTICLE
Suture pulley countertraction method reduces procedure time and technical demand of endoscopic submucosal dissection among novice endoscopists learning endoscopic submucosal dissection: a prospective randomized ex vivo study Phillip S. Ge, MD,1,2 Christopher C. Thompson, MD, MHES,1,2 Pichamol Jirapinyo, MD, MPH,1,2 Hiroyuki Aihara, MD, PhD1,2 Boston, Massachusetts, USA
GRAPHICAL ABSTRACT
Background and Aims: The lack of reliable countertraction in endoscopic submucosal dissection (ESD) contributes to its technical demand and increased procedure time. We aimed to prospectively evaluate the efficacy of the suture pulley countertraction method in endoscopists new to both suturing and ESD. Methods: Two 30-mm circular lesions were created in an ex vivo porcine stomach model. Endoscopists considered novices for both endoscopic suturing and ESD were randomized to either traditional or suture pulley ESD first and performed ESD using each technique. Procedure time was recorded including time of circumferential incision, suture pulley placement, and submucosal dissection. After completion of each ESD, participants graded the difficulty of the procedure using the National Aeronautical and Space Administration (NASA) Task Load Index. Results: Thirteen participants (8 fellows, 5 attendings) completed the study using both methods. Mean total procedure time was shorter using suture pulley ESD compared with traditional ESD (26.7 7.3 vs 59.4 20.4 minutes, P < .001). The suture pulley required a mean 6.2 2.1 minutes to place. Submucosal dissection time was shorter using suture pulley ESD compared with traditional ESD (8.4 2.9 vs 47.2 16.3 minutes, P < .001). All 7 individual indices and total score on the NASA Task Load Index were significantly improved using the suture pulley ESD method (P < .001). Conclusions: The suture pulley countertraction method significantly decreases procedure time and technical demand of ESD among endoscopists at all skill levels who are new to ESD. The results of this study have potential implications for ESD training in the United States. (Gastrointest Endosc 2018;-:1-8.)
(footnotes appear on last page of article)
Endoscopic submucosal dissection (ESD) allows for the en bloc resection of superficial lesions throughout the upper and lower GI tract. Adequate visualization followed by controlled dissection of the submucosal layer is critically www.giejournal.org
important to achieving both safety and efficacy in ESD. In open or laparoscopic surgery, an assistant serves to provide effective countertraction; however, this is not feasible with endoscopic surgical procedures such as ESD. As a Volume
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result, ESD is a technically challenging and potentially time-consuming procedure, partially because of the lack of countertraction to elevate the mucosal flap and reliably expose submucosal dissection planes.1 Because of these inherent challenges, various countertraction methods have been described to enhance direct visualization of the submucosal layer. A suture pulley countertraction method was initially described in 20112 and was subsequently demonstrated in an ex vivo study to enhance direct visualization of the submucosal layer and facilitate ESD when performed by an expert in ESD.3 However, its utility among typical endoscopists learning ESD in the United States remains unclear. We therefore aimed to prospectively evaluate the efficacy of the suture pulley countertraction method for ESD in endoscopists new to both suturing and ESD.
METHODS Ex vivo model Resected porcine stomachs were used for this ex vivo study. A 5-cm incision was created along the greater curvature of the proximal gastric body. The stomach was inverted to an inside-out position to expose the mucosa. After careful lavage, 2 adjacent 30-mm simulated circular lesions were created in a standardized fashion using a circular template and marking dots along the dependent portion of the greater curvature of the distal gastric body (Fig. 1). The stomachs were then everted to a normal anatomic configuration, and the incision line was closed with a running suture. The stomachs were affixed to a previously described simulator platform.4 An overtube was then inserted to facilitate entry into the stomach. During the procedure, the stomach was kept moisturized with immersion in normal saline solution to facilitate electrosurgical current transmission.
each technique. All procedures were supervised by a single ESD expert (H.A.), and verbal guidance was provided, but participants were required to complete both ESD procedures without assistance. In both arms, a submucosal injection of saline solution was performed, and a round circumferential incision was made using a standard upper endoscope and standard needle-type and insulated-tip ESD knife (Dual knife and IT knife 2; Olympus America, Center Valley, Pa). In the traditional ESD arm, submucosal dissection was performed in a traditional method with alternating cycles of saline solution injection and submucosal dissection. In the suture pulley ESD arm, after completion of the circumferential incision, the standard endoscope was replaced with a double-channel therapeutic endoscope equipped with the endoscopic suturing device. The first bite (fulcrum) was taken at the gastric wall opposite of the lesion. The second bite (anchor) was placed along the margin of the isolated mucosal flap. The T-tag anchor from the endoscopic suture was deployed to serve as a lifting retainer. The suture pulley was positioned such that traction force was directed toward the opposite side of the dissection plane. The suture tail was withdrawn through the esophagus, and tension was held by the assistant. To avoid misplacement of the suture pulley, detailed verbal instructions were given with regards to the locations for both the fulcrum and the anchor. After successful placement of the suture pulley, ESD was continued with alternating cycles of saline solution injection and submucosal dissection. The assistant held tension on the suture as instructed to provide countertraction throughout the remainder of the submucosal dissection process (Fig. 2). After completion, each participant randomized to the traditional ESD arm subsequently performed a second ESD using the suture pulley method, and each participant randomized to the suture pulley ESD arm subsequently performed a second ESD using the traditional method.
Participants Participants were recruited and enrolled into a structured learning session. This session consisted of a 30-minute lecture on the steps in ESD, a short video presentation of an ESD case, and detailed instruction on operating the suturing device (Overstitch; Apollo Endosurgery, Austin, Tex). The participants included both senior gastroenterology fellows and attending gastroenterologists and were recruited both within our institution and outside our institution through ESD courses. All participants were considered novices for both endoscopic suturing and ESD, as defined as having performed fewer than 5 ex vivo procedures in endoscopic suturing and fewer than 5 ex vivo ESD procedures, with no human or live animal experience in either endoscopic suturing or ESD.
Procedure Participants were randomized to perform either traditional or suture pulley ESD first and performed ESD using 2 GASTROINTESTINAL ENDOSCOPY Volume
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Data analysis For all ESD procedures, time was recorded separately for circumferential incision, suture pulley placement (for suture pulley ESD), and submucosal dissection. The suturing device was set up before the start of the procedure, and thus the amount of time required to set up the device was not included into the total procedure time. Circumferential incision time was defined as the time from which the first incision was made to the time the incision was completed. Suture pulley placement time was defined as the time from which the double-channel endoscope was inserted to the time the suture tail was withdrawn through the esophagus. Submucosal dissection time was defined as the time from which submucosal dissection started to the time the entire simulated lesion was resected. Any incidences of perforation, piecemeal resection, and failure in suture pulley placement were recorded. www.giejournal.org
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Figure 1. Experimental setup. A, For each participant, 2 adjacent 30-mm simulated lesions were created in a standardized fashion in the dependent portion of the stomach (lower gastric body, greater curvature) using a circular template. B, Endoscopic view of the 2 adjacent lesions.
After completion of each ESD, participants graded the difficulty of the procedure using the National Aeronautical and Space Administration (NASA) Task Load Index, a quantitative scoring system developed and validated by NASA to evaluate the workload in a procedure. The NASA Task Load Index comprises the following 7 factors:5 1. Mental demand. How much mental and perceptual activity was required? Was the task easy or demanding, simple or complex? 2. Physical demand. How much physical activity was required? Was the task easy or demanding, slack or strenuous? 3. Temporal demand. How much time pressure did you feel because of the pace at which the tasks or task elements occurred? Was the pace slow or rapid? 4. Performance. How successful were you in performing the task? How satisfied were you with your performance? 5. Effort. How hard did you have to work (mentally and physically) to accomplish your level of performance? 6. Frustration. How irritated, stressed, and annoyed versus content, relaxed, and complacent did you feel during the task? 7. Technical difficulty. How much difficulty did you experience during the procedure? Each factor was rated based on a 10-point visual analog scale. Each participant specified their level of agreement with each statement by indicating a position along the visual analog scale, from 0 (lowest) to 10 (highest).
Statistical analysis The primary outcome measurement of this study was total procedure time. Secondary outcomes included the time for each individual component of ESD (circumferential incision, suture pulley placement [if applicable], and submucosal dissection), the total NASA Task Load Index score, and the individual scores for each category on the NASA Task Load Index. Adverse events were recorded and included perforation, piecemeal resection, and www.giejournal.org
mucosal tear at the fulcrum or anchor point in the suture pulley. Mean procedure times and Task Load Index scores were compared using the Student t test. Data are shown as mean with standard deviations. P < .05 was considered statistically significant.
Sample size Power analysis for the paired sample t test was conducted using SAS Power and Sample Size Application (SAS Institute, Cary, North Carolina) to determine a sufficient sample size for the study with alpha of .05 and power of .95. Based on a previous nonrandomized, single operator with extensive ESD experience study, the total procedure time was 531 seconds for the suture pulley technique and 845 seconds for the traditional ESD technique.3 We hypothesized that with multiple operators with various levels of prior ESD experience, the difference between the procedure time for the 2 techniques would decrease by 20%. Based on the aforementioned assumptions, the desired sample size was 9.
RESULTS ESD techniques Thirteen participants (8 fellows and 5 attendings) completed the study using both methods and were randomized such that 7 performed traditional ESD first and 6 performed suture pulley ESD first (Table 1). All ESDs were completed as planned, with no occurrence of inadvertent tear at the fulcrum or anchor point in the suture pulley. Each suture pulley placement was able to successfully provide direct visualization of the submucosal layer to the endoscopist. Across all participants, mean total procedure time was 43.1 22.4 minutes. Mean total procedure time among the 5 attendings was 33.6 19.7 minutes and among the 8 fellows 49.0 22.5 minutes (P Z .236). There were no significant differences in mean total procedure time among those who performed traditional ESD first versus suture Volume
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Figure 2. Suture pulley method. A, The suture pulley is set up with the suture extending from the opposite wall to the proximal edge of the lesion. B, Gentle tension on the suture is held by an assistant, providing countertraction and exposing the dissection plane, which then greatly facilitates submucosal dissection (C).
pulley ESD first (42.6 23.6 vs 43.6 22.0 minutes, P Z .940). The mean total procedure time was significantly shorter using suture pulley ESD compared with traditional ESD for all participants (26.7 7.3 vs 59.4 20.4 minutes, P < .001), including among fellows (29.8 7.6 vs 68.1 13.9 minutes, P < .001) or attendings (21.8 3.1 vs 45.4 22.6 minutes, P < .001) (Fig. 3). When the total procedure time was subdivided into individual steps, there were no significant differences in circumferential incision time for either method (12.1 5.4 vs 12.2 4.8 minutes, P Z .996); however, submucosal dissection time was significantly shorter using suture pulley ESD compared with traditional ESD (8.4 2.9 vs 47.2 16.3 minutes, P < .001). The suture pulley required a mean 6.2 2.1 minutes to place. There were 4 cases of perforation during submucosal dissection in the traditional ESD group (3 by fellows and 1 by attending, P Z .608). There was no occurrence in the suture pulley ESD group (31% vs 0%, P Z .096).
Evaluation of technical workload Each participant evaluated their workload during each ESD procedure using the NASA Task Load Index 4 GASTROINTESTINAL ENDOSCOPY Volume
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(Table 2).5 The total NASA Task Load Index score was significantly improved using the suture pulley ESD method compared with the traditional ESD method (29.9 6.0 vs 50.7 4.0, P < .001). When subdivided into individual components, there was significant improvement using the suture pulley ESD method compared with the traditional ESD method with regard to mental demand (5.3 1.2 vs 8.6 1.0, P < .001), physical demand (4.4 1.7 vs 8.4 .9, P < .001), temporal demand (2.9 1.6 vs 7.2 1.4, P < .001), performance (7.0 1.8 vs 2.2 1.1, P < .001), effort (3.9 1.1 vs 8.2 1.1, P < .001), frustration (2.8 1.5 vs 7.8 1.5, P < .001), and technical difficulty (3.5 1.6 vs 8.2 1.4, P < .001).
DISCUSSION ESD is an effective treatment modality for superficial lesions of the GI tract, with favorable outcomes compared with surgical interventions.6-8 However, widespread adoption in the United States has thus far been limited because of the technical difficulty and length of the procedure and associated challenges in availability and standardization of training.9-12 In a recent systematic review and metaanalysis that demonstrated the safety and efficacy of www.giejournal.org
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TABLE 1. Comparison of procedural time between traditional ESD versus suture pulley ESD
Traditional ESD first (fellows)
No. of participants
Traditional ESD submucosal dissection time (min)
Suture pulley ESD submucosal dissection time (min)
4
57.52 13.42
9.23 3.66
P value
Traditional ESD procedure time (min)
suture pulley ESD procedure time (min)
P value
<.001
72.69 18.05
32.15 10.34
.008
Traditional ESD first (attendings)
3
31.43 12.77
7.27 1.64
.031
38.25 14.38
20.83 1.56
.105
Suture pulley first (fellows)
4
50.05 7.70
7.23 3.08
<.001
63.56 8.37
27.54 3.48
<.001
Suture pulley first (attendings)
2
44.77 30.62
10.57 1.70
.256
56.17 35.38
23.15 5.26
.322
Traditional ESD first
7
46.34 18.41
8.39 2.95
<.001
57.93 23.89
27.30 9.53
.008
Suture pulley ESD first
6
48.29 15.18
8.34 3.04
<.001
61.10 17.52
26.08 4.24
<.001
Fellows
8
53.79 10.89
8.23 3.31
<.001
68.13 13.91
29.84 7.56
<.001
Attendings
5
36.77 19.22
8.59 2.31
.012
45.42 22.64
21.76 3.12
.049
All participants
13
47.24 16.33
8.37 2.86
<.001
59.39 20.39
26.73 7.30
<.001
Values are mean standard deviation. ESD, Endoscopic submucosal dissection.
90 80
Time (minutes)
70
Total Time (Traditional ESD)
60
Submucosal Dissection (Traditional ESD)
50 40
Total Time (Suture Pulley ESD)
30
Submucosal Dissection (Suture Pulley ESD)
20 10 0 Fellows
Attendings
All Participants
Figure 3. Comparison of procedural time between traditional ESD versus suture pulley ESD (mean standard deviation; *P <.05, **P <.01). ESD, Endoscopic submucosal dissection.
colorectal ESD, most studies were from Asia and only 5 of 104 studies were from the United States.13 Similarly, studies evaluating new advances in ESD training and techniques have primarily originated from Asia, with a notable lack of U.S. studies.14-17 ESD is fundamentally challenging because of the level of technical ability required to maintain visualization of the submucosal dissection plane, and this is often considered the most difficult aspect of the ESD procedure.3 Loss of visualization of this dissection plane results in blind dissection, which can then lead to bleeding and perforation. ESD is currently facilitated by the use of a transparent cap; however, this is limited by the diameter of the cap and requires the endoscope to be positioned www.giejournal.org
very close to the area of dissection. Although this allows for the endoscopist to closely visualize the dissection plane, it also requires the endoscopist to frequently reorient oneself during submucosal dissection to prevent over-tunneling through the submucosal space or dissecting in the wrong direction. We previously reported favorable results using the suture pulley countertraction method in facilitating direct visualization of the submucosal layer during ESD and significantly reducing procedure time and technical workload when performed by a single ESD expert.3 Because ESD has not yet reached widespread adoption in the United States, the findings of the study may not have been applicable to the typical U.S. endoscopist learning Volume
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TABLE 2. Comparison of NASA Task Load Index scores between traditional ESD versus suture pulley ESD Traditional ESD
Suture Pulley ESD
P value
Mental demand
8.6 1.0
5.3 1.2
<.0001
Physical demand
8.4 .9
4.4 1.7
<.0001
Temporal demand
7.2 1.4
2.9 1.6
<.0001
Performance
2.2 1.1
7.0 1.8
<.0001
Effort
8.2 1.1
3.9 1.1
<.0001
Frustration
7.8 1.5
2.8 1.5
<.0001
Technical difficulty
8.2 1.4
3.5 1.6
<.0001
Total score
50.7 4.0
29.9 6.0
<.0001
Values are mean standard deviation. NASA, National Aeronautical and Space Administration; ESD, endoscopic submucosal dissection.
or beginning to incorporate ESD into their practice. However, it was postulated at the time that the significant decrease in procedure time and improvement in the NASA Task Load Index score among an ESD expert may be even more pronounced among ESD novices. The findings of our present study convincingly demonstrate that the suture pulley countertraction method is able to significantly reduce procedure time and technical workload among endoscopists considered to be novices in both endoscopic suturing and ESD, including both fellows and attendings. Specifically, the countertraction method appears to be most effective in reducing the amount of time required to perform submucosal dissection. In helping to expose the dissection plane, the initial time investment required to set up the suture pulley ultimately pays off by facilitating submucosal dissection. This is evident in the individual NASA Task Load Index scores, which demonstrate decreased mental, physical, and temporal demand; improved performance; and decreased effort, frustration, and overall technical difficulty, all of which achieved statistical significance. Furthermore, by facilitating exposure of the submucosal dissection plane, the suture pulley countertraction method may potentially increase the safety profile of ESD among learners, as evidenced by the lower perforation rate among suture pulley ESD as compared with traditional ESD, although this did not reach statistical significance (31% vs 0%, P Z .096). Multiple internal and external countertraction devices and techniques have been proposed and investigated to enhance visualization of the submucosal space. External traction methods have included external grasping forceps,18 a second thin endoscope,19,20 percutaneous traction,21 and peroral traction using a pulley.15,22 Internal traction methods have included a sinker device,23 the use of a nylon suture,14 the clip–rubber band technique,24,25 and an injectable reverse-phase polymer that transitions from a liquid to a more solid substance.26 Other described internal traction methods include a
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novel spring-action “S-O” clip16,27,28 and the dental floss– clip traction method.17,29,30 The suture pulley method uniquely differs from these other techniques (most notably the dental floss–clip method) in that it uses a fulcrum point, which provides the ability to vary the amount of countertraction needed during various phases of the ESD procedure simply by adjusting the tension of the suture tail, which ultimately results in a wider and more visible dissection plane. Despite the potential of the suture pulley method in facilitating submucosal dissection, a working knowledge of the endoscopic suturing device is still necessary to correctly place the suture. In setting up the suture pulley, the edge of the mucosal flap must always be placed between the curved needle and the exchange assembly of the suturing device. This ensures that the stitch is always placed into the mucosal flap alone and avoids damage to the muscularis propria. Although our previous study suggested that the suture pulley countertraction method may be effective even for lesions in difficult locations throughout the stomach,3 this method may be more technically challenging in narrow confined locations such as the duodenum and colon because of the size of the endoscopic suturing device. Our study has several limitations. Because of its ex vivo nature, this study was not designed to determine whether effective countertraction using the suture pulley method would reduce unexpected intraprocedural bleeding. However, it would be reasonable to presume that improved visualization of the submucosal layer would allow endoscopists to more readily identify and thus pre-emptively coagulate submucosal vessels. Second, although ESDs were performed by endoscopists considered to be novices in both endoscopic suturing and ESD, all procedures were still performed under the supervision of a single ESD expert in a controlled ex vivo setting where both size and location of the simulated lesions were tightly controlled, which may limit its applicability to real-life ESD training and practice. Nonetheless, the experimental setup of this study allowed a direct comparison of these
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techniques and their associated workload in a typical U.S. endoscopist learning or beginning to incorporate ESD into their practice. Further limitations related to the suture pulley technique include the additional expense of the suturing device, familiarity with the device and its setup, and learning curve associated with endoscopic suturing. However, we believe these limitations are offset by advantages that include the ability to control the amount of countertraction and defect closure using endoscopic suturing. Finally, because this is a small ex vivo study, larger human feasibility studies are warranted to validate these results. In conclusion, by enhancing direct visualization of the submucosal dissection plane throughout the ESD procedure, the suture pulley countertraction method significantly decreases procedure time and technical demand of ESD among endoscopists at all skill levels who are new to ESD. The results of this study have potential implications for ESD training in the United States. Further clinical studies are warranted to assess in vivo application of this technique in facilitating ESD.
REFERENCES 1. ASGE Technology Committee; Maple JT, Abu Dayyeh BK, Chauhan SS, et al. Endoscopic submucosal dissection. Gastrointest Endosc 2015;81: 1311-25. 2. Rieder E, Makris KI, Martinec DV, et al. The suture-pulley method for endolumenal triangulation in endoscopic submucosal dissection. Endoscopy 2011;43(Suppl 2 UCTN):E319-20. 3. Aihara H, Kumar N, Ryou M, et al. Facilitating endoscopic submucosal dissection: the suture-pulley method significantly improves procedure time and minimizes technical difficulty compared with conventional technique: an ex vivo study (with video). Gastrointest Endosc 2014;80:495-502. 4. Maiss J, Prat F, Wiesnet J, et al. The complementary Erlangen active simulator for interventional endoscopy training is superior to solely clinical education in endoscopic hemostasisdthe French training project: a prospective trial. Eur J Gastroenterol Hepatol 2006;18: 1217-25. 5. Hart SG, Staveland LE. Development of NASA-TLX (Task Load Index): results of empirical and theoretical research. Adv Psychol 1988;52: 139-83. 6. Pimentel-Nunes P, Dinis-Ribeiro M, Ponchon T, et al. Endoscopic submucosal dissection: European Society of Gastrointestinal Endoscopy (ESGE) guideline. Endoscopy 2015;47:829-54. 7. Tanaka S, Kashida H, Saito Y, et al. JGES guidelines for colorectal endoscopic submucosal dissection/endoscopic mucosal resection. Dig Endosc 2015;27:417-34. 8. Man-i M, Morita Y, Fujita T, et al. Endoscopic submucosal dissection for gastric neoplasm in patients with co-morbidities categorized according to the ASA Physical Status Classification. Gastric Cancer 2013;16: 56-66. 9. Draganov PV, Gotoda T, Chavalitdhamrong D, et al. Techniques of endoscopic submucosal dissection: application for the Western endoscopist? Gastrointest Endosc 2013;78:677-88. 10. Coman RM, Gotoda T, Draganov PV. Training in endoscopic submucosal dissection. World J Gastrointest Endosc 2013;5:369-78. 11. Rex DK, Hassan C, Dewitt JM. Colorectal endoscopic submucosal dissection in the United States: Why do we hear so much about it and do so little of it? Gastrointest Endosc 2017;85:554-8.
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Suture pulley countertraction in ESD 12. Draganov PV, Chang M, Coman RM, et al. Role of observation of live cases done by Japanese experts in the acquisition of ESD skills by a Western endoscopist. World J Gastroenterol 2014;20:4675-80. 13. Akintoye E, Kumar N, Aihara H, et al. Colorectal endoscopic submucosal dissection: a systematic review and meta-analysis. Endosc Int Open 2016;4:E1030-44. 14. Chen PJ, Chu HC, Chang WK, et al. Endoscopic submucosal dissection with internal traction for early gastric cancer (with video). Gastrointest Endosc 2008;67:128-32. 15. Li CH, Chen PJ, Chu HC, et al. Endoscopic submucosal dissection with the pulley method for early-stage gastric cancer (with video). Gastrointest Endosc 2011;73:163-7. 16. Sakamoto N, Osada T, Shibuya T, et al. Endoscopic submucosal dissection of large colorectal tumors by using a novel spring-action S-O clip for traction (with video). Gastrointest Endosc 2009;69:1370-4. 17. Yoshida M, Takizawa K, Ono H, et al. Efficacy of endoscopic submucosal dissection with dental floss clip traction for gastric epithelial neoplasia: a pilot study (with video). Surg Endosc 2016;30:3100-6. 18. Imaeda H, Hosoe N, Ida Y, et al. Novel technique of endoscopic submucosal dissection by using external forceps for early rectal cancer (with videos). Gastrointest Endosc 2012;75:1253-7. 19. Ahn JY, Choi KD, Choi JY, et al. Transnasal endoscope-assisted endoscopic submucosal dissection for gastric adenoma and early gastric cancer in the pyloric area: a case series. Endoscopy 2011;43:233-5. 20. Uraoka T, Kato J, Ishikawa S, et al. Thin endoscope-assisted endoscopic submucosal dissection for large colorectal tumors (with videos). Gastrointest Endosc 2007;66:836-9. 21. von Delius S, Karagianni A, von Weyhern CH, et al. Percutaneously assisted endoscopic surgery using a new PEG-minitrocar for advanced endoscopic submucosal dissection (with videos). Gastrointest Endosc 2008;68:365-9. 22. Jeon WJ, You IY, Chae HB, et al. A new technique for gastric endoscopic submucosal dissection: peroral traction-assisted endoscopic submucosal dissection. Gastrointest Endosc 2009;69:29-33. 23. Saito Y, Emura F, Matsuda T, et al. A new sinker-assisted endoscopic submucosal dissection for colorectal cancer. Gastrointest Endosc 2005;62:297-301. 24. Matsumoto K, Nagahara A, Sakamoto N, et al. A new traction device for facilitating endoscopic submucosal dissection (ESD) for early gastric cancer: the “medical ring.” Endoscopy 2011;43(Suppl 2 UCTN):E67-8. 25. Parra-Blanco A, Nicolas D, Arnau MR, et al. Gastric endoscopic submucosal dissection assisted by a new traction method: the clip-band technique. A feasibility study in a porcine model (with video). Gastrointest Endosc 2011;74:1137-41. 26. Fernandez-Esparrach G, Shaikh SN, Cohen A, et al. Efficacy of a reversephase polymer as a submucosal injection solution for EMR: a comparative study (with video). Gastrointest Endosc 2009;69:1135-9. 27. Hashimoto R, Hirasawa D, Iwaki T, et al. Usefulness of the S-O clip for gastric endoscopic submucosal dissection (with video). Surg Endosc 2018;32:908-14. 28. Ritsuno H, Sakamoto N, Osada T, et al. Prospective clinical trial of traction device-assisted endoscopic submucosal dissection of large superficial colorectal tumors using the S-O clip. Surg Endosc 2014;28:3143-9. 29. Yoshida M, Takizawa K, Suzuki S, et al. Conventional versus tractionassisted endoscopic submucosal dissection for gastric neoplasms: a multicenter, randomized controlled trial (with video). Gastrointest Endosc 2017;87:1231-40. 30. He Y, Fu K, Leung J, et al. Traction with dental floss and endoscopic clip improves trainee success in performing gastric endoscopic submucosal dissection (ESD): a live porcine study (with video). Surg Endosc 2016;30:3138-44. Abbreviations: ESD, endoscopic submucosal dissection; NASA, National Aeronautical and Space Administration. DISCLOSURE: The following authors disclosed financial relationships relevant to this publication: C. C. Thompson: Consultant for Boston
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Scientific, Apollo Endosurgery, and Olympus. H. Aihara: Consultant for Boston Scientific and Olympus. All other authors disclosed no financial relationships relevant to this publication. Copyright ª 2018 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 https://doi.org/10.1016/j.gie.2018.08.032
Hepatology and Endoscopy, Brigham and Women’s Hospital, Boston, Massachusetts, USA (2). Presented at Digestive Disease Week, June 2-5, 2018, Washington, DC (Gastroenterol 2018;154:S441-2).
Received May 15, 2018. Accepted August 10, 2018.
Reprint requests: Hiroyuki Aihara, MD, PhD, Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115.
Current affiliations: Developmental Endoscopy Lab, Harvard Medical School, Boston, Massachusetts, USA (1), Division of Gastroenterology,
If you would like to chat with an author of this article, you may contact Dr Aihara at [email protected].
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Suture pulley countertraction method reduces procedure time and technical demand of endoscopic submucosal dissection among novice endoscopists learning endoscopic submucosal dissection: a prospective randomized ex vivo study Phillip S. Ge, MD,1,2 Christopher C. Thompson, MD, MHES,1,2 Pichamol Jirapinyo, MD, MPH,1,2 Hiroyuki Aihara, MD, PhD1,2 Boston, Massachusetts, USA
GRAPHICAL ABSTRACT
Background and Aims: The lack of reliable countertraction in endoscopic submucosal dissection (ESD) contributes to its technical demand and increased procedure time. We aimed to prospectively evaluate the efficacy of the suture pulley countertraction method in endoscopists new to both suturing and ESD. Methods: Two 30-mm circular lesions were created in an ex vivo porcine stomach model. Endoscopists considered novices for both endoscopic suturing and ESD were randomized to either traditional or suture pulley ESD first and performed ESD using each technique. Procedure time was recorded including time of circumferential incision, suture pulley placement, and submucosal dissection. After completion of each ESD, participants graded the difficulty of the procedure using the National Aeronautical and Space Administration (NASA) Task Load Index. Results: Thirteen participants (8 fellows, 5 attendings) completed the study using both methods. Mean total procedure time was shorter using suture pulley ESD compared with traditional ESD (26.7 7.3 vs 59.4 20.4 minutes, P < .001). The suture pulley required a mean 6.2 2.1 minutes to place. Submucosal dissection time was shorter using suture pulley ESD compared with traditional ESD (8.4 2.9 vs 47.2 16.3 minutes, P < .001). All 7 individual indices and total score on the NASA Task Load Index were significantly improved using the suture pulley ESD method (P < .001). Conclusions: The suture pulley countertraction method significantly decreases procedure time and technical demand of ESD among endoscopists at all skill levels who are new to ESD. The results of this study have potential implications for ESD training in the United States. (Gastrointest Endosc 2018;-:1-8.)
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Endoscopic submucosal dissection (ESD) allows for the en bloc resection of superficial lesions throughout the upper and lower GI tract. Adequate visualization followed by controlled dissection of the submucosal layer is critically www.giejournal.org
important to achieving both safety and efficacy in ESD. In open or laparoscopic surgery, an assistant serves to provide effective countertraction; however, this is not feasible with endoscopic surgical procedures such as ESD. As a Volume
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result, ESD is a technically challenging and potentially time-consuming procedure, partially because of the lack of countertraction to elevate the mucosal flap and reliably expose submucosal dissection planes.1 Because of these inherent challenges, various countertraction methods have been described to enhance direct visualization of the submucosal layer. A suture pulley countertraction method was initially described in 20112 and was subsequently demonstrated in an ex vivo study to enhance direct visualization of the submucosal layer and facilitate ESD when performed by an expert in ESD.3 However, its utility among typical endoscopists learning ESD in the United States remains unclear. We therefore aimed to prospectively evaluate the efficacy of the suture pulley countertraction method for ESD in endoscopists new to both suturing and ESD.
METHODS Ex vivo model Resected porcine stomachs were used for this ex vivo study. A 5-cm incision was created along the greater curvature of the proximal gastric body. The stomach was inverted to an inside-out position to expose the mucosa. After careful lavage, 2 adjacent 30-mm simulated circular lesions were created in a standardized fashion using a circular template and marking dots along the dependent portion of the greater curvature of the distal gastric body (Fig. 1). The stomachs were then everted to a normal anatomic configuration, and the incision line was closed with a running suture. The stomachs were affixed to a previously described simulator platform.4 An overtube was then inserted to facilitate entry into the stomach. During the procedure, the stomach was kept moisturized with immersion in normal saline solution to facilitate electrosurgical current transmission.
each technique. All procedures were supervised by a single ESD expert (H.A.), and verbal guidance was provided, but participants were required to complete both ESD procedures without assistance. In both arms, a submucosal injection of saline solution was performed, and a round circumferential incision was made using a standard upper endoscope and standard needle-type and insulated-tip ESD knife (Dual knife and IT knife 2; Olympus America, Center Valley, Pa). In the traditional ESD arm, submucosal dissection was performed in a traditional method with alternating cycles of saline solution injection and submucosal dissection. In the suture pulley ESD arm, after completion of the circumferential incision, the standard endoscope was replaced with a double-channel therapeutic endoscope equipped with the endoscopic suturing device. The first bite (fulcrum) was taken at the gastric wall opposite of the lesion. The second bite (anchor) was placed along the margin of the isolated mucosal flap. The T-tag anchor from the endoscopic suture was deployed to serve as a lifting retainer. The suture pulley was positioned such that traction force was directed toward the opposite side of the dissection plane. The suture tail was withdrawn through the esophagus, and tension was held by the assistant. To avoid misplacement of the suture pulley, detailed verbal instructions were given with regards to the locations for both the fulcrum and the anchor. After successful placement of the suture pulley, ESD was continued with alternating cycles of saline solution injection and submucosal dissection. The assistant held tension on the suture as instructed to provide countertraction throughout the remainder of the submucosal dissection process (Fig. 2). After completion, each participant randomized to the traditional ESD arm subsequently performed a second ESD using the suture pulley method, and each participant randomized to the suture pulley ESD arm subsequently performed a second ESD using the traditional method.
Participants Participants were recruited and enrolled into a structured learning session. This session consisted of a 30-minute lecture on the steps in ESD, a short video presentation of an ESD case, and detailed instruction on operating the suturing device (Overstitch; Apollo Endosurgery, Austin, Tex). The participants included both senior gastroenterology fellows and attending gastroenterologists and were recruited both within our institution and outside our institution through ESD courses. All participants were considered novices for both endoscopic suturing and ESD, as defined as having performed fewer than 5 ex vivo procedures in endoscopic suturing and fewer than 5 ex vivo ESD procedures, with no human or live animal experience in either endoscopic suturing or ESD.
Procedure Participants were randomized to perform either traditional or suture pulley ESD first and performed ESD using 2 GASTROINTESTINAL ENDOSCOPY Volume
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Data analysis For all ESD procedures, time was recorded separately for circumferential incision, suture pulley placement (for suture pulley ESD), and submucosal dissection. The suturing device was set up before the start of the procedure, and thus the amount of time required to set up the device was not included into the total procedure time. Circumferential incision time was defined as the time from which the first incision was made to the time the incision was completed. Suture pulley placement time was defined as the time from which the double-channel endoscope was inserted to the time the suture tail was withdrawn through the esophagus. Submucosal dissection time was defined as the time from which submucosal dissection started to the time the entire simulated lesion was resected. Any incidences of perforation, piecemeal resection, and failure in suture pulley placement were recorded. www.giejournal.org
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Figure 1. Experimental setup. A, For each participant, 2 adjacent 30-mm simulated lesions were created in a standardized fashion in the dependent portion of the stomach (lower gastric body, greater curvature) using a circular template. B, Endoscopic view of the 2 adjacent lesions.
After completion of each ESD, participants graded the difficulty of the procedure using the National Aeronautical and Space Administration (NASA) Task Load Index, a quantitative scoring system developed and validated by NASA to evaluate the workload in a procedure. The NASA Task Load Index comprises the following 7 factors:5 1. Mental demand. How much mental and perceptual activity was required? Was the task easy or demanding, simple or complex? 2. Physical demand. How much physical activity was required? Was the task easy or demanding, slack or strenuous? 3. Temporal demand. How much time pressure did you feel because of the pace at which the tasks or task elements occurred? Was the pace slow or rapid? 4. Performance. How successful were you in performing the task? How satisfied were you with your performance? 5. Effort. How hard did you have to work (mentally and physically) to accomplish your level of performance? 6. Frustration. How irritated, stressed, and annoyed versus content, relaxed, and complacent did you feel during the task? 7. Technical difficulty. How much difficulty did you experience during the procedure? Each factor was rated based on a 10-point visual analog scale. Each participant specified their level of agreement with each statement by indicating a position along the visual analog scale, from 0 (lowest) to 10 (highest).
Statistical analysis The primary outcome measurement of this study was total procedure time. Secondary outcomes included the time for each individual component of ESD (circumferential incision, suture pulley placement [if applicable], and submucosal dissection), the total NASA Task Load Index score, and the individual scores for each category on the NASA Task Load Index. Adverse events were recorded and included perforation, piecemeal resection, and www.giejournal.org
mucosal tear at the fulcrum or anchor point in the suture pulley. Mean procedure times and Task Load Index scores were compared using the Student t test. Data are shown as mean with standard deviations. P < .05 was considered statistically significant.
Sample size Power analysis for the paired sample t test was conducted using SAS Power and Sample Size Application (SAS Institute, Cary, North Carolina) to determine a sufficient sample size for the study with alpha of .05 and power of .95. Based on a previous nonrandomized, single operator with extensive ESD experience study, the total procedure time was 531 seconds for the suture pulley technique and 845 seconds for the traditional ESD technique.3 We hypothesized that with multiple operators with various levels of prior ESD experience, the difference between the procedure time for the 2 techniques would decrease by 20%. Based on the aforementioned assumptions, the desired sample size was 9.
RESULTS ESD techniques Thirteen participants (8 fellows and 5 attendings) completed the study using both methods and were randomized such that 7 performed traditional ESD first and 6 performed suture pulley ESD first (Table 1). All ESDs were completed as planned, with no occurrence of inadvertent tear at the fulcrum or anchor point in the suture pulley. Each suture pulley placement was able to successfully provide direct visualization of the submucosal layer to the endoscopist. Across all participants, mean total procedure time was 43.1 22.4 minutes. Mean total procedure time among the 5 attendings was 33.6 19.7 minutes and among the 8 fellows 49.0 22.5 minutes (P Z .236). There were no significant differences in mean total procedure time among those who performed traditional ESD first versus suture Volume
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Figure 2. Suture pulley method. A, The suture pulley is set up with the suture extending from the opposite wall to the proximal edge of the lesion. B, Gentle tension on the suture is held by an assistant, providing countertraction and exposing the dissection plane, which then greatly facilitates submucosal dissection (C).
pulley ESD first (42.6 23.6 vs 43.6 22.0 minutes, P Z .940). The mean total procedure time was significantly shorter using suture pulley ESD compared with traditional ESD for all participants (26.7 7.3 vs 59.4 20.4 minutes, P < .001), including among fellows (29.8 7.6 vs 68.1 13.9 minutes, P < .001) or attendings (21.8 3.1 vs 45.4 22.6 minutes, P < .001) (Fig. 3). When the total procedure time was subdivided into individual steps, there were no significant differences in circumferential incision time for either method (12.1 5.4 vs 12.2 4.8 minutes, P Z .996); however, submucosal dissection time was significantly shorter using suture pulley ESD compared with traditional ESD (8.4 2.9 vs 47.2 16.3 minutes, P < .001). The suture pulley required a mean 6.2 2.1 minutes to place. There were 4 cases of perforation during submucosal dissection in the traditional ESD group (3 by fellows and 1 by attending, P Z .608). There was no occurrence in the suture pulley ESD group (31% vs 0%, P Z .096).
Evaluation of technical workload Each participant evaluated their workload during each ESD procedure using the NASA Task Load Index 4 GASTROINTESTINAL ENDOSCOPY Volume
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(Table 2).5 The total NASA Task Load Index score was significantly improved using the suture pulley ESD method compared with the traditional ESD method (29.9 6.0 vs 50.7 4.0, P < .001). When subdivided into individual components, there was significant improvement using the suture pulley ESD method compared with the traditional ESD method with regard to mental demand (5.3 1.2 vs 8.6 1.0, P < .001), physical demand (4.4 1.7 vs 8.4 .9, P < .001), temporal demand (2.9 1.6 vs 7.2 1.4, P < .001), performance (7.0 1.8 vs 2.2 1.1, P < .001), effort (3.9 1.1 vs 8.2 1.1, P < .001), frustration (2.8 1.5 vs 7.8 1.5, P < .001), and technical difficulty (3.5 1.6 vs 8.2 1.4, P < .001).
DISCUSSION ESD is an effective treatment modality for superficial lesions of the GI tract, with favorable outcomes compared with surgical interventions.6-8 However, widespread adoption in the United States has thus far been limited because of the technical difficulty and length of the procedure and associated challenges in availability and standardization of training.9-12 In a recent systematic review and metaanalysis that demonstrated the safety and efficacy of www.giejournal.org
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TABLE 1. Comparison of procedural time between traditional ESD versus suture pulley ESD
Traditional ESD first (fellows)
No. of participants
Traditional ESD submucosal dissection time (min)
Suture pulley ESD submucosal dissection time (min)
4
57.52 13.42
9.23 3.66
P value
Traditional ESD procedure time (min)
suture pulley ESD procedure time (min)
P value
<.001
72.69 18.05
32.15 10.34
.008
Traditional ESD first (attendings)
3
31.43 12.77
7.27 1.64
.031
38.25 14.38
20.83 1.56
.105
Suture pulley first (fellows)
4
50.05 7.70
7.23 3.08
<.001
63.56 8.37
27.54 3.48
<.001
Suture pulley first (attendings)
2
44.77 30.62
10.57 1.70
.256
56.17 35.38
23.15 5.26
.322
Traditional ESD first
7
46.34 18.41
8.39 2.95
<.001
57.93 23.89
27.30 9.53
.008
Suture pulley ESD first
6
48.29 15.18
8.34 3.04
<.001
61.10 17.52
26.08 4.24
<.001
Fellows
8
53.79 10.89
8.23 3.31
<.001
68.13 13.91
29.84 7.56
<.001
Attendings
5
36.77 19.22
8.59 2.31
.012
45.42 22.64
21.76 3.12
.049
All participants
13
47.24 16.33
8.37 2.86
<.001
59.39 20.39
26.73 7.30
<.001
Values are mean standard deviation. ESD, Endoscopic submucosal dissection.
90 80
Time (minutes)
70
Total Time (Traditional ESD)
60
Submucosal Dissection (Traditional ESD)
50 40
Total Time (Suture Pulley ESD)
30
Submucosal Dissection (Suture Pulley ESD)
20 10 0 Fellows
Attendings
All Participants
Figure 3. Comparison of procedural time between traditional ESD versus suture pulley ESD (mean standard deviation; *P <.05, **P <.01). ESD, Endoscopic submucosal dissection.
colorectal ESD, most studies were from Asia and only 5 of 104 studies were from the United States.13 Similarly, studies evaluating new advances in ESD training and techniques have primarily originated from Asia, with a notable lack of U.S. studies.14-17 ESD is fundamentally challenging because of the level of technical ability required to maintain visualization of the submucosal dissection plane, and this is often considered the most difficult aspect of the ESD procedure.3 Loss of visualization of this dissection plane results in blind dissection, which can then lead to bleeding and perforation. ESD is currently facilitated by the use of a transparent cap; however, this is limited by the diameter of the cap and requires the endoscope to be positioned www.giejournal.org
very close to the area of dissection. Although this allows for the endoscopist to closely visualize the dissection plane, it also requires the endoscopist to frequently reorient oneself during submucosal dissection to prevent over-tunneling through the submucosal space or dissecting in the wrong direction. We previously reported favorable results using the suture pulley countertraction method in facilitating direct visualization of the submucosal layer during ESD and significantly reducing procedure time and technical workload when performed by a single ESD expert.3 Because ESD has not yet reached widespread adoption in the United States, the findings of the study may not have been applicable to the typical U.S. endoscopist learning Volume
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TABLE 2. Comparison of NASA Task Load Index scores between traditional ESD versus suture pulley ESD Traditional ESD
Suture Pulley ESD
P value
Mental demand
8.6 1.0
5.3 1.2
<.0001
Physical demand
8.4 .9
4.4 1.7
<.0001
Temporal demand
7.2 1.4
2.9 1.6
<.0001
Performance
2.2 1.1
7.0 1.8
<.0001
Effort
8.2 1.1
3.9 1.1
<.0001
Frustration
7.8 1.5
2.8 1.5
<.0001
Technical difficulty
8.2 1.4
3.5 1.6
<.0001
Total score
50.7 4.0
29.9 6.0
<.0001
Values are mean standard deviation. NASA, National Aeronautical and Space Administration; ESD, endoscopic submucosal dissection.
or beginning to incorporate ESD into their practice. However, it was postulated at the time that the significant decrease in procedure time and improvement in the NASA Task Load Index score among an ESD expert may be even more pronounced among ESD novices. The findings of our present study convincingly demonstrate that the suture pulley countertraction method is able to significantly reduce procedure time and technical workload among endoscopists considered to be novices in both endoscopic suturing and ESD, including both fellows and attendings. Specifically, the countertraction method appears to be most effective in reducing the amount of time required to perform submucosal dissection. In helping to expose the dissection plane, the initial time investment required to set up the suture pulley ultimately pays off by facilitating submucosal dissection. This is evident in the individual NASA Task Load Index scores, which demonstrate decreased mental, physical, and temporal demand; improved performance; and decreased effort, frustration, and overall technical difficulty, all of which achieved statistical significance. Furthermore, by facilitating exposure of the submucosal dissection plane, the suture pulley countertraction method may potentially increase the safety profile of ESD among learners, as evidenced by the lower perforation rate among suture pulley ESD as compared with traditional ESD, although this did not reach statistical significance (31% vs 0%, P Z .096). Multiple internal and external countertraction devices and techniques have been proposed and investigated to enhance visualization of the submucosal space. External traction methods have included external grasping forceps,18 a second thin endoscope,19,20 percutaneous traction,21 and peroral traction using a pulley.15,22 Internal traction methods have included a sinker device,23 the use of a nylon suture,14 the clip–rubber band technique,24,25 and an injectable reverse-phase polymer that transitions from a liquid to a more solid substance.26 Other described internal traction methods include a
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novel spring-action “S-O” clip16,27,28 and the dental floss– clip traction method.17,29,30 The suture pulley method uniquely differs from these other techniques (most notably the dental floss–clip method) in that it uses a fulcrum point, which provides the ability to vary the amount of countertraction needed during various phases of the ESD procedure simply by adjusting the tension of the suture tail, which ultimately results in a wider and more visible dissection plane. Despite the potential of the suture pulley method in facilitating submucosal dissection, a working knowledge of the endoscopic suturing device is still necessary to correctly place the suture. In setting up the suture pulley, the edge of the mucosal flap must always be placed between the curved needle and the exchange assembly of the suturing device. This ensures that the stitch is always placed into the mucosal flap alone and avoids damage to the muscularis propria. Although our previous study suggested that the suture pulley countertraction method may be effective even for lesions in difficult locations throughout the stomach,3 this method may be more technically challenging in narrow confined locations such as the duodenum and colon because of the size of the endoscopic suturing device. Our study has several limitations. Because of its ex vivo nature, this study was not designed to determine whether effective countertraction using the suture pulley method would reduce unexpected intraprocedural bleeding. However, it would be reasonable to presume that improved visualization of the submucosal layer would allow endoscopists to more readily identify and thus pre-emptively coagulate submucosal vessels. Second, although ESDs were performed by endoscopists considered to be novices in both endoscopic suturing and ESD, all procedures were still performed under the supervision of a single ESD expert in a controlled ex vivo setting where both size and location of the simulated lesions were tightly controlled, which may limit its applicability to real-life ESD training and practice. Nonetheless, the experimental setup of this study allowed a direct comparison of these
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techniques and their associated workload in a typical U.S. endoscopist learning or beginning to incorporate ESD into their practice. Further limitations related to the suture pulley technique include the additional expense of the suturing device, familiarity with the device and its setup, and learning curve associated with endoscopic suturing. However, we believe these limitations are offset by advantages that include the ability to control the amount of countertraction and defect closure using endoscopic suturing. Finally, because this is a small ex vivo study, larger human feasibility studies are warranted to validate these results. In conclusion, by enhancing direct visualization of the submucosal dissection plane throughout the ESD procedure, the suture pulley countertraction method significantly decreases procedure time and technical demand of ESD among endoscopists at all skill levels who are new to ESD. The results of this study have potential implications for ESD training in the United States. Further clinical studies are warranted to assess in vivo application of this technique in facilitating ESD.
REFERENCES 1. ASGE Technology Committee; Maple JT, Abu Dayyeh BK, Chauhan SS, et al. Endoscopic submucosal dissection. Gastrointest Endosc 2015;81: 1311-25. 2. Rieder E, Makris KI, Martinec DV, et al. The suture-pulley method for endolumenal triangulation in endoscopic submucosal dissection. Endoscopy 2011;43(Suppl 2 UCTN):E319-20. 3. Aihara H, Kumar N, Ryou M, et al. Facilitating endoscopic submucosal dissection: the suture-pulley method significantly improves procedure time and minimizes technical difficulty compared with conventional technique: an ex vivo study (with video). Gastrointest Endosc 2014;80:495-502. 4. Maiss J, Prat F, Wiesnet J, et al. The complementary Erlangen active simulator for interventional endoscopy training is superior to solely clinical education in endoscopic hemostasisdthe French training project: a prospective trial. Eur J Gastroenterol Hepatol 2006;18: 1217-25. 5. Hart SG, Staveland LE. Development of NASA-TLX (Task Load Index): results of empirical and theoretical research. Adv Psychol 1988;52: 139-83. 6. Pimentel-Nunes P, Dinis-Ribeiro M, Ponchon T, et al. Endoscopic submucosal dissection: European Society of Gastrointestinal Endoscopy (ESGE) guideline. Endoscopy 2015;47:829-54. 7. Tanaka S, Kashida H, Saito Y, et al. JGES guidelines for colorectal endoscopic submucosal dissection/endoscopic mucosal resection. Dig Endosc 2015;27:417-34. 8. Man-i M, Morita Y, Fujita T, et al. Endoscopic submucosal dissection for gastric neoplasm in patients with co-morbidities categorized according to the ASA Physical Status Classification. Gastric Cancer 2013;16: 56-66. 9. Draganov PV, Gotoda T, Chavalitdhamrong D, et al. Techniques of endoscopic submucosal dissection: application for the Western endoscopist? Gastrointest Endosc 2013;78:677-88. 10. Coman RM, Gotoda T, Draganov PV. Training in endoscopic submucosal dissection. World J Gastrointest Endosc 2013;5:369-78. 11. Rex DK, Hassan C, Dewitt JM. Colorectal endoscopic submucosal dissection in the United States: Why do we hear so much about it and do so little of it? Gastrointest Endosc 2017;85:554-8.
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Suture pulley countertraction in ESD 12. Draganov PV, Chang M, Coman RM, et al. Role of observation of live cases done by Japanese experts in the acquisition of ESD skills by a Western endoscopist. World J Gastroenterol 2014;20:4675-80. 13. Akintoye E, Kumar N, Aihara H, et al. Colorectal endoscopic submucosal dissection: a systematic review and meta-analysis. Endosc Int Open 2016;4:E1030-44. 14. Chen PJ, Chu HC, Chang WK, et al. Endoscopic submucosal dissection with internal traction for early gastric cancer (with video). Gastrointest Endosc 2008;67:128-32. 15. Li CH, Chen PJ, Chu HC, et al. Endoscopic submucosal dissection with the pulley method for early-stage gastric cancer (with video). Gastrointest Endosc 2011;73:163-7. 16. Sakamoto N, Osada T, Shibuya T, et al. Endoscopic submucosal dissection of large colorectal tumors by using a novel spring-action S-O clip for traction (with video). Gastrointest Endosc 2009;69:1370-4. 17. Yoshida M, Takizawa K, Ono H, et al. Efficacy of endoscopic submucosal dissection with dental floss clip traction for gastric epithelial neoplasia: a pilot study (with video). Surg Endosc 2016;30:3100-6. 18. Imaeda H, Hosoe N, Ida Y, et al. Novel technique of endoscopic submucosal dissection by using external forceps for early rectal cancer (with videos). Gastrointest Endosc 2012;75:1253-7. 19. Ahn JY, Choi KD, Choi JY, et al. Transnasal endoscope-assisted endoscopic submucosal dissection for gastric adenoma and early gastric cancer in the pyloric area: a case series. Endoscopy 2011;43:233-5. 20. Uraoka T, Kato J, Ishikawa S, et al. Thin endoscope-assisted endoscopic submucosal dissection for large colorectal tumors (with videos). Gastrointest Endosc 2007;66:836-9. 21. von Delius S, Karagianni A, von Weyhern CH, et al. Percutaneously assisted endoscopic surgery using a new PEG-minitrocar for advanced endoscopic submucosal dissection (with videos). Gastrointest Endosc 2008;68:365-9. 22. Jeon WJ, You IY, Chae HB, et al. A new technique for gastric endoscopic submucosal dissection: peroral traction-assisted endoscopic submucosal dissection. Gastrointest Endosc 2009;69:29-33. 23. Saito Y, Emura F, Matsuda T, et al. A new sinker-assisted endoscopic submucosal dissection for colorectal cancer. Gastrointest Endosc 2005;62:297-301. 24. Matsumoto K, Nagahara A, Sakamoto N, et al. A new traction device for facilitating endoscopic submucosal dissection (ESD) for early gastric cancer: the “medical ring.” Endoscopy 2011;43(Suppl 2 UCTN):E67-8. 25. Parra-Blanco A, Nicolas D, Arnau MR, et al. Gastric endoscopic submucosal dissection assisted by a new traction method: the clip-band technique. A feasibility study in a porcine model (with video). Gastrointest Endosc 2011;74:1137-41. 26. Fernandez-Esparrach G, Shaikh SN, Cohen A, et al. Efficacy of a reversephase polymer as a submucosal injection solution for EMR: a comparative study (with video). Gastrointest Endosc 2009;69:1135-9. 27. Hashimoto R, Hirasawa D, Iwaki T, et al. Usefulness of the S-O clip for gastric endoscopic submucosal dissection (with video). Surg Endosc 2018;32:908-14. 28. Ritsuno H, Sakamoto N, Osada T, et al. Prospective clinical trial of traction device-assisted endoscopic submucosal dissection of large superficial colorectal tumors using the S-O clip. Surg Endosc 2014;28:3143-9. 29. Yoshida M, Takizawa K, Suzuki S, et al. Conventional versus tractionassisted endoscopic submucosal dissection for gastric neoplasms: a multicenter, randomized controlled trial (with video). Gastrointest Endosc 2017;87:1231-40. 30. He Y, Fu K, Leung J, et al. Traction with dental floss and endoscopic clip improves trainee success in performing gastric endoscopic submucosal dissection (ESD): a live porcine study (with video). Surg Endosc 2016;30:3138-44. Abbreviations: ESD, endoscopic submucosal dissection; NASA, National Aeronautical and Space Administration. DISCLOSURE: The following authors disclosed financial relationships relevant to this publication: C. C. Thompson: Consultant for Boston
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Scientific, Apollo Endosurgery, and Olympus. H. Aihara: Consultant for Boston Scientific and Olympus. All other authors disclosed no financial relationships relevant to this publication. Copyright ª 2018 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 https://doi.org/10.1016/j.gie.2018.08.032
Hepatology and Endoscopy, Brigham and Women’s Hospital, Boston, Massachusetts, USA (2). Presented at Digestive Disease Week, June 2-5, 2018, Washington, DC (Gastroenterol 2018;154:S441-2).
Received May 15, 2018. Accepted August 10, 2018.
Reprint requests: Hiroyuki Aihara, MD, PhD, Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115.
Current affiliations: Developmental Endoscopy Lab, Harvard Medical School, Boston, Massachusetts, USA (1), Division of Gastroenterology,
If you would like to chat with an author of this article, you may contact Dr Aihara at [email protected].
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