In this Heart Rhythm Challenging Case Discussion, Mayo Clinic cardiology experts Samuel J. Asirvatham, M.D., Abhishek J. Deshmukh, M.B.B.S., Siva K. Mulpuru, M.D., M.P.H., Ammar M. Killu, M.B.B.S., and guest Bryan C. Cannon, M.D., discuss congenital arrhythmias such as intra-atrial reentrant tachycardia (IART).
Oh uh huh. Thanks everyone for joining. So today's focus is going to be congenital heart disease, one aspect macro re entrant Petrotech courteous will also visit with congenital heart disease as part of a pathology session and then subsequently we can look at device management and congenital heart disease later in the year. Several of you have anticipated the session and sent in questions to us. We'll put this up for you the questions that have already come in and the question and answer uh folder. But please keep your questions from today. What you hear, what you think about as we go ahead as many as possible, we'll get to during the session and what we don't will answer and put it as part of the recording for what will be available on the Youtube link. So today we have dr brian can and my colleagues x very experienced with ablation and complex congenital heart disease. You've met brian commenting as a Panelist before he's going to introduce some of the important ideas to get us started in the conversation and then we'll all regular panelists myself and brian and anyone else who wants to join in. We'll tackle the questions as they come up brian. Well thank you very much. Doctor says it's a pleasure to be here and it's quite an honor to be such a distinguished group of people. So um we're just gonna start out by kind of going through a couple of basic principles about about adult in general and this is in my opinion, one of the most important things because it's one of the most difficult things to see. So I'm just gonna kind of leave this slide up for just one second. Pretty simple question. What is the rhythm? So you can kind of see there's a p way before your dress looks pretty good. But let's take a little closer look. And the question is, are you sure, were your first thoughts about this rhythm potentially correct? Was there anything about the scg that kind of piqued your interest? Was there anything that changed your mind, your thoughts or what are some unusual features? Because if you look at this, there's a pretty flat baseline here and we see if you even a cure? S but now as we look closer, there's some little funny things that are in here. So what could potentially that be? Well, I'd like to spend a little bit of time talking about this because I think this is one of the easiest adult congenital rhythms to overlook, but it's also one of the most important. So this is as the draft Chevanton said called scar flutter, intra atrial reentering tachycardia. Micro macro reentered atrial tachycardia that we see pretty commonly in congenital heart disease. In fact, we see it in 50% of patients after the Fontane, 30% of patients following the mustard are sending and you can see basically any patient that has structural heart disease. They can have thrombosis, symbolic complications and it can be terminated by atrial by cardioversion for atrial overdrive pacing, but it's distinct from the flutter seen in normal heart. So let me show you a couple of diagrams that have been it and there can be multiple circuits. But the key is that the rate is typically slower. It's simply between 130 to 220 beats per minute. Which is important. And the fact that some of these young people that have normal A. V. Notes may conduct 1 to 1 through the A. V. Node, resulting in hypertension or circulatory collapse. So in standard atrial flutter, we have a circuit that involves the whole atrium and it's all healthy tissue that's rotating around in this macro re entrant fashion. So that gives us this pretty characteristic sawtooth pattern on the sCG with continuous electrical activation. That's distinct from intra atrial re entrant tachycardia where there's a zone of poorly conducting or non conductive tissue. But there's another area of unhealthy slowly conducting tissue. So there's an area of healthy atrium that makes a good sized P. Wave. But then this is there's this area of slow conduction with very low voltages. So as the circuit goes around it creates quite a unique pattern on the BCG. And what you'll actually see is this very flat baseline. But if you look closely you can march through p waves that are there. So at times it's pretty easy to see, you can see that the p waves marched through here and you notice the variability of the interval. So when the atrial signals are big and there's atrial enlargement relatively easy to discern. However in many of these patients the atrial signals are very small. So it's very difficult to see unless you look closely. But if you follow it closely you can see that there are p waves that are marching through once again in patients that have other structural heart disease relatively straightforward to see. But it's important to look at the end of the cure S or in the T. Wave for hidden P waves because frequently these patients will have a bundle branch block or other conduction abnormalities. Yeah if you look at this CCG there's a P wave in a curious, so sometimes you have to look at the whole sug you have to look for areas where it slows down or blocks in order to see those p waves come through. So what are some clues to diagnosing IR T. These are the things that I look for. So if you have a prolonged PR interval or a variation in the P. R. Interval and a patient that otherwise has a normal Pr interval always think IR T. These patients may have conduction defects and other things that prolong the P. R. Interval. But anytime you see an increased PR interval think I. R. T. Change in P wave appearance If their sinus P wave always looks one way and all of a sudden it looks different if there's no variation in heart rate And patients whose typical heart rate is in the 40s and 50s. If they come in with a heart rate of 90, that may clue you in. So patient that's chronically Britta Kartik that presents with any form of tachycardia, even what we would consider mild may need that. And the reason it's important because these atrial arrhythmias can definitely affect ventricular function and sometimes you need a dentist in to see them. So if you take a look at this monitor tracing looks pretty good. But if you look closer, you'll see that they're blocked P waves. So you really have to keep an eye out because this arrhythmia can certainly sneak up on same thing with this. If you look closely you can see that there's a variable pr interval. But when you see a prolonged pr interval are especially this variability that tells you that the atrial rate is out of conjunction with the adrenaline effect on the davina. So, if you see this variable conduction, think I RT or some other type of abnormal rhythm. Right? We all have variations in our heart rate. But if you see pretty flat heart rate trends that you see it won't be perfectly flat, there will be little variations. But you can see in general if the heart rate trend is very flat and then when they go to sleep, they have further block. This is another clue if you see no variability in the heart rate that you may be in an abnormal rhythm. Sometimes you need a dentist in to see it because here you can see the p waves but then with the dentist sing it makes it much clearer that this is an arrhythmia. So why do we care? It's just an atrial arrhythmia. Well if you look at the issues sudden death can be as high as 6 to 10% and associated with recurrent I. R. T. And in patients with appropriate I. C. D. Shocks and transposition of the great arteries. Super ventricular technique cardiac procedure coexisted with the T. And 50%. So in these adults in general patients these atrial arrhythmias have a significant effect and can have a significant effect on ventricular function. Well we're going to move on from talking to I. R. T. To just talk about a couple of basic principles that you absolutely have to do. If you're going to take care of. In general patients. The first is know the anatomy. You have to know where things are and just realizes that anomalies of the superior vena cava are present in 9% of patients with congenital heart disease as well as 1% of normal heart. So you can see here there's a left superior vena cava and on this image as well. This is a MRI reconstruction of the patient that I did last friday. Um and you can see there's a left superior vena cava. So understanding that and understanding that the signals that you get and where things me maybe an unusual positions is very important. In addition, if you're putting in a pacemaker and there's not a bridging vein, you'll be in trouble as far as getting that catheter into the right position in the heart. In addition it's important to have some type of image. For example, this is a patient who, this is the right atrium. It goes from the sternum all the way back to the spine. So you know, you're in for a long day of ablation. So it's very important to understand where structures are how big structures are and other things in order to do a successful ablation. In addition, it's important to know where is the A vina because in patients particularly with Angelique corrected transposition or a V septal defect or complete 80 canal, the conduction system does not run in the normal area. So if you're not aware of these variations or these changes, you can you can accidentally damage the A. V. Node and cause a V. Block. In addition it's important to know the specifics about the surgery. For example, when they say the patient was on bypass, that may mean a bi a bi atrial cancelation where one candidate goes through the spc, one goes through the I. V. C. Or it may mean a single candle through the superior portion of the superior vena cava or coming to camellias that go through the lateral atrial wall. So understanding this will show you zones that were you expecting scar to be Eurozone's? We expect disease tissue to be. In addition each surgeon does the repair a little bit differently. So it's important to get the operative notes to know exactly what was done. And that will help guide you for your ablation. So um thank you very much for your attention. Now. We'll kind of open it up to questions and hopefully this will be kind of a primer to uh diagnosis, diagnosing and treating congenital heart disease. So thanks brand. So you know that's like uh overview for clinician and for electro physiologists planning a case what we need to know. And I think when we get into the questions we'll get into some more specific areas, especially for the invasive electro physiologists. I just like to take you know, maybe one which is a very common question and a uh common kind of mistake that can happen when interpreting the the big in terms of where we want to M blade. You know, you very nicely pointed out that you find p waves. You look you see that it is a flutter. Yeah that it is there's more p waves there than what's obvious in front of the Q. R. S. But another piece that we have to translate from normal heart abrasions is looking at the P wave access to try and figure out where we need to oblate. So early in our E. P. Training in a repeat career. We learned this diagnostic algorithms based mostly in normal hearts and automatic technique cardiac. So for p. wave is positive and b. one and B. one is the right sided lead. We think that this means that this is originating on the left side. If a P. Wave is positive in 23 A. B. F. We think origin high in the heart. But I think it's important for us to explain that uh the analysis of the P. Wave and reentry intact cardio itself is not straightforward but especially when you're dealing with highly diseased hearts. And the reason for that is that and maybe I'll just draw something here. The reason for that is in a re entrant tachycardia. There's really always some electrical activities somewhere in that atrium or ventricle for Bt. So there's no real focus that will determine what the P. Wave accesses that P. Wave part of it is going to be one part of the circuit. Another part of the heart that's getting activated late early. It's really almost impossible to make sense of the P. Wave and diseased hearts. Re entrant et but one of the uses that there can be is because it's so diseased that diseased portion doesn't contribute to the P. Wave. It's electrically silent. And what really makes the P wave however small it is is from where that circuit exits to the rest of the heart that's relatively normal. And this can be especially useful clue in congenital heart re entrant tachycardia. Because the circuits are in such diseased portions, low voltage can't generate enough of a voltage stream to be part of the E. K. G. Where you do start seeing. It gives you an idea of that transition between the normal heart and the diseased portion that's housing the circuit. So kind of a way of interpreting is to say, let me do my usual electrocardiogram analysis. But then let me interpret it differently here by trying to back in from that exit site to where I am anticipating the type of signals and abnormalities. That's going to help me find the circuit. So, you know, that's uh that's one frequent question that comes up. There are a few others as well that we uh if we have time we'll get get to but we have some that I'd like to get started with those questions. And anyone here please do add in uh anything that you'd like to look through? So one of them is a very important question. And that is how do we figure out how do we figure out how to check for black when doing linear ablation in patients who are postdoc congenital heart disease. So, you know, we've gotten used to saying, how do we check for block when we have normal heart bi directional block? We're putting a catheter, Multi electrode wavefront two ways and see if there's a reversal of conduction. But how do we figure that out in patients who've got congenital heart disease, difficult to access the anatomy? And is there bi directional block after the ablation that we've done? So maybe I'll just open that up a little bit for comments. I see we've got Molony who's Molony mother, one who is also very experienced and congenital heart inflation. And maybe I'll just start with you brian comments about like how do we uh look for block when we can't get easily to those structures that we've done a linear ablation on and then we'll get some comments from dr moderate. Yeah, I think that's an excellent point and I think that's one of the most challenging things about these abrasions. Is there are multiple lines of block and multiple candy circuits going through there. So I think it's important, at least when I look at it is to do spend your time and your due diligence and mapping before you do an ablation. See what the activation patterns are. See if you can find areas of scar or areas of low conduction and that may help you plan your ablation lines as well as check for a block. But it can be very difficult to figure things out. Another important thing is is having some type of imaging whether that be ice imaging or ct or MRI before to make sure that you are mapping the entire circuit because one of the biggest problems that we run into is there's an area of the circuit that's critical that either you can't get too easily with your catheter so you miss it with the mapping system or is completely blocked off from access based on the surgical results. So I don't know if you want to add anything to that or that's great. Um in terms of checking block, I would just had a couple of other things um checking block across lines after a trip later ablation is the concepts are very similar in a CHD versus compared to someone who doesn't have congenital heart disease. But there may be challenges. Right? So, because sometimes pacing from certain portions of the heart, such as access to the approximate CS may not be present. But the concepts are very similar. So if I can share a couple of slides, doctor asked about them and they would be okay if I just show a couple of examples of um checking block. Um just a second, mm hmm. Is that coming across? Okay. So the most common way we check for block across the line is probably the best way I would say, is to place closely spaced multi electrode catheter across the line. So that's the most common way and we want to pace on either side of the line and show that the activation is occurring on the other side of the line in a reverse direction. So that's the concept. We apply for checking for C. T. I. Blog. And the same concept would apply for any line that we perform in a a CHD flutter ablation or for that matter any bt ablation like in a technology as well. Um Some of the other ways this can be done is this is for example a common type of flutter. This is the right atrial map. And the second most common flutters we see in these patients after cT I. Platter is sensational flutter occurring on the lateral right hatred. So on this map you're seeing the lateral aspect of the right atrium. We have a plated through a previous surgical scar and anchored this line to the I. V. C. And this previous surgical scars start started at the base of the right atrial appendage that you can see here. So it really wasn't anchored to the sbc but was anchored to the abc. And that terminated. So then one of the questions this is the block across this particular line. So the way we check for this is instead of putting the catheter across the line, the multi electrode capital was placed on one side of the line straddling that line. And uh up to down fashion and then there was facing from the ablation from the other side of the line. So in this tracing. Hairier seeing facing from the ablation catheter. And the east Miss catheter is catheter here that's labeled here is getting activated from top to bottom here. So I. Istvan is on the top And 1920 is on the bottom so there is block across this line. So the activation is going around to the right atrial appendage and then coming back. So there is block across this line. Similar concept. If we do Intercable line, we can either place a catheter across the line or we can place a parallel and show that there is block across the line. The other way to do this. If there isn't some way of placing a catheter across the line is to pace one side of the line and then map on the other side. So this is another example and this is a map from a patient with a mustard procedure who had a ct ablation. So what we are seeing here is we have done retrograde access into the pulmonary venus atrial side and then through the I. V. C. We have gone into the system of venus atrium. I don't know if my um is my arrow coming across. Okay, so this is a map of the system of venus atrium and this is the map of the pulmonary venus a trick. So although this was seti I flatter in this particular situation, the large part of the cable. Try prosperous thomas is now in the parliamentary venus atrium which is the opposite side of the path the surgeon had put in and the coronary sinus was also located on the other side. So what we did for this patient to check Pablo was we paste from the medial side of the C. T. I. Line that we had done in the parliamentary venus atrium and then we took the ablation catheter and using the mapping system map the activation sequence. So you can see the activation sequences earlier away from the line which is the red dot and then has become closer and closer to the line, it becomes later and later which is the purple dog. Right? So that's another way you can check for block across lines in patients who have difficult access to certain chambers. So um but the concepts are similar, you're pacing on one side of the line and mapping on the other side whether that's using a mapping system or using a multi alec. Uh depends on the situation and there were a blatant and then we can also doctor asked about them if we can also talk about how to interpret doubles and all that later if that's thank thank thanks a lot. So so just to kind of explain this to approach is to be sure everyone's on the same page. So the problem with our congenital heart disease patients is we draw lines in places we're not accustomed to doing so we have to have like a generic game plan for how can I check for block anywhere? The second is it's not easy where we drew the line to place more than one catheter. If we had to go through a baffle puncture a retrograde approach it can be difficult. So dr madeleine here's pointed out two things. Let's say this is where we've done the ablation. Somewhere in the atrium could be in the ventricle. And we want to know that there is no gap here because the premise is this has been anchored. We haven't anchored to both sides to anchors because we didn't want to isolate for delayed conduction entirely to one portion of the atrium. But we don't want to have a way for a circuit to make its way back. So in that example that dr martin show there was anchoring to the I. V. C. So how to know that this line is blocked. So simple one there there's you pace On one side of your line. Mhm. And you have at least two preferably a multiple electrode. Or even just a proximal and distal electrode from a single catheter. You pace here and see how is the activation to these catheters. If it's coming like this chances are this is blocked. And the activation is coming down. If on the other hand you are leaking through then this will come earlier. But very difficult to use this technique which is single catheter or a few points because anybody can distinguish conduction from block. The trick the talent, the skill is distinguishing block from almost block. So extremely slow conduction. So if we are using this technique we have to make sure that the catheters are close to where the conduction might be happening and try to take closely spaced catheters to show the entire wavefront, even close to where this line was created, his reverse activated. And to exaggerate that further, you want to pace close to where that line is as well. So in other words, you're trying to make it best case scenario for conduction to occur if it's possible to occur. Some. The second technique that Dr Madeleine pointed out was you don't even need to have a multi electrode catheter on the other side of the line, as long as you pace on one side and you can map on the other side. So just take several points and show that even though you're pacing all the conduction is moving towards where you did that line. So here also a few caveats. If you use this technique is you have to make sure that you're pacing close to but not too close to the line because if you're too close, you might inadvertently capture tissue on the other side. 2nd is your map should be strictly only on the side of the line that you're checking for blood. If by mistake, you interpret a signal from this side or you take a point on this side, it will become an entirely meaningless map. So you can do it. But with those caveats and the nice thing about that technique is you can do that even in the ventricle. So this is an example of a patient with post tetralogy of fellow VT. And the line was done connecting a patch, a non trans annular patch to the pulmonary analysts and want to know do you have blocked it? You know, good luck with trying to get a multi electrode catheter there. So one way to do it is simply take a pacing site and that piecing site might be in the other ventricle. It could be a second catheter. Keep pacing from that same location and then map on the other side. Here's your line, you're pacing close to the line and the whole wavefront is coming towards the line. And if that's happening, you can say your block in this direction and then what you can do is just reverse this face here to the map on the other side to show that you have bi directional blocks. So that's some of the things we would think about. You know, there's an allied question that also comes up sometime is what can you anchor to in patients who have congenital heart disease. So this is actually a very important question. So you can anchor to anything that will not conduct. That's our premise for when we say anchor. So not possible to conduct and that usually is valves in the normal heart, but in congenital heart disease of potential pitfall is when we have a scar and the scar, we say let's anchor to the scar. This is a very frequent cause of recurrence of a Rodney because what we call scar is not really scar. So in other words, we might have defined scar as this is something with lower voltage with some arbitrary cut off. But little living tissue could be there. And then when we draw a line here, you can force conduction through that little living tissue and this can become an incessant slow flutter. So if you call something scar while doing a map, thinking that I might do align to connect that. You have to be 100% sure there is no viable to shoot there. That's why many electro physiologists, even if they think it is car, they'll actually a blade all across that to kind of make sure or homogeneous the scar to be sure that that really has no viable to shoe into it. The other kind of unique thing that comes up in congenital heart disease is sometimes as a result of the surgery, there may be isolated portions of the atrium, isolated portions. This has its own rhythm. It's already been isolated from the rest. Even though this is entirely viable, this is a potential anchor for land because this is isolated. It's not going to go anywhere. It can be treated like scar even though you have viable tissue. And there's also another unique situation where the isolated portion might be in a rapid rhythm, like fibrillation, even while the rest of the heart is in flutter, I don't know if any of the panelists here have a quick example to share otherwise, uh I can find one as well, but uh if anyone does let me know uh Okay, great. Uh why don't you show that to us? Mhm. Let me get rid of this. So you can actually see there. That's okay. We can see it. That's beautiful. That's a beautiful example. So maybe I'll just talk through this one as you point Molony. So, if we look at that instead, we see that even though there is an organized arrhythmia uh in one portion of the atrium there is fibrillation. So how can this fibrillation be an anchor point? Well, how come the fibrillation hasn't spread so effectively, this could be an isolated portion. Now to know for sure. This is only valid if the rest of the atrium is in a paced rhythm, a stable flutter or in sinus rhythm. If it's a flutter, that's changing, then it's iffy if whether this is a good anchor because there may be conduction, it's just slow and delayed and that's what's changing the organization of the flutter. Thanks. Thanks Melanie. That's a that's an exact example of what we had in mind. Now we have a question. Uh and I believe if I could just make a just a couple of quick comments. First of all, I think it's sometimes it can be challenging, figuring out which arrhythmias the clinical arrhythmia and if there's a connection between the two. So sometimes you have to spend time doing that. The second point is is sometimes the most obvious area to connect involves a very large portion of atrium. You have to look at several different options, including going through old areas of scar to potentially look for ways to not damage the other atrium because you can cause atrial to synchrony by putting too many ablation lesions in there. And sometimes these patients are very dependent upon their atrial kick for the cardiac output. So I think your points are excellent about trying to figure out that and then but you have to map and figure out what's the clinical arrhythmia. What's the best route to get rid of it so that we can leave the limited amount of healthy tissue that's in place intact. Great, thanks. Thanks brian. So we have another question. Kind of genetic, it's like it's difficult to interpret signals in congenital heart disease annotate the signals, et cetera. So, difficulty with signal interpretation. I think this is also a very important point and we'll get some uh multiple opinions here. But I see Dr Del Carpio has joined as a Panelist and I know he's given a lot of thought to signal interpretation and how we include in the map Freddy. Do you want to share some thoughts with us. Well, when mapping, you know the atrial flatters. Typically we want to deal with complex signals. We want to make sure that we I'm not a right activation. See question of the law collateral electron program. So the difficulties are typically dealing with double potentials or So there are difficult different strategies. Um, but we want to make sure, you know, that we want to take the near field signal all the time. But sometimes that's not possible. So, uh, for example, we have a fractionated electrical. Yes. Pretty. I think you're cutting out. I think I know what you mean. And then let me share an example of uh, uh, Freddy. You're you're cutting out. I'll just share an example with the thing of what I think you're referring to. So, you know, sometimes sometimes what will, what we'll get is uh, something we're used to now a little bit more because we're doing structural heart bt. But it's a very important principle for especially new electro physiologists, the smallest signals are sometimes the most important to kind of have an understanding of and recognize and attack of cardia. So, especially with congenital heart, uh, arrhythmias you have to be really cautious about saying is this car or not. And recognizing that there may be a big signal on our catheter because surrounding tissue might be what's contaminating the signal and the real critical signal might be something in between. So these kind of fragmented fractionated signals. I'll just give a few tips from my own practice and then we'll hear from brian and Molony as well. But one of the things that's useful is understanding where is your catheter. So in a congenital heart B. T. For example, if the catheter you know, is in a position where multiple structures are popularly muscle overlapping changers, china chambers nearer baffled In those circumstances anticipate that there could be two sets of signals. The second thing that comes into it is ask yourself which of these signals is more likely to be relevant to the circuit. So in other words, you look at the BCG, you look at the cycle length of the tech accordion and then look at the signals that are present in the catheter you have the surrounding tissues already met. Which of these signals fits best if this is really completing a circuit in that location. But beyond that, I personally find the most important maneuver is facing. So if you pace from that site, when you have that luxury, you're not worried about the arrhythmia changing when you pace, see what it is that you captured and if what you capture is what is allowing perfect entrainment of that circuit, then that signal is relevant and that's the one that you need to include. Now sometimes we just can't tell. It's like, you know which one do you want to go with this one or this one which component of this one. It's good to just step back and say I can't tell and just annotate on the map that there is a location where I couldn't tell and I'm just gonna say this is an abnormal singing and then when you have the rest of the map you can come back to that location and see. Well now can I tell, looking at what else is around that. So just some things to share about one type of difficult signal, small but maybe high frequency and fragmented signals uh brian any comments about signal interpretation. And then mommy. Yeah, I think that this can be one of the most difficult things and the most one of the most sure fire way to derail derail your case is to have a map that doesn't make any sense. And so I think you have to be very careful when you annotate or use auto annotation programs just because it may not be annotating the right thing, especially lines of block and other things can really throw your map off quickly. So I agree with you any points, You have questions about our double potentials. You should probably just take as a location and then come back and look at that in the scheme of things because you can get a completely different map depending upon where you take the points individually and trying to figure out what small signals are relevant and not something that can be difficult. But I agree. I think pacing and looking to see how those signals respond is very important. Um Honey, before I get a question comment from you, I just want to share quickly. Another situation where this is important is when we are uh when were bleeding, I'm sorry when we're bleeding accessory pathways and we have in congenital heart disease. Sometimes a situation where we have to try and figure out for our map. Just a simple concept of early site or early activation location. So there's some very simple maneuvers can be very helpful, also related to pacing. So you have, this is a patient with abstain and Emily an accessory pathway ablation and what you wind up is we're trying to map for a pathway potential early V. And you also know the atrial signal can be complex and multi component of ventricular signal can be complex and multi component. So sometimes while we have all the signals of interest in line, we paste to just change something like block in the pathway And then everything that was related to the path three is going to move. So then you just backtrack from what moved back to your original beat in whatever electrodes you have, even if it's a very small signal in one electrode like this one here, you'll say that's related to the pathway. It's we or its pathway potential related to the pathway. So another unique challenge and congenital disease where you sometimes even a so called simple arrhythmia because the signals are complex from surgery. Maybe Priore ablation. Good to have a few maneuvers up your sleep that you can use. Mommy mommy, you have an example to share with us. Oh you're, you're still muted I think. Sorry about that. Yes, sure. I can show show an example maybe to highlight on what you and Dr Cannon said about facing to help distinguish with signal is relevant and I think it's worth again emphasizing what Dr Cannon said about these automatic annotation programs. I think they are good but they're not good enough to always know exactly which component of a multi component signal is of relevance. So it's really important to pay attention. I always tag some of these multi component signals as location only come back face and figure out waters of relevance to the circuit. The other thing to keep in mind is when we try to place, it's really important not to place to pass much faster than the uh, the cycle mint going about maybe 10 to 20 milliseconds shorter than the cycle and rarely leads to degeneration or changes in the water or termination of the flooded. So facing maneuvers and train mint maneuvers can be extremely helpful but just need to be used very carefully. Making sure that we have good sensing when we start pacing and we are not facing too much faster than the underlying flutters flatter or any other VT. We are mapping. So this is one example where there is a multi competent signal, we can see there are three different components on this electrode and when we pace we see that two of those continents actually are not getting captured and it is this third component here with the red arrow on it that is actually getting captured. Now we know exactly what is the relevant signal at that site and we can annotate to that. Um and it also tells us that this is a probably a site that is relevant to the circuit and likely within the circuit based on the entrainment we have just done. Um So I do find it very helpful and treatment is very helpful to sort out which signal is relevant. Great thanks. Um Now maybe while I'll ask someone to just check with the doctor who's asked question if they'd like to just ask the question online about atrial fibrillation, making arrhythmia difficult and we'll come to that in a in a bit. Um and will maybe go to another question here. It has to do with coronary sinus position in congenital heart disease. Any principles, anything where we look at to say of where it's important to know before going into the procedure, how to anticipate where the coronary sinus is maybe molly I'll ask you this question um uh planning before the procedure is really critical that any kind of repaired congenital heart disease and part of the planning is knowing where the coronary sinus is. So I routinely um either obtain a CT or MRI or if there is already one in the system, I would review it in detail with the radiologist to really figure out, depending on the complexity. Things like where is the coronary sinus opening into. Um If it is something very complex like Kuantan um you know which part of the atrium has been excluded, how to get to that portion is the administration. There are so many aspects to this planning, but coronary sinus catheter of knowing where the CS is opening into Israeli, important ahead of the case at. Um during the case, ice imaging is also really important. So that also helps us really know which part of the chamber the CS is opening into and that becomes more relevant. And patients, for example, with the mustard procedure where they at least in my limited experience. Uh I find that it's about 50 50 50% of patients that I have seen have the coronary sinus opening to the system of being a side and 50% on the pulmonary venous side, Fontanne flatters would also be very important knowing where the CIA's opens into another reason to know that as if somebody has had trikus put valve replacement surgery. Um, knowing the see if the CSS atrial or ventricular to the replace strikers, put valve can also be very helpful ahead of time. So it helps us plan how to place the CS capital. Most of my cases. I placed the CS capital from the uh I j I find that to be the most table location for a CS capital. But if it's a coronary sinus that is ventricular to replace strikers. But wow, I tend to do that more often from the leg. I just find it more helpful that way. But it is really critical because whenever we are mapping something in the atrium, the CS is often our reference electron. The other trick to some of these cases is if we have a patient where the CS is not accessible and we are unable to place a reference electrode in the CS. One of the things I do is use a screw and a tree lead. So I take a regular pacing lead. Place it through typically the IJ or the subclavian vein and then screwed into some part of the atrium. And then that is uh connected to alligator clips, through alligator clips to the cardo system or whichever mapping system we are using and that would serve as a very stable reference for us. Having a stable reference is really important Before we start mapping and figuring out ahead of time what a reference is going to be as part of the planning. So Molony, I'll just share this image here where we go to the next question. This is what dr madeleine was mentioning. Mhm. Are you, wow, Okay. No, it's okay. No, I think it's yours. Yeah, I get that back here. So this question of where is the see us to identify? I think it's important for a couple of different things. You know one issue that comes up is CSS our landmark for avian artie ablation. So slow pathway. So it's not always just access to the C. S. Just the anatomical location of the CS can be important. That's useful to know from imaging. One useful thing is if the patient has had a coronary arteriogram sometimes if we can look at the the venus face when they had the arteriogram that will give you a nice clue if there's been a ct that's useful. But this is what dr madeleine was mentioning about CS positioning in patients with G. T. G. A. And A. And an atrial level baffled. So this is really kind of surgical preference. So it's not so much that the CS is misplaced. It's just where the suture line is. So if it includes the See Us then you can only access from the left side of circulation. If not you can even place a by V. Device through the CS. And patients who see us is not included in the baffled. You also have these like kind of in between situation where you may have a part of the CS On one side and part of the CS on another side. Few surgeons do that. Especially in the middle period for the mustard and sending procedures and so sometimes you might be able to get in but there's still part of the C. S. On the other side of the circulation but just getting that orientation for the anatomy can be, can be important. So allied question also is you know which situations where we have to worry about A B node reentry? I'll just make a quick point here. Relationship to the CS. And the conduction system in most normal hearts and most congenital heart disease is fairly consistent. You'll see the CS. Is posterior clothes and clothes and inferior compared to the compact Davy known. And the CS starts out relatively atrial to the compact Davy known and then winds up being more ventricular to the compact. Every. No it's a good rule of thumb to keep even in congenital heart disease. But sometimes there's a dis joint. And what that this joint comes down to is when there's a defect in the normal location of the compact Davy. No. So a defect in the triangle of cook. And this is our primary asd complex with endo cardinal cushing defects that this is punched out. This is the defect part of the defect all or part of the defect. But yet these points persons don't have a V. Block. So what that tells you is the heavy note has gone from and that's very difficult to define but pattern wise most of the time they we noticed displace posterior lee and will be located not just opposed to the coronary sinus but in the coronary sinus in the same region where either the coronary sinus is or where you are anticipated to be. So this is kind of one rule to keep in mind. This particular set of conditions are safety of a blading in the coronary sinus has gone. So we have to think about more difficult ways more involved waves to try and figure out can you a plate there or not? So sam, can I just want to study? Is one example that's okay with you. Um So this is is important to know where the coronary sinuses and realize that the coronary sinus can be a tragic. So as dr Mahadevan pointed out um a lot of times it's important to know where this is. You can sometimes see with ice. Another thing that you can do is as dr astro often said is shoot a coronary angiogram and watch it on the Leveaux phase and see where the coronary sinus fills. Another thing to remember is that the left superior vena cava than most people disappears in embryology connects to the coronary sinus and this is where it is where it normally will absorb to creating the phenomena vein. So shooting a picture in into the left I. J. Or into this phenomena vein and a lot of can frequently show you the anatomy of that. And in addition there are there are several, there are several things and I can send this link out but there's different publications that will actually show you just as dr as I've often said. What about casually corrected transposition. What about navy septal defect? They will actually show you pictures of where the conduction are. So if you're not that familiar with it, there are resources that you can go to to figure it out. If you don't know off the top of your head. So maybe uh we'll try and do one more question life and then we'll definitely get to the others and keep that as part of the uh huh. A session So quick one here is typical flutter ablation when there's a prosthetic valve or a baffle how to kind of tackle that. And I think well maybe address some of the nuances of that on off line. But any quick comments maybe brian you want to make on this. Sure. I think it can be very challenging. Um I think if you're careful with you want to try to not pass your catheter through prosthetic valves. Although in unusual circumstances you can a lot of times there are different areas or different crevices around there where they place the value that you can actually oblate that tissue without actually going through the battle. So, I'd be also interested with me. The other panelists have to say about their experience with artificial apples rick why don't we plan on looking at that issue in uh more detailed offline and we'll post a turn uh the youtube link. I think it's an important question and many things are associated with that. Uh huh. Shake you had a quick slide to share with us? Yes I can just show this one example again where sometimes it is difficult to access or have a block across the C. T. I. If there is a valve which is located which is present. I hope you can see it and sometimes you may have to actually cross the valve because there could be some it'll tissue which is hanging out a little bit ventricular to the placement of the valve. And you may actually see an atrial signal here like this pistol to it which can be targeted for ablation to have a block. So sometimes you do have to map beyond the well to look for any it'll signals great. Uh So you know really nice questions and I know we didn't get to everyone's but please keep asking and feel free to send us. I did see the a couple of the questions uh come in just now and we will get to them, will answer them now offline and pleased to use the link for the recorded session And which will also have this additional I would guess it would take us about 20-30 minutes to discuss the remaining questions we didn't get to. Thanks everyone for joining Brian Mulroney. Thanks for joining in as well. So we had several questions that we didn't quite get to and we'll try to answer uh answer some of these questions now. Um This is So 1 1 question that came up that's uh what isn't related specifically to congenital heart disease. But one of you wanted to know when doing trial balloon ablation or for that matter any type of ablation. And you want to check entrance and exit block into the pulmonary vein. Do you have to cardio vert the patient or not? So siva any thoughts on that? So entrance block, you know if you see signals go away all at once potentially there is entrance block. Exit block is kind of difficult to demonstrate that the patient is in atrial fibrillation. You potentially would have the cardio work him to to see if there is both entrance and exit blocked. And if there are signals, you may want to perform maneuvers in sinus rhythm. So a few things are just add to that uh as uh points. So you know just for anyone who's new in E. P. So you know this concept of entrance and exit block as we have this line of ablation or circle of ablation and we want to show that the vein and atrium have no electrical continuity between them. So if the patient is in atrial fibrillation as ever pointed out as you're a bleeding in the atrium to try to create this. You'll have initially a fib and a fib like arrhythmias in the rain. Now while you're a plating each site. The local electra graham will decrease or fragment each site, but there will be no change in the pattern of the signals in the vein that will stay exactly the same until you're close to or actually complete the circle and you have an abrupt loss of signals intervene, abrupt loss of signals in the vein. That's actually a really good marker for entrance blocked because you're bombarding your line with all kinds of way friends on one side and you're not able to get it now for exit block, it's true that you can't look for exit blocked the same way you can't pace and say, did I get out to the atrium? But there are a few things that would tell you that you probably don't have to worry about exit plan and what does our our if you have an independent rhythm in the pulmonary vein. If you consistently see an independent rhythm in the pulmonary vein and it's not suppressed at all. It's like such good entrance block that no matter how much source, think mismatch you have the chance you'll be able to exit out is very low. The other is if you pace and you can capture the wing, this is important, especially with balloon ablation because sometimes you might lose the signals just because you're a bladed a little bit into the vein and you've lost the signals in the venus mccurdy. So still that attempt to check for exit block is useful because if you pace and capture it means there's muscles still alive here. It's just that you're captured wavefront is met by this line so affect can't get in theoretically you don't know if you're pacing can't get out. But if this is holding true even after 5:10 minutes from your ablation very good chance. When you do cardio work you'll find that there is exit plug in the vein as well. Anything you'd like to add to that the sheikh. Otherwise we'll go to the next question. I think this is perfect. Okay so the next question and related to this is how do you get to an excluded chamber in a patient? Post congenital heart disease to complete the ablation. So I'll just share very quickly here. An example of where this can be relevant is, Yeah a situation like this where we have a patient post Fontane careful patch that's map the circuit of flutter on one side and you can't quite get the whole circuit left. If you can't get the circuit length you have to be wary that there is a portion of atrium on the other side of the surgical psyched and that other side does have conduction that can allow continuation of the flutter even if you are bladed on this one side. So there the issue is even entrainment on one side may be perfect. But your ablation just going from the baffle two I. V. C. May not be sufficient because you have leaks where you can go to the other side and continue the conduction. So that's where it becomes an issue. How do I get there? So specific question is trans baffled puncture and uh other approaches to get there. Hello? As brian to comment on transfer fel puncture. But I would like to point out that remember that Always also keep all your options in mind. So if you have a patient who has I. V. C. S. V. C. Right atrium, a neo left atrium in continuity with the left atrium because of surgical patch here it may still be possible to get there without necessarily puncturing the patch. If you have a large VSD you could get retrograde across the VSD and get to the site. If it's functionally a single ventricle you could get retrograde your time. Get your catheter here. If the ventricular septum is intact you might be able to prolapse your retrograde transparency catheter through the left davey valve through a big continuity between left atrium and this new left atrium and get your catheter there. So these are technically difficult maneuvers but there are always options to keep in mind if you just have a high risk baffled puncture because of calcium or because our way to get across the baffle is not straightforward but brian some comments about puncturing baffles. Sure I think the first comment I have is it's it's very difficult to do. Um When we used to only have trans septal needles, there's a little bit of a risk of perforating outside the heart because you have to use quite a bit of force to get through. Now that there are radio frequency wires and other things, it is a little more straightforward doing so. But I guess the key point is, you know, just like real estate location, location, location. You have two very well plan out where you're going to make the connection, make sure that there's a lot of scar around the area. So you don't get bleeding. You have to be careful most of the time. We will not necessarily put she's through there, but you certainly can. But it can be very challenging to get to places retrograde. You may sometimes have to do a baffle puncture, but it's usually very thick calcified material and you may need to use such things as ice, trans esophageal echocardiogram or even angiography to determine the best place to make a baffle puncture. That also will be likely to close on its own at that point, I think you should involve cardiac surgery and you're interventional catheterization colleagues. So, if you get into a place that you don't want to or create an unstable hemo dynamic situation, uh you can have them either assist you in closing it or getting you out of that situation. All right. So, you know, one thing that brian you pointed out is calcium on a battle. And it's always a good thing when you're thinking about baffle puncture to do Sonny Flora Skopje and try to do the sunny floor Flora Skopje in a view that catches the patch in orthogonal views and look to see, do you see evidence of calcium? So although shadowing with the ice, uh maybe a marker for this? I've I've been surprised how many times with ice it looks like nothing there. We should be okay. But then you do sinning and you see clear calcium and it's not a good idea to push that out into the circulation while doing, even if you successfully go with the thing with the with the puncture using an R. F. Needle using Co tree. Our techniques some some folks use for getting across definitely a standard. Just pressure with the transept er isn't working, You could do it if you have a patient who has uh uh if you have an out of needle you could try that. If not if you're using car tree, just a few caveats is oneness. Uh you should use the regular mono polar car tree. The bipolar car three pens are not enough to do to get your energy to do the puncture. Remember that. Make sure you have a fresh sheet in what I mean by that is if you have a sheet for the needle, you're trans septal puncture sheet and dilator have been used and traumatized, there may be breaks. And when you car tree you could deliver energy to the ventricle. You don't want that to happen. So as a practice, if I'm going to use car tree, I'll just switch out sheets when ah doing it at that time and technique. As you get the needle with ice. You make sure that the needle is onto it. And then you just take simple car tree, like what we used in the facing lab and then put the country on the raw end of the needle to see if we uh deliver it to the tip. You'll see some bubbles appearing on the tip. And then while that's you see the bubbles, it's forward pressure to try to get across in that needle Brian? one Thing is this is of course a whole different level of difficulty when it's an extra cardiac condo. So we actually have an extra cardiac conduit and we've got cardiac tissues here. So here we fundamentally are leaving the chambers were actually exiting and reentering. So the chance that we might have bleeding that could even be surgically difficult to correct is very significant. So, you know, some of the things that we would look at is careful look at imaging a sit down talk with the CV radiologist, very familiar with this type of anatomy to see. Are these just a post. Is there a place with a large atrium for example, is against this. Then we're like more willing to do the puncture another is after the puncture is done. We're always going to leave a wire and then watch with ice to see is there bleeding? Because if there is, we might have to be ready to close this per cutaneous lee having the right personnel equipment type of fluoroscope. E ready to try to close it to avoid like a surgical catastrophe. Anything else anyone would like to add? I agree with you completely. I think you have to be very well prepared if you're going puncturing through baffles, whether they're intra cardiac baffles. Extra cardiac baffles have to have a very good idea of the anatomy where you're going how you're going to get there and then how you're going to close. But more importantly, what are you gonna do if you end up in a space or with bleeding that you don't want? Thanks brian. So, this next question um is a very practical question. It's asking how important is it to a blade, all potential businesses rather than get the clinical flutter or clinical tech cardia and then just leave everything else alone. So, obviously, no golden answers to these. But let's just take a few comments. This is a very similar question that comes up in structural heart sweetie as well. But it always comes up in congenital heart atrial arrhythmias. So maybe I'll get some thoughts from uh dr Kalu and then ah Uh our how about seven do you want to give us some thoughts? You know? Um I I think it's it's uh when when we're dealing with congenital heart flutter. Trying to target all the potential asthma's based on the prior history where the potential slow zones would be sometimes targeting abnormal electra grams um is reasonable to do as within that timing of the procedural constraints. But in the end, you know aggressive program stimulation to see what the acute outcome is. Also very reasonable. Great. And we shake any thoughts. So practical question. Do you what do you do like do you clinical flutter a blade then go or do you recognize system uses and a blade all of them. I think it happens all the time, especially when you are more than one flatter which is going on at the same time. Or you induce a second flutter during the same case. So certainly my approach would be to target the clinical flutter of what you have if it is not a city dependent, flattered, try to do a ct line as well and then try to see if you have more flutters. Because as dr Cannon pointed out, you also don't want to a blade over aggressively in the atrium to isolate part of atrium because more atrial dissent in the sinus node dysfunction. And all the other challenges which can happen. And there is always can be another day for second flatter shows up. So I will target the clinical flatter and maybe target the ct. Yeah. So that that is one approach to do it And you've given a rationale. What about you brian? You know, I'd say that, you know, if you take a look at these a lot of times, the whole atrium is disease and if you do a map, there's three quarters of the atrium that has low voltage signals and slow conduction. So the approach I usually take it is um, I agree because about 30% of cancer heart disease flutters are still cT dependent. So the cT line is your friend and I don't ever have a problem with putting them in As a bonus leash. I think if you're going to go after all the circuits that you see anatomically you're going to probably be in there all day and realized that in some of these general hearts, the atrium can be a centimeter thick. So a single line, even with a saline tip called ablation Catherine may be very difficult to make one line. So my approach has been is agree go for the clinical flutter Christmas bird is always a reasonable thing to do. And then see if you induce anything else because if you look at the recurrence rates pretty high, it's about 50% after five years for this. So these other circuits may become clinically relevant. But my thought is if they're not induce able at that time you can spend all day and they're bleeding all these little circuits without much clinical success. Well, you know, uh thanks brian. So it's a just just for uh fairness, you know different groups, different electro physiologists have different approaches. And uh you know the early work that showed the relevance of isthmus, how to recognize on a mapping system. A lot of that work was from dr Nakagawa, dr Jackman and have emphasized complete ablation. That is if you recognize he's circuit a bladed, I can just maybe briefly go over. My own approach may be a little bit of hybrid from what we heard from uh huh be chic and some of the classical work. So you know, the the issue is the one thing that uh the sheikh alluded to is if we have several areas of scar or very poor conduction When we do an ablation for one islamists or circuit, if that's the clinical attack accordion, we are making more of a boundary for other red meals. The more boundary you make, the more likely those arrhythmias are going to come. This is just an electro physiological fact. So we have to keep in mind that if we do an ablation in a diseased heart, it's not only could this be a future flutter, but if what I have done is making it more likely for another flood. And the simplest way to do that is programmed stimulation. So if in the beginning of the procedure, all you induced was one after you do the ablation even if you've shown block across the line that you've created, it's a good idea to do programs stimulation and if you do program stimulation and your readily and reproducible. E inducing a stable flutter. The writing is on the world. It's not enough. I don't think to say this is non clinical. You already have a good map. You have a good idea where potential boundaries can be. It shouldn't take too much time or effort to map and and play that. So I think that's an easy case scenario but of what you should do. But the more difficult one is what if you have recognized extremely slow conduction. Even if you can't induce flutter. Should you still a plate? And at least my way of thinking about that is a risk benefit ratio for everything that we do in this type of arrhythmias. So what does that risk benefit? We think of three things. How likely is that ablation to be pro arrhythmic? In other words, how big a line and how difficult is it to a blade in that tissue? Because what you never want to do is make slower conduction. Second is how likely am I to affect the conduction system specifically isolate the sinus? No. And third is how likely am I to produce significant atrial dis imprint. So how to kind of answer that is if you found slow conduction, chances are the isthmus is small. So rather than just physically saying I've got valve and scar. Look at the conduction in between and if it is slow, very, very good chance that you have a narrow distance. Why is that? Because we front curvature has to condense to make for slow conduction. And what will force that curve to increase in a way front is the narrowest miss. If it's just diseased tissue and the neighboring tissue is fine and there is the biggest miss, you'll never get slow conduction, it just won't conduct, it will conduct through the neighboring sites. So, in addition to looking at scar and potential business, look at the conduction velocity at that site. And if that looks really slow bunched up signals as you're going through, that means it's narrow the chance that you're going to cause this synchrony etcetera is small. Go ahead and blake Now two caveats to this. Why wouldn't you just induce tactic cardiac? Because if this is so slow, you're going to induce it anyway. Maybe it's a slow conduction to a dead area in the hard dead end. The problem with induction is if you randomly pick a site to induce, you may pick a site that to this particular slow zone has got to wave fronts coming into it. You'll never induce. You'll have to get the right extra stem to block one and get the other. So if you use stimulation protocols purely, then make sure you do multiple sites. So, you know where the likely slow zones are, where the businesses are, do your stem on both sites or if you find it's really narrow and you've demonstrated slow conduction. Go ahead and a blade. Now a question of isolating the sinus node is very important and it's very hard to predict. I personally had a case consciously thought about this, thought about where we do the trains to leave this alone, get the line and isolated the sinus. No, completely did not anticipate it happening. That's because sometimes we've missed some scar, we don't know where exactly the sinus node exit is. So it is a problem. Good rule of thumb is don't do lines on both sides of the crystal terminals. If you keep your linear ablation to one side of the crystal thurman Alice posterior or anterior it's highly unlikely you'll isolate the sinus. No, that's just kind of a rule of rule of thumb. I personally use for this type of thing in terms of the synchrony. Another little rule of thumb is even if you isolate the free while of the right atrium, it's not going to affect atrial syndrome. So in other words where this comes up is you've done a line going from sbc to a lateral scar and maybe took it to the ibc still had conduction but now what you did is did a cable trick hospitals Miss lang good bet you'll isolate a portion of the right atrial free work. We never like to isolate but in general this atrium is so diseased in patients that we have these issues that the contribution of that portion of the lateral atrium to the overall atrial contraction is probably small and sometimes I don't mind and maybe even I like to see this because it tells me both these lines are great, very different story. If you're doing lines closer to the subject or in the left atrium on the roof there, the issue is not isolation but you can get severe dissing Quran E between the right and the left A tree. That can be a big problem, patients can get high wage pressures, pulmonary oedema, things like that. So just some kind of tips that you've heard different approaches. Just how you kind of try to answer that question. I think all of us would agree though. Whenever we do a line in addition to checking for block, you do program stem at the end of the procedure. I mean unless of course the patient is very sick or something like that. So maybe what we'll do is we'll keep the remaining questions to try and incorporate in our next congenital heart session. Uh We can maybe call it a day at this point. Thanks a lot. Everybody