Before we go into the lab, I'm going to just go over the poem deconstructed into four different steps, four steps to success. So what we want to do over the next day and a half is really break it down into these four steps to help you master the different portions and get very comfortable with handling the knife and scope deflections. So the four steps are mucosal incision, submucosal tunneling, myotomy of the esophagus and the stomach, as well as closure. So as far as mucosal incision, there's the option of the anterior and posterior approach. You saw that the faculty were almost split 50-50. So the anterior approach is theorized to preserve the posterior sling fibers alongside the angle of hiss and decrease post poem related reflux. There is an advantage of scope stability in an orientation similar to ESD. The posterior approach is thought to decrease bleeding from branches of the left gastric artery located in an anterior approach. And one reason that a lot of people prefer this is that the six o'clock orientation is more comfortable for them. So what is the difference between the two? So this is a paper out of Johns Hopkins where they looked at 150 patients randomized to either anterior or posterior approach. There was no difference in clinical success. They were virtually the same. And there was no difference in really abnormal esophageal acid exposure. And the GERDQ scores were similar between the studies. So essentially, it really does not make a difference. It's really your personal preference and how you want to handle the endoscope. So this is the first portion of the procedure. So you always want to have a transparent cap. You will have a tapered cap in the lab today. So this is demonstrating an anterior approach. I like to make a soft coagulation mark just to show I don't want my incision to go anywhere beyond that because there is a tendency to really start to lengthen your incision. And you want to avoid that. As far as your submucosal injection, sometimes it can be a little difficult to get it perfectly in that submucosal space. I'll just tap on the yellow pedal once. And then that allows you to get in. And then you can get your injection. This example shows a very easy entry. So you can see the muscle there. And the blue is really what you want to target. So I call this blue heaven. And blue is where you tend to cut because the muscle does not take up the dye. So once you get in, it's a tip deflection. That one, of course, is a very easy example. This is a little more standard. This is a posterior approach. Can I ask a quick question? Yeah, please. We are waiting. Now, at what level you start the injection and incision? Does that depend on the end? I'm sure you are covering that later on, but just for discussion. Yeah. So that's a great question. I mean, I think it depends on how long of a myotomy that you want to perform. But for a lot of people, I would say 10 centimeters proximal to the GE junction would be, I would say, probably an average that people would start. Any other comments from the rest of our faculty in terms of answering that question? Peter? Yeah. I used to do exactly that. And actually, from Northwestern, the bone-out myotomy data, presumably, that is contributed by too long myotomy in the esophagus. True or not, we don't know. Is John still around? He'll be here later today. So I'm sure he can give us a earful about that. But there is a tendency to shorten the esophageal portion of the myotomy. That was supported by three case series studies. But now we have a randomized control study out of Hyderabad, India, that indeed shows that the results are equivalent in between 3-centimeter esophageal myotomy and 7-centimeter – and that's those average numbers – esophageal myotomy. So I currently am kind of splitting the difference and do roughly 5 centimeters in the esophagus, 2 in the cardiac, for a total of 7-centimeter myotomy. But we need more data because you don't want to lose efficacy, but you're trying to decrease reflux and at the same time avoid blown-out myotomy. Because if the patient develops blown-out myotomy, that's a major, major problem. And then you're left with basically esophageal – oh, sorry, I didn't see you sitting there. Please give us your point on this. Hearing from the horse's mouth. No, I agree with everything you said. I was also probably originally when I started doing longer and have shortened probably doing 5 or even 3 to 5 sometimes for types 1 and 2. Type 3, I look at the manometry and I measure the spastic segment and you can do basically the entire esophagus sometimes in type 3. But I agree with everything you said. And just because we may have people that are new to POEM, whatever the length of the esophageal manometry, you want to do, let's say, 5. You go 5 above and you allow 2 more centimeters to offset your myotomy to the mucosal incision. So underneath your mucosal incision, you have intact muscle. So you enter 2 centimeters above. And that's pretty much standard, I don't think, that everybody – Yvonne, you had a comment? Yeah, I just also like the use of endoflips. So we actually standardly do the endoflip before and after to help tailor the length of the myotomy and just double check. So in addition to looking at the manometry beforehand, also look at that. And definitely with type 3 and some EGJ outflow obstructions, it's very helpful. But I've even found it helpful in type 2, which can sometimes hide a little bit more. Excellent. Thank you. Great. So just to carry on. So this is a posterior approach. So again, you might get a little bit of an injection if you use the hybrid knife, for example. And then you'll tap. And that gives you good access to the submucosal space. You get a really good incision. So generally, you'll take your knife. And I'm just looking for my mark that I had there, because that's going to show – there it is right there. So I know kind of the general direction that I want to aim my knife. And then you'll take your knife and kind of in one single motion advance forward. I tend to tap the pedal for endocut rather than continuously holding it and letting it cycle, because I prefer the control. Here's a good example of muscularis mucosa. You'll see that thin white layer. That is not the muscularis propria. So you just want to cut through that. And now you can see the nice blue of the submucosa. Now to get in, you really – it's a series of dissection of the submucosa, and you tend to want to do it – I do it towards the lateral edges. So I don't want to extend it lengthwise. You want to work – it's about a 15 millimeter to 2 centimeters max distance. So what I do is I – if I'm doing an approach like this, I'll do it kind of an elliptical shape. So you kind of do from proximal to distal. And then you'll work on the edges. So I'll dissect on the edges, and then once you've done that, then you can deflect the tip of the endoscope into that area, and then work distally. So you want to kind of open up the submucosa distal to the incision to help the scope get in. You really want to avoid making the incision any longer than it needs to be, because then it's going to be a lot of clips to close and issues like that. As far as injecting solution, I personally just use methylene blue and saline. I do not put any epinephrine into the bag, because in the esophagus, since the mucosa is so thin, you can get this kind of crepe paper effect, and it just starts tearing away when you try to put your clips in at the end of the procedure. So here I'm just kind of looking at my orientation and everything, and again, you kind of want to use the tip of the endoscope and kind of work yourself in. You don't want to put too much pressure, of course, as you're trying to deflect the tip into the incision. So now that I've made my incision, I'm just kind of deflecting the scope tip, and now I'm kind of going big wheel towards me. Now I feel like I'm kind of halfway in. My scope is not like super stable yet, and this is what you want to do about dissecting a little bit distally from your incision just into the submucosa. And then once you do that with a little bit of dissection, you should be comfortably entirely into the submucosal tunnel. And then again, you're just going to kind of big wheel towards you, and then you're fully in here, and then you can go on with your tunneling. So when you do your submucosal tunnel, you can run into insufflation-related adverse events. You also have to manage bleeding and any potential mucosodomies. So for the tunneling, you really want to stay close to the muscle layer, and you want to avoid any sort of spiraling. So you want to keep your horizon, and the horizon is generally the muscle layer. So you want to really avoid over-torquing the scope. A lot of people, when they begin this procedure, they're kind of torquing in all sorts of directions, and they lose their orientation, and this can cause a myriad of issues. So I just, in an anterior approach at least, try to keep the muscle at the 12 o'clock position. I come in and out of the tunnel frequently so that you can make sure that you're following the trajectory of the lumen of the esophagus, because in a lot of these patients, right, they do have abnormal turns and sigmoid-shaped. So you'll of course carry this throughout the esophagus and into the stomach. I tend not to dissect too much into the stomach. There's a lot of vessels in there. I only perform like a one centimeter myotomy in the stomach. It's not necessary to exceed too much myotomy in the cardia, because it'll only lead to more reflux and potential for bleeding. So I generally will do a two centimeter tunnel in the gastric cardia. It can be particularly difficult at the GE junction to continue on with your tunnel. So if you just do a lot of injection, that will continue to A, show you where you need to go, and also give you enough space to get your endoscope through. So here's just careful dissection. Some people advocate for sacrificing some of the muscle to give yourself some space. I would say that's rarely necessary. This is an example where it's a very tight GE junction. With very careful dissection, you should be able to get in and not really have to cut too much of the muscle on your way in. And this just kind of preserves your orientation, the different layers. So you just take your time, especially as the esophagus narrows towards the GE junction. For the very small capillary type of bleeds, you can use the tip of the knife. And here, I'm just angling the cap and the scope tip down, kind of big wheel away. And again, just a very careful dissection will get you in. As this progresses on, you can see it's starting to create a little more space. And finally, now this is starting to open up a little bit more. I feel like this shouldn't be too difficult at this point. You don't want to push too hard with the scope. A lot of people also have that inclination to just kind of use the scope to do some auto-dissection. That's how you get mucosotomies, and that can really cause you issues later on. Once you kind of carry on through the GE junction, it starts to open up a bit. Then you'll start to see the cardia. Again, coming in and out of the natural lumen of the esophagus and the GE junction and taking measurements will be very helpful. And now you're clearly, you're seeing a lot of different type of vessels. Dissection-related adverse events are very common. Dr. Maselli ran through this, but it's just important to know that pneumomediastinium, pneumoperitoneum, and subcutaneous emphysema are extremely common. You may have patients that are admitted in the hospital, and then somebody who's not familiar with this procedure gets some imaging, and then they get some concerning findings. Or worse, your patient is discharged, they come back, maybe not even at a separate hospital, and they are seen in the emergency room, and it just sets off a whole cascade of issues. So it's important to kind of educate people who might be taking care of these patients that these kind of findings are very normal. If you do find yourself in a situation when you're getting a tense pneumoperitoneum, very tympanic, this can cause cardiac issues, so you may have to decompress the abdomen. This is a kind of real-world example of what you need to do. So you quickly prepare the abdomen. And then what I do is I get a needle and a saline syringe. So you'll just insert the needle. And then I take out the needle, leave the catheter in place, and then I'll attach the saline syringe. And you aspirate, you're getting air. And then if you remove the plunger, you get a free flow of air bubbles. And that works great to decompress the abdomen. As far as bleeding, bleeding can result in a blood bath, and it gets rid of your blue heaven, and it's a mess. So you want to prophylactically coagulate the vessels. So here's an example. You know, I mean, to be honest, I rarely need to use the coagulation grasper. I think if you preemptively coagulate these vessels, and there's various modes, the new PreciseSect is very good. This is just an example of forced coagulation. But what I'm doing here is I want to dissect the submucosa away from these vessels, and I want to increase the surface area that my knife is going to contact these vessels. And for large vessels like this, you want to use the shaft of the knife, again, big surface area. So now I've kind of split the submucosa between these two vessels here. And just with one full swoop, one sweep, you should be able to just coagulate and not have any issues with bleeding. And then you can carry on with your dissection and whatnot. As far as esophageal myotomy, you have options of intercircular versus full thickness. There's the myotomy length, which was brought up in the use of endoflip as well. I think most people try to just do a selective myotomy. Although there was a retrospective study comparing full thickness versus intercircular, the procedure times were shorter in a full thickness, no increased adverse events, and similar treatment outcomes. My personal preference, just so I'm not exposing too much mediastinum, is to do a selective myotomy. When you do your myotomy, you, of course, want to identify the circular fibers, which are horizontal. And then you'll continue to do that until you expose the interface between the circular and longitudinal muscles. And then once you've done that, then you can carry on. I won't get into this too much. As Peter Dragunov mentioned, this study out of Hyderabad, the short myotomy was not inferior to a long myotomy. Short myotomy defined as about 3 centimeters. So when I do this, I make my incision, the distal part of my incision, about 6 centimeters from the GE junction. So I give myself about a 3 centimeter gap between the end of my incision, so the start of my tunnel, until where I'm going to do my myotomy. These are the outcomes that I'm going to skip through. Again, not inferior. The use of endoflip. So various studies have shown this to be very helpful. In our institution, we have found that a cutoff of 2.8 is abnormal. So we do endoflip before and during the procedure. The corollary is to building a house without a measuring tape, and just eyeballing it is not always effective. Here's an example of what that looks like. Here you can see, the numbers are going to be very hard to see, but you can see the colors. So here, this is before. This is a 60 ml fill volume, and you have a diameter of about 9 millimeters, and a distensibility index in the low twos. And then after the myotomy, you'll see the color changes from red to yellow. So for our non-intelligent endoscopists like myself, the color coded seems to help a lot. And here you see the diameters opening much more. Here at 70 ml fill volumes, we have nearly a 15 millimeter diameter, and a distensibility index of about 3.8. So in our study that we did using endoflip guidance to look at outcomes for short versus long myotomy, we found no difference, and no difference in reflux either. So why is this important? So if you do a short myotomy, it is possible if you're below that threshold that you set, so for myself, it's 2.8, that you can extend the myotomy laterally instead of proximally. So you can still fit within a 3 centimeter myotomy, and I'll just extend that in an anterior orientation towards the 3 o'clock position. Even in patients who got standard length myotomies, the endoflip was helpful, and we did have to do a myotomy revision during that index procedure in 20% of cases. So the bottom line here is that the short myotomy is safe, similar efficacy. The endoflip provides a lot of value, indicating the need for extension of that myotomy. Clips versus suture, admission versus discharge. The short story on this study here is that closure time was shorter with clips, and there are some cost savings with clips as well. Finally, with your closure, I always try to close from a distal to proximal orientation, making sure that you're really opposing that incision. You don't want to introduce extra folds into that, and then you get a nice little linear line here. So the takeaways here, it's important to become familiar with the general principles of knife usage. That's why you're here. That's why there's a significant hands-on component. So for today in the lab, we're going to focus on just the incision and tunneling and closure for today. And then tomorrow, when we do the live animals, you'll be doing the complete procedure. There are various technique modifications. Again, everyone has their own secret sauce. They don't necessarily impact the clinical success of the procedure. Please ask plenty of questions when you're in the lab and in the lecture hall today. Don't be afraid to ask for hands-on demonstrations. Thank you. Any burning questions before we move? Yes? Can you clarify, when you say revision of the myotomy, what are you doing? Cutting into the stomach, or proximal esophagus, or? Yeah, so neither, actually. So if I'm within, let's say, my G-junction's at 40 centimeters, and I've gone from 37 to 40. So within that same segment, if I'm at an anterior 1 or 2 o'clock, I will extend laterally. So I will then do, at the 3 o'clock position, do additional myotomy in that segment. At that point, you're having to torque the scope a lot. And actually, it becomes almost like a posterior orientation, where your knife is then at 5 or even 6 o'clock. Yeah, but they end up being connected, essentially. I might. I use endoflip as well to indicate effectiveness. And in that case, if I find that it's not, I will do full thickness, as opposed to just extending laterally. I'm not sure what the data is either way, to say what it is that needs to be done additionally. But I think we're still discovering how to use that information. But clearly, there's some indication that it's not enough. I think that's essentially the same principle, is that you'll see that there's still a lot of circular fibers that have not been cut. So whether you do it full thickness or you extend it a little bit laterally, I think the same idea is you're expanding that luminal diameter and getting rid of that resistance right at the G-junction. The one other thing that I'll say is that I'm not sure a single number is the answer. You can have a patient with achalasia that has a DI baseline of 0.7. And you can have someone with achalasia with a DI of 2.5. And so if you're targeting 2.8 on both of those patients, that may not be the same thing for both of them. So there's what we need to learn more. I'm not certain that targeting a specific number is the perfect answer right now, because I don't know what that is or whether it's a percent gain or whatever it is. And I think as you get more comfortable, you look at the different parameters. You look at the balloon pressure. You look at if you're having ongoing spasm and contractility at the G-junction. And if you're having features of that, but you still have that single number, you may have to do additional myotomy. So we had a question from the virtual audience, actually, regarding the technique that you were mentioning that you try not to torque very much. And the question is, is that dependent on the knife type of knives that you use? So we're pretty heavy on the Irby knife in the faculty group. But if we could get some way in from faculty, how many of you do more of the knife in and out versus keeping the knife in a fixed position and torquing the scope? Because there are some differences that if you do ESD, you may also find. Peter? So I want to distinguish two maneuvers, which frequently are both referred to as torquing, but they're different. One is true torque, where you put your hand on the shaft of the scope and you crank it, as opposed to maneuvering the whole scope, which also provides you with a change of the angle. So I personally leave the knife at one position, and all I do is manipulate the scope. And I do it all the time, because typical 7 o'clock position of the instrument allows you to reach the left side of the tunnel easily, but does not allow you to reach the right hand side of the tunnel easily. So I'll cut on the left side, flip it, cut on the right side, flip it. So I do that multiple times as I am advancing with the knife staying steady, but not truly torquing and cranking the shaft of the scope, because that creates too much tension. In my opinion, you lose precision. And that applies. I'm the one who uses the TTJ, from what I saw. It's not that much knife dependent. Yeah. And I would say that, I mean, following the principles sometimes of ESD, that it's a little like painting. And exactly what Peter's saying is that it's more, or like EUS, it's more of controlling and letting the scope function as a unit, as opposed to really twisting at the shaft. And the other thing that's important, especially if you're not going to torque that much, is not to make your tunnel too narrow. So it's very easy to just sort of keep going in the view of your cap, but that can run you into problems both with orientation as you go down, not being able to recognize if you have veered off orientation, as well as things like bleeding and controlling bleeding. So do try to keep your tunnel a little bit wider, probably like two to three scope widths, and in order to get to those edges on either side, exactly how Peter was describing. I mean, since this is the title of our course is pearls, I wanted to go back to that video that you showed of doing the hemostasis with the knife. One thing that I have learned over the years is that nothing messes you up more than having a bleeding vessel in the tunnel. It slows you down. It may be hard to control. And even if you control it, then the whole submucosa gets stained with blood. It's harder to keep your planes. So if you have the skill as is, you can certainly do a vessel this size with the knife, but I will strongly suggest in the beginning that if you see a vessel like that, use your coag grasper instead until you really feel comfortable with this low power coagulation and skeletonizing the vessels. And there is no hard and fast rule how big the vessel should be before you use a coag grasper. But early in your learning curve, favor the coag grasper over knife hemostasis. It may slow you down, but not even close to hitting a vessel and then having to control the bleeding. Any other questions before we move into the lab? Yes. Is there any long-term data available on selective myotomy based on endoflip measurement? Because one concern is that we hope that we don't cut less of a muscle trying to prevent reflux, and it's an inadequate myotomy. Like, how did those patients do post-myotomy based on endoflip findings? So, Joe, you want to take that? Yeah. I mean, we have no long-term data on endoflip-specified myotomy or short myotomy. There's no, like, long-term data on that. Yeah. So, but short-term, patients are doing as well, I would say. They're doing as well as... Yeah. But we just don't know. I mean, the longest studies now are the 10 years, I think, and they're doing very well with standard, sort of more the older technique, I would say. See, the core of your question is, does secondary peristalsis function similar to primary peristalsis? And the answer is probably no. You should probably go by what primary peristalsis does in spasm rather than secondary peristalsis, because I'm not sure that balloon distention reliably induces a spastic primary peristaltic-like contraction. So, you could be missing a spastic segment if you're not looking at the high-resolution manometry study. At least that's my take. Yeah. So, just to add on that, so manometry looks at primary peristalsis, and so secondary peristalsis is what endoflip looks at. So, it's balloon distention. So, if you had a food bowl that's stuck in your esophagus, it's secondary peristalsis that you're looking at with endoflip. And so, they're different things is, I think, your point. Yeah. So, these are great topics that are going to be covered in deep, deep dive during talks today and tomorrow. So, we're going to hold the rest of those nuances for later today. So, let's go ahead and break. So, if you're in group A, you're going to transition to the skills lab. It should be noted on your badge. And if you're in group B, we're going to stay here, and we're going to get started in about two minutes.

POEM procedure

mucosal incision

submucosal tunneling

myotomy

closure

endoflip

bleeding prevention