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EP Fellows Curriculum: Electro-anatomical Consider ...
EP Fellows Curriculum: Electro-anatomical Consider ...
EP Fellows Curriculum: Electro-anatomical Considerations for the Catheter Ablation of Accessory Pathways
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All right. Thank you, Nishant and Brad Knight, for putting together a fantastic lecture series and inviting me and allowing me to participate in this kind of all-star list. So thanks everybody for joining us. I wanted to talk about this topic because I think it's quite important for all EPs, early career, mid-career, late career. And it's something that we need to know as far as catheter ablation and electronatomic considerations are very important when it comes to accessory pathways. So with that, we'll start. And if you need to contact me with questions or anything else, I'll show you my email at the end and I'm also on Twitter. So if anything you see here you want to discuss further, please feel free to reach out. No disclosures financially, but I am a huge Los Angeles sports fan and I love soccer. So those are my disclosures. And just a slide on the history of WPW, really. The three here, gentlemen here, 1930, Wolf, Parkinson, and White, discovered the EKG characteristics of this unusual phenomenon back in the day. Charles Woolworth first thought conceptually about what's actually happening in the heart. What does pre-excitation mean? And he drew this figure, which is quite accurate actually for the bundle of Kents and the AV node and pre-excitation here and a reciprocating tachycardia using the AV node and a quote unquote bypass tract here. In addition, the histologic, the first histologic example of an accessory pathway was described many years later. So this is kind of the trajectory as far as understanding the electroanatomy of accessory pathways. So I got to click on this. Okay. So when it comes to EGMs and your mapping of WPW, and again, we're not going through differential diagnosis. We're going to go straight to a diagnosis of WPW, either concealed or manifest. There's really three things you should be looking at. Appearance, location, and timing. And that kind of analogy to that is really real estate. If you look at real estate, you're looking at appearances, what does the signal look like? What does this house look like to you on the outside? You're also looking at location. Again, a beachfront villa is going to cost a lot more than a bigger house in the suburbs. And one of the most important things for you guys as you map WPW concealed or manifest is timing. Now, if you look at timing, timing is always going to be relative. For example, US house prices over the decade from 2008 to 2018. I could buy a house in 2014 and that would have been a great or a good price, but it wouldn't have been the best price, which would have been in 2012. So good doesn't necessarily mean best and early does not equal earliest. So appearance, location, and timing. And we're going to start off with an example of this that was a case that was referred to us. And you guys are going to help me on this one. This is a young male referred for a fourth redo concealed accessory pathway ablation. And at our center, we probably get about five to 10 multiple redo accessory pathway or manifest WPW ablations per year. This patient had a first ablation for a concealed left lateral accessory pathway. And the second and third ablations were for a concealed septal accessory pathway. The outside hospital record was obtained. This was sent as a package to us. And this was the EGMs that they saw on the last ablation at the hospital. And again, this is a very experienced electrophysiologist doing these procedures. The patient's in ORT right now. This is the surface EKG. This is the His bundle electrogram, CS proximal to distal, and this is the RV electrogram. And you can see here that there's a VA time of around 120 or something like that. His bundle electrogram B and A. And this is the earliest atrial retrograde atrial electrogram. And again, when they put their ablation catheter here, they're really mapping to beat the earliest atrial electrogram here. And so this signal was labeled as a great signal and they ablated and ablated and really nothing happened. And therefore they referred this patient to us. So when you look at this signal, I want you to ask yourself, does this signal represent AV fusion, 15 milliseconds earlier than the His, therefore a good place to ablate, absence of AV fusion, therefore not a good place to ablate, a great place to ablate, but too close to the His, or none of the above? I'll give you 30 seconds or so to answer. If you want, Ashkan, you could put the electrogram back up because they'll have the- I'm sorry. Yeah. Thank you. All right, we're getting some final votes and I'll take it to a minute. Let's see All right, I think we're done there, okay so fantastic so Absence of a B fusion therefore not a good place to play. Okay, the actual answer to this is Is none of the above and I'll tell you why and we'll go through what a B fusion actually means, right? This is a case I can take the pole off, correct? Yeah this is a case where a Septal AP was thought to be present but in actuality The left lateral AP was still existent. Why is that? Well what happened was? During the first ablation there was extensive amount of ablation of that left lateral accessory pathway without Actual effect on the pathway. So what's happening here? Is that you are recording electrograms that are all relative? These are all septal and CS electrograms. You have not recorded the actual accessory pathway electrogram or region of interest and there's a remote distant site Activating during ORT if you pay close attention to the electrogram that they sent And you look at this area You'll notice that CS distal has a very interesting signal on it That's earlier or sometime on time to the next proximal bipole That really can't be the case when you have true proximal to distal activation of the CS Therefore there's a way front coming in to the tip of the CS catheter That's slightly early than the most proximal bipole in that case. What's happening? Is there is Block basically a CS dissection with atrial activation coming all the way to the his bundle acting it activating it relatively early based on your electrograms and Also activating CS proximal distal almost like an incomplete mitral isthmus line So again You could use a unipolar signal here and understand that this is not early ist It is early, but it's not early ist and therefore this is Left lateral accessory pathway mimicking a septal accessory pathway. So what we did was We advanced our corneal sinus catheter all the way around to try to bracket at least some part of the epicardial aspect of the region and Here you can see extensive amount of atrial low voltage and also Fractionation, so there was an expense extensive amount of ablation done here but this was relatively early a and Here is the signal that actually got the pathway, which was the left lateral anterior accessory pathway. This is the pathway potential and This terminated tachycardia and also rendered it non inducible With no evidence accessory pathway So remember this is a case point where timing is always relative and it's relative to your recording so our agenda really is a Couple of few things and we may not get through everything But I want you to understand really basic concepts of electroanatomy of an annulus and we're going to use the lateral mitral annulus as an example we're going to go through electroanatomy during ablation and we're going to use the lateral tricuspid annulus as an example of an anatomic obstacle and We're going to go through the posterior septal space. We're going to just touch touch on some epicardial connections We're also going to talk about the paraceptal space in brief and we're going to talk about regional Electroanatomy because this is a very important space I think an EP kind of the septal space the paraceptal space and the poster septal spaces All right, so let's talk about the lateral mitral annulus and we're going to talk about some anatomy here as an EP when you were ablating or you're mapping the heart you really have to Visualize in your brain kind of imagine what you're actually touching and what what region you're ablating So whenever I go in into the left atrium and I'm going toward the mitral annulus in my brain Not just the mapping system. Not just fluoro in my brain I'm thinking about this type of structure the topography the anatomy The relative atrial tissue relative to the ventricular tissue the spacing and also the mass of the tissues together All right. So if you can see here the annulus This is a cross-section and this is lateral. Basically. These are all lateral cross-sections. This is the LIPB this is the LV part of the LV is the This is the LV part of the LV here. This is the ventricular myocardium. This is the atrial myocardium You see the left circumflex artery here and the venous system here. This is a great cardiac vein There's a lot of epicardial fat and there's also some annular fat here, right? this is where the the the fat pad you see and also this is where the arterial and venous Vessels run so there's fat here Notice the relative mass of the ventricle compared to the relative mass of the atrium at the actual annulus right and that'll come in when we look at signals later and here, there's some variant anatomy as far as the GCV and the circumflex and Sometimes it may be a little flat topography. Sometimes there may be a little ridge topography here. And again, this is the histology where this is ventricular myocardium fibrous tissue a V and atrial tissue here So the true annulus is really, you know, kind of a complex structure ventricular mass atrial mass fat Epicardial space artery vein and some topography changes around this area And when you look at all these areas and this is a study diagram from you know many Autopsied hearts pig hearts and dog hearts done by one of my colleagues Zhengjian Wang back in his day There may be some variant Anatomic areas around the annulus that will change What I mean by that so the lateral mitral annulus may have atrial tissue that abuts the ventricular tissue on the endocardial side But also may have a variant anatomy as far as atrial tissue abutting the ventricular myocardium on the sub-epicardial side Okay, that's also goes for the tricuspid annulus that also goes for the posterior septal space, which is quite complex So you may have epicardial connections You may have endocardial posterior septal mitral annular connections And again, this area may be very small and may make the difference between success on one side versus unsuccessful ablation on the other side So I don't want you to think of the annulus as a uniform structure throughout the patient's heart Nor should you think about it as a uniform structure across patients? It's quite complex and it may have variants atrial and ventricular tissue in the actual space So let's look at the lateral mitral annulus I use ice for transeptal Why not put it across into the right ventricle and look at the annulus while you're doing ablation. And so this is a catheter ablation of a left lateral accessory pathway And I have an ablation catheter inside around the annulus and this is the mitral valve This is the left atrium for those orientation wise and this is left ventricle And notice catheter movements annulus movements and Ventricular side and the atrial side and we'll go through this a little bit So if you look at it, it almost looks like a pyramidal space, right and the true annulus Extends from the atrial myocardium here to the ventricular myocardium here and the annular apex is right here. Just like that Anatomic picture that I showed you So think about it like this when you when you're not actually having the ice in there if you do have ice take a look It's actually more complex than a flat structure and the atrial myocardium ventricular myocardium about each other at different places potentially So the thickness also carries over from Atrium to the ventricle from the apex all the way to the epicardial fat here It's probably around 1.9 centimeters in this heart and you can see that there's variant thickness here Across that annulus. So again, don't think of it as a straight structure But it's quite complex when you think about it And when you get the ablation catheter out of the mapping catheter out this anatomy is going to affect your signals So let's talk about that So when I position my catheter on the apex of The annulus right remember the myocardial mass that the ventricle provides relative to the atrial side Okay, so when I'm at the true apex of that annulus, I'm gonna be recording a lot of ventricular tissue Right. So look at my signal. This is pre and post ablation Before ablation on the ventricular side, which is basically the apex of the heart apex of the annulus I have a large V signal and a small a signal Even after ablation during sinus rhythms large V signal small a signal so now even if you don't have an image of the heart either by ice or another way to look at real life imaging You can tell where you are just based on the signal of your ablation catheter or your mapping catheter alone So if I have a large V small a I know that I'm on the true apex of the annulus right here Now This is what happens when you're sliding on the annulus and you're coming toward the atrial side This is real this signal corresponds to this Video of my catheter really sliding across from the atrial vent the apex to the atrial side and look at this You get a V bigger a Bigger a and then all of a sudden you get this beats, which is a PAC basically from my catheter on the extreme atrial side of the annulus and that causes a different activation CS 1 2 becomes early and Interestingly enough all the signals here are fused on the annulus So CS 910 fusion with V a V fusion a B fusion a B fusion and we all know This was a left lateral pathway. This pathway did not occur at CS 910, but yet there's fusion there So again, we're gonna talk about this fusion does not necessarily mean the right place to ablate Okay fusion can happen for various reasons but notice When you come along and you blate on the atrial side of the annulus, which most people are gonna bleed there You're gonna have a equal a and B Right. So the the the matricular mass here. You're a little bit away from it You could be even recording some far field a little bit But you get a lot more a here on the atrial side of the annulus So now, you know where you are as far as the electro anatomy As far as your signals are concerned Now let's talk about fusion and Fusion really represents timing of atrial events relative to ventricular events. Okay Here's an example This is the tricuspid annulus and let's say there's a accessory pathway right here and number two and That accessory pathway doesn't go away, but you pace From number five here or you let sinus rhythm Occur so sinus rhythm activation versus pacing activation in number five. You're pacing from the a here so depending on the pacing wave front you may get different degrees of fusion at different spots and the reason is this So when I let sinus rhythm come through The accessory pathway is engaged early So then there is atrial activation coming and then the accessory pathway activation to the V Coming at the same at same time simultaneous timing, right? So the timing across all these electrodes the a and the V are gonna look fused Because I'm following the same path around the annulus from the a and the V because I engaged the accessory pathway relatively early except for pole number one, which is Proximal to it. So you don't get much fusion there. But after this you're gonna get some fusion all the way across. Okay, so Number five doesn't have an accessory pathway, but there is still a fused electrogram there If I pace from number five here, what's gonna happen? Is that I'm gonna engage the accessory pathway a little bit later than I did here Right and what happens is yes Now once the accessory pathway is engaged from a to V I get really intense fusion at one Definitely at two because two is accessory pathway location. So it's always gonna be fused But then four or five three four five are always gonna be later Because it's gonna wave fronts gonna have to come around and come to the V All right And V at five here is gonna be much later than a at five here because you pace from a so timing is always relative Don't think of fusion as a good spot to oblate fusion can occur anywhere along the annulus in the presence of an accessory pathway So other signals this is a huge a signal really no V maybe a far-field B This is on the true atrial myocardium. This is really not on the annulus. This is kind of left atrial body here So again, not a place you want to oblate you want to keep your ablation catheter on that annulus apex on the annulus So the atrial side of the annulus or even the ventricular side of the annulus and I'll show you some examples So now let's go to our second pole This these are signals from that case that I just showed you so which bipolar signal represents the most likely site of successful ablation and We'll talk about these individually We'll give you 30 45 seconds Okay, good. So most people picked D and I think we'll go through them. A represents really no contact. This is a poor signal. B, there is fusion there but the V electrogram relative to the QRS in pre-excitation is early but not the earliest that you could probably see. C represents a very relatively late ventricular electrogram and probably some amount of poor contact. And it's really between D and E. And I'll tell you E was the actual site. The reason is both of them look very good. The timing of the sharp deflection is relatively early here. Their timing of the onset of the QRS, sorry, the local EGMV here is just a little bit earlier than this. So even though this appearance looks good, just be careful. Just like I told you with real estate, it's all about timing and it's all about location. So D and E, I would say, are good choices and E, if you measure correctly here, may be a little bit early, even three or four milliseconds earlier than the local V here. And so this was actually the successful side of ablation. So I wanted to show this to you because I wanted to prove to you fusion here, here, it does not necessarily mean success. Okay. And this is edema from ablation. You can see this is edema on the atrial side. Most of the time people are going to be ablating here. This is going to be an equal A to V ratio. Just like I said, from the apex to the atrial side, you're going to get bigger A ratio here, AB ratio here, and it's going to be equal A to B. Now there's some new techniques with advanced mapping and I love multi-electrode mapping, high-density, ultra high-density mapping. Just beware that if you don't know the electroanatomic foundation of what you're doing, don't rely on mapping systems to take you where you need to go. That's one. Sometimes there are some errors in annotation. And number two, you can't ablate with a mapping catheter. So you really have to focus on catheter, an ablation catheter, to guide you during ablation. Stability, orientation, EGM, and contact all need to play a role in success. Okay. This is just a fancy example of mapping of an accessory pathway, left lateral. Earliest breakout site of the V's here is pre-excitation here. Okay. So we talked about the basics, the electroanatomy of the mitral valve, or basically an annulus in general. Now we're going to move to the tricuspid annulus. Okay. And here we're going to talk about a little bit of more anatomy, now that you know the electrophysiology, and how to how to approach an ablation, especially when it doesn't go well the first time around. Okay. So it took some time to get some ice images of the inferior lateral and the lateral tricuspid annulus. Okay. And I think whenever you think about the annulus now, you should really visualize these pictures in your mind when you're taking an ablation catheter or mapping catheter there, and understand why the difficulty exists. And this will kind of give you a hint. So when we do a CTI ablation, right, we may be dealing with a relatively flat topography, basically from the atrial side of the annulus to the ventricular side of the annulus. Okay. And that makes it relatively easy. Okay. Again, everybody's had their difficult CTI flutters, and that could be because of anatomic variance and obstacles, but it's relatively flat. Okay. Now think about the infralateral tricuspid annulus. Now we're going to move our ice catheter a little bit more laterally, and you start seeing that there's some topographic change between the atrium and the ventricle. And you start seeing some ridges on the annulus between the atrium and the ventricle here. Okay. And that may make it difficult for you to stabilize your catheter there, get good contact, and you may not be able to even touch the apex. You may slide into the ventricle, slide into the atrium, and you're always sliding all the time. Okay. With your ablation catheter. And if you look at the lateral tricuspid annulus, it's kind of exaggerated. You know, and some people, it may be just like this. The tip is here, the apex is here, and you have this exaggerated atrial side to ventricular side. A lot of ventricular myocardium here, atrial myocardium abutting here, and this is the atrial side of the annulus, and it could be quite different than the mitral annulus topography. So you have to take into consideration these factors when you are struggling or having difficulty ablating a right free wall pathway. In fact, we get a lot of referrals for redo right free wall pathways, and I think this has something to do with it as far as contact and position. All right. So think about these things the next time you do a right free wall pathway. Don't think of it as a straight flat surface. The variability may be quite extensive all along this patient's annulus. You see that from CTI all the way to the lateral side and even the anterior side. Okay. And this is just from my calpine. This is the annulus, and you can see that there is some topographic change. The topography here is quite variable from the atrial side to the ventricular side. So here's a right free wall accessory pathway concealed, ablated during V pacing for retrograde activation. Okay. This is a rapid but very transient effect. 35 watts to 50 watts with a sheath at this area. Okay. And this is a V and A signal. VA. VA. Okay. And pathway block here, and you see a relatively equal A and B signal here. So this indicates that you're on the atrial side. On the atrial side of the annulus. Including ablation proximal has a large A here. Small far-field B. And here they're in the sinus beat. Obviously you see a large A and a small B. So this is the atrial side. I want you to think about sides of the annulus. This is the atrial side of the annulus. And multiple attempts here did not work. Transient, very quick, but transient effect. So again this is right free wall. This is pole number three. Knowing now what you know from the first few slides, AP recurs despite your best efforts. And your next best step is to employ half normal saline. Continue mapping on the atrial side of the annulus, which you've done extensively now. It's been two hours. Change the ratio of A to B signal ablation. Get a different manufacturer's developable sheath or none of the above. Ashkan, while they're looking at that, I can ask a couple questions here. There's one about transeptal versus retroaortic for left lateral pathways. Do you have any thoughts on that? Yeah, I do. I think transeptal offers you the benefit of getting better contact on the atrial side as opposed to a retrograde approach where it may be quite difficult. I think it really has to do with how you're trained and what you're comfortable with. But this day and age, I think we haven't done any retrograde approaches. And I think the approach from the transeptal aspect to be able to get good contact on the atrial side of the annulus, I think that gives you a little bit of advantage for the transeptal. Okay. And then the value of maybe having a unipolar tracing on your ablation catheter when you're trying to figure out the different signals. Yes. So unipolar helps. I'll tell you from a unipolar standpoint, and obviously if you read about unipolar signals, they are very good when they're bad. So a bad unipolar is very helpful. A good unipolar, the problem with that is, is if you have a small space that you're mapping, you can still have good unipolar in a vicinity of an area. And that goes for every kind of ablation, that's alpha-attractive ablation, PBC ablation. So don't rely always on the unipolar to get you to where you need to go. I think the quality of the bipolar electrogram matters. And I think that you have to take different approaches from a AV ratio, and that matters too. So we don't, you routinely employ a unipolar mapping on our recording system, but we do use a bad unipolar on the mapping system, like any of the three or four major mapping systems to say that, is this a good area or this is a bad area? So unipolar, very sensitive for a good spot, but not very specific in a small region. Okay, I'll end this poll for you. Okay, great. So I love the answer. Change the ratio of AV signal ablation. I think that's the right answer for this case, and that's what was done. Different manufacturers, deflectible sheath may not help you in these situations because you pretty much have good contact. You're on the atrial side, but you just have transient effect. And you could start ablating and ablating and ablating here, but maybe to save yourself time, try to change the ratio. And that's kind of a key point, if you're going to take away from the first half of this talk, is the ratio of the AV you can change, and you may be more effective with a different ratio in each patient. All right, so here's what we did. And what we did was change the ratio to bigger V, smaller A here. Again, timing was pretty good. And notice the position of my ablation catheter with a sheath. And I've gone across, this is the annular line, this is the corneous sinus. So this is kind of the annulus right here. And you'll notice here, where I did a lot of ablation here, which was A equals V, then I really honed in on getting stability and getting a bigger V and A, bigger V relative to A. And this is the difference from here to here. And again, visually, you see it on the map, but I want you to think about it like those videos show you where you are actually on the annulus. I'm on the very apex, or even maybe a little bit of the V side of the annulus. And here was success. So we consolidated these lesions. And basically the sinus beat after the ablation was performed. Now look, this is V and this is A. After some consolidation, obviously the V can change the bipolar signal a little bit because you've been ablating there. But again, the V is much bigger than the A here, and V and A. And again, during sinus rhythm versus retrograde activation of the A, there may be some differences because we all know that activation wavefronts change voltages recorded underneath your ablation catheter. But this is more V, and this was successful. So don't be afraid to change up the ratio and really prove to yourself that you can be successful on the V side or the A side. Now, in our minds, and this is what I thought when I was a fellow, Now, in our minds, and this is what I thought when I was a fellow starting out, that all accessory pathways basically had to look like this. They're all straight connections from A to V. I really think, and again, there's been some anatomic studies on this, but they're very limited because most of these patients are humans that are living, unless they're autopsies. I really think that this is the probable reality, that you have connections that are three-dimensional. They may be a little bit superficial on the A, they may be deeper on the V. They may be superficial on the V, may be deeper on the A, on the epicardial side of the A. And again, we could go through all these things called slant and all these, but I really think that you should understand that there's a lot of variation in these accessory pathways, not just from location, but how they connect from endoepi to endoepi A and B. And again, you may be successful here, whereas you may have very much, a lot of difficulty on the atrial side of the annulus when you're trying to ablate these things. And again, we see a lot of redos and I learn a lot from redos. And I will tell you this, if you're in an institution and your partner has a redo ablation for WPW, it's worthwhile to sit in on that procedure, which I do always with my other partners, or my partners come in and do the EP study for a redo when I'm doing, when I'm scrubbing in. So I think they're very valuable lessons to doing a redo. Here's a fifth redo, fifth referred to our center. The previous four were done at very, very good centers. Okay. Two at one center, two at another center, and this is a right free wall pathway. Okay. Manifest in an 18 year old. And here, I'm going to show you the LAO of, obviously we're using a sheath and here, this is the RAO, and this is the ratio. And this is the signal that we obtain. It's early V somewhat fused, small A and V here, but look at the variable signal, you know, and this may be one of those annuli that has very pronounced topography change from atrial to the ventricular side. And you may not be able to stabilize and get an effective lesion here, no matter how much you push, how much contact you have, or there may be a connection that is a little bit different than what you're expected. You know, maybe sub-epicardial on the atrium and sub-endocardial on the ventricle. You don't know. But this is the fifth redo. So now, here, this was tried, but it was unsuccessful. So this is the alternative to our previous case. And what happened was the catheter was pulled back and really brought to the atrial side. Okay, so now you can see RAO on the annulus. I'm a lot more posterior than I was before, right? A little bit posterior, a little bit higher, a little posterior, but this is going to be a large A. And in fact, there's a large A on ablation proximal. There's this fractionated signal that's mostly A, okay? And I didn't show the pacing to show you that the AV difference, but I'll show you after the fact. And this was successful. So this is within three seconds of RF. Now you see the street pathway abolished, and you see a large A, small V, large A, small V, large A, small V, okay? So this is exactly the opposite of the other case. So if you're finding difficulty with these cases on the right free wall, think about changing the AV ratio, all right? Go to the V side, go to the A side, try there. You'll get similar signal timing, but maybe you can actually affect the accessory pathway if it's somewhat unusual in an epicardial to endocardial, quote unquote, slant or variance. So this was successful with more A and less V. Fifth reader. Now, again, on the right free wall, I want to show you when you can kind of see that the instability is there, and there's some dynamic EGM changes really due to poor contact or instability. So from left to right, this is again, a free wall pathway, right free wall, and ablation distal, this is a very low amplitude signal representing poor contact, better contact, better contact here, better contact here. And then finally, there's some good contact that ablation is successful, but this may not be permanently successful, okay? So you got to make sure that you do have contact there and you have a stable catheter. And sometimes we do employ an alternative approach. This is not a case of WPW, because I don't have the floral for that case. This is a case of an atrial flutter that was ablated at the same free wall area to make a line, and we had to employ a curved U-shaped approach to the annulus and have the catheter lay on the annulus almost like a duodeca catheter, which is here to get stability. So think about these approaches when you're thinking about the annulus, and it's a variable, it's dynamic, there's respiratory motion, there's also cardiac motion here. So it's pretty dynamic. Okay, so let's move on to the posterior septal space. As a trainee, I think this is, as an EP basically, the septal, posterior septal space is quite complex, and we get a lot of referrals for failed post-receptal accessory pathways and ablation. We've done some epicardial stuff as well. I'll show you an example of those. But again, you have to understand myocardium of the atrium interacts with myocardium of the ventricle, and that interaction is variable across from right to left and can be epicardial, can be in epicardial veins or the MCV or diverticula, can be endocardial, and could be separated from the right and left endocardium by one centimeter. Okay, so think about these concepts as you approach the posterior septal space. All right, let's go to another poll. This is manifest pre-excitation, and this accessory pathway localizes to the parahystine region, the left posterior septal space, the right posterior septal space, the epicardium of the posterior septum, or the non-coronic cusps as an AP connection. I'll give you about 45 seconds for this. Ashkan, could you weigh in on an IJ approach for the lateral right atrium? Have you ever done that? Do you find better contact in some cases? Yeah, I've seen it done. I've seen it done for kind of the 12 o'clock or the 11 o'clock tricuspid annulus, and it may work for that region. You may get better catheter stability. With an approach from the IVC with a sheath, I think you can still get the same catheter stability, just knowing kind of which side of the annulus you're on and which side is more stable. But it is an approach to try, absolutely, and it may work a little bit better. All right, good. We got a little distribution here. Good. So everybody is in the right general region. Obviously, this is the posterior septal part of this talk, so I'm glad everybody picked somewhere around the posterior septal space. This represents an epicardial connection, and I'll tell you why. But this is basically an epicardial connection, either at the MCV or a diverticulum. And the reason is, really, you're looking at lead II and the inferior leads mostly, but lead II has an initial negative delta. I know there's a positive here and it continues negative here. So this represents, at least initial negative delta, this represents somewhat of an epicardial tract. And sometimes we see that lead II is extremely negative, and that will point you more towards the epicardium, but this was actually in the epicardial space. So I'm glad people picked between BC and D. This was actually from the epicardium, and we'll go through the diverticulum. And this is actually a nice study in 2002, circulation from Warren Jackman, University of Oklahoma, and the group there, looking at all these accessory pathways and specifically coronary sinus accessory pathway conduction. And if you look at the coronary sinus, we know it has a myocardial sleeve. We know it's very close to the ventricular myocardium, and there's atrial myocardium abutting ventricular myocardium. When you have that, you have the potential for an accessory pathway connection, and we'll talk about that more when we go to the paraceptal space. So this is the right atrium. This is the entrance to coronary sinus. This is the great cardiac vein. And here you'll have epicardial connections. And depending where they're connected, you may get a difference in lead II notching and deep Q wave. So for example, this is mentioned in this article as an MCV pathway, and a deeper kind of deeper QS would be representative of a diverticular pathway, almost like you're going a little bit more inferior into the ventricle to get a deeper QS. Now here's this case, and whenever we see an EKG like this, I think you should look for a diverticulum. So go ahead and break out whatever tools you have to do a coronary sinus venogram, and here you'll see that there's a diverticular little pouch right here, okay. So what you want to do is really assume that the accessory pathway is there, otherwise why does a patient have a diverticulum? So start mapping, and you can map everywhere, but really start your focus here, all right. So this is a diverticulum, and here our ablation catheter and RAO and LAO is kind of diving into that diverticulum and really is going to be on the ventricular side of things. And what you're going to see is that you're going to see a lot more V than A here, all right, especially when you're a little bit more anterior or ventricularized compared to the annulus because you're diving in into that aneurysm, so the diverticulum, okay. And the diverticulum may be more most likely on the ventricular side, all right. It's really going to be a little bit more posterior to you on the atrial side, so they're going to be more ventricularized signals. And here's the signal that we had. In fact, this is probably an accessory pathway potential, very sharp between the A, which is very small, and the V, all right. And this was successfully ablated in this diverticulum. So the point of this is to tell you that anywhere there's A and V close together, atrial myocardium close to ventricular myocardium, there is a potential for an accessory pathway connection. So that's on the annuli, anywhere along the myocardial seas of the CS. In fact, there's going to be some cases where you'll see accessory pathways around the aortic root and rarely around the pulmonic valve. Again, because there's some myocardium there that is in close proximity ventricular myocardium to atrial myocardium. Okay, so let's talk about the posteroceptal space. And really, we're going to look at another case where we mapped basically the CS os, the posteroceptal tricuspid annulus, posteroceptal mitral annulus, posteroceptal mitral annulus, a little bit farther on the mitral annulus side. And here you can see fusion, like I told you, fusion of the A and V together. And if you look at this electrogram, there's decent size A and V here. So this is probably on the atrial side of the annulus. Okay, probably on the atrial side of the annulus. This is a lot more V than A here, and you can tell that by ablation proximal. So this is kind of on the ventricular or apical apex of the annulus. And here you still have A and V. And here you have small A, big V. So I can tell you where you are just by the ratio of the signal. And this is on the apex. This is probably apex or even beyond. And this is the atrial side of the annulus. And this is the atrial side of the annulus. Okay, so think about those things when you're looking at those signals. And here there's a small difference between these two. Both of them, even on the ventricular side, sorry, on the apex of the annulus with more V, it is still pre-delta. Okay. But if you come to the actual true post-receptal mitral annulus, you'll actually see a better timed signal. This is much earlier. I won't say much earlier, but five to ten milliseconds earlier than the signal here compared to the delta. All right. And why is that? Well, you do have to if you go, and again, this is kind of to answer your question as far as retrograde or transeptal, I think transeptal is really the easiest way to get here for the post-receptal side. You really, to get to that anatomy, to get and touch that tissue, you really have to curve your catheter almost around the mitral, like a candy cane, all the way down here. If you just map like this, you'll get this signal and you'll totally miss this area. All right. So again, left-sided avian node ablation, sorry, avian artery ablation, post-receptal mitral annulus, or any kind of PVC coming from the post-receptal area, your catheter should look like this if you're going to fully map the area out. And this was the successful side of ablation. Now, some tips and tricks. Here is a couple of series of patients that we published from our group on the post-receptal side of things and looking at EKGs and trying to understand the exits of the success rate pathway for manifest pre-excitation. And if you look at this compared to your other EKG that I just showed you, yeah, you're going to say, hey, Dr. Dai, you basically told me that this is kind of an MCV pathway, that there's a Q and an R and an S, Q and an R and S. Okay. So, and these are negative three and negative AVF. AVF is not as negative as you expect for a true diverticular pathway, but you need to map everywhere. You can't assume that you go, the first place you go to, you're going to find success. So here, this post-receptal space was mapped extensively. A coronary venogram was performed just in case, but there was no diverticulum, okay, in the coronary sinus. And if you look at this signal here on ablation distal and ablation proximal, AV, this is a big A, even bigger V, so it's probably on the atrial side. And here you have a 25 millisecond early, but it's really failed you. You ablated, you ablated, this did not work. Okay. If you go to the post-receptal mitral annular side, you may find success even though you're not as early. Okay. And here again, where am I? Small A, big V. This is on the apex or even on the ventricular side of the annulus. And this was successful, even though the local V measured carefully was three milliseconds later than the earliest that you found on the post-receptal tricuspid annulus. In post-ablation, this is the signal. So don't be afraid to go across transeptal and map the post-receptal mitral annulus and ablate at a place that's not as early, but it's relatively close and get success there. Okay. Because again, these pathways could have various connections, subendocardial, epicardial, and the post-receptal space, again, you could have a distance of one centimeter between the two and you may be successful here and not successful here. So this was transient effect. This was permanent effect of abolishment of accessory pathway. And again, this is the area you want to go to, transeptal all the way across and curve back on yourself to get to this area. And this ventricular myocardium represents this ventricular septum here, kind of the posterior superior process of what's called the ventricular septum around that area where you get to the apex of the posterior part. Coronary sinus, tricuspid annulus here. So mapping from here to here, this transient success, this permanent success. All right. We got about seven minutes left. I think this should be the last one. This is a poll for this EKG. And this accessory pathway localizes to, I'll give you about 35-40 seconds here, septal parahysion, right infralateral, superior paraceptal, and MCV, epicardial. Ashkan, there's a question about ablating in the diverticulum here. Do you have any recommendations for power settings or precautions? And if you're ablating down there, do you always shoot a venogram maybe even during ablation to make sure you're in the right spot? Venogram or arteriogram or a corneagram? Actually, that's a good question. I think it's a CS venogram was being asked. That's a good point though. Yeah. So I think I'll hit on those points. So one is generally speaking, you're not going to encounter a very deep rooted accessory pathway down there. So you're not going to be using high power. And what we do is even with a non-irrigated, we'll use like 20 watts, 25 watts and go there. Really, it's about timing and mapping the entire diverticulum carefully. My suggestion to you is map as much as you can, but also if you're going to ablate and you're going to think about where to ablate first, ablate more distally in the diverticulum as opposed to more proximally. Because if you ablate to the proximal neck of the diverticulum, if there's some stenosis after you ablate, you may not be able to move your catheter as well. So err on the side of more distal if you find a good spot there. The second issue is we don't do a venogram during the actual ablation, but you should consider doing an angiogram. Remember, you are in the epicardial space. There's a diverticulum and you could be close to a posterior extending artery or you could be close to a branch. We generally don't because we're using very low power settings. So if you're ablating 50 watts in that diverticulum, you're not in the right spot. That's my that's my thought. Okay, good. Fantastic. So this is an accessory pathway that's not perihistion technically. This is superior paraceptal. And why is that? Good. I want you to pay attention. And another key point to take away from this talk, when you look at some of these EKGs, especially for something that has a relatively inferior axis, positive and lead to an aceptal, look at the V1 pattern and look for a small r wave. Okay, small sharp r wave. This indicates pre-excitation that's relatively posterior and anterior initially compared to a true QS wave of a perihistion EKG. All right. So if you see this pattern, think superior paraceptal and think about, yes, I'm going to map this accessory pathway and I could potentially successfully ablate it without even being close to the hiss. All right. And I'll show you why. Okay, good. So this is from our institutions. This is a kind of a review of this anatomy. And I like the color scheme and the images here. So remember, when you're looking at atrial myocardium around the aortic root and the perihistian area, there's obviously atrial myocardium around the mitral valve extending to the left coronary cusps, the non-coronary cusps clearly, right? Because that's straddling the atrial septum. And there's atrial tissue all along here and then going to go across the tricuspid valve. When it comes to ventricular myocardium, look how far back or posterior the ventricular myocardium can extend in the root. All right. And this is a lot of anatomy that's been published that you have myocardial sleeves that extend beyond the junction, the AV junction, sorry, beyond the annular junction of the aortic cusps down into the outflow tracts and the roots. So there's ventricular myocardium all the way back here. All right. And this is posterior. So this is the pulmonic valve, the aortic valve, tricuspid valve, mitral valve. And you're looking at a superior view, kind of a posterior superior view. All right. Now, if you look at these three regions, yeah, between the right and non-cusps is going to be the perihistian area just underneath there. And on the right side, yellow is really perihistian. But these two areas are really periceptal. Right. This is posterior to the his and this may be a little posterior and anterior to the his. Okay. And in LAO view, this is going to look like this. So you have just off the septum, you have an accessory pathway here. Or at the non-corneal cusps, kind of leftward in LAO, which would be posterior and close enough to the fossa, just between the fossa and the non-corneal cusps, you may actually have an accessory pathway connection here. Okay. The most interesting thing though is all of these will result in a his EGM that'll be either on time with delta or the retrograde concealed A or earlier than the delta or the retrograde concealed A at the his. And again, I told you early does not mean earliest. Okay. So when you're mapping, mapping is free, meaning that you can map all you want and really look at that periceptal area without causing any damage because you're not ablating there and really look at what is the earliest signal that you can obtain. Here's a histologic example. We're gonna have to believe at the point between left and right atrial tissue and the non-corneal cusp and some ventricular tissue intermixed. Okay. So there is a potential for a connection between the non-corneal cusp ventricular tissue and atrial myocardium. And we'll talk about that a little bit more. Here's a case again, published. This was probably another fourth or fifth redo of a, what's called a septal accessory pathway to us. But initially the V1 vector was shown here with a small R wave indicating that this was maybe periceptal or superior periceptal. The successful area of ablation was kind of on the behind the non-corneal cusp on the atrial side behind the his. So this is the his catheter. This is my ablation catheter. You know I'm posterior to it. Right. This is the RV catheter in the CS. And in an LAO you see that my ablation catheter is just leftward in LAO toward the left side of the patient of the his indicating that I'm behind the his and basically getting to the fossa without actually going to the fossil valus posteriorly. Right. So this is posterior. And look at the signal here. Even though I don't even think I'm close to ventricular myocardium, you get A and here you get what's a very fractionated signal leading into kind of V signal here. And once you ablate, there is no his, there is no junctional, you eliminate AP, accessory pathway is gone, and you have an AV ratio here. And this is a big V, relatively big V in this posterior septal space, excuse me, the periceptal space. So again, you can have AV connections, non-corneal cusp area. And this has been described actually ablating, this is a paper from Sam Asterbotham and his group, ablating in the non-corneal cusp. And this is pretty much the exact same area just on the aortic side versus the atrial side on the right atrium here. So think about the anatomy, think about the connections, and don't be afraid to map around this area. And you have to focus on your ablation catheter being posterior and leftward of this area. Now when it comes to another area which we talked about that's a little bit off the septum, again, you get that signal here on V1, my ablation catheter in LAO is just rightward of the his, which is here. So I'm far away from the his, about a centimeter or two, and I can ablate successfully and safely. Even though his VEGM is pre-delta, his distal is pre-delta, I have a much earlier signal just two centimeters away, right? And if I am stable there, and I can ablate AV here, it's a small A big V, so it's like on the ventricular side of the apex of the annulus, I'm able to successfully ablate this accessory pathway 30 milliseconds early V, no his, no junctional, no nothing. So you're two centimeters away and you can successfully ablate, even though some people would be scared to even touch this pathway because the his VEGM is early. All right, so we're finishing up. This is the key points, takeaways. Think about the annular anatomy. It's complex and it's non-uniform. Atrial and ventricular mass dictates what the electrophysiologic signals are recorded, right? Large ventricular mass at the apex. The topography may make stability very difficult, especially laterally. And the ventricular myocardium extends as far posteriorly back as the non-chorionic cusps, so you have to know that key point for the septal pathways. And timing, so crucial to accessory pathways, is all relative, always relative. Thank you guys and thank you Nishant, Brad, everybody for hosting this. It was a pleasure to kind of present what we've done in our lab and hopefully this will help you moving forward with your careers. And if you need to send me any correspondence or questions, please feel free. This is my email. I think Nishant's recording the video of this lecture and then you have my Twitter name so you can direct message me if you need. Thank you everybody. All right, thanks. That was great. There are a couple questions on the paraceptal region. Yeah. Do you make any adjustments to the power settings? Ever use cryo rather than RF for those pathways? We've never used cryo. I'll tell you from the standpoint of efficacy, I think there's some recurrences with cryo. We're pretty, as far as RF, if we see junction, it'll come off very quickly. I think you should take the time to ensure stability in these regions, especially when you're kind of two centimeters away. If your catheter is moving and your electrogam is changing, that's not the time to start ablating. And then also in the posterior spade, this is relatively safe. You're behind the tendon of Tadaro. And again, this is quote unquote, the fast pathway exit for the AV node. But you're not really, if you're behind the tendon of Tadaro, you're going to be pretty far away from the AV conduction system in his bundle. So this is relatively safe, but ensure that you're stable and watch your electrogram, watch your recording very carefully for any junctional beats. In this series, there was two true parahysian cases. One case where we did, and there was junctional, you have to recognize it early. So out of I think seven or eight superior paraceptal, there was one area where there was junctional rhythm. So, start your power low. If you're going to use, we do non-irrigated on the right side. We start power like at 20, 25 for these regions and then titrate up. But usually they're going to be fairly superficial here. I don't think you're going to have to go high power. If you find yourself doing high power, you're not in the right area when it comes to these pathways. you're not in the right area when it comes to these pathways
Video Summary
In this lecture, the speaker discusses the importance of understanding the electroanatomy of accessory pathways for successful catheter ablation. They explain that when mapping and ablating accessory pathways, it is crucial to consider appearance, location, and timing. By analyzing these factors, EPs can accurately identify the location of the pathway and target it for ablation. The speaker emphasizes that fusion does not necessarily indicate the best place to ablate and that timing is always relative. They also discuss the complex anatomy of the annulus, including the variability and topography of different regions. The speaker provides examples and case studies of mapping and ablating accessory pathways, highlighting the importance of mapping all areas thoroughly and being willing to change the AV ratio for successful ablation. They also discuss the paraseptal space and how to effectively map and ablate pathways in this region. The speaker concludes by reminding EPs to consider the specific electroanatomic characteristics of each patient's pathway and adjust their approach accordingly.
Keywords
electroanatomy
accessory pathways
catheter ablation
mapping
ablation
appearance
location
timing
fusion
annulus
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