Peroral Endoscopic Myotomy in a Porcine Model: A Step to Achalasia Patients

is an idiopathic motility disorder that results from degeneration of the myenteric plexus in the wall of the esophagus and the lower esophageal sphincter (LES). 1 In esopha-geal manometry, achalasia is characterized by impaired relaxation of LES and loss of peristalsis in the body of the esophagus. Achalasia results in severe dysphagia for solids and liquids. Additional symptoms can also develop such as chest pain, regurgitation, aspiration, weight loss, and irreversible di-latation of the esophageal body. The therapy for achalasia focuses on the forced relaxation of the LES by endoscopic method or surgery. The treatment modalities using endoscopy or surgery have mainly included endoscopic pneumatic dilation and laparoscopic Heller myo-tomy (LHM). Recently, peroral endoscopic myotomy (POEM) has been introduced as a novel endoscopic procedure for the treatment of achalasia. A submucosal esophageal myotomy was first described in a porcine model by Pasricha et al., 2 and POEM was first performed to achalasia patients by Inoue et al. 3 Since 2010, several small-sized case series for POEM have shown safety and excellent short-term outcomes. The advantages of POEM are theoretically based on those of endoscopic operation such as no skin incisions, decreased pain, and less blood loss. Furthermore, POEM incorporates the advantage of LHM consisted of durable surgical myoto-my and single procedure. A recent porcine study showed that the preservation of longitudinal muscle layer does not compromise the effectiveness of the myotomy. 7 In a paper published in Clinical Endoscopy, Bang et al. 8 reported a study that evaluated the feasibility of POEM in a porcine model. The authors showed successful POEM procedure and no definite perioperative complications in two mini pigs. After 2 weeks from POEM procedure, the histopatho-logic evaluation of the necropsy specimens revealed complete loss of the inner circular muscle and replaced fibrosis at the myotomy site. The authors concluded that POEM is a technically feasible treatment in the animal model. This study has several limitations. First, the authors used only two pigs in the study. Second, the observation period was short for follow-up after the procedure. Third, the authors did not perform esophageal manometry to analyze the difference of LES pressure before and after the procedure. However, this study seems to be a step for transition of the treatment method for achalasia in the near future. In addition, this study was the first animal study of POEM in Korea. The porcine model is the most useful animal …