talking about this important arithmetic. Thanks for the wonderful job you're doing. I think it's what you've done in this, you put this together in this COVID era for fellows teaching is just remarkable. I hope we can keep this going post COVID era. So anyways, let's get along with it here. So we're gonna talk about management of LV7 VT. And I say VT, I mean, PCs, also non-stay VT and of course monomorphic VT. So some of these cases can be pretty downright challenging. My goal here is to kind of discuss a systematic approach to this arithmetic in the EP Lab and hopefully we can make these cases not so daunting and sometimes even fun. See here. So, a number of these arithmetic we're gonna kind of call them as a subset of alpha-track VT and can present as I said, as PCs, non-stay VT, monomorphic sustained VT. The mechanism is proposed to be the calcium overload. So we're talking about delayed alpha depolarization. We're also talking about trigger mechanism here. They can comprise through about 10 to 20% of the alpha-track VT. I feel like I see a lot higher in my practice, at least a little while. And in terms of, you know, why is it important to go after this? I mean, it can certainly cause troubling symptoms for the patients, but if you have a high enough burden, they will also be implicated in developing PVC-mediated cardiomyopathy. So very important to know how to get rid of these things. Here's the outline of my talk. The first and most important element, I think, is the anatomy. Once you understand the anatomy of this region, everything else becomes very intuitive. We'll then talk about a systematic approach which starts with, to help you set up VT cases, which starts with ECG localization. Remember that the ECG localization is important because it allows us to set expectations in clinic, allows me to do a better job explaining risks to the patient, but it is also very sensitive to electrode position. We will spend time talking about ice imaging. Again, a very important feature in these arrhythmias, both in terms of safety and efficacy, allows you to see some very vital structures in this region, allows you to see where your catheter is when you're doing mapping and ablating. Then we're going to talk about a systematic approach to mapping all these structures adjacent to the LV summit. Sometimes when you are trying to bring the LV summit, it's precluded because of either coronary blood flow or it could be a fat. So what you have to do is you have to basically systematically map all the structures that are adjacent to the LV summit and figure out where you're going to ablate to get rid of these arrhythmias. So in the next slide, we're going to go over the anatomy of the LV summit and the surrounding structure. I would say that these are probably six most important slides of my talk. So I'm trying to pay special attention here before after that I can start those off if you want. So again, anatomy, anatomy, anatomy. This is the key. Once you get a handle of this thing, targeting some of these arrhythmias becomes quite simple. So, all right. So where is, what is the LV summit? So if you look at the McAlpine definition, it is the highest point, if you're looking at the LV from the LPR view. So this white area here is pointing toward the LV summit. You mentioned the right here is the left ventricular osteum. So the aortic valve and the mitral valve are removed. So the basis of the left coronary cusp, the right coronary cusp and the mitral valve basically form the LV osteum. These are the sources of all the ventricular arrhythmias that arise here. So you can see the LV summit is located as the upper end of the anterior interventricular groove, which is right here, shown by the red dots here. And between the upper end of the AIV, anterior ventricular groove, and the aortic portion of the LV osteum. So that's where your LV summit is going to be. Let's look at this view here. So this is a sagittal view of the heart. You can see that the aortic root kind of occupies the middle of the heart. And it's surrounded by all the different structures here. So anteriorly you have the RVOT, and the pulmonic valve here is designated by this blue ring. So remember the aortic valve and the, sorry, the aortic root and the pulmonic root kind of cross over each other. So that see the RVOT is anterior and goes leftward. The LVOT is posterior and goes rightward. This sort of this complex orientation creates the complexity in terms of both ECG localization, mapping, and ablation in this region. The LV summit, which is right here, is close to the anterior part of the RVOT and the left coronary cusp. We're going to see this better in some of the other views but we'll talk about that in a second. The other thing to kind of pay attention in the coronal view is that the pulmonic valve is higher than the aortic valve. It can be about one or two centimeters above the aortic valve here. So what happens is you get this interventricular fold. So we talked about the RVOT septum. It's not really a true septum. You have this invagination and then you have this interventricular fold. So you can ablate in the RVOT septum and actually get a pericardial fusion if you've got a perforation here. This number, a lot of these arrhythmias in the outflow tracts are going to be perivalveular. So the RVOT is going to be near, up and around the pulmonic valve. The LVOT, a lot of these ventricular arrhythmias are going to be around the aortic valve. So they're not necessarily going to be higher up by the left main takeoff, to give you an example. So we're going to exploit this height difference to kind of get a sense of where some of these, where you're going to find the site of origin. So if you're mapping the RVOT, you find that the activation times are already kind of farther down. It's sort of a broad activation pattern. The activation maps are not so great. The pace maps are not so great. And you might want to, at that point, consider looking on the left side. So exploit that height difference to kind of make sense. All right, this is a very important slide here. So the measurement right here, again, is the LV osteon with the aortic valve and the mitral valve removed. The LV summit sits here as the epicardial structure. So the ventricular atrial junction here has both a fibrous portion, seen here, and a muscular portion. The muscular portion is much more extensive. It includes the interventricular septum, the right coronary cusp, and the anterior part of the left coronary cusp. The fibrous portion is almost like a curtain, which kind of extends from the anterior leaf of the mitral valve down to the non-coronary cusp of the aortic valve. This fibrous curtain, if you will, is the aortomitral continuity, the AMC. So there are some people out there, if we say, well, the VT is coming from the AMC, they may get upset because, well, there's no muscle there, so how can you have VT coming from that? All right, I mean, I'm not one of those guys, but I'm just letting you know. All right, so the image on the left here, so now we have the aortic valve and the mitral valve put back in view. The AMC is kind of tethered both anteriorly by these fibromuscular extensions, and this is the left fibrous fibroid anteriorly, and posteriorly is the right fibrous fibroid. By the way, the right fibrous fibroid is kind of where the avenoid hangs on as well. So if you have a catheter, and it's, sorry, I didn't mean to hit that. You have a catheter here that is placed sort of through the aortic valve. If you go in the direction of the mitral valve, you're gonna be touching the aortomitral continuity. If you counter-clock it, you're gonna hit the endocardium, and what you're doing there is you're hitting the left fibrous tribome. So the aortomitral continuity, the AMC haters, I guess, would say that it's not the AMC where the VT's coming from, the PVC's coming from, it's the left fibrous tribome. It's simply an endocardial extension of the LV summit here. Now, if you were to clock your catheter, you're gonna get more subtle, you're gonna get to the right fibrous tribome, and sometimes you can actually record all left-sided history. So again, I think this is a very important view from McAlpine, it kind of gives you a view of where the LV summit is, and some of the adjacent structures here. So now, since we know where the LV summit is, again, it's sort of, here's the anterior interventricular groove, okay? The LV summit is pictured by this sort of like shaded red region in all these views. So one way you can get to it is by the RVOT, right? So come across the tricuspid valve, go to the anterior septum, high anterior septum, just underneath the pulmonic valve, and that'll get you close to the LV summit. It also gets you close to some of the structures here. So you can see as you're right there by the LED, all right? So who says you can't take down the LED by ablating the RVOT? That's one of the complications you need to worry about. You can also get up and across, up and around the pulmonic valve, and that'll get you right up next to the LV summit region as well. You can come trans-aortic, that'll get you the LV summit. And then also just directly into the left coronary cuspid, the base of the left coronary cuspid will make you get close to the LV summit. The reason I'm showing you this is because, okay, if you have an, so remember how CLV-LV kind of tapers there? If you've got an arrhythmia of sign of origin is right at the tip, well, guess what? You can kind of lay it from all over the place, right? But what if it was down here? What if it was in the middle? That's when things can get a little bit challenging. So again, it's a nice view to look at and how we can approach the LV summit in different ways. One other way to get to the LV summit region, which is, which would be the region right here, it's the highest point in the LV, the LPOU, it's used more of an AP view, I'd say, is by using the coronary venous circulation. So here's the coronary sinus, turns into the great cardiac vein, and kind of just runs down the anterior to ventricular groove as the AIV. So if you put a catheter in the coronary sinus, you're gonna get right up into the LV summit. In fact, the great cardiac vein bifurcates, bisects this region. There is an extension of the great cardiac vein that actually runs more subtle and goes between the pulmonary artery, pulmonary trunk and the aortic trunk. Different names have been used to describe it, the LV summit vein is the communicating vein or the distal branch of the GCU, whatever you wanna call it. Sometimes you can exploit that and actually put a catheter down that LV summit vein and get recordings directly on top of the LV summit. So that can be done too. This is just me just drawing you a kind of catheter kind of showing, coming up the GCD right up to this red shaded region of the LV summit. All right, so as I said earlier, the GCD kind of bisects the LV summit. So this is the highest portion of the LV summit, which is, like I said, kind of where the LV tapers. So how far does it go? Well, it depends on which definition you look at. So one of the things that says is that the base of it is on the first subtle perforator to the left side. So the GCD essentially bisects the LV summit region into two regions. So there's one that's more basal and subtle, and there's another region that is more apical and lateral. The basal and subtle region has been called the inaccessible region, you can see why. You're gonna be right up next to some of the coronary circulation. You're gonna be right up next to some of the epicardial fat here. In fact, this region, this subarachnid region is where you can see some of the highest content of the epicardial fat. Interesting to point out here, but look at the coronaries, they kind of run in the epicardial fat. So if you're in the GCD, which runs closer to the epicardial surface here, you can probably safely oblige here because the fat can insulate the coronary blood flow and get rid of these LV summit arrhythmias using the GCV here. I'm not saying that you should rely on the epicardial fat. I mean, I think if you're in the GCV, you always have to do a coronary angiogram to make sure that you're at least about a half centimeter away from any great epicardial vessels before you apply RNF. All right, so I think that's sort of like a summary of the anatomy of this region. I think it's very important to understand that. I think it helps you kind of get a better sense of sort of the ECG features of this region, which we're going to talk about next. My goal here is to kind of go through this systematically. We talked about the anatomy. We're going to talk about the ECG features. Then we'll look at some of the formoscopic imaging. We'll look at the ice imaging. And lastly, we'll look at electroanatomical mapping of this region. I feel like this is more of an anatomy talk than anything else. Because at the end of the day, what you're going to do is you're going to map all these regions near the LV summit and the LV summit itself, sometimes by using the GCV and figure out where your best activation times are, best base maps are, et cetera, before you apply RNF. All right, why don't we take this question, so this question is the one where is the most likely site of origin of this PEC? So the choices are post-receptal RVOT, the left coronary cusp, the right coronary cusp, and the LV summit. So why don't you guys go ahead and answer that? This one's meant to be not, not tricky. That might give you a little bit of a hint there. All right. Are we sharing the results here? Okay, well, majority of you got it right. So this is, this is in fact, the post-receptal RVOT. So remember V1 is directly behind the right side of the sternum. RVOT is directly behind that. So most of the vector in this region is going to be going away from a V1. So what you're gonna do is you're gonna inscribe a small R, R, R, big S or a QS in V1. The posterior RVOT, hold on a sec, do I have to share results here? All right, here we go. We got 42% of the RVOT correct. All right, let's get rid of that. Okay. Some of the posterior RVOT is, is, is more subtle. So you're gonna inscribe a narrow QRS. It's gonna be less than 140 milliseconds. Since it is more posterior, there's some of the vector forces going in the direction of the anteropicordial lead. This results in a radio transition. Since it's also posterior, you engage the conduction tissue faster. You can activate the right ventricle together simultaneously. As compared to the anterior freewall RVOT where you get like a sequential activation of the right and left ventricle, which then results in sort of a notching, characteristic notching in the inferior leads. The PA is a little bit tricky. There's no really good ECG features. But what's interesting is there's these muscular extension that go above the pulmonic valve. And majority of the time, some reports greater than 90% of the time. What's interesting is that the height of the pulmonary valve is often overestimated on fluoroscopic imaging. So the actual ventricular arrhythmias that are targeted in the RVOT, maybe the pulmonary artery ventricular arrhythmias are more than half the time. Like I said, there's no real specific ECG features. Remember the pulmonary artery goes leftward compared to the LVOT. So it kind of wraps around the LVOT. So you have a vector going away from lead one, a vector going away from ADL, and going more towards lead three rather than two. And since it is very high in the alpha tract, you're gonna have more pulmonary arteries in your inferior leads. All right, let's take question number two. Same question. What is the most likely site of origin for this PVC? So posteroskeletal RVOT, left coronary cusp, right coronary cusp, alveocenter. All right, why don't you guys go ahead and answer that. So we have about, there you go, okay. So, all right, so we've got about half of you voting for left coronary cusp and not nearly other half voting for the left ventricular summit. So it's tricky here. I mean, so the answer is left coronary cusp and I'll show you some of the ECG features that we'll discuss here in a second. The reason why I also know this is because that's where we mapped it. This was one of my cases, that's where we mapped it, that's where we ablated it, that's where we had the best sort of activation times. So that's why I think that's the answer here. Okay, so one of the things, you know, when you start looking at these outflow track areas of the other summit in the RWT, RWOT, is when you're looking at the ECG, you want to try to start predicting the site of origin first. And the first thing you want to look at is the orientation of the coronary lead. Now, there's a lot of indices out there that are laid out for you on the slide. And unfortunately, one thing I will say, though, is that the more complex these algorithms get, the more accurate you also get as well. But the general idea here is that the LVOTs oppose to your structure. So you're going to inscribe more of a prominent R-wave in the anterior corneal leads. So all these algorithms are basically doing that. So here you're looking at the R-wave duration index, you know, your LVOTs have a bigger R-wave duration compared to the R-VOT sites. You can have a bigger sort of amplitude. You can look at transitions and earlier transitions with LVOT sites. You can even look at transition zone indexes where you're comparing the transitions on the PBCs compared to sinus rhythm. I'm not going to go through the six of them, but it's all there for you to review. One of the other things you can look at is the earliest onset of the QRS. If the earliest onset of the QRS or the earliest peak or nadir of the QRS is in V2, that is suggestive of an R-VOT site compared to the LVOT site. For an LVOT site, again, the earliest onset may be earlier. Maybe I can be in V1 or something like that, okay? So it'd be an earlier transition. So sort of recurring themes. So here's a sort of a gradient of flow sort of of the ECGs as you go from the most anterior structure, which is the free wall of the R-VOT, the most posterior structure, which is the lateral angles. What happens is you get more and more posterior and the overall ECG vector forces start going in the direction of V1, V2. You start describing it more and more R-V in V1. So you have almost no R-V in V1 than you have a big R-V in V2. All right. The free wall will also give you this characteristic notching that we talked about. I don't wanna go through all this stuff again because I've looked at this. The one thing I will mention is this very, his PECs, you're gonna have a very linear QRS. You get the conduction tissue faster. Characteristically, you'll have a sort of an isoelectric. Sometimes you get a negative AVL, something we'll go on for. We'll talk about the LVOT sort of ECG features in this next slide here. Generally, what you're gonna see is, you know, broader R-waves, taller R-waves in your anterior pericardial leads because the LVOT is the posterior structure. This example, this is an example I showed here, this characteristic W or M morphology in V1, which is very typical for left-cornering cusps. The other thing that's consistent with left-cornering cusps is the small R, big S, or QS in V1. This notch in the downward deflection of V1, I'll show you an example of that down the line, is characteristic of the left-cornering cusp, right-cornering cusp junction. Since the right-cornering cusp is more rightward, you're gonna see more of a positivity in V1 compared to the left-cornering cusp, something to keep in mind. At the end of the day, when we can talk about these ECG features all we want, we're gonna just go out there and map it. This is a nice algorithm. I use this once in a while just to, you know, kind of, it's fun. We look at this when we're doing a PVC, a PVC facing down the table, and we're trying to make a guess. This works quite well, actually. In fact, we did a case yesterday, and we were able to predict, you know, where the PVC was coming from pretty accurately using this algorithm. Obviously, I'm not gonna go over all these things, but again, it's there for you guys to review, you know, offline. But let's talk about, let's talk about the ECG characteristic of the LASUNCLE. And that's what we're here to discuss. So remember, it's an epicardial structure, and the epicardial origin is gonna be suggested by the slurring of the initial portion of the QRS. And that can be describing what's called pseudo-delta wave here, which is greater than 34 milliseconds. You can see this intrinsical deflection time, greater than 55 milliseconds, and the myocardial deflection index is more than half, more than 55% of the QRS, the entire QRS duration. And then also some of the shortest RS complex is broad. So again, all these things are showing, suggesting they're slurring your QRS, which is suggestive of an epicardial, epicardial site of origin, or epicardial exit. The other thing that is also suggestive of that is this pattern break. So positive, negative, so positive in V1, negative in V2, positive again in V3, is consistent with an epicardial origin as well. Typically with your LVSUNCLE VT, you're gonna have an atypical lumbar branch morphology. You have Q in V1. You're, a lot of times you have a monophasic R wave in V1, and characteristics of the S waves are absent in V5, V6. All right, so we talked about this inaccessible regions of the LVSUNCLE. Remember the inaccessible region, which is this region number one, is more subtle. So typically you're gonna get a characteristic left bundle branch morphology since it's more subtle. And since it is more subtle, you kind of have like a sort of, like a paragliss look where the AVL is more, is smaller compared to the, compared to the AVR. The accessible region is more, more rightward or more lateral. So you're gonna inscribe a right bundle branch morphology with this. I don't ever do percutaneous, you know, mapping, epicardial mapping for these. One of the reasons, again, you know, the coronary arteries are right there. You're really severely limited by that. Your epicardial fat is right there. You're gonna be limited with oblation, with percutaneous mapping. This is not just an opinion. This isn't systematically looked at. The success rate is low with pericardial, percutaneous epicardial mapping in the range of about 20%. But these are some of the EKG features that you can look at that may potentially predict a successful epicardial, percutaneous epicardial approach. I generally would advise against that. I think it's probably not worth the risk of doing that, you know, running to just a lot of roadblocks with that approach. So let's take question number three again, just going along the same thing. What is the most likely site of origin for this PVC? The choices are A, post-receptal RDOT, B, left coronary cusp, C, right coronary cusp, D, the inaccessible or sort of a subtle, sort of a basal subtle region of the LV summit, or the accessible or the more apical lateral region of the LV summit. I expect a lot of you guys to get this right. So we kind of, we discussed this a little bit here. I see the answers coming in. Looks positive. All right, so, well, sorry, let me go back here. It's just like a 50-50 split. Everybody got the yellow summit part, right? But look at this, you have this, again, you know, this R, almost like almost a monophysic R, there's a little bit of an S there, which is okay, which is allowed. In V1, you've got a Q in lead one, right? So all of these sort of features are suggested while we summit. But then in terms of differentiating between accessible and inaccessible, what do we say? We say, well, look at, oh, by the way, the other thing is you have the slurring, right? Which is suggestive of an epicardial sign as well, which is what the RV summit is. In terms of accessible versus inaccessible, we looked at a right bundle branch pattern, which is right here, which is more suggestive of, so it tells you that it's more lateral, it's closer to the left ventricle rather than right ventricle, so a right bundle branch pattern. The other thing is the Q wave in AVL is bigger than the Q wave in AVR, which is also suggestive of more of a lateral focus. So this is more typical for the accessible RV summit region rather than the inaccessible region. So not bad, everyone got the RV summit part right. Excuse me. So a lot of limitations of the ECG criteria. One of them is the morphology is very sensitive to pericardial leads. You get an EKG in clinic and the lead B1, B2 may not be placed in the exact same spot where the patient gets into the EP lab. So, you know, even just, you know, one inner space, one space below or higher B1, B2 will really throw off your morphology. Typically the complex algorithms work better than the simple ones, which the reverse works true. The cardiac mal-rotation is not uncommon, which obviously will throw off your ECG criteria. And then there's this description of preferential conduction between the outflow tracks, which can actually end up pointing the operator in the wrong direction. All right, so we've kind of scattered these EKGs a bit. We kind of have a good sense of what's going on with the anatomy here. Let's start doing some actual imaging and mapping. So again, ice imaging, extremely helpful in these procedures to visualize the coronaries, also to determine the location of the ablution catheter here. Okay, so I actually, I would say I actually recommend ice imaging for all outflow track VT cases. I use it actually routinely for the RVOT cases, and I'll tell you why in a second. The first thing I like to do is to get the short axis view of the urethra. You can see the left main coronary artery kind of take off here. And look what's right here. That's actually the pulmonic valve, pulmonary valve kind of coming into view. So remember what I said. So this is the left main, you can see characteristically in like a nine o'clock position. The pulmonic valve characteristically at the three o'clock position, the short axis is Mercedes-Benz sign of the urethra. Remember what I said, it's not that hard to underestimate the height of the pulmonic valve using fluoro. So if you're mapping the RVOT above the pulmonic valve, because you don't have a good sense of where it is, using fluoroscopy, well, guess what? Your catheter is gonna be right up here against the left main coronary artery. So here's a view showing the pulmonic valve, left main, this is not a great view of the left main, but you're gonna be right there. Here's a calpine image showing that. So if you come above the pulmonic valve, which is shown right here, you're gonna come right up next to the left main artery. Now, one of the clues to keep in mind is that if you're mapping the RVOT and you start seeing atrial signals, watch out. The reason why you're seeing the atrial signals is because you're right up against the left atrial appendage there, so you're seeing far from your left atrial signals with mapping above the pulmonary artery. So if you ever see that, it's time to back off or do a coronary angiogram and figure out exactly where your left main artery is. All right, so this is where we kind of talked about on the prior slide here, in the bottom view, what I'm showing you is actually we have an ablation catheter inside the left main, okay? I'm not recommending you do this all the time. In CARDO, using CARDO is kind of nice. You can actually map the left main coronary artery and actually tag it directly on your electron-anatomical mappers. Using some of the other mapping systems you don't have that allows you. Now, I will say that when you're doing a lot of OT cases and you're trying to go, you pass the catheter through the aortic valve, a lot of times the catheter does pop into the left main. So you have to be careful when you do this. You know, I mean, these catheters can be traumatic and you can actually, if you have a plaque somewhere in the left main, that can result in disastrous consequences. You can cause, you know, dissections. So you have to be careful when you do that. Left main is very easy to image. The right coronary artery, which is shown here, can be a little bit tricky. It's at one o'clock, two o'clock position. One way I do this, sometimes if I'm having trouble imaging the coronaries, is actually I'll do the electron-anatomical map or a FAM map or the auto-map, whatever you want to call it, first, and then with the FAM map, especially when you actually can see the FAM, the fan, I should say, of the ice catheter, you can actually point in the specific structures and start looking with more precision. You can identify a lot of these structures that way. Ice is also helpful because it'll tell you where your catheters are. Here's a catheter above the sinusoidal cell and here's a catheter below the sinusoidal cell. So again, ice is very helpful here. This is just, again, a McAlpine image. Again, we talked about this. You go above the pulmonary valve, you start seeing left atrial appendage signals. This image here is showing the same thing. In the RV outflow track, if you're at atrial septal, you can take down the left LED, so you gotta watch out. Oh, sorry. Let's go back here. Here's a catheter, by the way, in the left atrial appendage. There's been reported cases of ablating the LV summit, which is right here, right? Right next to the left ventricle at the proximal coronary arteries. Ablating the LV summit through the left atrial appendage, I'm definitely not advocating that, but just wanna let you know, from an anatomic perspective, where things are, you can see why that can theoretically be done. Here's just a case report showing that if you're ablating the septal horn of the RVOT, the anterior septal RVOT, you can cause LED coronary injury, okay? So you gotta watch out for all those things when you're doing these cases. So the next step is sort of the electron anatomical mapping. I don't always start mapping the RVOT. It's a clear-cut R-wave lead V1. I don't think there's any reason to map the RVOT, and it's certainly, you can do that. It's not gonna take that long, but I usually start on the left side first. And what I usually do is we'll start with actually mapping the coronary sinus system first. I don't routinely do a coronary sinus, but we're gonna have a show this year, doing this year, to show you guys the anatomy of that. So here you got your coronary sinus turning into the great coronary vein, and then extending down into the anterior ventricular vein. The LV summit would be right up around here. Now you can see that the AIV kind of turns away or proximal to the LV summit. This is that communicating branch that I was talking about. So it goes more subtle. So the distal branch of the GCV, the LV summit branch, the communicating branch, whatever you wanna call it, it goes more subtle, and it runs right on top of the LV summits. If you can get a catheter, whether it's your ablation catheter or mapping catheter, or some type of microelectrode catheter, you're gonna be able to get activation times here pretty nicely. Let's go to the next slide. Here's just a static image with the same stuff here. This is the coronary sinus turning to the GCV, AIV coming straight down. If you have the spider view here, the LAD would be running right up against the AIV here. And again, here's your communicating branch running subtly in relation to the AIV. In the REO view, by the way, the communicating branch runs below the AIV. So again, if you can get the ablation catheter right up against that, you can ablate the LV summit epicardial here. Again, you cannot rely on the presence of epicardial fat. Again, here, you see that there's, in this view, it looks like you're right on top of the LAD, but in the REO view, you're not. You always wanna do two views on your coronary angiograms to figure out if you're a major epicardial muscle or not. So here, you can actually safely ablate this LV summit VT in the vicinity of that communicating branch. This is just sort of the anatomic part showing the same thing here. This is the fat pad in place of the fat pad sort of dissected away. So the catheter in the great cardiac vein actually running into the communicating branch. The AIV would be going down this way. The LV summit is gonna be right here. So right under this coronary circulation. So there's sort of the ablation catheter going into the great cardiac vein, into the communicating branch. But again, your LAD is right there. So there may be fat pad on top and also even underneath the LAD, but that doesn't mean that you can get away without doing a coronary angiogram. You're still obligated to do that. This slide I'm showing you just sort of like where I place my catheter. So this is what I use, something called MAPIC catheter. It comes with either 10 electrodes or 20 electrodes. And this is an RAO view showing the MAPIC catheters in the anterior ventricular vein, the AIV. This is a HD grid catheter that is just sitting right underneath them. So again, in the RAO view, going up top and down, and the LAO view coming up around like this, like what you'd see with the LAD doing in a spider shot. The MAPIC catheter in this view is in that communicating branch. So look what happens in the LAO view. Instead of coming straight down, you actually go subtle. So this is where the LV summit, the epicardial LV summit is gonna be, and allows you to take some recordings from there. In the RAO view, the AIV would be over here, and the communicating branch is gonna be below it. So that's another nice way of getting some LV summit activation times when you're doing these cases. Again, you gotta do a coronary angiogram. In this case, in this particular case, we were right on top of the LAD here in the spider shot, and you're pretty close to the LAD in the RAO view. So we were not able to ablate this, but that's okay. So if you're not able to ablate it, what are you gonna do? We're not gonna stop there. We're gonna look for the adjacent structures, and that's where the whole point of this talk is to look for activation times in adjacent structures and figure out where we're gonna be delivering RF. So the next step here then is to do these electron anatomical maps. I don't make these detailed electron anatomical maps all the time. I'm just kind of doing this just to kind of show you these anatomical relationships again because that's what it's all about. So the current theme is all about anatomy here. So we've looked at the McAlpine images, right? And we looked at the ice imaging here. We looked at some of the flora shots. So let's look at some of the electron anatomical imaging here. So here in the LAO view, you can see this coronary sinus turning to the GCV, the AIV coming around on top of the summit. If you were to look at a superior view, the AIV would come in the front, and here's the communicating branch. So here's the LV summit. This is your aortic root, and the communicating branch would run right up on top of the LV summit. I was not able to get a catheter in here in this particular case, but you can see if you were able to get it in there, it would come right on top of it. Look at the RVOT, by the way. Look at the relationship of the RVOT to the aortic root here. So RVOT going into the pulmonary artery. Here's a catheter actually sitting there. I believe this was a tachy cath catheter sitting in the left main. Look what happens. The pulmonary artery, as you come up and around, if you're oblating high up in the RVOT beyond the pulmonary valve, you're gonna be right up against the left main. So here, this patient, as I said, we were sitting right next to the LED. We were not able to deliver RF there because we were within five millimeters of the LED, but we were actually successfully able to oblate this. So our activation times, what I did here is I mapped the earliest activation time in the AIBGCB area, and then we oblated just underneath it, endocardioid, and also oblated the base of the left coronary cuff, as I showed you in some of the McAlpine images, and we were able to successfully get rid of the VT here. I actually did take some activation time in the RVOT, but look how high it is compared to where I would have liked to have laid. So the RVOT times, or the pulmonary artery times, I should say, were very late compared to the AIB, and certainly very late compared to the AIBGCB, the endocardioid times were also later compared to some of the endocardioid times and the left coronary cuff times. So this is where we ended up ablating, which is not necessarily where the site of origin is, but it's the closest spot you can get to and still get rid of this LV sunlit VT. All right. Oh, I kind of threw this in here. Sometimes when you're mapping with sort of these high-fidelity catheters, you'll see these pre-potentials. This is just showing this in sinus rhythm. These are pre-potentials that are seen with the HD grid map, with the HD grid catheter. These are pre-potentials seen with something called a NovaSTAR catheter, which is a cardinal-specific catheter. A little unclear as to what they mean. You know, these may represent sort of specialized conduction fibers. They connect the urinogenic site to the site of exit. These fibers may be insulated. They may be hard to do an active, sort of a pace map in these regions, and maybe pace mapping actually may be unreliable here. The reason is you can actually get far-field capture, and that can actually point you in the wrong direction. So be careful. I'm not saying that you shouldn't do a pace map. Just be careful of, you know, watching what your output is set to when you're actually doing a pace map, and what you don't want to do is get far-field capture. When you're doing it in this region. Here's a view of the catheter in the LV Summit. Here's the, again, the map of catheter in the LV Summit branch. I believe it's not in the LV, because in the LAO, you see how it's not going straight down. It's kind of coming at you. It's not really going subtle, so maybe in one of the other branches. Hard to know. Either way, it's in the region of, certainly at the cardio in, more or less in the region of the LV Summit. Here's the HD grid, just underneath it. Look how thick this structure can be. Can have about two centimeters here, okay? What I've done here is I've actually superimposed the McAlpine images on top of what we're doing here with the fluoroscopic images to give you a sense of what you're mapping here. So as you come retro-radiotic here, you have the HD grid catheter just sitting endocardially. You might want to call this the left fibrous trigone. You know, as you get, as you go towards the mitral valve, you go a bit more anterior from there. And this is the map of catheter sitting endocardium. So again, as I said, you know, listen, if your LV, if your side of the world is right here, certainly you can ablate from the base of the left coronary cuff. You can come on retro-radiotic and ablate it here. You may even be able to ablate endocardially. And in our case, obviously we're not able to do that, because we're sitting right next to the, to the left coronary arteries. But this kind of gives you a sense of this region with a flora and a meccatine superimposed on top of each other. It gives you a sense of what we're dealing with here. As far as the actual ablation is concerned, I will say one thing is, again, it's all about mapping in all these specific regions, finding out the earliest spot. If you're able to ablate endocardially, that's great. If you're not able to ablate endocardially, then look for other regions. So my first go-to spot is going to be the endocardial spot. Very safe to ablate. One thing I will say is that if you want to ablate here and it's not the site of origin, you're close to the site of origin, you're going to need high power, high duration. So I typically will ablate at 50 watts for 180 seconds. So three minute lesions, you know, you're trying to create big lesions here as you ablate there. So there are some predictors of whether or not ablation in these remote sites is going to be successful. You can look at the activation time of these remote sites. If the activation time is within several milliseconds of the GCV site or the endocardial site, you're likely able to get it. If it's a short distance from the site of origin, you're likely able to get it. So, I mean, in this patient, you know, I mean, imagine if this is a two centimeter distance, I mean, forget it. You can ablate all you want. You're not going to be able to get a two centimeter burn through and through it. Let's go on to the next slide here. Oh yeah, so this is actually from one of our cases. This is epic endocardial ablation here, high power, high duration. So this is one of the complications you do need to worry about. I would recommend doing these not in general anesthesia because it's very important to be doing ECG monitoring. It's very important to be doing patient monitoring as you ablate these regions because if someone starts having chest pain, you've got to come off. You're going to be ablating the coronary vessels. This was just a LAD spasm. We realized we gave Venus intracoronary nitroglycerin and resolved almost immediately in this particular case. So I think that's sort of basically, I want to summarize here. I think when you're talking about LV summit in a particular way over the years, it's all about anatomy, anatomy, anatomy. I can't stress that as more. If you understand anatomy, you understand the 3D relationship of the different structures there, you understand the fluoroscopic anatomy, the alkalpine anatomy, the electro-atomic anatomy, the ice anatomy, and you're able to correlate all of that stuff. This ends up being a pretty simple case and ends up being quite a fun case. And you can actually be very efficient with this. You can get these done in less than an hour. They're not daunting. You got to do a systematic. You can use ECG for localization. Helps you set expectations for the patients. You can do systematic activation. You've got to do this mapping of all the adjacent structures. You can certainly map the RVOT, the aortic sinuses, and the LV endocardium that we talked about. I highly stress ice imaging here for catheter location and imaging of some of the critical structures that we talked about. Remember that if you're not able to directly ablate in the epicardial region, then ablating in the adjacent structures is going to be the way to go. The shorter activation time between the site of origin, the epicardial site of origin, and where you're ablating endocardially or in the left coronary cusp, the shorter the differences between the activation time, the more likely you're going to be successful. The shorter the distances, so you're more likely to be successful. We talked about high power, high duration ablation. If you're endocardial, you can certainly get away with that. In the left coronary cusp, I usually limit it to about 30, 35 watts. You can certainly image the left main. I think if you're ablating in the left coronary cusp and you're imaging the left main with ice, that's probably okay. If you're endocardial, or if you're, especially if you're in epicardial in the great cardiac vein, I think you're obligated to do a coronary angiogram before you deliver RFTAB. One of the reasons is because it's, ice imaging is good for proximal coronary structures, not so good for some of the distal coronary structures. So that sort of proximality, proximal search, not so much easy to image with ice. You can see thermal facilitation when you ablate your viral. In fact, in your case yesterday, it was intramural foci. And I knew it was intramural because the activation times were kind of equal all over the place. It was about 20 milliseconds PQRS in the AIDGCV area. It was 20 milliseconds PQRS in the left coronary cusp, and it was 20 milliseconds PQRS in the endocardium. So we ablated in the endocardium first. We actually suppressed the ablation to get a high power, high duration. We got thermal facilitation. Actually, the patient went into ventricular rhythm. We pretty much matched the exact morphology as the PVC. And that just sort of suppressed us spontaneously with time. The other thing that you may notice, though, is the patient comes in, and you're having infrequent PVCs. They're able to map it, and you ablate it, and all of a sudden, that PVC burden goes up. So again, it may also be some form of thermal facilitation. There's clearly reported cases of late success. So you watch these patients overnight. They're having tons of PVCs, and all of a sudden, overnight, everything just goes away. So you can certainly see that as well. There, if all of this doesn't work, then one of the things that have been described, and I think, you know, Rod Tunks talks about this. This is sort of the surgical ablation. This is your left atrial appendage here that's gonna lift it up and exposes the summit region. There's a lot of different, you know, strategies that folks have talked about. The only one that I've really tried in this region is the half normal standing. I know that that's something that has been described. I think Bill Summers is on the line here. He's talked a lot about this. The irrigated needle, we've tried that. In intramural VT, we've not tried this in this region. I don't know if Bill Stevenson has described this in this region or not. That would be a good question for me to ask him. The WashU group with full cucurbit should certainly try ablating with, you know, with radiation here, and develop some successful data. Some of the other more sort of kind of exotic approaches that I don't really know too much about, but if our panel here knows enough and plays by all means, happy to have them comment on it. So I think I'll stop here. I wanna thank you for your time. And I think we have about nine or 10 minutes here for plenty of time if there's any questions. Thanks. I'll hand it over to you, Michel. Oh, that was great. Amazing images. Thanks so much for that. There were a couple of questions here. You touched on some of them just there on that last slide, but one of them was your settings within the coronary venous system. How high are you willing to go and how long are you willing to ablate in there? Yeah. So I try, in the coronary venous system, I'm usually around that 25, 30 watt range. You know, as far as, I mean, we're not gonna be delivering sort of high-end. We're not gonna do three minutes in the coronary venous system. So about 30 seconds. You're watching everything. You're watching the patient, and somebody in your coronary vessel. But I usually will do 30 seconds of RF, about 25, 30 watts, and then reassess. Okay, great. And then this other question is, you touched on this as well, but if the timing on adjacent structures is not that good, but anatomically it's directly across from where you've gotten good timing, is it still worth ablating there just to try and get suppression? Oh, absolutely. I mean, I think that's one of the major points of this talk. So I mean, look at this case right here. Can you guys still see my screen here or not? I'm not sure. Can you guys still see my screen, Nishant? Yeah, we can see it. We can see it. Yeah, I mean, look at this case. The earliest activation time here was in the EIV. Basically, I was able to eliminate this PVC from endocardial ablation. This was right on top of a coronary artery. So absolutely, that's the whole point, is that you map all these regions, you get the activation time from all these regions, and then you're gonna deliver. If you're able to ablate in the epicardial region, you have great activation times, then by all means, you're away from the coronary muscle by all means. But if you're not able to do that, that's when you have an understanding of anatomy here, you can exploit that and ablate these LV-summit VTs from ablating all these other regions. Absolutely. All right, great. Jeff Winterfield says hello. Hi, Jeff. If there's any other comments anyone wants, oh, here we go. So can you use a cryocapter in the EIV if the LAD is close? I don't have, you know, I don't realize the amount of cryo is, it's already been reported. One of the EIVs, a region where you can, you have pretty low flow, you can get high impedance, and that can be, that can limit how much RF you can deliver there. There's still even reports of doing that. I don't have a lot of experience with that. I don't know if anyone in our panel here has experience with the blade with cryo in the EIV. I personally don't have any experience with it, but I know it's been reported.

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