Modified submucosal tunneling by blunt dissection for peroral endoscopic myotomy

Article information

Clin Endosc. 2024; Epub ahead of print.

Publication date (electronic) : 2024 April 1

doi : https://doi.org/10.5946/ce.2024.011

Yusuke Hashimoto^,1, Kuniyo Gomi², Bruno De Souza Ribeiro¹

¹Division of Gastroenterology, Department of Internal Medicine, University of Florida, Jacksonville, FL, USA

²Division of Gastroenterology, Department of Internal Medicine, Fujigaoka Hospital, Showa University, Yokohama, Kanagawa, Japan

Correspondence: Yusuke Hashimoto Division of Gastroenterology, Department of Internal Medicine, University of Florida, Jacksonville, FL, USA653-1 West 8th Street, L20 Jacksonville, FL 32209, USA E-mail: Yusuke.Hashimoto@jax.ufl.edu

Received 2024 January 10; Revised 2024 March 2; Accepted 2024 March 3.

Esophageal achalasia is a disorder of esophageal motility characterized by incomplete relaxation of the lower esophageal sphincter (LES) at the esophagogastric junction and the absence of primary peristaltic waves, leading to obstruction of the passage of liquids and solids from the esophagus to the stomach. Peroral endoscopic myotomy (POEM) was first developed by Inoue et al.1 An important step in completing the POEM procedure is submucosal tunneling.2 Preserving the mucosal layer minimizes air and fluid leakage into the mediastinum and prevents procedural complications, such as pneumoperitoneum, pneumomediastinum, subcutaneous emphysema, and mediastinitis. The submucosal tunneling technique allows for safer entry into the mediastinum. After mucosal incision, submucosal tunneling is usually performed along the muscle layer using electrocautery knife dissection to avoid mucosal layer injury. Additional injections were administered during tunneling, as needed, and hemostasis was appropriately achieved for visible vessels. We used a modified blunt dissection technique for submucosal tunneling with a tapered distal attachment and EndoClot Submucosal Injection System (EndoClot SIS; Olympus) for submucosal injection, which is made of absorbable modified polymers derived from plant polysaccharide powders. Informed consent was obtained from all patients involved in this report. We report the case of a 45-year-old female who complained of solid food dysphagia refractory to multiple esophageal dilatations. She was referred for evaluation and treatment of suspected achalasia. Esophageogastroduodenoscopy revealed abnormal motility in the lower third of the esophagus and spasticity was observed in the esophageal body. Subsequently, endovascular balloon insufflation was performed using an EF-322N catheter (Medtronic) to assess esophageal motility. The serial LES measurements revealed a diameter of 5.2, distensibility of 0.5, balloon volume of 40, diameter of 7, distensibility of 0.7, balloon volume of 50, diameter of 9.5, distensibility of 1.55, balloon volume of 60, diameter of 11.1, distensibility of 1.53, and balloon volume of 70. Decreased LES diameter and distensibility were observed with esophageal spastic contractions. The patient was diagnosed with type 1 achalasia. POEM was performed after obtaining informed consent. As for the tapered distal attachment, the small caliber tip (ST) hood (outer diameter 11.0 mm, inner diameter 8.0 mm, DH-28GR; Fujifilm) was attached to a gastroscope (GIF–HQ190; Olympus) (Fig. 1). A dual knife (KD-650U; Olympus) was used for the mucosal incision. A normal saline bag (100 mL) was mixed with 0.5 g absorbable modified polymer powder (EndoClot SIS) and several drops of methylene blue. EndoClot SIS was prepared in 10 mL syringes for submucosal injection. The patient was placed in a supine position and sedated under general anesthesia. Antibiotics were intravenously administered throughout the study period. The gastroscope was introduced into the mouth, and submucosal injection using a 26-G injection needle was performed extensively on the posterior side of the mid-esophagus, 29 cm from the gastroesophageal junction (39 cm). A longitudinal mucosal incision of 29 cm was made (Fig. 2), and an ST-hood-mounted gastroscope was inserted into the injected tunnel. Submucosal dissection was initiated using Endocut 1 Effect 4 (ERBE VIO300D), and the entry of the submucosal space was subsequently dissected using a Forced Effect 2 35 W to allow the gastroscope to enter 2 cm from the incision. The gastroscope was slowly pushed down along the muscle layer to bluntly dissect the submucosal space using the tapered distal attachment (Fig. 3). The visible vessels coagulated appropriately during tunneling. The blunt dissection was extended to the cardia and completed. Gastroscopy identified a submucosal bleb in the cardia to confirm the adequacy of submucosal tunneling. Myotomy was performed by full-thickness cutting of the inner circular and external longitudinal muscle fibers using a dual knife, starting 2 cm past the gastroesophageal junction into the cardia and ending 2 cm distal to the incision site. After completion of the myotomy, the gastroscope was withdrawn from the submucosal tunnel and passed through the true lumen to examine the esophageal mucosa overlying the submucosal tunnel for any mucosal injury. Finally, the mucosal defect was firmly closed using seven clips (G58010; Cook). The submucosal tunneling time was 3 minutes, whereas the total procedure time from submucosal injection to mucosal defect closure was 32 minutes (Supplementary Video 1). The patient’s condition was uneventful, except for mild chest pain that lasted for a few days after the procedure. Esophagography showed no leak, spasm, or contrast retention. The patient eventually developed a tolerance to a normal diet.

Fig. 1.

Tapered distal attachment for blunt submucosal dissection. ST hood (outer diameter 11.0 mm, inner diameter 8.0 mm, DH-28GR; Fujifilm).

Fig. 2.

(A) Longitudinal submucosal injection from the middle part of the esophagus to the gastroesophageal junction was performed using normal saline mixed with the EndoClot Polysaccharide Hemostatic System (EndoClot PHS; Olympus) and methylene blue. (B) An incision was started using a dual knife (KD-650U; Olympus) in the middle part of the esophagus.

Fig. 3.

Submucosal tunneling was performed using a blunt dissection technique with an ST hood. The submucosal tunneling extended to the cardia after blunt dissection.

Submucosal tunneling is a minimally invasive technique routinely used in third-space endoscopy procedures such as endoscopic submucosal dissection or POEM. This is one of the steps of POEM that must be carefully performed. The submucosal tunnel was created from the incision entry point to a few centimeters toward the gastric side, beyond the cardia. Mucosal incisions were initially made at the entry point after the submucosal injection, followed by submucosal dissection between the mucosal and muscular layers to create a tunnel space.2 An electrosurgical knife is commonly used to create an initial mucosal incision at the entry point, dissect the submucosal space during the submucosal tunneling process, and achieve hemostasis by coagulating the bleeding vessels to advance the dissection path. However, the drawback of electrosurgical cutting is the potential damage to the mucosal and muscle layers, potentially leading to procedural complications such as perforation or mucosal tears.

The caps provide an optimal field of focused view during submucosal dissection, prevent redouts, help in submucosal dissection by applying pressure over the resected lesion, help store accessories during bleeding control, provide tamponade, and help maintain a clear plane of dissection by draining accumulated fluid and blood from side holes. A tapered, small-caliber-tip, transparent hood is a useful distal attachment. The pocket-creation method is a new endoscopic submucosal dissection technique that uses a tapered, small-caliber-tip, transparent hood to allow the fixed tip of the endoscope to easily enter underneath the mucosa and provide traction and countertraction, resulting in rapid submucosal dissection with clear visualization of the muscularis propria.3

Recently, a blunt dissection technique was reported.4 Blunt dissection with a transparent cap demonstrated only 2 minutes of tunneling to create a 10-cm tunnel. When performing third-space endoscopy, this technique is promising for reducing the procedure time and avoiding complications. A case series of navigational injections has been reported for gastric peroral endoscopic pyloromyotomy.5 The average time for submucosal dissection was reduced by 50% to between 25 and 30 minutes. This technique avoids the need to exit the tunnel repeatedly to determine its direction. Although shot-length myotomy or bottom-up techniques have been reported to reduce procedure time with favorable efficacy, the procedure time is still >40 minutes, and there is room for technical improvement in submucosal tunneling.6,7

Considering these technical aspects, we developed a modified technique using a tapered transparent cap, ST hood, and navigational injection using EndoClot SIS before the mucosal incision. First, the tapered transparent cap has the advantage of exerting more axial force on the middle of the submucosal layer while avoiding tangential force on the mucosal and muscular layers owing to its tapered shape. Second, the navigational approach using pre-injection of EndoClot SIS into the esophagogastric junction results in prolonged and improved lifting, as demonstrated by ex vivo and in vivo studies.8 EndoClot SIS supports an optimal submucosal lift of gastrointestinal mucosal lesions, before excision with an endoscopic knife or snare. Long-lasting high lifts may create significant mucosal separation, facilitating an easier endoscopic resection. This technique eliminates the need for additional injections during tunneling, enabling a dedicated focus on tunnel creation. In this case report, we describe a successful technique of blunt dissection for submucosal tunneling using a tapered distal attachment and EndoClot SIS. This new technique provides a rapid and safe submucosal tunneling procedure for POEM.