Acalasia patients, particularly those with a large-caliber esophagus or sigmoid esophagus, have large amounts of food debris, despite adequate preparation. Therefore, prior to per-oral endoscopic myotomy, POEM, we often start the procedure with a gastroscope with a large accessory channel 6 mm in size, also known as the clot-sucker microscope, manufactured by Olympus, shown here. POEM utilizes principles similar to endoscopic submucosal dissection and therefore a distal clear cap attachment is used at the end of the endoscope to assist with tissue dissection. Dislodgement of the cap has been reported within the POEM tunnel by other investigators. A highly adhesive, water-resistant tape is used to firmly attach the cap at the end of the endoscope. Dissection POEM requires high-frequency electro-surgical generators, such as the Irby VO300 shown here, which permits sophisticated adjustment of current settings for dissection. Two commonly used current settings with the hybrid knife, also shown here in front of the display, are shown on this short clip. Endocut Q current, with the setting provided here, is used for dissection and a forced coagulation current is used for coagulation of vessels with the tip of the knife. Here we demonstrate the two main knives we currently use for POEM. Initially, in our experience, we use the TT knife and currently the hybrid T-type knife. The hybrid knife allows needleless injection of the submucosa through a tiny port at its tip that is approximately a tenth of a micrometer wide and thus obviates the need for exchange between needle injection and knife as is required when using the triangular tip knife. This short video demonstrates the operating room setup. The patient is placed in the supine position. The general anaesthesia machine and anaesthesiologist are at the head of the patient. The main monitor is placed in the right upper side of the patient. The endoscopist is located at the left side of the patient and the assistant is located to the left of the endoscopist. General anaesthesia with a paralytic agent is used and carbon dioxide is used for insufflation. Proper orientation within the esophageal lumen is very important. By convention, the anterior-most point of the esophagus is considered to be the 12 o'clock position, and the posterior-most point the 6 o'clock position. The submucosal tunnel and myotomy are generally performed in the 2 to 5 o'clock positions in order to avoid vital posterior structures such as the aorta and achieve myotomy of the clasp fibers of the lower esophageal sphincter, LES, located along the lesser curvature, while preserving the sling fibers located along the greater curvature, and anterior and posterior walls, which preserves the angle of HIS and may minimize reflux. Proper orientation within the esophageal lumen can be determined by using imprints of recognisable extrinsic structures such as the spine when visible, pooling of instilled water along the posterior wall, and, in thin patients, ballotment of the anterior wall of the cardia using short jabs with the fingers of the endoscopist. Here we demonstrate the technique of water pooling along the posterior wall of the esophagus following gravity to mark the 6 o'clock position within the esophageal lumen. To also ensure proper orientation of the endoscope, once it is located in the submucosal tunnel where the pool of water will not be visible, a mark is placed on the shaft of the endoscope, as shown here, that when facing upwards marks the torque of the endoscope that brings the 12 o'clock and 6 o'clock luminal positions to coincide with the uppermost and lowermost parts of the endoscopic image. We will now demonstrate two techniques for POEM. The first technique we demonstrate uses a dilation balloon for submucosal tunnel initiation. Initially in our experience we used a dilation balloon to complete the submucosal tunnel or later on to initiate tunnel formation. The balloon dilation method for submucosal tunnel formation may be more accessible to endoscopists with a more limited endoscopic submucosal dissection, ESD, experience. Care is required during blunt insertion of the balloon to avoid muscularis propria or mucosal injury. The second technique we demonstrate is the technique that we currently favour that does not utilise dilation balloons but instead utilises the ERBI hybrid knife for submucosal dissection and myotomy. We start by demonstrating the balloon dilation technique. Initially the esophagus is irrigated with an antibiotic solution and cleared of debris. Then a submucosal injection is initiated at the cardia in the two to three o'clock position. The injection is carried approximately 10 centimetres proximal to the lower esophageal sphincter. Then, a needle knife is used to create a mucosal defect and allow entry into the submucosa. A dilation balloon is gently inserted into the submucosa and dilated to 12 mm to initiate the submucosal tunnel formation. The endoscope fitted with a clear cap is then inserted into the submucosal tunnel. ESD technique is then used using the triangular tip knife to extend the submucosal tunnel through the LES and into the cardia. Here you can see the muscularis propria as a white layer. Vessels are coagulated using a coagulation grasper. Here, the start of the myotomy is demonstrated. Careful dissection is performed in order to reach a plane of dissection between the longitudinal fibres, shown here, and the circular fibres of the muscularis of the esophagus. Once this plane is achieved, dissection of the circular layer is performed and carried into the cardia. Here, dissection of the muscle of the gastric cardia is performed. Peritoneal tissue is seen at the base of the dissection. On withdrawal of the endoscope, the cut edges of muscle can be clearly seen. Here is the extent of the myotomy and the endoscope is withdrawn from the tunnel. The endoscope is then inserted into the cardia to assess the effect of the myotomy. Here, with a blue discolouration, you can see the extent of the tunnel down into the cardia. The entry to the submucosal tunnel is sealed with placement of endoclips. We will now demonstrate the technique that we currently favour, which utilises the hybrid knife T-type for submucosal dissection and myotomy. Tunnel initiation is performed by injecting the submucosa through the tip of the knife, performing a mucosal incision and beginning submucosal dissection. The hybrid knife allows injection of the submucosa and immediate dissection as shown here, with injection of the submucosa performed using the tip of the knife. After injection, dissection is continued. Small blood vessels are coagulated using the tip of the knife and forced coagulation current. For larger vessels, the technique of irrigation is demonstrated here to precisely identify the location of the bleed and proceed with coagulation using the tip of the knife. After completion of the submucosal tunnel, the myotomy has begun 2-3 cm distal to the opening of the submucosal tunnel and 3-6 cm proximal to the LES. As shown here, initially, dry-cut current or endocut current is used to dissect the muscularis propria until the proper dissection plane is found between the longitudinal muscle layer and the circular muscle layer. Once this plane is found, dissection is continued using endocut Q or spray coagulation current. As shown here, the dissection is continued to the cardia, where the muscle is somewhat thicker. Attention is being paid to dissect all circular fibers. It should be noted that the longitudinal layer is very insubstantial, and, as shown here, it often splits, with defects created within the longitudinal layer, even when the intent is to only cut the circular layer. Preliminary data suggest that an intentional complete myotomy of both layers may result in lower LES pressures. Here, the myotomy has been completed. Closure of the tunnel is performed again with Boston Scientific Resolution Endoclipse. It should be emphasized that POEM is a procedure that requires advanced therapeutic endoscopy skills, including the ability to decompress tense capnoperitoneum using a ferrous needle, as shown here. Our preferred position for insertion of the ferrous needle in patients that have not undergone prior abdominal surgery is the right upper quadrant. The ferrous needle is connected through tubing that is placed underwater to confirm escape of gas. Positioning the patient in the supine position allows the endoscopist to frequently assess by palpation for tense capnoperitoneum. Elevated airway pressure on the ventilator serves as an alternate marker of tense capnoperitoneum requiring decompression. One of the challenges of POEM is to confirm tunnel extension through the gastroesophageal GE junction and into the cardia. The techniques used to ensure that this extension has been achieved are listed here. Depth of insertion as determined by the centimetre marks on the endoscope. Resistance to endoscope insertion at the level of the sphincter. The wider submucosal space with large perforating vessels that is seen in the cardia. Blue discolouration of the cardiomucosa that is seen on retroflexion of the endoscope intraluminally. This is due to the blue stain that is used for the submucosal injection. The palisading vessels that mark the GE junction from the luminal side are also visible while in the submucosal tunnel. Spindle-like veins are seen in the submucosa and muscularis at the level of the GE junction. And finally, one or more bundles of longitudinal muscle fibres running in the submucosa and inserting into the circular layer of the muscularis propria are often seen at the level of the GE junction. We will now proceed to demonstrate the last four indicators of the GE junction and cardia that may be harder to appreciate by POEM operators early in their experience. This short video clip demonstrates the palisading vessels. The endoscope is located in the submucosal tunnel and mucosa can be seen on the left of the endoscopic image. The palisading vessels consist of long, thin, slender vessels running along the long axis of the esophagus. On the right side of the endoscopic image, the completed myotomy can be seen in this patient. Here we demonstrate the enlarged spindle-like veins that are often seen at the GE junction. Another marker of the GE junction is these bundles of aberrant longitudinal muscle fibres located in the submucosa and inserting into the circular layer of the muscularis propria. Such bundles located along the path of the extension of the submucosal tunnel are cut, as shown here. Confirmation of extension of the submucosal tunnel to the cardia can be obtained if inspection of the cardia with a retroflexed endoscope reveals markedly raised mucosa with blue discolouration, as shown here.

per-oral endoscopic myotomy

POEM procedure

achalasia treatment

endoscopic tools

tissue dissection