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Summary

To minimize the technical difficulty and improve the safety of peroral endoscopic myotomy (POEM), we describe a protocol for using a scissor-type knife for the main steps of POEM, including mucosal incision, submucosal tunneling, myotomy, and hemostasis.

Abstract

Peroral endoscopic myotomy (POEM) is one of the first-line treatment modalities along with pneumatic dilation and Heller myotomy for patients with achalasia. Endoscopists, especially trainees during the learning phase, commonly face difficulty in tissue plane dissection and selective myotomy while working near the esophagogastric junction, with increased risks of inadvertent injury, unexpected bleeding, and inadequate myotomy. To minimize the technical difficulty and improve the safety of POEM, we describe a protocol for using a scissor-type knife for the main steps of POEM, including mucosal incision, submucosal tunneling, myotomy, and hemostasis. The standard techniques used with the scissor-type knife involve grasping the target tissue, and then dissection or coagulation. The confirmation of the cutting line after grasping improves the accuracy and reliability of dissection, which is particularly useful for the selective myotomy of the internal circular muscle. Meanwhile, the scissor-type knife provides enhanced hemostatic capability and enables hemostasis and pre-coagulation without the device exchange for hemostatic forceps. Evaluation of the clinical outcomes in three patients who successfully received POEM using the scissor-type knife revealed no perioperative adverse events. At the 3-month follow-up, all patients achieved clinical success with postoperative Eckardt scores ranging from 0 to 1. In conclusion, the use of a scissor-type knife could minimize the technical difficulty and improve the safety of the POEM procedures, which may be suitable for trainees during the learning phase.

Introduction

Peroral endoscopic myotomy (POEM) has gained worldwide acceptance as one of the first-line treatment modalities along with pneumatic dilation and Heller myotomy for patients with achalasia¹. To date, most POEM procedures have been confined to a few high-volume, specialized centers. Previous studies have shown that even operators skilled in laparoscopy or endoscopy have a steep learning curve when they are beginning to perform POEM and a higher volume of cases is required to manage challenging situations and prevent adverse events^2,3. During POEM procedures, endoscopic needle-knives are most commonly used for both submucosal tunneling and myotomy, combined with hemostatic forceps for managing large vessels and active bleeding. However, because of the impaired esophagogastric junction (EGJ) relaxation in patients with achalasia, the limited space at the level of the EGJ increases the technical difficulty of tissue plane dissection and selective myotomy using the needle-type knife. Besides, operators who are still in the learning phase could be less proficient in exchanging the hemostatic forceps for bleeding control, which may lead to poor visibility and even further inadvertent mucosal injury.

Various endoscopic knives have been used in the POEM procedures for better manipulations and safety profiles^4,5. The junior scissor-type knife (Stag-beetle Knife Jr.) with two monopolar blades that are both insulated externally was originally developed for accurate manipulations in colorectal endoscopic submucosal dissection (ESD)⁶. The standard techniques used with the scissor-type knife involve grasping the target tissue, and then dissection or coagulation. Theoretically, tissue injury caused by unintentional movement could be avoided with a scissor-type knife as compared with a needle-type knife⁷. Several studies have demonstrated the feasibility and safety of using the scissor-type knife for all ESD procedures, including mucosal incision, submucosal dissection, and hemostasis^7,8. Meanwhile, a recent randomized controlled trial showed that the scissor-type knife significantly improved the trainees’ self-completion rates for colorectal ESD⁹. It can be speculated that these advantages of the scissor-type knife can promote a safer POEM procedure, especially during the trainee’s early cases. To minimize the technical difficulty and improve the safety of POEM, we described a protocol for using a scissor-type knife for the main steps of the POEM procedure, including mucosal incision, submucosal tunneling, myotomy, and hemostasis. Three patients with achalasia who received POEM using the scissor-type knife were presented to evaluate the feasibility and clinical outcomes of this protocol.

Protocol

The protocol was conducted in accordance with the Declaration of Helsinki and the protocol was approved by the Institutional Review Board at the First Affiliated Hospital of Sun Yat-sen University.

1. Patient selection

1. Diagnose achalasia by clinical manifestations and diagnostic testing (barium esophagram, high-resolution manometry (HRM), and upper endoscopy)¹⁰: the presence of symptoms such as dysphagia, regurgitation, chest pain, and weight loss; the "bird's-beak" appearance on barium esophagram; impaired relaxation of the lower esophageal sphincter and absent peristalsis on the results of HRM; and ruling out malignancy by upper endoscopy.
2. Use the following inclusion criteria: diagnosis of achalasia; Eckardt score¹¹ > 3; age between 18-80 years; written informed consent for POEM using the scissor-type knife.
3. Use the following exclusion criteria: coagulopathy and systemic disorders that precluded safe general anesthesia; pregnancy; ulcerated esophagitis.

2. Preoperative preparations

1. Administer a liquid only diet 1 day before the POEM procedure.
2. Administer intravenous antibiotics (Cefazolin) and proton pump inhibitors (PPIs) 30 min before the induction of anesthesia.
3. Perform an upper endoscopy to aspirate any residual contents to reduce the risk of aspiration immediately before the induction of anesthesia.
4. Administer general anesthesia (propofol) with endotracheal intubation.
5. Place the patient in a supine position.

3. Surgical technique with a scissor type knife for the POEM procedure

NOTE: See Figure 1 for the POEM procedure using a scissor-type knife.

1. Identify the EGJ by the puckered and tight appearance. Confirm the increased resistance when maneuvering the endoscope through the EGJ. Note the location of the EGJ by measuring the distance from the incisors.
2. Choose an injection point 7 to 9 cm proximal to the EGJ in the posterior wall (the 5-6 o'clock position) of the esophagus. Inject saline with methylene blue into the submucosal space with an endoscopic injection needle.
   NOTE: Use an extended proximal injection point for patients with Chicago type III achalasia.
3. Make a 1.5 to 2 cm longitudinal mucosal incision with the scissor-type knife (endocut Q mode: effect 3, duration 2, interval 4).
4. Rotate the blades of the scissor-type knife parallel to the muscle layer. Then grasp and dissect (endocut Q mode: effect 3, duration 2, interval 4) the submucosa tissue to create a submucosal tunnel to a location 2 to 3 cm below the EGJ. Keep the dissection plane close to the muscle layer. Inject saline with methylene blue into the submucosal tissue to expand the working space with tunnel progression.
5. Confirm the adequate submucosal tunnel length by the blue discoloration of the gastric mucosa on the retroflexed view.
6. Use the scissor-type knife for intraoperative vessel sealings and bleeding controls (forced coagulation mode: effect 2, 50 W) without changing the hemostatic forceps.
7. Begin the anterograde myotomy at approximately 2 cm distal to the mucosal entry. Selectively grasp and dissect (endocut Q mode: effect 3, duration 2, interval 4) the internal circular muscle bundle with the scissor-type knife. Extend the myotomy 2 to 3 cm onto the gastric cardia.
8. After the completion of myotomy, confirm the smooth passage through the EGJ by reinserting the endoscope into the esophageal lumen.
9. Close the mucosal entry with endoclips.

4. Postoperative management

1. Admit patients to the inpatient ward following the POEM procedure for observation.
2. Administer intravenous antibiotics for 24 h after the POEM procedure. Continue the intravenous PPIs until discharge, and then switch to the oral PPIs (single dose) for 6 weeks.
3. Initiate a liquid diet 24 h after the POEM procedure. At discharge, instruct patients to adhere to a soft diet for 2 weeks, and then resume regular diet gradually.

5. Follow-up

1. Schedule an initial follow-up by outpatient visits and telephone interviews at 3 months postoperatively.
2. At the follow-up visit, obtain standardized questionnaires from patients, including Eckardt scores¹¹, GerdQ scores¹², body weight, and information about PPIs use. Schedule objective tests, including HRM, barium esophagram, and upper endoscopy.

Representative Results

Compared with the needle-type knife, the scissor-type knife enables coagulation and dissection after grasping the target tissue. Meanwhile, the scissor-type knife is equipped with an enhanced hemostatic capability similar to hemostatic forceps and insulated coating external of the two blades (Table 1). Three patients with achalasia received POEM using the scissor-type knife in our institution. Sigmoid esophagus was present in one patient. One patient had previously undergone pneumatic dilation. Technical success was achieved in all the patients with no occurrence of perioperative adverse events. All bleeding controls and vessel sealings in the three POEM procedures were managed by the scissor-type knife without the use of hemostatic forceps. The procedure time was 60, 45, and 40 min, respectively (Table 2).

At the 3-month follow-up, all patients achieved clinical success with postoperative Eckardt scores ranging from 0 to 1. The postoperative HRM and barium esophagram data showed significant reductions in lower esophageal sphincter pressure, 4-second integrated relaxation pressure, and esophageal diameter. One patient had an endoscopic finding of low-grade esophagitis (Los Angeles grade A) without reflux symptoms (Table 3).

Figure 1: The procedure of peroral endoscopic myotomy using the scissor-type knife. (A) An image of the tight EGJ before POEM. (B) After submucosal injection, the mucosa in the posterior esophageal wall was incised by the scissor-type knife. (C) A submucosal tunnel was created using the scissor-type knife. (D) The selective myotomy of the internal circular muscle was performed using the scissor-type knife. (E) The mucosal entry was closed with endoclips. (F) An image of the relaxed EGJ after POEM. EGJ, esophagogastric junction; POEM, peroral endoscopic myotomy. Please click here to view a larger version of this figure.

Parameters	Scissor-type knife	Needle-type knife
Structure	Scissor-type with a forceps length of 3.5 mm and a maximal open width of 4.5 mm	Needle-type with lengths ranging between 1.5 and 4.5 mm
Insulating coating	Insulated coating external of the two blades	No
Dissection technique	Grasp the tissue before dissection	Hook the tissue before dissection
Hemostatic capability	Enhanced hemostatic capability similar to hemostatic forceps	Usually combined with the use of  hemostatic forceps
Water-jet injection function	No	Equipped in some advanced needle-type knives

Table 1: The characteristics of the scissor-type knife in comparison with the needle-type knife.

Parameters	Patient 1	Patient 2	Patient 3
Age  (year)	62	52	26
Gender	Male	Male	Male
Body mass index (Kg/m2)	20.5	22.5	17.4
Disease duration (month)	60	24	120
Chicago classification
Sigmoid type	No	Yes	No
Previous therapy	No	No	Pneumatic dilatation
Length of myotomy (cm)	9	7	8
Esophageal	6	5	6
Gastric	3	2	2
Procedure time (min)	60	45	40
Hemostatic forceps usage	No	No	No
Length of postoperative hospital stay (day)	3	3	3
Perioperative adverse events	No	No	No

Table 2: Details of patient characteristics and POEM procedures.

Parameters	Patient 1	Patient 2	Patient 3
Weight gained (Kg)	5.5	4.5	2.5
Eckardt score
Pre-POEM	7	8	5
Post-POEM	0	0	1
GerdQ score	6	6	6
Use of proton pump inhibitors	No	No	No
Lower esophageal sphincter pressure (mmHg)
Pre-POEM	47.6	58.1	42.5
Post-POEM	10.7	23.5	20.5
4-second integrated relaxation pressure (mmHg)
Pre-POEM	39.0	37.2	42.4
Post-POEM	10.3	13.0	14.4
Esophageal diameter on barium esophagram (cm)
Pre-POEM	3.7	9.1	7.5
Post-POEM	2.3	2.9	4.0
Esophagitis on postoperative endoscopy	LA-A	No	No

Table 3: Clinical outcomes of POEM using the scissor-type knife at 3-month follow-up.

Discussion

As an evolving endoscopic surgical treatment for achalasia, POEM requires both advanced endoscopic skills and knowledge of surgical anatomy. A recent study demonstrated that POEM comes with a considerable learning curve that increases the risk of technical failure, adverse events, and clinical failure². Endoscopists, especially trainees who have not completed their learning phase, commonly face difficulty in accurate manipulations of the endoscopic knife while working near the EGJ with limited working space and less distinct tissue planes. This may result in inadvertent injury, unexpected bleeding, and inadequate myotomy.

Endoscopic needle-type knives have been used since the development of POEM. However, using the needle-type knife requires advanced endoscopic techniques to achieve a safe and adequate selective myotomy, while additional hemostatic forceps are frequently needed for managing large vessels and active bleeding. Unlike the needle-type knife, the scissor-type knife enables coagulation and dissection after grasping the target tissue. The confirmation of the cutting line after grasping improves the accuracy and reliability of dissection and minimizes the risk of tissue injury, which was particularly useful for the selective myotomy of the internal circular muscle. In addition, the scissor-type knife can function as hemostatic forceps and enables precoagulation and hemostasis without device replacement. In the three POEM procedures reported here, all hemostasis and vessel sealings were achieved by the scissor-type knife without using the hemostatic forceps. Furthermore, the tip of the scissor-type knife also has the capability of rotation and an insulated external coating. The capability of rotation offered endoscopists high flexibility for manipulations even at the level of the EGJ, while the insulated external coating of the two blades could protect the surrounding tissue from thermal damage.

The appropriate selection of endoscopic devices is essential for a safe and effective POEM procedure. The operators’ skills and patient characteristics were two important factors to consider in the selection of devices. The characteristics of the scissor-type knife are helpful to minimize the technical difficulty and improve the safety of the POEM procedures, which make it an appropriate device for the trainees during the learning curve phase. Under the supervision of endoscopic specialists, trainees can get verbal agreement on the cutting line of the scissor-type knife before the next dissection. Additionally, the scissor-type knife has better hemostatic capability and could be used as a substitute for additional hemostatic forceps. Thus, the scissor-type knife may be suitable in situations when a high risk of intraoperative bleeding is predicted, such as in patients on antiplatelet or anticoagulant therapy.

Previous studies have shown the feasibility of using the scissor-type knife for myotomy during POEM procedures, while additional devices were still needed for mucosal incision and submucosal tunneling^13,14. The present protocol describes our experience with the use of the scissor-type knife in assisting the whole POEM procedure. However, compared with water-jet equipped needle-type knife, the scissor-type knife is less efficient in submucosal tunneling and mucosal incision, which requires an exchange of accessories for submucosal injection and good cooperation between the endoscopist and the assistant. In technically challenging cases with submucosal fibrosis, the combined use of a needle-type knife (preferably equipped with a water-jet function) is recommended when the scissor-type knife alone may not be effective in dissecting fibrotic tissue. As for the orientation of myotomy, existing evidence showed that the anterior and posterior myotomy in POEM have comparable clinical outcomes in terms of clinical success, post-procedure GERD, and adverse events¹⁵, while the posterior approach allows for better alignment of the endoscopic accessories with the working channel of the endoscope. The use of the scissor-type knife for posterior POEM in this protocol may be helpful to minimize the technical difficulty.

There are several limitations in the present study. First, the present study showed our initial experience of using the scissor-type knife for POEM with a relatively small sample size and short-term follow-up. The favorable outcomes still need further validation. Second, there was no direct comparison data between the scissor-type knife and other needle-type knives. Therefore, future randomized controlled trials are warranted to evaluate the safety, efficacy, and learning curve for POEM using thescissor-type knife compared with the needle-type knife.

In conclusion, the use of the scissor-type knife could minimize the technical difficulty and improve the safety of the POEM procedures, which may be suitable for trainees during the learning curve phase. Future large randomized controlled trials are needed to confirm the safety, efficacy, and learning curve of using the scissor-type knife for POEM compared with conventional knives.

Materials

Electrogenerator	ERBE Elektromedizin	VIO 200S
Endoclip	Micro-Tech (Nanjing)	ROCC-D-26-195-C
Endoscope	Olympus	GIF-H260
Injection Needle	Olympus	NM-400L-0423
Stag Beetle Knife Jr	Sumitomo Bakelite	MD-47703W
Transparent Distal Cap	Olympus	D-201-11804