Maybe if the panelists stop talking, I can introduce them. Oh, they did. It actually worked. That was awesome. I think we're going to be joined by Usha Todaro. Hopefully she shows up. We've got Roy John at the end there from Stanford, Emil Dowd coming from Ohio, Ed Gerstenfeld from UCSF, and Eric Prostowski from Eric Prostowski Land. No? That's not what it's called? It's Indiana. Come on, it's Saturday. We have to have fun. So everybody's done the QR code because we do want you guys voting. We do want your input. So we're going to show a tracing like this. We're going to have a question, and then we're going to have the panelists talk before we give an answer. So the point of this is not to get the answers right, even the panelists. The point is to develop the thought process, the sort of intuitive nature of going through these tracings. So our first tracing here, actually this one's mine, Dave. So 31-year-old with narrow complex tachycardia, atrial pacing at 520. And my question is, this EGM shows an atrophicicular pathway, catheter ectopy, dual abnormal physiology, or intrahysian delay. So we'll give you a few more moments with the tracing. That's unfortunate. With narrow complex tachycardia? Really? Did you say narrow complex? Yeah. Is that what you said, narrow complex? No, it's at like 75 speed. She actually does, like her QRS measures out to be 102. No, I mean, during tachycardia. Yes, this is not tachycardia. This is atrial pacing. She has a history of narrow complex tachycardia. Narrow complex? Narrow. Okay. Yes, not wide, but narrow. So here we got the voting, and you lose the tracing during the voting. So you have to remember your answer. Okay. And the spread begins. So no consensus. Let's see what we get from the experts. Okay. Who wants to take that one? Emile, do you want to talk to it? Well, okay. Going... I was left to... Are they seeing the electrograms? There you go. There's the electrograms. Okay. So going from left to right, so you're pacing which looks like the CS, I think. But your atrial pacing, you get an AH that looks normal. HV looks normal. And then as you do progressive atrial pacing, one, two, three, four. On the fourth beat, the AH begins to shorten. And on the fifth beat, the H even shortens further. The interesting thing is that the right ventricular EGM on that fifth beat is almost simultaneous with the HISS. I was dropping a line with a piece of paper. And that's right. And I think... I mean, I think it's more consistent with the atrial fascicular, but usually I'd like to see some reversal of the HISS electrogram polarity. And then the next beat afterwards when the AH gets longer, I think you're obviously... You're having probably some competitive conduction down the AV node versus an atrial fascicular. The curiosity is that you said it's a narrow complex tachycardia. So that kind of makes me a little bit worried because usually it's a wider QRS. But I think it's an... There's presence of an atrial fascicular. I don't know if the tachycardia was... That pathway was participating in the tachycardia. And it looks like the antegrade conduction is a little bit wimpy compared to the AV node because on the next beat you get a long AH, which would imply to me that... And the HISS potential on the HISS distal doesn't change like it did in the beat before. So it implies to me that that's primarily antegrade conduction down the AV node. And then the other, the beat before it, which is maybe a fusion or accessory pathway with a retrograde conduction activating the HISS. Can I add one thing to that, please? Of course. We know you will. Well, the other thing... I agree with everything you said. The history of a narrow complex tachycardia also threw me off. But can we... No, don't go... So go back out because the key... You have to look at the RV apex electrogram. That also comes in very early. So if that comes in, it means you're reaching it earlier. So either it's ectopy and she's fooling us or it's real. And if it's real, then there has to be a bypass of the normal system to get there. And that's also consistent with your atrial fascicular diagnosis. So wait, when you said the RV was earlier, you mean relative to the HISS? Yeah. If you made sure the stimulus to the RV electrogram, you can see how it comes in. I was looking at the HISS RV electrogram. No. Well, I look at where the pathway ends. You look at where it begins. Okay. The HISS activation though. So what I'm saying is it's consistent with everything you've said because when atrial fascicular is activated, it gets to the distal right bundle earlier. And typically the right ventricular apex area is coincidental almost with the start of the QRS. So that is consistent with everything you've said. But I'm with you though. She said this patient has a narrow complex tachycardia. So I think this observation is, I agree with you. It may not be the cause of tachycardia. It's a little wimpy, don't you think? In terms of the pathway integrate property. And do you usually see that intermittent pre-excitation with an atrial fascicular? And don't you see the AH widening before the development of pre-excitation? Yeah. That's the other thing that doesn't make a bit of sense. And so the other thing that worried me, that's why I thought you were just playing with us here, Melissa, because the other thing makes no sense. Why would I do that? No, the consistent thing is you don't see the pathway come out because it's slow conducting until the HISS gets long enough. So that worried me. And if this was just like a routine session back home, I wouldn't look for some weirdo thing. I mean, especially it's just one beat. Okay. So we're arguing. Well, there's two beats. The H progressively shortens. So this was a repetitive finding that I had over many, many respiratory cycles. And I got very confused at first. I was, oh, you know, I have this booked as a very simple case. What's going on? And then I moved the HISS catheter and it went away. So it really just was catheter ectopy. But I think sometimes you have to put all the data together and pointing out the RV apical catheter timing is really important. It's easy to sort of see those patterns and make it fit when it's not quite there. How does the RV come in earlier? I think I put the RV fairly basal. No, but the HISS RV. Well, if she put the RV basal and the catheter moved, that could explain that. I thought it was apex. But the QRS morphology is identical throughout. Now, the key thing is it's your tracing. So you get the final say. I'm just telling you, I moved the catheter and it went away. So it's artifact. Yeah, exactly. No, it's artifact. Yeah. Boo. That's okay. I think that's fair. I think artifact's really important because we do spend time looking at it. And mapping systems don't know the difference between artifacts super well either, even though some artifactual signals should, by their very intrinsic deflections and by the fractionation, be not picked up. So we see it when we're mapping outflow tract tachycardias. This is a pulmonic valve closure artifact that's been published and we see that a lot. So it is important to go after that. Did they have an aero-complex tachycardia? She did, yeah. She had AVNRT. AVNRT, okay. Fair enough. Yeah, that's you. Thank you. Okay, let's do this with the ARS to start. This is a wide-complex tachycardia and there's information given on the slide that I think could direct you to the most likely diagnosis as listed. Please vote. Got it, I'm sorry. I like this physical separation, it keeps us away from these guys. Okay, so the crowd's favorite is AVRT. How about Roy, do you want to look through this? Yeah, sure, give it a try. So you have a, I guess it's a wide complex tachycardia on the left side. Atrial and ventricular cycle lengths are the same to start with. And then you have what looks like 1, 2, 3, 4. The fifth beat is different because you have possibly a right ventricular PVC, maybe? Actually, it's left ventricular PVC, right? There is a PVC of some sort. Spontaneous PVC, yes. And it's kind of pre-excited the atrial activation. It's pretty late. So late PVC bringing in or... Yeah, I guess the late PVC bringing in the atrial beat kind of argues towards an accessory pathway of some sort. Anybody else? Any contributions? I think I would appreciate a commentary, and again, it's labeled, so therefore inherently important. You know, the 350 or 348 in red is describing a phenomenon that makes this diagnosis unassailable. Unassailable? I think there are two choices. So it's not AT and it's not AVRT. I'm okay with that. You don't have a hiss catheter in there, so it's macro. Presently. Well, it's macro. It's macro, okay? So could it be bundle branch reentry? Yeah. Could it be AVRT? Yeah. Why can't it be AVRT? I mean, you've got a right bundle branch block tachycardia. I mean, I think it's macro. You only know if you prove macro. Left bundle branch. Right? Right. It's a left bundle. That red thing, it's exact capture phenomenon. It's what? Exact capture phenomenon. All right. If you like that term, yeah. How would you improve upon it? Well, I was just talking. I mean, people use terms that others don't always use. Exact capture phenomenon. Do you mean the PV? So it falls in the hiss? In other words, it falls where a hiss would be anticipated. You don't think so? No, no. The prematurity index matches. The prematurity on that. Yeah. Well, I wrote that paper, so I understand it. I wrote that paper, and we called it the prematurity index. We never said exact capture phenomenon. So, yeah, I'm familiar with the paper. No, but it means something different, though. It means you're in a circuit. It means you're in the circuit. Right. Okay, but if you have a separate accessory pathway, you could also be in the circuit. You could still be in the circuit. That's my only point. Or bundle branch reentry. Or bundle branch reentry. Yes. That's all I'm saying. It would be a little bit weird. Then I'll call it bundle. I know you want to go. I'll give you bundle branch reentry. I'm sorry? Bundle branch reentry. He'll give you it back. No, I think it's either one. I've already told you that. So, it's a PVC, right? Spontaneous PVC, I presume. Right. And it comes in. It's a little hard, but it looks like it comes in. It's a PVC, right? It's a PVC. It comes in, well, it comes in 50 milliseconds ahead of the next beat, which the next tachycardia beat. It's a fusion beat. It looks, yeah. It's a fusion. So, you know, you're, you've captured it. Yes, yes. So, the next day is pulled in. The question is whether, I don't know, is there enough information to exclude bundle branch for entry? I think you've, I think you've excluded an AT. Have we excluded? Yeah, I think you've excluded the other two. No question. An AVNRT you've excluded, at least, yeah. This is one of these classic gutture slides. Like, you know, it could be either one. I don't think it can. I think the relationship to the atrium is against bundle branch for entry. Why? Just because you don't usually get one-to-one VA in bundle branch for entry? I'd give you that. That's true. And I'll also give you it's too slow. It's pretty slow, though. I'll give you all that. It's also slow. If I had to be forced to pick the two, I would have gone with AVRT. But what I'm saying is, I didn't know you could rule out bundle branch for entry. If you're requiring that premature beat to go through the AV node via bundle branch for entry mechanism, you're going to expect some decrement, right? Like, it's premature to something. It's premature by 50 milliseconds. So I think it would be unusual. But you're assuming the retrograde, let's see how PPC goes. Yeah, I think that's fair. Okay. This makes that point, I think, a little bit more, it was hiding from you, exact capture phenomenon. No, no, I'm, I can't see that at all. So just, just the fact that, that, that PVC is, is synchronous. Well, you sort of knew that with the fusion beat, right? It's hard to tell if it's a fusion beat, I think. Really? Well, cause it's a spontaneous PVC. Oh, anyway, if you put a PVC in there, spontaneous or not, you think you'd get a narrow QRS with a wide, you don't start with a wide mark. Josephson should have taught you that. You don't start with a wide and then suddenly get a narrow and not think something's fusing. He taught me everything I know, just not everything he knew. That sounds like a rehearsed line. That's a classic. I like it. I think it's a fusion beat. I'll just go online and say, well, now it's a fusion beat. It was a fusion beat before, but anyway, okay. Or either way, if you, unless the HV is super long, it's asynchronous. And so you're bringing in the A's point that there's a pathway there, presumably, right. And you're saying, because it's exactly on time that tells you it's part of the circuit, right? Yeah. And so the HV really isn't part of the circuit in Boundary Venture Entry. So it could be a coincidence, but it's unlikely, I thought. Yeah. So, uh, no, if you're doing test smart, which is important, right? When you're thinking about it, you're right. First of all, this is fairly slow for Boundary Venture Entry. Number one, number two is a one-to-one VA. All those things are in your favor, but I was just looking at it like, you know, Melissa said the ground rules were supposed to be a thought process today. So I'm thinking to myself, it's macro. And then what are your macro choices? And yeah, of course I would have gone to ABRT, but I just wanted to say, if I'm thinking this through, I would have just thought of those as a potential mechanism. That's all I'm saying. And does it reset the next V? I guess that would be more convincing to me if, if the next V after that premature A is, is reset to the tachycardia. I can't measure with my fingers. Yeah. Eric's got his calipers. It does. It resets. You're right. Okay. So if it both advances the A and resets the V, then it's, it's more strong, more strongly part of the circuit. Yeah. Perfect. Let's move forever onward. This is, uh, Ed's case. Ed, do you want the clicker? So I'll start. 65 year old with recurrent ICD shocks for wide complex tachycardia. Unsuccessful ablation times three. And we're doing ventricular overdrive pacing from the RV apex during the wide complex tachycardia. And Ed's got us comparing to what RV pacing would look like in sinus rhythm. All right. Wait, what are we doing? Just think Dave taught me everything I know, but not everything he knows. So it's just dissipating. Not everything that I forgot already. Down the generations. I'll give you the background is that he had three ablations, all targeting the anterolateral papillary muscle, including an endoepi, the last one that was at a reasonable outside place. You had to get the outside place in there. Yeah, of course. Not us. Did you guys see those choices quick enough? Ed, can you go back? Back, back, back, back. And I hope that, so go back. I don't know if we can. So there are the one forward. So there are the choices. Is this SVT with a Barentsy? Is this pre-excited tachycardia, a myocardial VT or bundle branch reentry VT. And when we think they've looked at it long enough, then you'll go forward and get the body. So let's see if we can go forward and vote. Hopefully we didn't kill the ARS. Right. So most people think it's bundle entry entry. And then we have that second slide there. That's your aortic overdrive pacing hurts our atrial drive pacing those weird which is a great example to make my point from the last case Eric. I'm sorry what you were talking about. No I think so this is it's not a it's not ventricular stimulation but look at look at the atrial overdrive pacing in Bonneville entry. So we're showing the same tachycardia, but now in training from the A, and the same answers. And then to help the audience who hasn't looked at these tracings before, like we have, Ed's given us that measurement there, 320, and then taken that same measurement forward in the tachycardia. About the same. D1. A little more D. D1 a little higher. Yeah. Barely. Who wants to take it? Thank you. You want to walk us through it, Ed? Yeah, I'll walk everyone through this. So yeah, I thought this was interesting because, again, often we go right to entrainment from where we think the tachycardia is coming from, and I think pacing from distal sites gives you a lot of information in this slide. So if you look at the morphology of the Y-complex tachycardia to the right, right, it's a right bundle inferior axis, very negative in one, some transition. So it's coming, you know, the exit at least is more of the anterolateral LV. With overdrive pacing, there is fusion, right? I don't know if we have the, I don't know if we have some boxes, but there is fusion and the pacing stimulus, you know, the QRS is too soon. It's already starting to depolarize right after that stimulus. So it's not capturing the immediate QRS, but the next one, and the post-pacing interval from the RV is in, and if you look at the degree of fusion, there's fusion, but not as much as, I mean, if you have a circuit in the anterolateral LV, you're pacing from the RV, and I'm showing you to the right what RV apical pacing looks like, you'd expect, you know, you'd have to capture the entire RV and LV before getting to that site. You'd expect a lot more of a RV pace morphology than a right bundle LV pace morphology. So I think we tend to think of concealed versus manifest fusion often as dichotomous. Is it concealed or is it manifest? But the degree of fusion also gives you a lot of information. So there's not much fusion so that you're near the circuit. Your stimulus is capturing the next beat over, so it tells you this has to be reentrant, right? Because you have, you wouldn't expect an automatic or triggered rhythm to act that way. You've got fixed fusion, and the post-pacing interval from the RV apex, you're pacing from the RV is in. So you've got clearly a macro-reentrant circuit. You're in the circuit essentially what you'd call an outer loop because you have some fusion, but pretty close to the circuit. And so I think of those possibilities, the most likely thing you would think about here is that you actually have reverse bundle branch reentry. It's coming down the left anterior fascicle, and somehow you have to be also in from the RV apex, right? So to be both in with a minimum amount of fusion, you've got to be near the circuit in an outer loop, and that this strongly suggests that actually reverse bundle branch reentry rather than, you know, they were mapping, I think, the exit from the anterolateral fascicle, but this was actually clearly involving the RV as well. So just showing you how much information you can get from pacing from a distant site. I don't know if anyone else wants to add. I have a question for Ed. Is the next page in here, that's the same patient that you're atrial pacing? Correct. So how often do you get into a bundle branch reentry? Did you do something like a vatropine or, I mean, this is really unusual, right? Yeah. I mean. You get into the circuit from the atrium? So you can. I mean, I think that's the point also that you're pacing from the atrium and you don't always get in, but if you can get in and the morphology is exactly the same as the white complex tachycardia, that also would argue that it's something engaging the conduction system and not a separate, you know, myocardial VT. So in this case, even though during tachycardia we had a two-to-one or we had, we didn't have one-to-one VA conduction, we were able to get in just pacing. I can't remember if we gave a little bit of isopryl. I don't think so because. Well, I'm a little confused. I want you to help me on this because yes, I know, I mean, well, I was just going to say. This isn't the. Oh, this is. This isn't the HISS. So. Oh, yeah. That's not a HISS? Well, it's. I was going to say it's in diastole. Yeah, but it's actually from the, if you went back to the original tracing, you don't clearly see the HISS because it's retrograde. So what we did, I'll go to the next one. And this is. Left side of HISS. Yeah. So let me go forward. So we actually put a catheter transeptally on the left anterior fascicle. And that's, now you see the fascicular potentials exceeding the QRS. So this was the same as this tracing, which is the duo catheter. So it's actually an anterior fascicular potential in that case, not the HISS. So here's the question. Yeah. That clears that part up. The other thing, though, that I normally, if you're pacing the A, you can engage the entire system. To have the same QRS. I mean, yes, you're going to go down the fascicle, but you're also going to go down the other. You don't have a circuit that's competing. Right. So why wouldn't you expect some difference in the QRS morphology? But you're pacing during tachycardia, right? Yeah. You're pacing during tachycardia. So you're going. Oh, you're captured during tachycardia. You're capturing during tachycardia. All right. You just pushed it ahead. And you've got it concealed. All right. So did they have left posterior hemiblock in sinus, or no? They did not in sinus, but they had sort of a functional at rapid rates posterior hemiblock as well. You're right. Is that, I mean, you would recognize it a lot easier if it were just intact left bundle conduction, even though a reverse boundary entry doesn't come up every day. Yeah. And what then we also did was, you know, I tried to map the right bundle to sort of work out the whole circuit. But as we were actually using a grid, and we bumped it and created right bundle branch block, and then the tachycardia was no longer inducible. So that gave us the answer as well. Basically, it took two lesions on the right bundle. And this guy, after all his ablations, was awful. What were the answers from the audience? Since you wanted to make this a teaching session. Bundle branch, we can't go back to that. Bundle branch was like 65%. Okay. Yeah. And the others were smattering. Okay. So again, I think just so much information you get just from entrainment. And this was something coming down the anterior fascicle, up the right bundle. So the fact that you're in, we didn't expect to be in from the RV apex, but you're in the circuit and such a minimal amount of fusion when you're pacing from so far away from where you expect the circuit tells you that you have to be close. So when you pace the atrial overdrive pacing during tachycardia, that's pretty compelling. That's using, like you said, the HISC conduction. Did you see any, was there like, I guess in this example, we talked about HH preceding VV changes in bundle branch rente. Did you see that with the, maybe that's something we can just out of curiosity. Some wobble or something. Yeah. I think there was, it wasn't completely convincing, but yeah, with the fascicular potentials, I think you might expect FF to precede VV, which we did see. We also tried to, you know, entrain from that fascicle and show that was in as well, but whenever we paced it would often terminate. So it was hard to prove that. But yeah, again, on, you know, it's uncommon. I can't say how many times I've seen, usually I've seen it once other time after aortic valve surgery when the right bundle's injured, but I haven't seen reverse bundle branch reentry, but it just shows you again, you know, the other maps people had described, we had 10,000 points. We saw early breakout near the anterior papillary muscle, but it's missing the fact that it's a macrogenital rhythm that you get with entrainment. One last question. We've been joined by Usha Tadrow. Thank you for that. Hi, sorry. No, no problem. Have you seen myocardial base VT be entrainable from the A? So I know conceptually that it could be, but I always feel like that's diagnostic. Yeah. I feel like also, especially if you're pacing in the A, like from the right atrial appendage, I feel like gets you right into that kind of conduction system area. That seems to be, whereas it would be much harder to get into a scar, even a basal septal scar. I think it would be hard to get in. Yeah. Good. Thank you, Ed. That was great. That was a great case. Moving on. So this, I guess, is breaking down. I'm not sure if you can see this. speaking the rules of the session, I apologize. It's a great case from my partner, Ram Kumar Swaran. And this just came up when he was reading an EKG Sunday. So I want to direct, this is something I learned from George Klein, I think, first. Looking at unknowns from, there's often a left side of the tracing, then a middle where something happens, and then a right side of the tracing. And I think it's really important in trying to decipher that, to follow that George Klein's rule. So, Y-complex tachycardia, which of the following is present? A, an accessory pathway, B, pacemaker malfunction, C, reentrant ventricular arrhythmia, or D, automatic ventricular arrhythmia. Give you a couple more seconds to look at that, and then we'll vote. Okay. The people have voted. I'm looking for a volunteer from our illustrious panel. You looked up, Amelia. You should never look up. Let's pick on Rory. Usha is new to the crowd. Yeah. I can give it a try. Okay. Do you want to give it a shot, Amelia? No, no. That's all right. I'm trying to... You want to see? Well, it's not a pathway. I don't think it's a pathway. Not a pathway. Yeah. So the observation is we have at the beginning of the tracing, if we just sort of look at lead two going across the long rhythm strip, we see atrial pacing and we see a wide complex ventricular activation that goes after that, that doesn't appear to have any kind of pacing stimulus in front of the ventricular activation. Then maybe the fifth from last beat is where something happens. There's a PVC or some kind of early wide complex beat at a similar timing to the atrial pacing. And then subsequent to that, the last four beats have only ventricular pacing. And I don't see any evidence of atrial pacing either. So the question is, you know, what could be happening there? There is like... Right, there is no pacing on the other beats, right? There is a pacing artifact. There's a pacing artifact, but there's for the ventricular, the wider complex beats at the beginning of the tracing. Is there any pacing stimulus at the beginning? No. I don't see any. What would you say if I told you... Oh, yeah. Go ahead. That there are only atrial pacing spikes throughout the whole tracing. Yeah, that's what we think. Yeah, that's what I... Oh, that there are only atrial pacing spikes? Yeah. And it's consistent to the whole tracing. If you... Here, you don't have a measurement stick. That's the problem. I probably should have given some measurements. They're consistent to the tracing now. You're saying that the last four beats are atrial pacing as well? Yeah, it's consistent. Well, what we can... You can see that, not in two, but what's that lower lead? You can actually see that it is capturing the atrium, but it is definitely atrial stimuli. And it's consistent. You can't... I have a... I have a caliper. Let me see. It's the same going through. Yeah, so there's spikes, atrial pacing, and then something changes in the middle, and now you've got a dissociation of what's going on. Usually, when you have AV dissociation, you usually have VT. Because after the PVC, obviously, it gets... The QRS changes, right? Yeah, so the thing we were... I was arguing, not arguing, we were discussing, do I want to make it re-entrant or automatic? And I know you have a PVC in there, so you want me to go re-entrant. I mean, it's not pacemaker... I don't think it's pacemaker malfunction, unless you're going to argue that the atrium should have seen what was going on. I don't know. And it's only a short strip, so I don't know what happened five beats later. But the PVC changes the timing, right? Like you were saying, the atrial pacing versus the ventricle, but it also changes the morphology, so does that not help you? That makes it seem like it has to be re-entrant. Yeah, I mean, I think it's VT. There was actually an atrial spike in here, by the way. You could measure it, Eric. You're in a special... Yeah, no, I did measure it. The stimuli is straight through. The QRS comes early, or not? The QRS comes early, yeah. Yeah, so clearly it's that. I don't think it's paced. And there actually isn't. In V4, if you look, unless it's just on the line, is that what that is? That's not a pacing spike? I don't know. That's probably on the... No, where it looks like AB, those are just the change of leads. Okay. So you have a PVC that comes early. You have a continual pacings going along. It measures consistent throughout. So that's the atrial pacing. It seems like you capture the P wave on one of these, and you have a dissociation. So I don't think it's apparent. I think it's VT. If you're convinced it's atrial pacing, you can make yourself say that on V4, you have P waves. Yeah. Yep. So... Yeah, that's what I think. It's also an unusual... I mean, the paced conducted morphology, it's unusual, this positive. Do you think it's pre-excited? So to ask it a different way, what is atrial pacing doing to the rhythm? The ventricular rhythm is constant through the tracing, except for the PVC. So what would you call that? What would I call what, sorry? What would you call what atrial pacing is doing to the ventricular rhythm? Pseudo pre-excitation. Are you thinking it's resetting it? It's entraining it. Yeah. Well, yeah, okay, yeah. Fusing it. It's fused though. Yeah, so... So the beat after the PVC, is that the same as the rest of them? I guess it is. There's a P wave. There's a fusion beat. So there's the PVC, and then the next beat after, there's a little bit of fusion there. Is not fused. It's only fused by the presence of the atrial stimulated. But that QRS and the next one are different. It's a little bit of a fake out, because in V3, your eye sees it as different, but if you look at the three rhythm strips, you've got tachycardia, and then, well, it's not that tacky, but rhythm, and then a PVC, and then another morphology. So only the single... PVC, after the PVC, you think that QRS is identical to the rest? We do, with the addition of the P wave in there somewhere. Yeah, I... So there's a lot going on. Let's unpack some of this. I don't think so. So this is that rhythm after the PVC, and you can see, again, Eric's demonstration that there is AV dissociation throughout this tracing with atrial pacing, and the ventricular arrhythmia being a little bit slower than that. So why complex tachycardia? There are P waves, but they kind of float in and out with the atrial stimulation. Morphology is not consistent with Bonobranch block. That's pretty clear. This is the original tracing again. We have A pacing with one-to-one AV conduction, and fusion, the PVC dissociates the A from the V. You can see the A if you look carefully, and again, the V is slower than the A. The PVC resets the tachycardia. So the fusion with atrial pacing and the reset of the tachycardia and the AV dissociation, like Eric pointed out, makes this re-entrant ventricular tachycardia. Really slow and really unusual. Yeah, it's a weird case. With an AAI pacer? Like, could it be any other mode? It's just strange. Oh, I think it was a DDD pacemaker, but it was faked out enough. Or MVP or something. Yeah. Ventricular-based timing was perfectly within the realm of, you know, it's like 100 beats per minute. Yeah. So why, this is a very slow VT, so what was going on, the patient on a bunch of drugs or just, this is a pretty slow VT. Oh, I think he's still in it. I read this ECG and it said- Come on, at 10, you're not gonna leave this guy. How many ablations? He's gonna be ablated for a time. How many ablations can he have? He'll be ablated before he wakes up. He's gonna wake up in the lab and say, where am I? Being ablated. Oh, yeah, you do have that. That's a very, it's a really nice ECG. Isn't it great? Yeah, it's really cool. It's kind of a band cure. Is this post-ablation? Why do you have to be a hater? No. Next. Okay, so next case. Which of the following is shown on this tracing? We're gonna have a couple of tracings from the same patient. Is this a septal pathway, a right atrial lateral pathway, a dual abnodal physiology, or VA block at the level of the hiss? We get some voting, and then we'll go back to the tracing. With the state, you know, file. We get five votes. You know what's good? It's a good session when the votes are, like, odd numbers, and it's not just 25% for one. It means that more than three people are voting, which is really exciting. What else is good? I love the conversation among the panelists. So there is a process to this, and it's not necessarily an individual one. Yes. This EP is not a solo sport. A solo sport? All right. Want me to do it? Yeah, you want to do it? Sure, I don't mind. There's more to it, so I have to be careful not to put my foot too much into it. But I'll just go beat by beat. So if you look at the first one, it's not sinus. I mean, if you look at the, I don't know, before that, but I would have said this is, unless it's just fortuitous, I would have said it's retrograde conduction. And then the next one looks like there's a V with no conduction retrograde, A coming down with a long AH, and then a pause. So it looks like concealed conduction, probably into the AB node. The question is then, this is always the question, have you jumped onto a slow pathway, or is this very slow conduction over a fast pathway? That's always the issue in the lab. The antegrade conduction of that second. Right, of the second beat. And the only way to really answer that is do a complete study, because you can't have it either way. So I don't know. So the reason I say that is because, can I say it's dual node? I don't know. From this observation, I would probably say possible. But don't you think the antegrade conduction in the AH is prolonged because you've concealed retrograde? I know, but you can conceal retrograde into the fast and jump onto the slow. Or you can conceal into the fast and be slow onto the fast. It's just decrement. There's no way to know. You don't know. But I think it's, it's. I just don't know. You have to have retrograde block in the fast, then, and penetration to the slow. No, you could have retrograde penetration into the fast with subsequent prolongation of conduction over the fast. The next antegrade. Yeah, you could. I just don't know what to do. I've seen them both ways in the lab. If she's going to give us one or two more slides, we can figure it out. Well, but again, we're playing the eight boards game. So D, we know, is wrong, right? Because you've gotten to the node to conceal to the node. So it's not VA blocking the HISS. So is there evidence of a septal or lateral pathway? I don't think so. I think that's, they're trying to throw distractors in because that high-low activation is really sinus. And they're trying to make you think there's a right lateral pathway. So I would probably say the answer is going to be C, just because it's the most reasonable of the possible options playing the game. But I don't know. I don't see any evidence of a lateral or septal pathway, clearly, from here. So I would. Well, the HV is normal. HV is normal, so it's not right lateral. It could be concealed. You don't have an answer for right lateral. It could be concealed, but you wouldn't. You mean to say that you're, I guess what you're saying is that in the second beat, you're actually going over slowly conducting right-sided accessory pathway. Well, who knows? I mean, you'd have to tell me where that catheter is. The H goes long. You wouldn't. Well, and then it's longer on the subsequent beat. You could still argue, well, here's where you could take one diagnosis or two. So now you'd have to say you're going retrograde over a slowly conducting right-sided accessory pathway, and you have dual AV nodes. Well, plus the activation is the same as sinus, so. I didn't say I agreed with it. I'm just saying, if they're playing with us, they can play with us. I would have gone with everything you said. I think it's what it is. It's actually just artifact. No, it's not artifact. It's not. Not artifact. It's not. All right, show us more. You said you got more. I just wanted to put this in because I really wanted to entertain Dave Callens. So this is a case from my fellowship. This is a case from 2009 where I would spend the time to make these cool ladder diagrams, which in this case shows ventricular extra stimulus, so ventricular pacing. We got our last S1 there, and it looks like it's going up one of the AV nodal pathways, most likely the fast pathway. I don't know that you can prove it one way or the other. And then we block in both pathways. But what we've retrograde concealed into the AV node, which is evidenced by that next sinus beat like you guys all just said. And we switch from slow pathway back to fast pathway. So did you have? No, I mean, those are the two choices. Did you actually have data to say it was a slow later in the study? Say it again, sir. Did you actually? That by itself doesn't make it as slow. So did you have other data? Correct, no, exactly. That's why I said you can't know for sure. OK, that's fair. That isn't the way we've defined it. But as you know, part of the game in the boards is exclude sometimes the other ones. That's the only reasonable answer, right, of the options that you have. I think mentioning the boards over and over again degrades the very holy process that's going on here in this exercise. Sorry. A more board-appropriate question. There, I just said it. Because you're right, it shouldn't have said this shows. It should have said most likely this shows. But here we are. The most likely diagnosis, same patient. Now we've initiated a tachycardia. So we've got. Sorry? Same patient? Same patient. You've gotten this reputation for being tricky. Same patient? It's not fair. That's not fair. So we've got atrial overdrive, or sorry, atrial straight pacing there. And we've induced a tachycardia. So we've got atrial tachycardia, AVNRT, AVRT, and junctional tachycardia as our choices. It's a very quiet, very large room. I'd also say those of you are putting questions in what you are trying to get to them And we're all happy to stay afterwards to answer questions. So we've got the audience down avn RT So it's our job to prove or disprove it Didn't say that I any of you Roy Yes, so you have atrial pacing atrial exostimulation Exostimulation an age interval and an a on V tachycardia which continues a narrow complex tachycardia no different from sinus rhythm and The a on V tachycardia makes it likely to be either avn RT or a junctional tachycardia Atrial tachycardia is not excluded. And then of course you have the classical block two-to-one block with a P wave falling exactly between the two QRS complexes always makes you wonder if this is avn RT with two-to-one block and So I think that's that's pretty much what it is avn RT with two-to-one block Induced by Usually it's by a long short interval Although I don't see much of a long short here Meaning that the two-to-one block is induced by that long to short Yeah, it's usually induced by you know, the onset of tachycardia you typically induce a long short and that produces the block There's one more thing I guess there is a bit of a long short, right? Yeah, I think there is a long short Yeah, there's one more thing. You only get one more thing then That's I totally agree with diagnosis, but it has another Peculiarity it also has cycle length alternans But you don't usually see in a situation like this most cycle length alternans occurs with a VRT But if you measure it carefully, you'll see the AA intervals or you know, at least how the short strip we have They are measuring, you know, the long the short the long the short so it's obviously a little more complicated I totally agree with the diagnosis that he said I think you know, it's avn RT But I would have added with cycle length alternate and does anyone want to comment on where the block is in the two-to-one? Well, there's no good history you can't say it's not a great hiss I'll concede that why isn't this junctional tachycardia? Do we just not see this with junctional? Well, there's wobble and it follows. That's what I was saying. There's wobble in the circuit Yeah, so you're right. I Played this game with me write that down No I'm Mark Joseph's and I discussed this guy knows how many times because it's really really really hard to say how you know It's not coming from the very proximal part of the hiss versus I mean and you really can't I'm a remark I'm having a long discussion not an argument just to figure it out How can we figure this out in the lab and neither one of us could come up with a way to actually nail that down? Except for the fact if you ablate around the ox you get a success All the time if the HV is shorter in the tachycardia that makes it junctional If you get something like that, yeah, I didn't I couldn't really measure. Yes. I totally agree Yeah, if there's a change in HV sure So the tachycardia continued and then we see this observation. So it goes one-to-one. So the first QRS With one-to-one conduction is narrow Why so we've got phase three block in the left bundle phase four block In the left bundle or the same choices in the right. So we're talking about the third QRS on the strip there Sorry, we don't have a laser pointer No lasers for us, yeah, can't be trusted. No And David you see And even numbers which makes me think there's only ten people who voted in this giant room, but anyway Anybody want to take it I Can take a yeah stab at it, but we have so you have the two-to-one going to one-to-one On the right you have the two beats with a right bundle branch block pattern and then you have as you mentioned this one Narrow beat, but I think the the HV before the narrow beat is longer than the HV of the narrow beat before that So to me it suggests you're getting Delay and that it's narrow because you have equal delay. We've already got a right bundle So you have delay you causing delay in the left bundle and it's early so it's phase three block in the left bundle branch a Is what I would gather Make sense So So what's really unusual about this right because I've studied this phenomenon over the years Classically the first beat is a barren right because it's a long short. That's why I thought it was weird Yeah, no, I mean just so it's a teaching session. Yeah, so classically you'd see it in the first one So then you have to explain why you see it in the second one and not the first one Because if it's not if it's not the longest and shortest then it's the shortest right then so that makes it attack We would have said an acceleration dependent bundle branch block Versus throwing out some funny phase four three, but it's the same thing No Just for people who have not seen this the typical thing and it's usually a left bundle about 70% of the time After the long short usually the first beat One to one is you know, because that that encompasses a long short interval tends to be a bundle, right? There's a lot of face So cute. It's so can I ask you something when you paste this patient and incrementally paste? Did you get a right bundle? We didn't it was only when there was this two-to-one stuff back and forth I believe this was a case that I did as a fellow in 2009 Yeah, that's interesting because I would have thought it was an acceleration dependent phenomenon. So that's interesting, right? Okay, but the HV being longer is what argues that there's delay. Yeah, I'm sorry. This was a slide we showed last year So I just included it to discuss the various mechanisms of aberration. This is a slide from Dave Callens here. So Eric didn't complain about this last year. He didn't and he's not listening. So we're gonna They were asking me something. I'm sorry start again. I apologize So you started helping him pick out a hiss the poor guy can't I'm sorry I can't see so that there are more mechanisms of aberration than phase three and phase four block which is a great invasion Acceleration dependent phase three phase four. Yes Okay, I think let's try to do let's try to go through this one quickly So Again there is ventricular pacing to start then a wide beat and a narrow beat Couple more seconds to look So is this patient Based on the phenomenon in the short tracing What arrhythmia are you expecting orthodromic SVT using a left lateral pathway AV node your entry both A&B Bundle branch reentry, which has made its way into every case and multiple bypass tractor entry Oh Yeah, I forgot sorry Usually by the end of the hour I get a little bit more what the pattern is supposed to be like, it's fine Okay. Very interesting. Very interesting. Who is up to explaining this? Can I go back? Oh, yeah. Sorry. Yeah. Did you already vote? Experts. Yeah, we're all voted. Okay. So you're pacing 600 with a coupling interval of 280. So it gets long and then a very short. And then you have, I think the next beat after the pace beat is a bundle branch reentrant beat. Could you point out as to why? It's absolutely right. But could you point out why you think that? I don't know. I didn't hear what you said, David. Oh, can you point out to the audience why you think that? It's absolutely true. I mean, there's a clear jump in the VH, right? The VH is short on the first beat and then it jumps out. So that's block retrograde in the right bundle, it's coming around and up the left. And then the conducted QRS is the same morphology as the one before. So that tells you you're blocking in the right, going around the left and coming around. Perfect. So the HV is the thing that I think that really defines that. Good. And then the retrograde beat with that bundle branch is eccentric. I think it's what CS distal looks earliest. So that makes you think that there's an accessory pathway present, not necessarily participating. And then there's also the AH probably is delayed because of the penetration from the bundle branch reentrant beat. That's why you have a long AH and normal, looks like a normal HV comes down. And then the next P wave, I don't think that's another accessory pathway. I think that's native conduction. That's one I'm not 100% sure. Both are distal proximal, right? No, no. There's a reversal of activation because the distal isn't. But the last one on the right. Yeah, the last one on the right. There's reversal. There's early to, I'm sorry, there's early to late on the distal CS. Eric's upset he's not talking. And then there's, but there's reversal on that last beat. Okay. So gentlemen, slow down. So first paced beat, I'm totally with you guys, a hundred percent. Then you have a bundle branch reentry beat, but note the retrograde atrial activation sequence that can't be coming up anything but an accessory pathway because we agree, right? You don't have calibers. If you measure the V to that A, it's from the bundle branch reentry beat to the distal CS. Yes. And then go measure the left bundle to that interval. This is just essentially the same consistent with the fact that you're in, you're in a loop. Right. Okay. So that, that for me takes care of that beat. I mean, that's what I would say. That's kind of what you were saying. But the age. And so you agree that the age is long next beat because bundle branch reentry. This age is long because it comes back up and activates the AV. Well, no, that's one way to look at it. The other way is it's really the AA interval. If you actually look at it another way, the AV node sees a shorter AA interval. I think that's the way to understand it. Yes. Right. So that blooms out the AH. And now when the AH moves out, you have a change in retrograde activation sequence and now it's septal. So now you have this, but it matches the actual activation sequence of the first pacing, which would then be consistent with you having a left, left free wall and a probable septal accessory. I would go with two pathways. How do you tell the difference between that being an AV nodal echo and a septal pathway echo? Well, your point was well taken, which I didn't recognize is the first pace beat has the same retrograde activation as that last native. And that's very compelling evidence of what? Of an accessory pathway. Why though? It's the AH. No, it's the AH. It's the AH. Yeah. Go ahead. Right. Yeah. So during the, go ahead. Yeah, we were just talking about it. Yeah, we were just talking about it. So the first ventricle paced beat shows an H after the pacing complex. And that HA interval. It's too bad we don't have pointers. I know. Sorry. That's a really important, but I'll amplify that a little bit if I'm, can you go back? That HA interval is 125 shorter than the HA interval during that echo beat. And that's got, that cannot be AV and RT, right? Because the HA interval during AV and RT or AV nodal re-entrant echo would have been simultaneous. It would actually activate the atrium and the ventricle simultaneously and be short. Here it's much longer. That would make it more likely to be an accessory pathway. So just to put in, it's absolutely true. And just to put it in a little bit different light, the HA with V pacing is in parallel. The HISS and the A are being activated at the same time. So it's falsely short with the echo. They're being activated in sequence. So it's really an HA measurement. The other way you could look at that, it's a little bit cheating and I should have put the, put the numbers on there. But if you look at the local VAs, the VAs are the same. So this is saying that activation of the atrium in both, both examples, pacing and in an echo is not dependent on the HISS, but it's dependent on the ventricle. When you're saying the local VAs, you mean the first pace beat and the last beat? Yeah. It takes a little bit. And the CS? The CS is easiest to see it. Yeah. Yeah. So, so you're saying, David, that's what I was trying to measure. So you're saying if you measure the RVA distal to the distal CSA, is that what you're saying? Oh, I was just looking at, you could do it that way. I was kind of looking at the CSs and their. Especially the proximal CS. Oh, local CS. Because you're talking about a septal pathway. No, I see what you mean. It's not going to be the distal CS if it's a septal pathway that you're looking at. Yeah, I understand what you're saying. So, so you think this is, this is enough with one beat knowing there could be wobble and variability to say for sure that a pathway versus AVN echo? I mean, I don't know. It's a poorly constructed question. It's a perfectly vague question. No, I, I always get worried because sometimes you see something that happens once in the lab and it's like, just, you know, something, you know, there's a concealed, something funny happened. If this persisted the phenomenon, HA stays the same, you know, and then, then I clearly on your side, one beat, I hear what you're saying, but I don't know that I'd go to, go to the mat on one beat. Oh, I, I, I think that that's God's honest. Well, what happened? One beat. What happened to the patient? Oh, it was my patient. It was not your patient? No. Oh, okay. It was stolen again. That's good. But I think it's a. He was still at Penn, right? He's in a lab somewhere. He's in a lab. They're blading. This is terrible. We're really terrible. We have five more seconds till the end of the session. I just want to say this was a fantastic session. I really appreciate the panelists. I really appreciate to have Callan's co-chair here. And I really appreciate you guys for participating. Please feel free to come up and ask any questions that you want of any of us. Thank you so much. It was fun. I feel so bad.

cardiac cases

cardiologists

ECG tracings

critical thinking

narrow complex tachycardia

wide complex ventricular rhythms

differential diagnosis

cardiac electrophysiology

ECG interpretation