SUMMARY Esophageal achalasia is a type of motility disorder characterized by incomplete relaxation of lower esophageal sphincter (LES) and absence of esophageal peristalsis. Peroral endoscopic myotomy (POEM) is a new treatment option for achalasia that is less invasive, more effective, and safe as compared to surgery. High-frequency electrotome is commonly used in POEM, but takes longer time to make the tunnel in the esophagus and causes many complications. The thulium laser decreases the risk of bleeding and perforation in endoscopy but has not been reported in digestive diseases, especially in POEM. Therefore, the aim of this study is to evaluate the feasibility of the 1940 nm thulium laser in POEM. From March 2015 to August 2015, five patients with achalasia at the Digestive department, Beijing Friendship Hospital, Capital Medical University, Beijing, China were included. Before the procedure, the patients’ gender, age, and duration of symptoms were recorded. Eckardt symptom score and LES thickness, which measured by endoscopic ultrasonography, were recorded. While the subtypes of achalasia (according to the Chicago classification), lower esophagus sphincter resting pressure (LESRP) and integrated relaxation pressure (IRP) were measured by HRM for all patients. Barium esophagram was also used to rule out anatomical lesions, esophageal varices, or neoplasia, which may cause similar symptoms. All examinations were performed one week before POEM. POEM was performed with the 1940 nm thulium laser under general anesthesia. Eckardt score, procedure duration, myotomy length, and complications were recorded one week after POEM. All the patients were followed-up at two weeks and four weeks after POEM. POEM was successfully performed in all five patients. The mean age of the patients was 38.8 years (24–54 years). Achalasia subtypes were type I (n = 1), II (n = 2), and III (n = 2). The operation duration was 186, 180, 111, 75, and 126 minutes for the five cases. Pre/postprocedure Eckardt scores were 3/0, 7/0, 5/1, 6/0, and 9/0. Pre/postprocedure LESRP (mmHg) were 45.3/26.4, 18.0/1.1, 25.8/10.4, 16.5/11.2, and 24.2/20.8. Pre/postprocedure IRP (mmHg) were 27.3/15.5, 15.4/4.2, 5.7/6.8, 15.5/10.1, and 13.1/14, respectively. No adverse events occurred during the procedure. After POEM, subcutaneous emphysema occurred in case 1 on the first day, which relieved spontaneously after two days without special intervention. Infection occurred in case 5 on the day of POEM was healed with antibiotics three days later. The 1940 nm thulium laser is feasible for POEM procedure. Further studies are needed to determine whether the 1940 nm thulium laser is better than high-frequency electrotome. INTRODUCTION Esophageal achalasia is a type of motility disorder characterized by incomplete relaxation of lower esophageal sphincter (LES) and absence of esophageal peristalsis.1 The main clinical manifestations of achalasia include dysphagia, regurgitation, retrosternal pain, and weight loss. Eckardt score2 based on the manifestations is used to evaluate the severity of achalasia (Table 1). Diagnosis of achalasia depends on esophageal motility testing or high-resolution manometry (HRM), which is widely used after mechanical obstruction is excluded by endoscopy.1 According to the Chicago classification, achalasia based on HRM is characterized by mean integrated relaxation pressure (IRP) above 15 mmHg and absence of peristalsis, and is further divided into three subtypes:3 Type I with 100% failed peristalsis, Type II with abnormal peristalsis, panesophageal pressurization with ≥20% of swallows, and Type III with abnormal peristalsis, preserved fragments of distal peristalsis or premature (spastic) contractions with ≥20% of swallows. HRM is used for diagnosis and to predict or evaluate efficacy of the treatment for achalasia.4,5 Recommended therapy for achalasia include pneumatic dilation (PD), laparoscopic surgical myotomy, botulinum toxin injection, and pharmacologic therapy.1 Recently, peroral endoscopic myotomy (POEM) has become a preferable choice for achalasia due to its less invasiveness and comparable efficacy.6-9 Table 1 Eckardt score Symptom Score Weight loss (kg) Dysphagia Retrosternal pain Regurgitation 0 None None None None 1 <5 Occasional Occasional Occasional 2 5–10 Daily Daily Daily 3 >10 Each meal Each meal Each meal Symptom Score Weight loss (kg) Dysphagia Retrosternal pain Regurgitation 0 None None None None 1 <5 Occasional Occasional Occasional 2 5–10 Daily Daily Daily 3 >10 Each meal Each meal Each meal View Large High-frequency electrotome, which is the main instrument currently used in endoscopic procedures, may increase the risk of complications such as perforation and bleeding because of its difficulty in controlling dissection depth. Thulium laser, which could be quickly absorbed by water in tissues, has high precise and safe dissection capability, so that it is widely used for stomatological, urological, laryngological, and neurological diseases.10-14 The clinical application of 2 μm thulium laser in NOTES and gastric endoscopic submucosal dissection (ESD) has been recently reported.15,16 As compared to electrotome, 2 μm thulium laser decreases the risk of bleeding and perforation in the treatment of bladder cancer.17 The 1940 nm thulium laser is a new type of surgical laser with a continuous wave and maximum absorption peak of water.18 Because of its high absorption, which makes penetration depth less than 2 μm, it has a reasonable depth for sufficient hemostasis, precise tissue ablation, and minimal thermal injury to adjacent tissue. Clinical trials indicated that 1940 nm thulium laser was safe and feasible in treating endobronchial lesion,19 turbinate hyperplasia,20 dermatosis,21 and benign prostatic obstruction,22 but there is limited evidence of its use in gastrointestinal endoscopy. The aim of this study is to evaluate the efficacy and safety of 1940 nm thulium laser in POEM for the treatment of achalasia. MATERIALS AND METHODS This study was approved by the ethical institute of Beijing Friendship Hospital, Capital Medical University, Beijing, China. Patients From March 2015 to August 2015, five patients diagnosed as achalasia by clinical symptoms and HRM at Beijing Friendship Hospital, Capital Medical University were included in this study. Exclusion criteria were esophageal ulcer, prior treatment (either endoscopic or surgical) for achalasia, previous gastric surgery, esophageal stricture, coagulation disorders, age <18 years old and severe complications like heart failure or respiratory failure. All five patients signed informed consent forms before enrollment. Before the procedure, patients’ gender, age, Eckardt symptom score, and duration of symptoms were recorded. The LES thickness was measured by endoscopic ultrasonography, while the subtypes of achalasia (according to the Chicago classification), lower esophagus sphincter resting pressure (LESRP), and integrated relaxation pressure (IRP) were measured by HRM for all patients. Barium esophagram was also used to rule out anatomical lesions, esophageal varices or neoplasia, which may cause similar symptoms. POEM procedure Before POEM, all patients fasted for at least 24 h. POEM was performed under general anesthesia with endotracheal intubation. The endoscope (GIF-HQ 240, Olympus) with carbon dioxide (CO2) insufflation was used. Besides the regular POEM procedure, the following steps were strictly executed (video): (1) a mucosal incision, 8–10 cm above the esophageal and gastrojunction (EGJ) and about 1.5–2 cm long at the posterior wall of esophagus, was made to create a mucosal entry by Dual knife (Olympus, Japan). (2) a submucosal tunnel was created using the 1940 nm thulium laser (vela XL (Tm: YAG), StarMedTec GmbH, Germany) (Fig. 1A) at 15–30 Watt by a bare-ended laser fiber (LightTrail reusable 365 μm, StarMedTec GmbH, Germany) (Fig. 1B). In order to control the laser fiber more stable and flexible, a 7 French sphincterotome (FS-OMNI, Wilson-Cook Medical, Inc., USA) could be used outside the laser fiber (Fig. 1C) . The tunnel extended from the mucosal entry to about 3 cm caudal of the EGJ. Additional indigo carmine solution was sequentially injected in the submucosal layer. (3) Only circular muscle was dissected by the 1940 nm thulium laser from nearly 6 cm proximal of the EGJ to the end of the tunnel. (4) The entry was closed by endoscopic clips. Fig. 1 View largeDownload slide The 1940 nm thulium laser system and equipment used during peroral endoscopic myotomy procedure. (A) The 1940nm thulium laser system. (B) A laser fiber. (C) A sphincterotome outside a laser fiber. Fig. 1 View largeDownload slide The 1940 nm thulium laser system and equipment used during peroral endoscopic myotomy procedure. (A) The 1940nm thulium laser system. (B) A laser fiber. (C) A sphincterotome outside a laser fiber. Total procedure duration, immediate complications like perforation or active bleeding were recorded during the procedure. Radiography and regular blood test were performed 24 hours after the procedure to exclude perforation and bleeding, which was defined as decrease in hemoglobin >20 g/L. If no complication occurred after 48 hours, the patients were given liquid diet for at least one day, and then transitioned to soft diet. Standard dose of proton pump inhibitor was given to each patient for seven days. The Eckardt symptom score, LESRP, and IRP were reevaluated seven days after POEM, and the patients were discharged from the hospital. All the patients were followed-up at two weeks and four weeks after POEM. RESULTS Demographic features of patients Table 2 shows the demographic features of the five cases (four men and one woman). Their median age was 39 (range: 24–54) years. Duration of symptoms varied from 8 months to 3 years. Eckardt scores were 3, 7, 5, 6, and 9. Case 5 received prior oral medicines (nifedipine 10 mg and glonoin 0.5 mg before meal, which were withdrawn 10 days before the operation) for ten months with poor effect. No patient received balloon dilation, botulinum toxin injection, or laparoscopic Heller myotomy. Achalasia subtypes were type III, I, III, II, and II, respectively. LES thicknesses were 4, 4, 3, 4, and 5 mm separately. The highest LESRP and IRP were 45.3 and 27.3 mmHg (case 1). Table 2 Demographic features and procedure-related data Case no. 1 2 3 4 5 Gender (male/female)/age M/39 M/40 F/37 M/24 M/54 Subtype III I III II II Duration of symptoms (year) 3 0.67† 1 3 2 Prior treatment No No No No Yes‡ LES thickness (mm) 4 4 3 4 5 Total procedure duration (min) 186 180 111 75 126 Eckardt score Preprocedure 3 7 5 6 9 Postprocedure 0 0 1 0 0 LESRP (mmHg) Preprocedure 45.3 18.0 25.8 16.5 24.2 Postprocedure 26.4 1.1 10.4 11.2 20.8 ⊿LESRP 18.9 16.9 15.4 5.3 3.4 IRP (mmHg) Preprocedure 27.3 15.4 5.7 15.5 13.1 Postprocedure 15.5 4.2 6.8 10.1 14 ⊿LESRP 11.8 11.2 § 5.4 § Case no. 1 2 3 4 5 Gender (male/female)/age M/39 M/40 F/37 M/24 M/54 Subtype III I III II II Duration of symptoms (year) 3 0.67† 1 3 2 Prior treatment No No No No Yes‡ LES thickness (mm) 4 4 3 4 5 Total procedure duration (min) 186 180 111 75 126 Eckardt score Preprocedure 3 7 5 6 9 Postprocedure 0 0 1 0 0 LESRP (mmHg) Preprocedure 45.3 18.0 25.8 16.5 24.2 Postprocedure 26.4 1.1 10.4 11.2 20.8 ⊿LESRP 18.9 16.9 15.4 5.3 3.4 IRP (mmHg) Preprocedure 27.3 15.4 5.7 15.5 13.1 Postprocedure 15.5 4.2 6.8 10.1 14 ⊿LESRP 11.8 11.2 § 5.4 § †Prior treatment was calcium channel blockers (nifedipine tablet) and nitroglycerin; ‡Duration of symptoms was eight months; §IRP pre-POEM is normal. ⊿LESRP, LESRP pre-POEM − ESRP post-POEM; ⊿IRP, IRP pre-POEM − ISRP post-POEM. IRP, integrated relaxation pressure; LES, lower esophageal sphincter; LESRP, lower esophagus sphincter resting pressure. View Large Procedure duration and efficacy POEM was successfully performed in all cases. Total procedure duration was 186, 180, 111, 75, and 126 min for the five cases (Table 2). Procedure duration was decreased from the case 3 to case 5 (Fig. 2A). Fig. 2 View largeDownload slide (A) Total procedure durations for the five cases. (B) Pre-/postprocedure Eckardt scores in all cases. (C) Pre-/postprocedure LESRP scores. (D) Pre-/postprocedure IRP scores. IRP, integrated relaxation pressure; LESRP, lower esophagus sphincter resting pressure. Fig. 2 View largeDownload slide (A) Total procedure durations for the five cases. (B) Pre-/postprocedure Eckardt scores in all cases. (C) Pre-/postprocedure LESRP scores. (D) Pre-/postprocedure IRP scores. IRP, integrated relaxation pressure; LESRP, lower esophagus sphincter resting pressure. Postprocedure Eckardt scores in the five cases were 0, 0, 1, 0, and 0, which were obviously lower as compared to pre-procedure scores (Fig. 2B). Post-POEM LESRP and IRP were lower in all five cases, but was most obvious in case 1(Fig. 2C,D). Complications No bleeding or perforation occurred during the operation. Case 1 had subcutaneous emphysema in the cervical region without any discomfort and radiograph also showed mediastinal emphysema one day after POEM. Without special intervention, the emphysema spontaneously disappeared two days after POEM. Case 5 had fever (38.4 °C) and increased neutrophil percentage on the operation day without any other symptoms and radiograph showed no signs of perforation. The body temperature and neutrophil percentage reverted to normal after moxifloxacin 400 mg/qd for three days. All five patients were followed-up, and no symptoms or complications occurred in one month after POEM. DISCUSSION Clinically, the thulium laser was mainly used in urology. However, it is now widely used in gynecology and neurology.23-26 The use of thulium laser in gastrointestinal endoscopy has been limited, especially the 1940 nm thulium laser. A previous study showed that the operation duration of POEM by high-frequency electrotome ranged from 49 to 140 minutes.27 Another study indicated that the operation duration for POEM was 155.8 ± 12.8 minutes.8 In this study, the operation duration varied from 75 to 186 minutes, which was a little longer than the previous reports. The reason may be that in our study only circular muscle myotomy was performed, which was more time-consuming than full-thickness myotomy.28 Operation duration in other trials that only incised the circular layer by electrotome was 88–220 minutes6 or 90–260 minutes,29 which was little longer than ours. So, it seemed that the 1940 nm thulium laser may shorten the operation duration, but it needs further investigation. Procedure duration in the first two cases was longer than the subsequent, because the thulium laser is a continuous wave, it needs more exercises to learn how to control it more precisely. The symptoms improved after treatment in all five cases. Eckardt score, LESRP, and IRP values were obviously modified, which is in accordance with the previous results.30,31 Therefore, POEM using 1940 nm thulium laser is effective in achalasia. Many clinical trials that included follow-up information indicated that majority of the patients could achieve symptomatic relief even two years after treatment.27,32-34 Therefore, follow-up data are needed to evaluate the long-term efficacy. Common complications that occurred during POEM were emphysemas (subcutaneous emphysema, mediastinal emphysema, pneumoperitoneum, pneumothorax), which always self-healed.8,27,33 Other complications such as bleeding, perforation and mediastinitis may be very severe, but majority of these events can be cured by conservative treatments. In this study, due to the precise cutting and effective hemostasis, no perforation or bleeding occurred during or postprocedure. Subcutaneous and mediastinal emphysema occurred in case 1 the day after POEM. Since the patient showed no obvious evidence of perforation, we considered that the emphysema was caused by CO2 diffusion during the operation, which lasted 186 minutes. Even without intervention, the emphysema gradually disappeared two days after POEM. Another patient had fever (38.4 °C) and increased neutrophil percentage on the operation day without discomfort or other meaningful physical examination. Radiography of chest and abdomen found no evidence of pneumonia or perforation. Postprocedure hemoglobin was normal, which excluded the possibility of fever caused by bleeding. So, we conjectured the infection may be associated with incision procedure or anesthesia intubation. After administering antibiotics for three days, the infection was relieved. There were several technical tips for using the 1940 nm thulium laser in POEM: First, we should keep a proper distance (about 0.5 mm) from the tip of the laser fiber to the tissue, which was different from electrotome. It would make cutting more secure and protect the tip of laser fiber not to be destroyed. Second, the laser fiber was soft, so a sphincterotome would be used outside the laser fiber to protect it and adjust the cutting angle and direction. Third, proper water injection would help us to reduce the smoke during the operation and give a clear view. Forth, although the 1940 nm thulium laser is a continuous wave, we can use it not only by continuous mode (like machine gun), but also by intermittent mode (like single shot) if needed. Finally, the thulium laser had an advantage in cutting the blood vessel, especially artery. The laser could cut it more rapidly with less hemorrhage than the electronic one. Therefore, it is more time-saving than electrotome to cut and coagulation on artery. According to this research, we thought the 1940 nm thulium laser was a promising device in POEM, because it could reduce the operation time without increasing treatment-related complications. It could be widely utilized in other therapeutic gastrointestinal endoscopies besides POEM. But this study had some limitations. Only five cases were included, without follow-up data. An RCT comparing the 1940 nm thulium laser and 2 μm thulium laser or high-frequency electrotome should be performed in the future. In summary, the 1940 nm thulium laser is a promising device for POEM. It could be widely utilized in other therapeutic gastrointestinal endoscopies besides POEM in future. SUPPLEMENTARY DATA Preliminary study of 1940 nm thulium laser usage in peroral endoscopic myotomy for achalasia Preliminary study of 1940 nm thulium laser usage in peroral endoscopic myotomy for achalasia Close ACKNOWLEDGMENT This work was supported by grants from the National Key Technologies R&D Program (No.2015BAI13B09). Notes National Clinical Research Center for Digestive Disease. Beijing Digestive Disease Center. The trial was registered in the Chinese Clinical Trials Registry as number ChiCTR-IOR-15006508. Conflict of interest: The authors declare no conflict of interest. References 1 Vaezi M F, Pandolfino J E, Vela M F. ACG clinical guideline: diagnosis and management of achalasia. Am J Gastroenterol 2013; 108: 1238– 49; quiz 50. Google Scholar CrossRef Search ADS PubMed 2 Eckardt V F, Aignherr C, Bernhard G. Predictors of outcome in patients with achalasia treated by pneumatic dilation. Gastroenterology 1992; 103: 1732– 8. Google Scholar CrossRef Search ADS PubMed 3 Bredenoord A J, Fox M, Kahrilas P J et al. Chicago classification criteria of esophageal motility disorders defined in high resolution esophageal pressure topography. Neurogastroenterol Motil 2012; 24: 57– 65. Google Scholar CrossRef Search ADS PubMed 4 Pandolfino J E, Kwiatek M A, Nealis T, Bulsiewicz W, Post J, Kahrilas P J. Achalasia: a new clinically relevant classification by high-resolution manometry. Gastroenterology 2008; 135: 1526– 33. Google Scholar CrossRef Search ADS PubMed 5 Ju H, Ma Y, Liang K, Zhang C, Tian Z. Function of high-resolution manometry in the analysis of peroral endoscopic myotomy for achalasia. Surg Endosc 2016; 30: 1094– 9. Google Scholar CrossRef Search ADS PubMed 6 Hungness E S, Teitelbaum E N, Santos B F et al. Comparison of perioperative outcomes between peroral esophageal myotomy (POEM) and laparoscopic Heller myotomy. J Gastrointest Surg 2012; 17: 228– 35. Google Scholar CrossRef Search ADS PubMed 7 Wei M, Yang T, Yang X, Wang Z, Zhou Z. Peroral esophageal myotomy versus laparoscopic Heller's myotomy for achalasia: a meta-analysis. J Laparoendosc Adv Surg Tech A 2015; 25: 123– 9. Google Scholar CrossRef Search ADS PubMed 8 Ujiki M B, Yetasook A K, Zapf M, Linn J G, Carbray J M, Denham W. Peroral endoscopic myotomy: a short-term comparison with the standard laparoscopic approach. Surgery 2013; 154: 893– 7; discussion 7–900. Google Scholar CrossRef Search ADS PubMed 9 Talukdar R, Inoue H, Nageshwar Reddy D. Efficacy of peroral endoscopic myotomy (POEM) in the treatment of achalasia: a systematic review and meta-analysis. Surg Endosc 2015; 29: 3030– 46. Google Scholar CrossRef Search ADS PubMed 10 Herrmann T R, Bach T, Imkamp F et al. Thulium laser enucleation of the prostate (ThuLEP): transurethral anatomical prostatectomy with laser support. Introduction of a novel technique for the treatment of benign prostatic obstruction. World J Urol 2010; 28: 45– 51. Google Scholar CrossRef Search ADS PubMed 11 Dostalova T, Jelinkova H, Sulc J et al. Ceramic bracket debonding by Tm:YAP laser irradiation. Photomed Laser Surg 2011; 29: 477– 84. Google Scholar CrossRef Search ADS PubMed 12 Zhang X R, Feng C, Zhu W D et al. Two micrometer continuous-wave thulium laser treating primary non-muscle-invasive bladder cancer: is it feasible? a randomized prospective study. Photomed Laser Surg 2015; 33: 517– 23. Google Scholar CrossRef Search ADS PubMed 13 Zeitels S M, Burns J A, Akst L M, Hillman R E, Broadhurst M S, Anderson R R. Office-based and microlaryngeal applications of a fiber-based thulium laser. Ann Otol Rhinol Laryngol . 2006; 115: 891– 6. Google Scholar CrossRef Search ADS PubMed 14 Ludwig H C, Kruschat T, Knobloch T, Teichmann H O, Rostasy K, Rohde V. First experiences with a 2.0-microm near infrared laser system for neuroendoscopy. Neurosurg Rev . 2007; 30: 195– 201; discussion. Google Scholar CrossRef Search ADS PubMed 15 Cho J H, Cho J Y, Kim M Y et al. Endoscopic submucosal dissection using a thulium laser: preliminary results of a new method for treatment of gastric epithelial neoplasia. Endoscopy 2013; 45: 725– 8. Google Scholar CrossRef Search ADS PubMed 16 Dray X, Donatelli G, Krishnamurty D M et al. A 2-microm continuous-wave laser system for safe and high-precision dissection during NOTES procedures. Dig Dis Sci 2010; 55: 2463– 70. Google Scholar CrossRef Search ADS PubMed 17 Liu H, Wu J, Xue S et al. Comparison of the safety and efficacy of conventional monopolar and 2-micron laser transurethral resection in the management of multiple nonmuscle-invasive bladder cancer. J Int Med Res 2013; 41: 984– 92. Google Scholar CrossRef Search ADS PubMed 18 Kou D, Chylek P. Refractive indices of water and ice in the 0.65- to 2.5-μm spectral range. Appl Opt 1993; 32: 3531– 40. Google Scholar CrossRef Search ADS PubMed 19 Gesierich W, Reichenberger F, Fertl A, Haeussinger K, Sroka R. Endobronchial therapy with a thulium fiber laser (1940 nm). J Thorac Cardiovasc Surg 2014; 147: 1827– 32. Google Scholar CrossRef Search ADS PubMed 20 Sroka R, Havel M, Betz C, Kremser T, Leunig A. Clinical feasibility trial on 1940 nm Tm: fiber laser intervention of hyperplastic inferior nasal turbinates. Photonics Lasers Med 2012; 1: 215– 22. Google Scholar CrossRef Search ADS 21 Miller L, Mishra V, Alsaad S et al. Clinical evaluation of a non-ablative 1940 nm fractional laser. J Drugs Dermatol 2014; 13: 1324– 9. Google Scholar PubMed 22 Netsch C, Becker B, Tiburtius C et al. A prospective, randomized trial comparing thulium vapoenucleation with holmium laser enucleation of the prostate for the treatment of symptomatic benign prostatic obstruction: perioperative safety and efficacy. World J Urol 2017; 35: 1913– 21. Google Scholar CrossRef Search ADS PubMed 23 Henes M, Vogt B, Neis F et al. Application of a thulium laser for treatment of cervical neoplasias and condylomas: a feasibility study. Photomed Laser Surg 2015; 33: 481– 5. Google Scholar CrossRef Search ADS PubMed 24 Mastronardi L, Cacciotti G, Scipio E D et al. Safety and usefulness of flexible hand-held laser fibers in microsurgical removal of acoustic neuromas (vestibular schwannomas). Clin Neurol Neurosurg 2016; 145: 35– 40. Google Scholar CrossRef Search ADS PubMed 25 Sciarra A, Von Heland M, Minisola F, Salciccia S, Cattarino S, Gentile V. Thulium laser supported nephron sparing surgery for renal cell carcinoma. J Urol 2013; 190: 698– 701. Google Scholar CrossRef Search ADS PubMed 26 Passacantilli E, Anichini G, Lapadula G, Salvati M, Lenzi J, Santoro A. Assessment of the utility of the 2-micro thulium laser in surgical removal of intracranial meningiomas. Lasers Surg Med 2013; 45: 148– 54. Google Scholar CrossRef Search ADS PubMed 27 Familiari P, Gigante G, Marchese M et al. Peroral endoscopic myotomy for esophageal achalasia: outcomes of the first 100 patients with short-term follow-up. Ann Surg 2016; 263: 82– 7. Google Scholar CrossRef Search ADS PubMed 28 Li Q L, Chen W F, Zhou P H et al. Peroral endoscopic myotomy for the treatment of achalasia: a clinical comparative study of endoscopic full-thickness and circular muscle myotomy. J Am Coll Surg 2013; 217: 442– 51. Google Scholar CrossRef Search ADS PubMed 29 Swanstrom L L, Kurian A, Dunst C M, Sharata A, Bhayani N, Rieder E. Long-term outcomes of an endoscopic myotomy for achalasia: the POEM procedure. Ann Surg 2012; 256: 659– 67. Google Scholar CrossRef Search ADS PubMed 30 Lee B H, Shim K Y, Hong S J et al. Peroral endoscopic myotomy for treatment of achalasia: initial results of a korean study. Clin Endosc 2013; 46: 161– 7. Google Scholar CrossRef Search ADS PubMed 31 Aslan F, Akpinar Z, Alper E et al. The last innovation in achalasia treatment; per-oral endoscopic myotomy. Turk J Gastroenterol 2015; 26: 218– 23. Google Scholar CrossRef Search ADS PubMed 32 Teitelbaum E N, Soper N J, Santos B F et al. Symptomatic and physiologic outcomes one year after peroral esophageal myotomy (POEM) for treatment of achalasia. Surg Endosc 2014; 28: 3359– 65. Google Scholar CrossRef Search ADS PubMed 33 Chen X, Li Q-P, Ji G-Z et al. Two-year follow-up for 45 patients with achalasia who underwent peroral endoscopic myotomy. Eur J Cardiothorac Surg 2015; 47: 890– 6. Google Scholar CrossRef Search ADS PubMed 34 Hu J W, Li Q L, Zhou P H et al. Peroral endoscopic myotomy for advanced achalasia with sigmoid-shaped esophagus: long-term outcomes from a prospective, single-center study. Surg Endosc 2015; 29: 2841– 50. Google Scholar CrossRef Search ADS PubMed © The Authors 2018. Published by Oxford University Press on behalf of International Society for Diseases of the Esophagus. All rights reserved. For permissions, please e-mail: firstname.lastname@example.org
Diseases of the Esophagus – Oxford University Press
Published: Feb 1, 2018
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