Thank you for having me. It's really an honor to be here with all this great faculty and seeing a lot of familiar faces among the attendants as well. So my task is to talk about principles of pocket tunneling and other retraction techniques during ESD. These are my disclosures. So it is clear we all know that ESD continues to gain traction in the West, right? We wouldn't be here if it wasn't the case, but ESD is inherently a technically complex procedure. And as such, it's associated with longer procedural times and potential for serious adverse events. And the reason for this is because ESD is like performing minimally invasive surgery within the lumen. Unlike the surgeon, as you can see from this image, the surgeon has the ability to use both of his hands. In many cases, they have assistants helping them, which thereby allows them to use multiple devices and tools to not only optimize the visualization of the surgical field, but also to provide traction when needed. On the other hand, ESD is like performing surgery with one hand. So the endoscope is basically an extension of your arm. And in a way, you can think of this as trying to cut a piece of meat or a steak with a knife without holding it with anything. In that case, you can imagine that this is very unstable, unsafe, and imprecise. So when you think about traction, think of it as having that fork, right? So the fork that sticks onto your steak that allows you to cut with the knife is what traction does for ESD. It provides that second hand that you need to optimize visualization and provide tissue tension. So what is the cheapest and most readily available form of traction? Anybody? Gravity. So it's even cheaper than your cap, right? So you have gravity for every single case. Sometimes it can be in your favor. Sometimes it's not in your favor. But it's a component that you need to consider in every single case. So again, you should determine the lesion location relationship to gravity when you start a procedure. And you oftentimes want to consider how you're going to tackle the gravity dependent side. So here's an example of a large protruding lesion. This is at the hepatic flexure. So it's quite bulky. You can see that it has a slight stock, but it's relatively broad. When you put water into the lumen, you see that it starts flowing away from the lesion. So you can tell that it's actually in your favor. And as you can see here, the main advantage is as soon as we make that mucosal incision, it actually just splays the lesion open. So we're using the advantage of the weight of the lesion itself to provide the traction we need. The other advantage of this is any kind of mild oozing, it's going away from our dissection field. So this is, in spite of the size of the lesion, it's a very advantageous position. And you can see there the entire lesion is floating towards the gravity dependent side, and thereby just providing the tension that you need in order to perform this ESD. So the hot dog dilemma. So, you know, I have a love and hate relationship with hot dogs. I love eating hot dogs, but it has to come with the adequate condiments, right? So I like to put stuff on it, but you always have that issue of spillage around the mucosal bun. And I felt like I was born yesterday when six years ago I went to UEG in Vienna, Austria, and you see these hot dogs, they actually dig this hole inside a baguette, and they actually stick the hot dog in the baguette, and they put everything inside, and it's very clean. It just keeps everything in place. So you can see where I'm getting to with this. The limitations of circumferential mucosal incision, right? So one of the problems about doing a circumferential incision, besides the fact that, you know, fluid can leak, and, you know, we had that debate earlier, that it's not that much of an issue nowadays with the newer knives. One of the issues that does happen with circumferential ESD, especially if you don't create a flap, is that the lesion starts losing traction from that mucosa. So it actually shrinks. And this is a problem that many people do, is that by not forming a flap and they just kind of keep going around and around the lesion, the lesion just gets smaller and smaller, and they can never get underneath. It almost forms like a little dome. So that's a problem that you can encounter when doing circumferential ESD. So you always want to create a flap and make sure that it's not just continuously shrinking on you. And I shamelessly stole these figures from Dr. Ihara, because I couldn't figure out how to make these drawings on PowerPoint. So I just changed the color of them and made them my own. So here you have two lesions. And with pocket creation, you basically make a mucosal incision on one side of the lesion, and you start dissecting underneath it, right? So just, again, like the hot dog, that pocket is going to maintain everything within that area. You then try to dissect the area on the gravity-dependent side, followed by the anti-gravity side, and then complete the backside. So mucosal tunneling follows the same principle, but in this case, you're going to open the backside first before you do the pocket or tunneling underneath the lesion. Again, you want to take out the dependent side first before going to the anti-gravity side. So here's the lesion where we use the pocket creation. It's ideal for lesions that are on the gravity-dependent side, right? So that way you no longer rely on gravity, but the pocket itself is going to provide you the traction. And being inside the pocket, it's going to provide scope stability and fluid retention. So here we have a lateral spreading non-granular lesion. This was in the descending colon. So we're going to make that mucosal incision, as Dr. Schlatterman mentioned earlier, you want to make a mucosal incision far away from your lesion. I talk about it as like that landing strip. You need enough to take off, I guess, if you want to put it that way. So once you create that this is preemptive hemostasis, right? You want to do that particularly in your pocket. You don't want to stain the entire pocket with blood even before you get started. So again, you can see how we're using a tapered hood and then staying within the pocket to open up the lesion. And you're going to continue doing that underneath the lesion using that lesion itself for traction. Once that is completed, we're going to start opening up the mucosal sites. And we start with the gravity-dependent site, trace the mucosa, followed by some mucosal dissection. This tends to be the more difficult portion of the procedure just because it's on the dependent side. Once you complete the dependent side and it's freed up, you can start going on to the non-dependent side, which again, now you have the advantage of gravity. One of the downsides about the pocket technique is you need to have a sense of where your backside is. So it's important to not inadvertently cut into the specimen on the backside. In this case, for speed purposes, I decided to switch to an insulated tip knife to easily hook that backside and complete the procedure. All right. So tunneling again, I won't spend too much time on this video, but the difference is you're going to open the distal side first. This is particularly important if you're using in the esophagus, unless you're planning on using some kind of retraction maneuver. You want to open the distal side or as you start dissecting the lesion, this is going to fall towards the stomach. So again, it's similar to POEM. We're going to make a mucosal incision, which allows us to get underneath the lesion, provide stability. Once you get across the lesion, you start taking out the sides. And again, we left the anti-gravity side last to provide us that tension that we need to complete the dissection. And then, you know, Dr. Fukami talked in touch base about traction systems as well, right? And probably many of you will have a chance to use some of these within the next day or two. When you think about internal traction systems, I think you need to remember that traction provides both force and direction. It's not that much the force. I see a lot of people when they're trying to do traction to pull the specimen as far as they can. They almost want to stretch it to the other side of the colon. And then the problem is this oftentimes is going to rip your specimen. It's more about the direction of the traction rather than how much you're actually putting tension. If you think about it, right, when you use underwater ESD, the buoyancy itself is providing the traction you need. It's not this massive force. So all you need to do is open the space. So deciding the direction of the traction is very important. When you provide traction vertically, it's going to improve visualization, provides tension. And that's generally the preferred method. Now, you can also put the tension a little bit more proximal to you. One of the advantages of doing that way is that as you continue with the dissection, because the tension is behind you, it's going to continue to provide you with some traction. The downside of it is as you continue, the space that you have may start getting more and more narrow, given that the traction is behind you. The worst type of traction, I think, is the one that you pull the lesion away from you. Because now you're everting the specimen, and sometimes it can be difficult to differentiate if you're dissecting on the flap side, on the submucosa, or you're approaching the muscle. So in these type of scenarios, as I was kind of talking to some of you during the lab, try to go to the edge of the lesion and follow the edge of the lesion to define your axis of where you're cutting. Again, here's just an example of clip and rubber band. These are the orthodontic rubber bands that Dr. Fukami mentioned. And it's very easy to apply along with two clips. And you can see that just by applying a simple traction mechanism, we're able to expose the submucosa and this lesion that was otherwise sitting in the puddle of fluid. So on the right-hand side, again, you have a larger lesion at the hepatic flexor that the main purpose I wanted to show the lesion on the right is that when you grab the lesion to apply traction, you have to understand that when you put traction, it doesn't simply pull up the flap in the submucosa, but it's also going to pull up your muscle. It pulls up the entire wall. So when you cut it, you have to be able to discern that or else it's very easy to to just cut straight and you're going to cut through the muscle. So here we are trying to use one of these dual action tissue clips for traction. The other thing that you notice there is I adjusted several times where to grab the lesion because those two first times I was grabbing actually onto the submucosa. So if you pull, it would have pulled probably more of the muscle portion as opposed to just the flap itself. And again, so now once you expose your plane, you just want to take your time as you're dissecting to recognize what is submucosa and what is your muscle plane. And similar to how Dr. Fukami mentioned about devices, right? So there's dynamic traction devices. Now you guys will have an opportunity to play with this one, which is the track motion. With this device, you're able to use this articulating forceps to help you direct the direction of your traction. The main downside, as Dr. Fukami mentioned, is that it's not independent to the movement of your scope. So it's still kind of tied to the movement of your scope. As you can see, the way you do ESD with this device is going to be different than what you normally do with a cap because now you're going to have to operate at a much further distance in order. It's almost like laparoscopic surgery. I think of it that way, where you have two tools instead of getting close with your cap. And last but not least, right, we already started hearing about the advantages of doing underwater or under sailing ESD. The advantages of this is it provides good field of vision. Looking at things underwater also provides you a zoom effect. And importantly, you stop fighting. So a lot of times when you have a lesion partially under gravity and you have that level of fluid, you have that halation, right, which is the interface between water and air. And when you instantly start developing bubbles. So it's kind of like, it's what I think of as a no man's land. You're not getting great underwater, you're not getting great air. So you kind of just have to commit. And here you're going to see a lesion. Again, it's on the dependent side. This is in the rectum on the first valve of Houston. And as you can see, we're first just focusing on opening that mucosal flap, keeping the knife right underneath the mucosa, keeping the knife parallel to the muscle to try to open up that flap. As you can see here, we're mainly using the cap to continue maintaining tension. As I come towards that portion of the lesion, the left side of the lesion, now you can see how it's becoming more difficult on that side because that's the more gravity dependent side where fluid is going to accumulate. So I decide to basically just start doing underwater. You can see the buoyancy helps lift the lesion and we can easily cut underwater. It really nicely lifts the lesion, the flap, as you can see here. And makes that portion of the exam or that portion of the dissection, which theoretically would have been the most difficult portion of the ESD quite easy by simply floating the specimen using this underwater technique. All right, so I'll probably skip this video for the sake of time. So again, just the main take-home messages, right? When you think about what technique, there's no right technique. You just need to know how each one of these techniques will help you for a particular case. In one given case, you may use a combination of techniques as well. So when you think about pocket creation tunnel, right, in a gravity dependent location, you want to have your scope to be straight. So if you can't maneuver underneath the lesion, you're not going to be able to tunnel or pocket. Locations in the esophagus and rectum where you have that one-to-one with the scope is going to be very advantageous. When you think about traction methods, as Dr. Bhatt was discussing with Dr. Dragan, you have to create the mucosal structure. You have to create the mucosal structure and you have to create the mucosal flap. So remember, the traction device is not going to obviate the need of forming the mucosal flap. And that's what people generally fail to understand, is they start doing the mucosal incision and they can't make a flap and they say, oh, I'm going to use traction. But that's why traction fails, because you have not made the mucosal flap. And you want to make sure you recognize your dissection plane. We talked And again, underwater, definitely it's a very advantageous thing to use by decreasing the luminal distension. It really allows the lesion to float. And it also a lot of times improves maneuverability if your scope reduces any looping. Thank you.

endoscopic submucosal dissection

pocket tunneling

traction techniques

minimally invasive surgery

underwater ESD