- Email: [email protected]
Peroral endoscopic myotomy for esophageal achalasia: Indication and technique
Techniques in Gastrointestinal Endoscopy 15 (2013) 131–134
Contents lists available at SciVerse ScienceDirect
Techniques in Gastrointestinal Endoscopy journal homepage: www.techgiendoscopy.com/locate/tgie
Peroral endoscopic myotomy for esophageal achalasia: Indication and technique☆ Haruhiro Inouen, Haruo Ikeda, Shin-ei Kudo Digestive Disease Center, Showa University Northern Yokohama Hospital, Chigasaki-Chuo 35-1, Tsuzuki-ku, Yokohama 224-8503, Japan
a r t i c l e in fo
a b s t r a c t
Keywords: Achalasia POEM Endoscopic myotomy Heller myotomy
Since the inception of peroral endoscopic myotomy (POEM) in 2008, more than 2000 POEMs have been performed to date in the world. The technique has been standardized to include the following 5 steps: mucosectomy, submucosal tunnel creation, esophageal myotomy, cardiomyotomy, and mucosectomy closure. Minor technique variations do exist as far as the equipment utilized as well as with the orientation and completeness of the myotomy. This article describes the equipment used during POEM as well as the essential steps to have a safe and successful procedure. & 2013 Elsevier Inc. All rights reserved.
1. Introduction The concept of natural orifice translumenal endoscopic surgery [1-3] has inspired gastroenterologists and endoscopic surgeons to create a less invasive method for treating various gastrointestinal diseases, including achalasia. The conventional treatments for achalasia include balloon dilation and laparoscopic myotomy, with Botox injection reserved for those not considered candidates for the aforementioned therapies [4-6]. Peroral endoscopic myotomy (POEM) is a less invasive endoscopic approach to Heller myotomy, and the shortterm data demonstrate that it offers excellent outcomes that appear to rival those of the laparoscopic Heller myotomy [7]. The technique and equipment used during POEM are discussed in detail in this section.
2. Equipment used A forward-viewing gastroscope with an outer diameter of 9.8 mm, with a transparent distal attachment cap (MH-588, Olympus) is used to perform POEM. The distal attachment cap allows for better endoscopic visualization of the submucosal space [8]. This obliquely tipped cap can allows easier insertion of the endoscope into the submucosal tunnel, whereas using a tapered cap (DH-28GR, Fuji) which can be used when entering the submucosal space is particularly difficult. At our center, all equipment including the gastroscope is sterilized using ethylene oxide gas. Most centers, however, perform high-level disinfection as is standard for endoscopic procedures.
The tunnel is typically created by progressive dissection using esophageal submucosal dissection technique. A high-frequency electrosurgical generator such as the VIO 300D (ERBE, Tübingen, Germany) is used in the spray coagulation mode. Electrosurgical dissection is accomplished using the triangle-tip knife (KD-640L, Olympus) (Figure 1A) or the Hybrid knife T-type (ERBE, Tübingen, Germany) (Figure 1B). The hybrid knife can inject a stream of saline through the tip of the knife, whereas with the triangle-tip knife a separate needle injector is used for submucosal injection. During dissection when large vessels are noted, coagulating forceps (Coagrasper, FD-411QR, Olympus) are used to coagulate and achieve hemostasis. Carbon dioxide gas is used for insufflation during the procedure, with a CO2 insufflator (UCR, Olympus) providing CO2 at a constant rate of 1.2 liters per minute. Endoscopic CO2 insufflation is beneficial for reducing mediastinal emphysema and air embolization. One should confirm that the air button on the endoscopy processor is off. Otherwise, air would also be supplied in addition to CO2 insufflation. Finally, for the closure of the mucosal entry site and any accidental injuries to the mucosal flap, hemostatic clips (EZ-CLIP, HX-110QR, Olympus) are applied. Some operators may use alternative clips and endoscopic suturing devices to achieve closure of the mucosal entry to the tunnel, particularly if a large mucosectomy defect and unfavorable mucosal edges are present or if fullthickness injury involving the muscularis is present.
3. Procedure ☆ The author reports no direct financial interests that might pose a conflict of interest in connection with the submitted manuscript. The author is an advisory to Olympus. n Corresponding author. E-mail address: [email protected] (H. Inoue).
0049-0172/$ - see front matter & 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.tgie.2013.05.003
Patients undergoing POEM are intubated and under general anesthesia. Severe mediastinal emphysema and pneumothorax may occur if POEM is done with only conscious sedation. Positive pressure ventilation reduces the risk of mediastinal emphysema.
132
H. Inoue et al / Techniques in Gastrointestinal Endoscopy 15 (2013) 131–134
Fig. 1. (A) Triangular-tip (TT knife) knife and (B) Hybrid knife T-type.
During POEM, pneumoperitoneum may occur in some cases. To prevent abdominal compartment syndrome, the upper abdominal wall is exposed and checked periodically during the procedure. When the abdomen is excessively distended, a puncture is made using an angiocatheter or Veress needle, to vent the pneumoperitoneum and reduce abdominal pressure. All POEM operators have reported using similar methods to decompress capnoperitoneum [8-16]. 3.1. Creation of the submucosal tunnel Before starting POEM, the position of the gastroesophageal junction (GEJ) and its tightness on retroflexion are confirmed (Figure 3A). A submucosal injection consisting of saline stained with 0.3% indigo carmine is used to create a mucosal bleb before performing a mucosal incision (Figure 2A). The mucosal incision is usually made along the right anterior wall. Incision along the 2-o'clock orientation leads to the lesser curve of the stomach, which enables smooth continuous dissection into the gastric
cardia muscle. Dissection along the 2-o'clock orientation also potentially avoids injury to the sling muscle fibers, which are a major component of the angle of His and may limit acid reflux. Submucosal injection is generally done first at the level of the mid esophagus, approximately 13 cm proximal to the GEJ. This location is just below the carina and approximately 29 cm from patient's incisors creating a submucosal tunnel length of approximately 16 cm. A 2-cm longitudinal mucosal incision is made on the mucosal surface to create a mucosal entry to the submucosal space (energy source at Endocut Q, 30 W, cutting duration 1: interval: 6). The submucosal tunnel is extended distally using a technique similar to esophageal submucosal dissection, passing over the esophagogastric junction and entering the proximal stomach for approximately 3 cm. The width of the tunnel is approximately onethird of the circumference of the tubular esophagus. The dissecting plane should closely follow the muscle layer (Figures 3B and 2B). Caution is taken never to dissect close to the mucosal layer, because the mucosal layer is the only barrier between the esophageal lumen and mediastinum after completion of the myotomy. Repeated submucosal injection makes the dissection easier whenever the demarcation between submucosal layer and muscle layer becomes obscure. The submucosal tunnel is extended beyond the GEJ. An important concern during POEM is appropriate identification of the GEJ in the submucosal space. For clear identification of the GEJ, the following indicators should be checked: 1. The first indicator is the insertion length of the endoscope from the incisors. The position of the GEJ in the lumen of the esophagus is recorded accurately before the endoscope is inserted into the submucosal tunnel, as the insertion depth of the endoscope in the submucosal space is almost the same as in the true lumen. The submucosal tunnel which is created ends at least 3 cm distal to the estimated GEJ. 2. The second indicator is a marked increase in resistance when the endoscope approaches the GEJ, followed by a prompt easing when the endoscope passes through the narrow GEJ and enters the submucosal space of the gastric cardia. The working space in the submucosal tunnel also becomes gradually narrower when the endoscope approaches the lower esophageal sphincter (LES). At the LES, movement of the endoscope is limited owing to the high resistance. Once the endoscope has passed
Fig. 2. (A) Mucosal entry. The mucosal entry to the submucosal space is usually made at approximately 13 cm proximal to esophagogastric junction (EGJ). (B) Submucosal tunnel. The Submucosal tunnel is created in the submucosal space and extended to the level of the gastric cardia. It is approximately 15-cm long (12 cm on the esophageal side and 3 cm on the stomach side). This long tunnel is the working space for the myotomy. (C) Endoscopic myotomy. The endoscopic myotomy is carried out with the endoscope in the submucosal tunnel. It is initiated 2 cm distal to mucosal incision. A circular muscle myotomy is shown here. (D) Completed myotomy. The endoscopic myotomy is extended beyond the EGJ to include a 2-cm cardiomyotomy. Complete dissection of the lower esophageal sphincter and cardiomyotomy are very important parts of this procedure. (E) Closure of the mucosal entry site. The mucosal entry site is closed with endoscopic clips.
H. Inoue et al / Techniques in Gastrointestinal Endoscopy 15 (2013) 131–134
133
Fig. 3. (A) EGJ. The position of the EGJ is confirmed at the start of the POEM procedure. (B) The submucosal tunnel is dissected. On the right half of the image is the surface of the muscle layer. (C) Endoscopic myotomy. The myotomy starts at 2 cm distal to mucosal incision. Using the TT (triangle tip) knife, the circular muscle bundle is lifted and then cut by electrocautery. (D) Mediastinum and mucosal flap. Complete myotomy is present here with exposure of the mediastinum (right half of image). The mucosal flap is also seen (left half of image; E) At the level of the phrenoesophageal ligament, the diaphragmatic crus is often directly visualized. (F) Closure of the mucosal entry site. The mucosal entry site is closed with endoscopic clips. EGJ, esophagogastric junction.
through this narrow segment, the submucosal space promptly widens in the submucosa of the cardia. 3. The third indicator is endoscopic visualization of palisading vessels in the submucosal layer. Palisading vessels are located at the distal end of the esophagus. 4. The fourth indicator is the presence of a web of spindle-like veins in the submucosa overlying the muscle at the GEJ. 5. The fifth indicator is the blue staining of the gastric cardia mucosa seen on endoluminal retroflexed view.
3.2. Endoscopic myotomy Dissection of the circular muscle bundle is begun at 2 cm distal to the mucosectomy, approximately 10 cm above the GEJ (Figure 2C). The edge of the knife is used to first catch a couple of circular muscle bundles and then to lift them up toward the esophageal lumen. The captured circular muscle bundle is cut by spray coagulation current (50 W, effect 2). The thickness of the circular muscle layer differs among patients. After the circular muscle layer myotomy is performed, the longitudinal muscle plane can be identified (Figure 3C). The longitudinal muscle layer is usually very thin, and its fibers can be easily split during the circular muscle myotomy thereby exposing mediastinal tissue (Figure 3D). Some centers intentionally perform complete myotomy (of both circular and longitudinal muscle layers). There are no direct comparative data at this time between circular layer myotomy only and complete myotomy. There are no negative clinical outcomes after complete myotomy secondary to the presence of the intact mucosal barrier. When complete myotomy is performed, the diaphragmatic crus is observed directly, which is a good anatomical landmark of the phrenoesophageal ligament (Figure 3E). Myotomy should be continued until approximately 5 cm from the level of diaphragmatic crus. Division of the sphincter muscle is continued from the proximal side toward the stomach until the endoscope passed through the narrowed segment of the LES. The myotomy is continued for at least 2 cm distal to the GEJ (Figure 2D). After completion of the
myotomy, the POEM operator should confirm smooth passage of endoscope through the GEJ to ensure all the LES fibers were cut. A few centers perform the myotomy at the right posterolateral “5-o'clock” orientation. Others and we perform the myotomy at a right anterolateral 2-o'clock orientation which in the supine position leads to the lesser curvature of the stomach. The angle of His is located in the 8-o'clock direction. Anterior myotomy potentially avoids damage to the angle of His, which may be a natural barrier to postoperative reflux of gastric contents. In surgical myotomy, an antireflux measure, such as a Dor procedure, is also carried out to avoid postoperative gastroesophageal reflux disease, as adjacent structures surrounding the distal esophagus (phrenoesophageal ligament) are inevitably dissected which may impair natural antireflux mechanisms. With POEM no antireflux procedure is carried out. However, as during POEM the endoscopist does not dissect paraesophageal structures with antireflux function, it has been argued that even without an antireflux procedure, the rate of reflux after POEM may be lower than that after laparoscopic Heller myotomy. The emerging data on gastroesophageal reflux disease are reviewed in detail elsewhere in this issue. It is expected that future studies would assess the effect of the orientation of the myotomy (anterolateral vs posterolateral) and the completeness of the myotomy (circular-layer-only myotomy vs complete myotomy) on the efficacy of dysphagia relief and the presumed trade-off in prevalence and severity of reflux. One of the major advantages of POEM over laparoscopic Heller myotomy is the ability to extend the myotomy effortlessly in the proximal esophagus to any length required. For example, patients with hypertensive esophageal motor disorders with long distal hypercontractile esophageal segments and prominent chest pain component may require longer myotomies. In our series the longest myotomy was 25 cm. Before closure of the mucosal entrance, 80 mg of gentamicin is injected into the submucosal tunnel. The entrance, which is usually 2-3 cm long, is closed with approximately 5-10 hemostatic clips (Figures 3F and 2E). Tight mucosal closure prevents leakage of esophageal luminal contents into the mediastinum. Successful closure of the mucosal entry is confirmed endoscopically (Figure 3L).
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H. Inoue et al / Techniques in Gastrointestinal Endoscopy 15 (2013) 131–134
4. Periprocedural care
References
As a preparation before POEM, liquid diet is instituted. Some centers perform endoscopic clearance of esophageal contents on the day before POEM. This may be particularly useful in patients with sigmoid achalasia. Gastroscopy before the POEM guarantees clear endoscopic view with no food and liquid residue in the esophagus. Empty esophagus also avoids aspiration during induction of anesthesia. On the day of the procedure, the patient is kept fasting. On the day after POEM, some centers including ours perform gastroscopy. The aim is to confirm mucosal integrity before the initiation of diet. If no mucosal damage is found, then gradual starting of diet is allowed; if mucosal defects are found, then the patient should continue fasting for a few more days until confirmation of defect closure. Fortunately, in our series, we have had no experience of mucosal damage seen on the second-look endoscopy. Most centers perform a barium swallow to confirm smooth passage of contrast media through the GEJ with no leakage and no stasis before the initiation of diet. It is important to remember that after complete myotomy, the mucosal layer is the only barrier between esophageal lumen and mediastinum. Ensuring mucosal integrity is important before initiating oral intake. At our institution, a post-POEM diet consists of liquids the evening of postPOEM day 1, initiating a soft diet on post-POEM day 2, and a normal diet on post-POEM day 3. Wide variation, however, exists among POEM centers with some centers maintaining liquid diet for longer periods of up to a week before initiating a solid diet. All POEM patients at our institution receive intravenous infusion of antibiotics for 3 days followed by 4 days of oral antibiotics for a total course of 7 days. Again, variability among centers exists with some centers only giving prophylactic antibiotics for as little as 3 days.
[1] Kalloo AN, Singh VK, Jagannath SB, et al. Flexible transgastric peritoneoscopy: a novel approach to diagnostic and therapeutic interventions. Gastrointest Endosc 2004;60:114–7. [2] Zorron R, Filgueiras M, Maggioni LC, et al. NOTES. Transvaginal cholecystectomy: report of the first case. Surg Innov 2007;14:279–83. [3] Marescaux J, Dallemagne B, Perretta S, et al. Surgery without scars: report of transluminal cholecystectomy in a human being. Arch Surg 2007;142:823–6. [4] Spiess AE, Kahrilas PJ. Treating achalasia: from whalebone to laparoscope. J Am Med Assoc 1998;280:638. [5] Pehlivanov N, Pasricha PJ. Achalasia: botox, dilatation or laparoscopic surgery in 2006. Neurogastroenterol Motil 2006;18:799–804. [6] Woltman TA, Pellegrini CA, Oelschlager BK. Achalasia. Surg Clin N Am 2005;85:483–93. [7] Inoue H, Minami H, Satodate H, et al. First clinical experience of submucosal endoscopic myotomy for esophageal achalasia with no skin incision. Gastrointest Endosc 2009;69:AB122. [8] Eleftheriadis N, Inoue H, Ikeda H, et al. Training in peroral endoscopic myotomy (POEM) for esophageal achalasia. Ther Clin Risk Manag 2012;8: 329–42. [9] Stavropoulos SN, Harris MD, Hida S, et al. Endoscopic submucosal myotomy for the treatment of achalasia. Gastrointest Endosc 2010;72:1309–11. [10] Von Renteln D, Inoue H, Minami H, et al. Peroral endoscopic myotomy for the treatment of achalasia: a prospective single center study. Am J Gastroenterol 2012;107:411–7. [11] Swanström LL, Rieder E, Dunst CM. A stepwise approach and early clinical experience in peroral endoscopic myotomy for the treatment of achalasia and esophageal motility disorders. J Am Coll Surg 2011;213:751–6. [12] Inoue H, Tianle KM, Ikeda H, et al. Peroral endoscopic myotomy for esophageal achalasia: technique, indication, and outcomes. Thorac Surg Clin 2011;21: 519–25. [13] Costamagna G, Marchese M, Familiari P, et al. Peroral endoscopic myotomy (POEM) for oesophageal achalasia: preliminary results in humans. Dig Liver Dis 2012;44:827–32. [14] Ponsky JL, Marks M, Pauli EM. How I do it: POEM. J Gastrointest Surg 2012;16:1251–5. [15] Swanstrom LL, Kurian A, Dunst CM, et al. Long-term outcomes of an endoscopic myotomy for achalasia: the POEM procedure. Ann Surg 2012;256: 659–67. [16] Chiu PW, Wu JC, Teoh AY, et al. Peroral endoscopic myotomy for treatment of achalasia: from bench to bedside. Gastrointest Endosc 2013;77:29–38.
Contents lists available at SciVerse ScienceDirect
Techniques in Gastrointestinal Endoscopy journal homepage: www.techgiendoscopy.com/locate/tgie
Peroral endoscopic myotomy for esophageal achalasia: Indication and technique☆ Haruhiro Inouen, Haruo Ikeda, Shin-ei Kudo Digestive Disease Center, Showa University Northern Yokohama Hospital, Chigasaki-Chuo 35-1, Tsuzuki-ku, Yokohama 224-8503, Japan
a r t i c l e in fo
a b s t r a c t
Keywords: Achalasia POEM Endoscopic myotomy Heller myotomy
Since the inception of peroral endoscopic myotomy (POEM) in 2008, more than 2000 POEMs have been performed to date in the world. The technique has been standardized to include the following 5 steps: mucosectomy, submucosal tunnel creation, esophageal myotomy, cardiomyotomy, and mucosectomy closure. Minor technique variations do exist as far as the equipment utilized as well as with the orientation and completeness of the myotomy. This article describes the equipment used during POEM as well as the essential steps to have a safe and successful procedure. & 2013 Elsevier Inc. All rights reserved.
1. Introduction The concept of natural orifice translumenal endoscopic surgery [1-3] has inspired gastroenterologists and endoscopic surgeons to create a less invasive method for treating various gastrointestinal diseases, including achalasia. The conventional treatments for achalasia include balloon dilation and laparoscopic myotomy, with Botox injection reserved for those not considered candidates for the aforementioned therapies [4-6]. Peroral endoscopic myotomy (POEM) is a less invasive endoscopic approach to Heller myotomy, and the shortterm data demonstrate that it offers excellent outcomes that appear to rival those of the laparoscopic Heller myotomy [7]. The technique and equipment used during POEM are discussed in detail in this section.
2. Equipment used A forward-viewing gastroscope with an outer diameter of 9.8 mm, with a transparent distal attachment cap (MH-588, Olympus) is used to perform POEM. The distal attachment cap allows for better endoscopic visualization of the submucosal space [8]. This obliquely tipped cap can allows easier insertion of the endoscope into the submucosal tunnel, whereas using a tapered cap (DH-28GR, Fuji) which can be used when entering the submucosal space is particularly difficult. At our center, all equipment including the gastroscope is sterilized using ethylene oxide gas. Most centers, however, perform high-level disinfection as is standard for endoscopic procedures.
The tunnel is typically created by progressive dissection using esophageal submucosal dissection technique. A high-frequency electrosurgical generator such as the VIO 300D (ERBE, Tübingen, Germany) is used in the spray coagulation mode. Electrosurgical dissection is accomplished using the triangle-tip knife (KD-640L, Olympus) (Figure 1A) or the Hybrid knife T-type (ERBE, Tübingen, Germany) (Figure 1B). The hybrid knife can inject a stream of saline through the tip of the knife, whereas with the triangle-tip knife a separate needle injector is used for submucosal injection. During dissection when large vessels are noted, coagulating forceps (Coagrasper, FD-411QR, Olympus) are used to coagulate and achieve hemostasis. Carbon dioxide gas is used for insufflation during the procedure, with a CO2 insufflator (UCR, Olympus) providing CO2 at a constant rate of 1.2 liters per minute. Endoscopic CO2 insufflation is beneficial for reducing mediastinal emphysema and air embolization. One should confirm that the air button on the endoscopy processor is off. Otherwise, air would also be supplied in addition to CO2 insufflation. Finally, for the closure of the mucosal entry site and any accidental injuries to the mucosal flap, hemostatic clips (EZ-CLIP, HX-110QR, Olympus) are applied. Some operators may use alternative clips and endoscopic suturing devices to achieve closure of the mucosal entry to the tunnel, particularly if a large mucosectomy defect and unfavorable mucosal edges are present or if fullthickness injury involving the muscularis is present.
3. Procedure ☆ The author reports no direct financial interests that might pose a conflict of interest in connection with the submitted manuscript. The author is an advisory to Olympus. n Corresponding author. E-mail address: [email protected] (H. Inoue).
0049-0172/$ - see front matter & 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.tgie.2013.05.003
Patients undergoing POEM are intubated and under general anesthesia. Severe mediastinal emphysema and pneumothorax may occur if POEM is done with only conscious sedation. Positive pressure ventilation reduces the risk of mediastinal emphysema.
132
H. Inoue et al / Techniques in Gastrointestinal Endoscopy 15 (2013) 131–134
Fig. 1. (A) Triangular-tip (TT knife) knife and (B) Hybrid knife T-type.
During POEM, pneumoperitoneum may occur in some cases. To prevent abdominal compartment syndrome, the upper abdominal wall is exposed and checked periodically during the procedure. When the abdomen is excessively distended, a puncture is made using an angiocatheter or Veress needle, to vent the pneumoperitoneum and reduce abdominal pressure. All POEM operators have reported using similar methods to decompress capnoperitoneum [8-16]. 3.1. Creation of the submucosal tunnel Before starting POEM, the position of the gastroesophageal junction (GEJ) and its tightness on retroflexion are confirmed (Figure 3A). A submucosal injection consisting of saline stained with 0.3% indigo carmine is used to create a mucosal bleb before performing a mucosal incision (Figure 2A). The mucosal incision is usually made along the right anterior wall. Incision along the 2-o'clock orientation leads to the lesser curve of the stomach, which enables smooth continuous dissection into the gastric
cardia muscle. Dissection along the 2-o'clock orientation also potentially avoids injury to the sling muscle fibers, which are a major component of the angle of His and may limit acid reflux. Submucosal injection is generally done first at the level of the mid esophagus, approximately 13 cm proximal to the GEJ. This location is just below the carina and approximately 29 cm from patient's incisors creating a submucosal tunnel length of approximately 16 cm. A 2-cm longitudinal mucosal incision is made on the mucosal surface to create a mucosal entry to the submucosal space (energy source at Endocut Q, 30 W, cutting duration 1: interval: 6). The submucosal tunnel is extended distally using a technique similar to esophageal submucosal dissection, passing over the esophagogastric junction and entering the proximal stomach for approximately 3 cm. The width of the tunnel is approximately onethird of the circumference of the tubular esophagus. The dissecting plane should closely follow the muscle layer (Figures 3B and 2B). Caution is taken never to dissect close to the mucosal layer, because the mucosal layer is the only barrier between the esophageal lumen and mediastinum after completion of the myotomy. Repeated submucosal injection makes the dissection easier whenever the demarcation between submucosal layer and muscle layer becomes obscure. The submucosal tunnel is extended beyond the GEJ. An important concern during POEM is appropriate identification of the GEJ in the submucosal space. For clear identification of the GEJ, the following indicators should be checked: 1. The first indicator is the insertion length of the endoscope from the incisors. The position of the GEJ in the lumen of the esophagus is recorded accurately before the endoscope is inserted into the submucosal tunnel, as the insertion depth of the endoscope in the submucosal space is almost the same as in the true lumen. The submucosal tunnel which is created ends at least 3 cm distal to the estimated GEJ. 2. The second indicator is a marked increase in resistance when the endoscope approaches the GEJ, followed by a prompt easing when the endoscope passes through the narrow GEJ and enters the submucosal space of the gastric cardia. The working space in the submucosal tunnel also becomes gradually narrower when the endoscope approaches the lower esophageal sphincter (LES). At the LES, movement of the endoscope is limited owing to the high resistance. Once the endoscope has passed
Fig. 2. (A) Mucosal entry. The mucosal entry to the submucosal space is usually made at approximately 13 cm proximal to esophagogastric junction (EGJ). (B) Submucosal tunnel. The Submucosal tunnel is created in the submucosal space and extended to the level of the gastric cardia. It is approximately 15-cm long (12 cm on the esophageal side and 3 cm on the stomach side). This long tunnel is the working space for the myotomy. (C) Endoscopic myotomy. The endoscopic myotomy is carried out with the endoscope in the submucosal tunnel. It is initiated 2 cm distal to mucosal incision. A circular muscle myotomy is shown here. (D) Completed myotomy. The endoscopic myotomy is extended beyond the EGJ to include a 2-cm cardiomyotomy. Complete dissection of the lower esophageal sphincter and cardiomyotomy are very important parts of this procedure. (E) Closure of the mucosal entry site. The mucosal entry site is closed with endoscopic clips.
H. Inoue et al / Techniques in Gastrointestinal Endoscopy 15 (2013) 131–134
133
Fig. 3. (A) EGJ. The position of the EGJ is confirmed at the start of the POEM procedure. (B) The submucosal tunnel is dissected. On the right half of the image is the surface of the muscle layer. (C) Endoscopic myotomy. The myotomy starts at 2 cm distal to mucosal incision. Using the TT (triangle tip) knife, the circular muscle bundle is lifted and then cut by electrocautery. (D) Mediastinum and mucosal flap. Complete myotomy is present here with exposure of the mediastinum (right half of image). The mucosal flap is also seen (left half of image; E) At the level of the phrenoesophageal ligament, the diaphragmatic crus is often directly visualized. (F) Closure of the mucosal entry site. The mucosal entry site is closed with endoscopic clips. EGJ, esophagogastric junction.
through this narrow segment, the submucosal space promptly widens in the submucosa of the cardia. 3. The third indicator is endoscopic visualization of palisading vessels in the submucosal layer. Palisading vessels are located at the distal end of the esophagus. 4. The fourth indicator is the presence of a web of spindle-like veins in the submucosa overlying the muscle at the GEJ. 5. The fifth indicator is the blue staining of the gastric cardia mucosa seen on endoluminal retroflexed view.
3.2. Endoscopic myotomy Dissection of the circular muscle bundle is begun at 2 cm distal to the mucosectomy, approximately 10 cm above the GEJ (Figure 2C). The edge of the knife is used to first catch a couple of circular muscle bundles and then to lift them up toward the esophageal lumen. The captured circular muscle bundle is cut by spray coagulation current (50 W, effect 2). The thickness of the circular muscle layer differs among patients. After the circular muscle layer myotomy is performed, the longitudinal muscle plane can be identified (Figure 3C). The longitudinal muscle layer is usually very thin, and its fibers can be easily split during the circular muscle myotomy thereby exposing mediastinal tissue (Figure 3D). Some centers intentionally perform complete myotomy (of both circular and longitudinal muscle layers). There are no direct comparative data at this time between circular layer myotomy only and complete myotomy. There are no negative clinical outcomes after complete myotomy secondary to the presence of the intact mucosal barrier. When complete myotomy is performed, the diaphragmatic crus is observed directly, which is a good anatomical landmark of the phrenoesophageal ligament (Figure 3E). Myotomy should be continued until approximately 5 cm from the level of diaphragmatic crus. Division of the sphincter muscle is continued from the proximal side toward the stomach until the endoscope passed through the narrowed segment of the LES. The myotomy is continued for at least 2 cm distal to the GEJ (Figure 2D). After completion of the
myotomy, the POEM operator should confirm smooth passage of endoscope through the GEJ to ensure all the LES fibers were cut. A few centers perform the myotomy at the right posterolateral “5-o'clock” orientation. Others and we perform the myotomy at a right anterolateral 2-o'clock orientation which in the supine position leads to the lesser curvature of the stomach. The angle of His is located in the 8-o'clock direction. Anterior myotomy potentially avoids damage to the angle of His, which may be a natural barrier to postoperative reflux of gastric contents. In surgical myotomy, an antireflux measure, such as a Dor procedure, is also carried out to avoid postoperative gastroesophageal reflux disease, as adjacent structures surrounding the distal esophagus (phrenoesophageal ligament) are inevitably dissected which may impair natural antireflux mechanisms. With POEM no antireflux procedure is carried out. However, as during POEM the endoscopist does not dissect paraesophageal structures with antireflux function, it has been argued that even without an antireflux procedure, the rate of reflux after POEM may be lower than that after laparoscopic Heller myotomy. The emerging data on gastroesophageal reflux disease are reviewed in detail elsewhere in this issue. It is expected that future studies would assess the effect of the orientation of the myotomy (anterolateral vs posterolateral) and the completeness of the myotomy (circular-layer-only myotomy vs complete myotomy) on the efficacy of dysphagia relief and the presumed trade-off in prevalence and severity of reflux. One of the major advantages of POEM over laparoscopic Heller myotomy is the ability to extend the myotomy effortlessly in the proximal esophagus to any length required. For example, patients with hypertensive esophageal motor disorders with long distal hypercontractile esophageal segments and prominent chest pain component may require longer myotomies. In our series the longest myotomy was 25 cm. Before closure of the mucosal entrance, 80 mg of gentamicin is injected into the submucosal tunnel. The entrance, which is usually 2-3 cm long, is closed with approximately 5-10 hemostatic clips (Figures 3F and 2E). Tight mucosal closure prevents leakage of esophageal luminal contents into the mediastinum. Successful closure of the mucosal entry is confirmed endoscopically (Figure 3L).
134
H. Inoue et al / Techniques in Gastrointestinal Endoscopy 15 (2013) 131–134
4. Periprocedural care
References
As a preparation before POEM, liquid diet is instituted. Some centers perform endoscopic clearance of esophageal contents on the day before POEM. This may be particularly useful in patients with sigmoid achalasia. Gastroscopy before the POEM guarantees clear endoscopic view with no food and liquid residue in the esophagus. Empty esophagus also avoids aspiration during induction of anesthesia. On the day of the procedure, the patient is kept fasting. On the day after POEM, some centers including ours perform gastroscopy. The aim is to confirm mucosal integrity before the initiation of diet. If no mucosal damage is found, then gradual starting of diet is allowed; if mucosal defects are found, then the patient should continue fasting for a few more days until confirmation of defect closure. Fortunately, in our series, we have had no experience of mucosal damage seen on the second-look endoscopy. Most centers perform a barium swallow to confirm smooth passage of contrast media through the GEJ with no leakage and no stasis before the initiation of diet. It is important to remember that after complete myotomy, the mucosal layer is the only barrier between esophageal lumen and mediastinum. Ensuring mucosal integrity is important before initiating oral intake. At our institution, a post-POEM diet consists of liquids the evening of postPOEM day 1, initiating a soft diet on post-POEM day 2, and a normal diet on post-POEM day 3. Wide variation, however, exists among POEM centers with some centers maintaining liquid diet for longer periods of up to a week before initiating a solid diet. All POEM patients at our institution receive intravenous infusion of antibiotics for 3 days followed by 4 days of oral antibiotics for a total course of 7 days. Again, variability among centers exists with some centers only giving prophylactic antibiotics for as little as 3 days.
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