POEM stands for "Per-oral endoscopic myotomy" and means cutting the muscle through the mouth with an endoscope. It is an incision-less endoscopic procedure that aims to recreate the Heller myotomy in a less invasive way. It follows similar surgical principles but is able to accomplish the myotomy less invasively. POEM was first described in 2010 in Japan and has since expanded worldwide to be performed in thousands of patients with excellent efficacy and safety.
The procedure depends on recognition and utilization of the layers of the esophagus. These layers can be separated from each other like the layers of an onion. The inner layer is called the mucosa (the layer that touches the food). The outer layer is the muscle layer and is the target layer for the myotomy. The layer between the mucosa and muscle is the submucosa, which is a thin layer of connective tissue that is expanded with injection of a fluid to form a working space (aka "submucosal tunnel").
The procedure is performed under general anesthesia in the hospital using a standard upper endoscope. After examination and cleansing of the esophagus and determining the appropriate measurements and landmarks, a point in the esophagus is selected and injected with a fluid solution to expand the submucosa. An incision (about 2 centimeters or 1 inch long) is made in the mucosa to serve as the entry point and the endoscope is maneuvered into the submucosal layer. Further injection of fluid in the submucosa followed by careful cutting of the submucosal fibers (dissection) allows for stepwise tunneling of the endoscope down the esophagus within the submucosal layer. This is continued through the GEJ and into the first few centimeters of the stomach. When this step is completed, a submucosal tunnel has been created that is bordered on one side by the intact mucosal layer and by the muscle layer on the other. The mucosal incision from the beginning of the procedure is the entry point to the submucosal tunnel. During the dissection, blood vessels are cauterized to prevent or treat bleeding as necessary (hemostasis). Once an adequate submucosal tunnel has been created, the first cuts of the muscle are performed. This myotomy is extended down the esophagus, the LES, and into the upper stomach (cardia). The typical length of myotomy is around 10 cm, though this may be shorter or longer as is necessary on a case-by-case basis. When the myotomy is deemed to be adequate (by a variety of methods), the mucosal incision that served as the entry point is sealed (with clips or sutures). In some cases, during the procedure, there is escape of gas into the abdominal cavity that requires decompression with a small caliber needle inserted through the abdominal wall to act as an escape mechanism for the gas that is insufflated during the procedure. This step is possibly necessary in up to 40% of cases. At the conclusion of the procedure, the needle is removed without consequence. The procedure is then completed and the patient is taken to recovery.
Watch video of the POEM procedure below.
In general, anyone who is eligible for a Heller myotomy is probably eligible for POEM. In some cases, POEM may be the preferred method over other treatment options. The indications for POEM include all types of achalasia. POEM may also be appropriate for other motility disorders of the esophagus (such as diffuse spasm, jackhammer esophagus, or other conditions). POEM may be offered for patients that have failed or have recurrent symptoms after Heller myotomy. Age is usually not an issue in the absence of major medical conditions; POEM has been performed in the pediatric population and in the elderly.
Some patients may not be eligible for POEM. These include patients with:
POEM is exciting for patients with achalasia and other motility disorders of the esophagus because it has potential significant advantages over other options.
For some disorders of the esophagus, POEM may be the best treatment option because it allows precise tailoring of the myotomy length in the esophagus as much as is needed to alleviate spasm and give a better chance at symptoms resolution. This is a distinct advantage over traditional laparoscopic surgery where the length of esophagus that can be cut in the chest is limited by the approach from the abdomen. Previously, this was overcome by a thoracic (chest surgery) approach to the myotomy, but this is felt to be more invasive and carry more potential side effects. Specific diseases that are probably best treated with POEM include type III achalasia, diffuse esophageal spasm, nutcracker esophagus, and jackhammer esophagus. In these disorders, the esophageal myotomy length can be tailored to treat the spastic segment as determined by high-resolution manometry.
POEM has a special advantage in cases of prior Heller myotomy. A minority of patients with achalasia will have either a failure of improvement or a recurrence of symptoms after Heller myotomy. Repeat surgical (Heller) myotomy is considered more difficult and higher risk, but POEM appears to offer an alternative to salvage these cases with a favorable efficacy and safety profile.
Besides these special disease entities, POEM appears to be equivalent or slightly better than traditional Heller myotomy for type I and II achalasia. There are currently no published head-to-head studies comparing POEM to Heller myotomy, but anecdotal and indirect evidence appears to show that POEM offers shorter hospital stay, less pain, and quicker return to usual activities. In some patients with difficult anatomy (such as obese or prior surgeries), POEM may be easier and safer to perform.
It is estimated that adverse events happen in less than 1-2% of patients undergoing POEM. These complications vary in severity and are similar to the types of complications that can happen with surgery. They include bleeding, infection, leaks or perforation, arrhythmias or other heart problems, fluid or air trapped in or around the heart or lungs, aspiration pneumonia, and reactions or problems with anesthesia. These complications may be mild or severe and result in longer or additional hospital stay and/or additional procedures or surgeries to address the problem. In general, these complications are very rare and POEM has an excellent safety record. There may be minor throat, chest, or abdominal pain after the procedure that can be expected but is usually easily controlled and lasts only a few days.
The major new symptom after any myotomy, including POEM, is potential reflux (GERD, gastroesophageal reflux disease). The normal LES acts as part of the body's normal anti-reflux mechanism. When the LES and surrounding muscles are cut to treat achalasia, reflux can result. The incidence of reflux after myotomy is up to 30-40% if reflux is defined by measurement of abnormal acid exposure by a pH probe; roughly one-half of these patients (15-20% of total patients) will have symptoms of reflux and the other half will have silent reflux. Most patients (60-70%) will not have detectable or significant reflux. Though controversial, it appears that the total rate of reflux is the same for POEM and Heller myotomy. Whether symptoms are present or not, reflux should be treated, usually with medications (proton pump inhibitors, PPI). Our protocol is to discharge all patients after POEM on PPI for a few months. After the esophagus has had a chance to heal and you are back to usual activity and diet, testing is performed to determine if PPI can be discontinued. It is important that everyone continue PPI during this initial period after POEM whether or not they feel reflux or heartburn.
After the procedure you are taken to the recovery room where you are monitored for post anesthesia care. When you are stable from anesthesia, you are admitted to an overnight observation bed. Typically, patients post-POEM can expect to spend the night in the hospital following the procedure and then go home the following afternoon. During the day and night immediately following the procedure you will be kept strictly nothing by mouth (NPO: this means no food, drink, pills, or anything!). You will be observed for any complications and given medications for nausea and pain as needed. You will be given certain standard medications: this includes intravenous fluids for hydration, preventative antibiotics, and around the clock (whether you think you need it or not) anti-nausea medications to prevent vomiting or retching that could disrupt the site of the POEM.
The next morning, if there are no concerns, an esophagram (xray of the esophagus taken after swallowing a special dye) is performed to exclude a leak. If the esophagram shows no leak, you are given liquids and then a soft diet and then discharged from the hospital if you are able to eat and drink without pain. You are discharged with a few days of antibiotics and a prescription for PPI to prevent acid exposure of the esophagus (whether you feel reflux or not).
Your diet is restricted to soft or blenderized food for two weeks after discharge. This basically includes all food that you can swallow with minimal or no chewing. These are foods with consistency similar to smoothies, milkshakes, mashed potatoes, pudding, ice cream, soup, pureed vegetables, etc. The purpose of this is to introduce food gently into the esophagus so that it has a chance to heal. There have been rare severe complications reported when patients have not complied with the dietary instructions. After two weeks, you can slowly introduce regular food to your diet as tolerated.
A few months after your procedure, the post-procedural evaluation will start with pH testing to determine if you have acid reflux. You will be asked to stop your PPI for seven days and then an upper endoscopy will be performed. The esophagus will be inspected for signs of reflux and a small pH-sensing capsule (Bravo probe) will be clipped to the esophagus to measure acid exposure and relay that information for 48 hours to a small recorder that you carry with you. The probe will pass through your system spontaneously and the recorded data will be analyzed to determine if you have significant reflux. If you have symptoms of reflux or if the pH study is positive for reflux, you will be asked to resume your PPI. Your doctor can then discuss treatment options for reflux as appropriate.
Often, high-resolution manometry and esophagram are also repeated a few months after POEM to evaluate the efficacy of the procedure objectively and to serve as reference point in the unlikely event that there are recurrent symptoms in the future.
Though there are no firm guidelines or rules for patients with achalasia, your doctor may discuss occasional upper endoscopy as a screening or monitoring tool over the years after your POEM.
Current studies of POEM for achalasia have indicated a >90% favorable response with normalization or near normalization of swallowing symptoms (post-POEM Eckardt scores typically are 0-1). For patients with non-achalasia spastic disorders of the esophagus (such as diffuse spasm or jackhammer esophagus), the outcomes are slightly less favorable (~80% response) but are much better than other treatment options. Because this is a new procedure, there is limited long-term data to know what the durability of the response is, but existing data suggest that the vast majority (>80%) of patients will maintain their response at least after 2 years (probably longer than that, but we don't yet have data to know for sure). If there are recurrent or residual symptoms after POEM, esophageal testing may be performed to determine what the problem is, and potentially additional therapy may be offered.