- Email: [email protected]
POEM Procedure: What the Radiologist Needs to Know for This New Surgical Intervention for Achalasia
Current Problems in Diagnostic Radiology ] (2016) ]]]–]]]
Current Problems in Diagnostic Radiology journal homepage: www.cpdrjournal.com
POEM Procedure: What the Radiologist Needs to Know for This New Surgical Intervention for Achalasia Brian Williams, MDa, Jonathan Kass, MDa,n, Rishi Maheshwary, MDa, Krishna Gurram, MDb, Matthew Hartman, MDa a b
Department of Diagnostic Radiology, Allegheny Health Network, Pittsburgh, PA Department of Gastrointestinal Medicine, Allegheny Health Network, Pittsburgh, PA
Achalasia is a debilitating condition resulting from the failure of appropriate lower esophageal sphincter relaxation. Traditionally, the treatment of choice for achalasia has been a Heller myotomy, performed either via laparotomy or laparoscopically. The latter method has gained wide popularity in its documented lower postoperative morbidity. Recently, however, a new technique has been developed that can be performed by both thoracic surgeons and endoscopists—Per-Oral Endoscopic Myotomy. This procedure offers an alternative to invasive surgery and provides excellent outcomes with minimal recovery time.1 This article would help familiarize radiologists with this new technique, as well as both normal and abnormal postoperative appearances. & 2016 Mosby, Inc. All rights reserved.
Introduction Achalasia is a relatively rare esophageal dysmotility disorder with an annual incidence of 1.6 cases per 100,000 and prevalence of 10 cases per 100,000. Patients are typically diagnosed between the ages 25 and 60 years, though rare disorders may cause achalasia in younger patients. Achalasia shows no sex predilection. This disorder can be secondary to a multitude of conditions such as cancer or Chagas disease but is often idiopathic.2 Achalasia is the result of the lower esophageal sphincter’s (LES) failure to relax and is thought to be secondary to a paucity of ganglion cells (Auerbach cells) in the distal esophagus. The disease typically manifests first as dysphagia with solid foods that soon progresses to both foods and liquids. In time, the tightened esophageal sphincter can lead to regurgitation of retained food products in the esophagus and even aspiration. Chest pain and heartburn are also common symptoms. When first afflicted, patients typically undergo an extensive work up that may include chest radiographs, barium esophagram, manometry, and endoscopy.
Imaging Features Plain radiographs may demonstrate a widened mediastinum with an absent gastric air bubble. Barium esophagram classically demonstrates a dilated esophagus proximal to the LES, retained food products, and abrupt narrowing at the gastroesophageal n Reprint requests: Jonathan Kass, MD, Department of Diagnostic Radiology, Allegheny Health Network, Pittsburgh, PA. E-mail address: [email protected] (J. Kass).
http://dx.doi.org/10.1067/j.cpradiol.2016.04.001 0363-0188/& 2016 Mosby, Inc. All rights reserved.
Fig. 1. A 43-year-old patient with 3-month history of dysphagia. Barium esophagram depicting the typical “bird's beak” deformity typical of achalasia. (Color version of figure is available online.)
2
B. Williams et al. / Current Problems in Diagnostic Radiology ] (2016) ]]]–]]]
Fig. 2. POEM procedure. (A) An enterotomy site is created in the mucosa of the midesophagus. (B) The surgeon dissects the mucosa to the gastroesophageal junction. (C) The circular muscle fibers are removed. (D) The appearance of the esophagus after myotomy. (E) The enterotomy is closed using multiple radiopaque endoscopic clips. (Color version of figure is available online.)
junction, an appearance commonly described as a “bird’s beak” deformity (Fig 1). During the examination, nonproductive, tertiary contractions may be seen, with antegrade and retrograde movement of a swallowed barium bolus. Delayed or absent clearing of barium from the esophagus is common. In patients with longstanding disease, epiphrenic diverticula may also be seen as a result of increased intraluminal pressure in the esophagus. Nevertheless, a normal-appearing barium swallow does not exclude achalasia, as early stages of the disease may not exhibit visible anatomic changes. In such cases, manometric evaluation is invaluable. Manometry findings typically demonstrate aperistalsis of the distal two-thirds of the esophagus. Although incomplete LES relaxation can first be identified at pressures greater than
8 mm Hg, it is not uncommon for pressures in the lower esophagus to surpass 45 mm Hg in more serious cases. On endoscopy, the esophageal mucosa can appear erythematous and possibly ulcerated. However, even in severe cases gentle pressure on the LES during endoscopy should allow passage of the endoscope, a useful finding to differentiate simple achalasia from cases with underlying neoplasm or stenosis, where the LES does not allow the scope to pass.3
Treatment Traditionally, the treatment of choice for achalasia has been a Heller myotomy, either laparoscopically or via laparotomy. This
B. Williams et al. / Current Problems in Diagnostic Radiology ] (2016) ]]]–]]]
3
Fig. 3. Normal endoscopic appearance of POEM clips within the esophagus. (Color version of figure is available online.)
involves incising the esophageal muscular layer from an external approach leaving the esophageal mucosa intact. Minimally invasive laparoscopic surgery has become the mainstay because of the decrease in postoperative morbidity across all surgical fields. As the long-standing primary treatment option, the success and complication rates of the Heller myotomy have been well documented. After this procedure, 89.3% of patients report “good to excellent” symptom relief over a 3-year follow-up period.4 However, relapse rates are common: approximately 5-10 years after surgery, 28%-33% of patients have symptom recurrences and require additional intervention (pneumatic dilatation, botox, or repeat myotomy or esophagectomy).5 The newest treatment option for achalasia, the Per-Oral Endoscopic Myotomy (POEM), uses an endoscopic or internal approach
Fig. 5. Esophagram in a separate patient showing postoperative leak into the mucosal tunnel created during the procedure (yellow arrows). This finding can be safely followed without intervention. (Color version of figure is available online.)
Fig. 4. Normal postoperative findings after POEM on a 36-year-old patient. (A) Scout chest x-ray on postoperative day 1 clearly shows endoscopy clips at the enterotomy site (open arrows) and free air under the diaphragm (solid arrow). (B) Esophagram on the same patient redemonstrates the clips (open arrows) and contrast freely crossing the gastroesophageal junction (asterisk). (Color version of figure is available online.)
4
B. Williams et al. / Current Problems in Diagnostic Radiology ] (2016) ]]]–]]]
to release the circular muscle fibers of the distal esophagus to relieve patients’ symptoms.6 In this procedure, thoracic or endoscopic surgeons introduce an endoscope into the esophagus and create a 2-3 cm incision within the mucosa of the midesophagus to act as the enterotomy site (Fig 2A). Using saline, carbon dioxide, and electrocautery, the surgeon dissects a tunnel in the mucosa toward the gastroesophageal junction (Fig 2B). Once an adequate tunnel is created, electrocautery is used to incise the circular muscle fibers (Fig 2C). An attempt is made to spare the longitudinal fibers to maintain some muscle and submucosal integrity in the distal esophagus. After completion, the endoscope is retracted from the mucosal tunnel and the enterotomy is closed using multiple endoscopic clips (Fig 2E). These endoscopic clips are readily identified during future endoscopies until they are passed (Fig 3). At this point, the procedure is complete.7 In the absence of intraoperative complication, the patient is woken from anesthesia, extubated, and transferred to the Post-Anesthesia Care Unit (PACU) for subsequent admission. A recent meta-analysis showed that when the POEM was compared to the Heller myotomy, there was no difference in operative time, analgesic requirements, complication rates, or even immediate postoperative symptom relief.8 At this time, the primary distinct advantage to the POEM procedure is its shorter hospital stay (mean difference ¼ 0.629; 95% CI: 1.256 to 0.002; P ¼ 0.049).8 Although it may be evident in the future that the POEM offers lower symptom-recurrence rates than the Heller myotomy, it is a too new procedure to have convincing long-term data. Clinical trials with extended follow-up of these patients would be of great benefit in the future.
Follow-Up
Fig. 6. A 6-month follow-up esophagram on patient from Figure 5 shows interval resolution of contained leak as well as passage of the endoscopy clips.
Typically, on postoperative day 1, patients undergo singlecontrast esophagram using iso-osmolar contrast agent to assess the integrity of the surgical site. Multiple endoscopy clips are typically visible overlying the mediastinum on the scout radiograph (Fig 4). Water soluble contrast is used to evaluate for a leak. If no leakage is identified, the patient is started on liquid diet for 7-10 days and reevaluated by the surgeon for advancement in diet.9 Owing to intraoperative insufflation of the esophagus with carbon dioxide, pneumomediastinum and pneumoperitoneum are common (Fig 4A). The prevalence of these findings have been
Fig. 7. Postoperative CT appearance. Although not indicated for postoperative monitoring, when CT is ordered for separate reasons, it readily demonstrates the expected postoperative findings. In this patient, CT was used to evaluate for possible pulmonary embolus on postoperative day 2. (A) Contained postoperative leak appears as an extra contrast-filled lumen (yellow arrow) distal to the enterotomy site, where the endoclips (asterisk) are located. (B) Pneumomediastinum (yellow arrows) and pneumoperitoneum (not pictured) are common normal postoperative findings. (Color version of figure is available online.)
B. Williams et al. / Current Problems in Diagnostic Radiology ] (2016) ]]]–]]]
5
location (Fig 7). Clinically significant mediastinal leaks are extremely rare, reported in 1 study with an incidence of 0.3%.11 Other adverse events that occur after the POEM procedure include pleural effusion (66%), pneumonitis (52%), focal atelectasis (21%), or pneumothorax (17%), all of which are readily identified on CT or radiograph.10 Multiple studies have shown that very few of these sequelae require interventional treatment.10,12 The radiologist also needs to be aware that patients often experience persistent esophageal dysmotility, putting them at risk for aspiration (Fig 8). Additionally, postoperative abscess has also been described with the POEM, which can occur virtually any time postoperatively.13 CT is the modality of choice to evaluate for a postoperative abscess.
Conclusion Achalasia is a common disease, for which there were previously limited and invasive surgical options. The new POEM procedure offers a new, less invasive alternative to patients with this condition, and it has been steadily increasing in popularity since its conception. Though the POEM is a generally safe procedure, when postoperative complications do arise, radiologists should be ready to identify the unique imaging findings to quickly and accurately diagnose problems when they come up.
References
Fig. 8. Esophageal dysmotility after the POEM procedure puts patients at risk for aspiration (open arrow). The 60-year-old patient had esophagram to evaluate for postoperative leak, but the study was aborted because of visualization of aspirated contrast. (Color version of figure is available online.)
reported to be as high as 48% and 37%, respectively, and are not correlated with postoperative complications.10 These should, however, resolve after 10-14 days; persistent findings of pneumomediastinum or pneumoperitoneum after this period are indicative of more serious complications.
Complications The most common complication is a postprocedural leak—the authors have found that in their experience this complication most often presents as a contained leak at the enterotomy site within the mucosal tunnel created during the operation (Fig 5). These patients are treated conservatively. In the case pictured, a 6-month follow-up esophagram revealed no evidence of persistent leak (Fig 6). As pictured, the endoscopy clips typically fall off and pass in the stool by 6 months. In the case of a suspected leak, computed tomography (CT) can be ordered to better evaluate its extent and
1. Phalanusitthepha C, Inoue H, Ikeda H, et al. Peroral endoscopic myotomy for esophageal achalasia. Ann Transl Med 2014;2:31. 2. Minami H, Isomoto H, Yamaguchi N, et al. Peroral endoscopic myotomy (POEM) for diffuse esophageal spasm. Endoscopy 2014;46(suppl 1) UCTN:E79-81. 3. Verlaan T, Rohof WO, Bredenoord AJ, et al. Effect of peroral endoscopic myotomy on esophagogastric junction physiology in patients with achalasia. Gastrointest Endosc 2013;78:39–44. 4. Richards W, Torquati A, Holzman M, et al. Heller myotomy versus Heller myotomy with Dor fundoplication for achalasia: A prospective randomized double-blind clinical trial. Ann Surg 2004;240:405–15. 5. Campos GM, Vittinghoff E, Rabl C, et al. Endoscopic and surgical treatment for achalasia. A systemic review and meta-analysis. Ann Surg 2009;249:45–57. 6. Von Renteln D, Fuchs KH, Fockens P, et al. Peroral endoscopic myotomy for the treatment of achalasia: An international prospective multicenter study. Gastroenterology 2013;145(2) 309-11.e1-e3. 7. Pescarus R, Shlomovitz E, Swanstrom LL. Per-oral endoscopic myotomy (POEM) for esophageal achalasia. Curr Gastroenterol Rep 2014;16:369. 8. Marano L, Pallabazzer G, Solito B, et al. Surgery or peroral esophageal myotomy for achalasia: A systematic review and meta-analysis. Medicine 2016;10:95. 9. Yang D, Wagh MS. Peroral endoscopic myotomy for the treatment of achalasia: An analysis. Diagn Ther Endosc 2013;2013:389596. 10. Cai MY, Zhou PH, Yao LQ, et al. Thoracic CT after peroral endoscopic myotomy for the treatment of achalasia. Gastrointest Endosc 2014;6:1046–55. 11. Patel K, Abbassi-Ghadi N, Markar S, et al. Peroral endoscopic myotomy for the treatment of esophageal achalasia: Systematic review and pooled analysis. Dis Esophagus 2015 [electronically published Jul 14, 2015. Accessed March 28, 2016]. 12. Yang S, Zeng MS, Zhang ZY, et al. Pneumomediastinum and pneumoperitoneum on computed tomography after peroral endoscopic myotomy (POEM): Postoperative changes or complications? Acta Radiol 2015;10:1216–21. 13. Ren Z, Zhong Y, Zhou P, et al. Perioperative management and treatment for complications during and after peroral endoscopic myotomy (POEM) for esophageal achalasia (EA) (data from 119 cases). Surg Endosc 2012;26:3267–72.
Current Problems in Diagnostic Radiology journal homepage: www.cpdrjournal.com
POEM Procedure: What the Radiologist Needs to Know for This New Surgical Intervention for Achalasia Brian Williams, MDa, Jonathan Kass, MDa,n, Rishi Maheshwary, MDa, Krishna Gurram, MDb, Matthew Hartman, MDa a b
Department of Diagnostic Radiology, Allegheny Health Network, Pittsburgh, PA Department of Gastrointestinal Medicine, Allegheny Health Network, Pittsburgh, PA
Achalasia is a debilitating condition resulting from the failure of appropriate lower esophageal sphincter relaxation. Traditionally, the treatment of choice for achalasia has been a Heller myotomy, performed either via laparotomy or laparoscopically. The latter method has gained wide popularity in its documented lower postoperative morbidity. Recently, however, a new technique has been developed that can be performed by both thoracic surgeons and endoscopists—Per-Oral Endoscopic Myotomy. This procedure offers an alternative to invasive surgery and provides excellent outcomes with minimal recovery time.1 This article would help familiarize radiologists with this new technique, as well as both normal and abnormal postoperative appearances. & 2016 Mosby, Inc. All rights reserved.
Introduction Achalasia is a relatively rare esophageal dysmotility disorder with an annual incidence of 1.6 cases per 100,000 and prevalence of 10 cases per 100,000. Patients are typically diagnosed between the ages 25 and 60 years, though rare disorders may cause achalasia in younger patients. Achalasia shows no sex predilection. This disorder can be secondary to a multitude of conditions such as cancer or Chagas disease but is often idiopathic.2 Achalasia is the result of the lower esophageal sphincter’s (LES) failure to relax and is thought to be secondary to a paucity of ganglion cells (Auerbach cells) in the distal esophagus. The disease typically manifests first as dysphagia with solid foods that soon progresses to both foods and liquids. In time, the tightened esophageal sphincter can lead to regurgitation of retained food products in the esophagus and even aspiration. Chest pain and heartburn are also common symptoms. When first afflicted, patients typically undergo an extensive work up that may include chest radiographs, barium esophagram, manometry, and endoscopy.
Imaging Features Plain radiographs may demonstrate a widened mediastinum with an absent gastric air bubble. Barium esophagram classically demonstrates a dilated esophagus proximal to the LES, retained food products, and abrupt narrowing at the gastroesophageal n Reprint requests: Jonathan Kass, MD, Department of Diagnostic Radiology, Allegheny Health Network, Pittsburgh, PA. E-mail address: [email protected] (J. Kass).
http://dx.doi.org/10.1067/j.cpradiol.2016.04.001 0363-0188/& 2016 Mosby, Inc. All rights reserved.
Fig. 1. A 43-year-old patient with 3-month history of dysphagia. Barium esophagram depicting the typical “bird's beak” deformity typical of achalasia. (Color version of figure is available online.)
2
B. Williams et al. / Current Problems in Diagnostic Radiology ] (2016) ]]]–]]]
Fig. 2. POEM procedure. (A) An enterotomy site is created in the mucosa of the midesophagus. (B) The surgeon dissects the mucosa to the gastroesophageal junction. (C) The circular muscle fibers are removed. (D) The appearance of the esophagus after myotomy. (E) The enterotomy is closed using multiple radiopaque endoscopic clips. (Color version of figure is available online.)
junction, an appearance commonly described as a “bird’s beak” deformity (Fig 1). During the examination, nonproductive, tertiary contractions may be seen, with antegrade and retrograde movement of a swallowed barium bolus. Delayed or absent clearing of barium from the esophagus is common. In patients with longstanding disease, epiphrenic diverticula may also be seen as a result of increased intraluminal pressure in the esophagus. Nevertheless, a normal-appearing barium swallow does not exclude achalasia, as early stages of the disease may not exhibit visible anatomic changes. In such cases, manometric evaluation is invaluable. Manometry findings typically demonstrate aperistalsis of the distal two-thirds of the esophagus. Although incomplete LES relaxation can first be identified at pressures greater than
8 mm Hg, it is not uncommon for pressures in the lower esophagus to surpass 45 mm Hg in more serious cases. On endoscopy, the esophageal mucosa can appear erythematous and possibly ulcerated. However, even in severe cases gentle pressure on the LES during endoscopy should allow passage of the endoscope, a useful finding to differentiate simple achalasia from cases with underlying neoplasm or stenosis, where the LES does not allow the scope to pass.3
Treatment Traditionally, the treatment of choice for achalasia has been a Heller myotomy, either laparoscopically or via laparotomy. This
B. Williams et al. / Current Problems in Diagnostic Radiology ] (2016) ]]]–]]]
3
Fig. 3. Normal endoscopic appearance of POEM clips within the esophagus. (Color version of figure is available online.)
involves incising the esophageal muscular layer from an external approach leaving the esophageal mucosa intact. Minimally invasive laparoscopic surgery has become the mainstay because of the decrease in postoperative morbidity across all surgical fields. As the long-standing primary treatment option, the success and complication rates of the Heller myotomy have been well documented. After this procedure, 89.3% of patients report “good to excellent” symptom relief over a 3-year follow-up period.4 However, relapse rates are common: approximately 5-10 years after surgery, 28%-33% of patients have symptom recurrences and require additional intervention (pneumatic dilatation, botox, or repeat myotomy or esophagectomy).5 The newest treatment option for achalasia, the Per-Oral Endoscopic Myotomy (POEM), uses an endoscopic or internal approach
Fig. 5. Esophagram in a separate patient showing postoperative leak into the mucosal tunnel created during the procedure (yellow arrows). This finding can be safely followed without intervention. (Color version of figure is available online.)
Fig. 4. Normal postoperative findings after POEM on a 36-year-old patient. (A) Scout chest x-ray on postoperative day 1 clearly shows endoscopy clips at the enterotomy site (open arrows) and free air under the diaphragm (solid arrow). (B) Esophagram on the same patient redemonstrates the clips (open arrows) and contrast freely crossing the gastroesophageal junction (asterisk). (Color version of figure is available online.)
4
B. Williams et al. / Current Problems in Diagnostic Radiology ] (2016) ]]]–]]]
to release the circular muscle fibers of the distal esophagus to relieve patients’ symptoms.6 In this procedure, thoracic or endoscopic surgeons introduce an endoscope into the esophagus and create a 2-3 cm incision within the mucosa of the midesophagus to act as the enterotomy site (Fig 2A). Using saline, carbon dioxide, and electrocautery, the surgeon dissects a tunnel in the mucosa toward the gastroesophageal junction (Fig 2B). Once an adequate tunnel is created, electrocautery is used to incise the circular muscle fibers (Fig 2C). An attempt is made to spare the longitudinal fibers to maintain some muscle and submucosal integrity in the distal esophagus. After completion, the endoscope is retracted from the mucosal tunnel and the enterotomy is closed using multiple endoscopic clips (Fig 2E). These endoscopic clips are readily identified during future endoscopies until they are passed (Fig 3). At this point, the procedure is complete.7 In the absence of intraoperative complication, the patient is woken from anesthesia, extubated, and transferred to the Post-Anesthesia Care Unit (PACU) for subsequent admission. A recent meta-analysis showed that when the POEM was compared to the Heller myotomy, there was no difference in operative time, analgesic requirements, complication rates, or even immediate postoperative symptom relief.8 At this time, the primary distinct advantage to the POEM procedure is its shorter hospital stay (mean difference ¼ 0.629; 95% CI: 1.256 to 0.002; P ¼ 0.049).8 Although it may be evident in the future that the POEM offers lower symptom-recurrence rates than the Heller myotomy, it is a too new procedure to have convincing long-term data. Clinical trials with extended follow-up of these patients would be of great benefit in the future.
Follow-Up
Fig. 6. A 6-month follow-up esophagram on patient from Figure 5 shows interval resolution of contained leak as well as passage of the endoscopy clips.
Typically, on postoperative day 1, patients undergo singlecontrast esophagram using iso-osmolar contrast agent to assess the integrity of the surgical site. Multiple endoscopy clips are typically visible overlying the mediastinum on the scout radiograph (Fig 4). Water soluble contrast is used to evaluate for a leak. If no leakage is identified, the patient is started on liquid diet for 7-10 days and reevaluated by the surgeon for advancement in diet.9 Owing to intraoperative insufflation of the esophagus with carbon dioxide, pneumomediastinum and pneumoperitoneum are common (Fig 4A). The prevalence of these findings have been
Fig. 7. Postoperative CT appearance. Although not indicated for postoperative monitoring, when CT is ordered for separate reasons, it readily demonstrates the expected postoperative findings. In this patient, CT was used to evaluate for possible pulmonary embolus on postoperative day 2. (A) Contained postoperative leak appears as an extra contrast-filled lumen (yellow arrow) distal to the enterotomy site, where the endoclips (asterisk) are located. (B) Pneumomediastinum (yellow arrows) and pneumoperitoneum (not pictured) are common normal postoperative findings. (Color version of figure is available online.)
B. Williams et al. / Current Problems in Diagnostic Radiology ] (2016) ]]]–]]]
5
location (Fig 7). Clinically significant mediastinal leaks are extremely rare, reported in 1 study with an incidence of 0.3%.11 Other adverse events that occur after the POEM procedure include pleural effusion (66%), pneumonitis (52%), focal atelectasis (21%), or pneumothorax (17%), all of which are readily identified on CT or radiograph.10 Multiple studies have shown that very few of these sequelae require interventional treatment.10,12 The radiologist also needs to be aware that patients often experience persistent esophageal dysmotility, putting them at risk for aspiration (Fig 8). Additionally, postoperative abscess has also been described with the POEM, which can occur virtually any time postoperatively.13 CT is the modality of choice to evaluate for a postoperative abscess.
Conclusion Achalasia is a common disease, for which there were previously limited and invasive surgical options. The new POEM procedure offers a new, less invasive alternative to patients with this condition, and it has been steadily increasing in popularity since its conception. Though the POEM is a generally safe procedure, when postoperative complications do arise, radiologists should be ready to identify the unique imaging findings to quickly and accurately diagnose problems when they come up.
References
Fig. 8. Esophageal dysmotility after the POEM procedure puts patients at risk for aspiration (open arrow). The 60-year-old patient had esophagram to evaluate for postoperative leak, but the study was aborted because of visualization of aspirated contrast. (Color version of figure is available online.)
reported to be as high as 48% and 37%, respectively, and are not correlated with postoperative complications.10 These should, however, resolve after 10-14 days; persistent findings of pneumomediastinum or pneumoperitoneum after this period are indicative of more serious complications.
Complications The most common complication is a postprocedural leak—the authors have found that in their experience this complication most often presents as a contained leak at the enterotomy site within the mucosal tunnel created during the operation (Fig 5). These patients are treated conservatively. In the case pictured, a 6-month follow-up esophagram revealed no evidence of persistent leak (Fig 6). As pictured, the endoscopy clips typically fall off and pass in the stool by 6 months. In the case of a suspected leak, computed tomography (CT) can be ordered to better evaluate its extent and
1. Phalanusitthepha C, Inoue H, Ikeda H, et al. Peroral endoscopic myotomy for esophageal achalasia. Ann Transl Med 2014;2:31. 2. Minami H, Isomoto H, Yamaguchi N, et al. Peroral endoscopic myotomy (POEM) for diffuse esophageal spasm. Endoscopy 2014;46(suppl 1) UCTN:E79-81. 3. Verlaan T, Rohof WO, Bredenoord AJ, et al. Effect of peroral endoscopic myotomy on esophagogastric junction physiology in patients with achalasia. Gastrointest Endosc 2013;78:39–44. 4. Richards W, Torquati A, Holzman M, et al. Heller myotomy versus Heller myotomy with Dor fundoplication for achalasia: A prospective randomized double-blind clinical trial. Ann Surg 2004;240:405–15. 5. Campos GM, Vittinghoff E, Rabl C, et al. Endoscopic and surgical treatment for achalasia. A systemic review and meta-analysis. Ann Surg 2009;249:45–57. 6. Von Renteln D, Fuchs KH, Fockens P, et al. Peroral endoscopic myotomy for the treatment of achalasia: An international prospective multicenter study. Gastroenterology 2013;145(2) 309-11.e1-e3. 7. Pescarus R, Shlomovitz E, Swanstrom LL. Per-oral endoscopic myotomy (POEM) for esophageal achalasia. Curr Gastroenterol Rep 2014;16:369. 8. Marano L, Pallabazzer G, Solito B, et al. Surgery or peroral esophageal myotomy for achalasia: A systematic review and meta-analysis. Medicine 2016;10:95. 9. Yang D, Wagh MS. Peroral endoscopic myotomy for the treatment of achalasia: An analysis. Diagn Ther Endosc 2013;2013:389596. 10. Cai MY, Zhou PH, Yao LQ, et al. Thoracic CT after peroral endoscopic myotomy for the treatment of achalasia. Gastrointest Endosc 2014;6:1046–55. 11. Patel K, Abbassi-Ghadi N, Markar S, et al. Peroral endoscopic myotomy for the treatment of esophageal achalasia: Systematic review and pooled analysis. Dis Esophagus 2015 [electronically published Jul 14, 2015. Accessed March 28, 2016]. 12. Yang S, Zeng MS, Zhang ZY, et al. Pneumomediastinum and pneumoperitoneum on computed tomography after peroral endoscopic myotomy (POEM): Postoperative changes or complications? Acta Radiol 2015;10:1216–21. 13. Ren Z, Zhong Y, Zhou P, et al. Perioperative management and treatment for complications during and after peroral endoscopic myotomy (POEM) for esophageal achalasia (EA) (data from 119 cases). Surg Endosc 2012;26:3267–72.