Chapters Transcript Heart Rhythm Webinar Series: Challenging case discussion with Mayo Clinic experts – Conduction pathways In this Heart Rhythm Challenging Case Discussion, Mayo Clinic cardiology experts Samuel J. Asirvatham, M.D., Abhishek J. Deshmukh, M.B.B.S., Christopher V. DeSimone, M.D., Ph.D., and Siva K. Mulpuru, M.D., M.P.H., discuss conduction pathways. Thanks everyone for joining. So interactive question and answer session. Just focus topic to get us started today's conduction pathways and we'll go over this as a series as the months and maybe years ago by with just a brief introduction to the normal conduction system and then we'll start taking questions from you cases that you would like to share with us um and some of ours that will share with you as well. Thank you for those who have already sentenced some cases and questions and feel free to send in any way. Some of the questions that were emailed to me well talk about and ones that we can't get to during this hour, like we did last time, the panelists and our guests, faculty will Just spend an extra 15, 20 minutes answering those questions and it will be available on YouTube when you go in after this one hour sessions. So those of us here are traditionally Doctor Marlborough, dr DeSimone and myself and several of you who want to join. We'll bring you on as a Panelist along with male faculty as well. Start with a brief introduction here. So overall the questions that we get our things that come from trainees practitioners about the conduction system will center around. How accurately can we know where the critical parts of the conduction system are and how do we leverage that information for facing? Including conduction system facing are avoiding damage during inflation. So we'll spend just a few minutes to go over. Remember the sinus node? Uh It is an Picardy in structure and it's not a structure that's located at one point, it's an area that's at the junction between the superior vena cava, the roof start of the atrial appendage and the highest point of the sulk. Ast terminal list between this spc I. V. C axis and the muscular portion of the atrium. Important issues that could come up in cases that you've had when you want to avoid damage to the sinus node or you purposely want to modify the sinus, the second spot, which is sometimes hard to understand when we're looking fluoroscope thickly or moving catheters, but we're saved because of the recording of the his bundle is the member Ernest septal region of the heart. So on the right side related to the troika spit valve apparatus, specifically the anterior and sector leaflets of Potrykus, spit bell and when billed to the right from the left side of the heart junction between the right and non coronary sinuses of ourselves. This is a very reliable location for recording the disbanded electricity now in between to get from the sinus node to this this bundle region, little furrow between the anterior and sector leaflets is the compact daily normal. And as most of you know, this is a site which is the most variable and we approximate by drawing a triangle, looking at the attachment point of the centre leaflet of the tracker squid, van, the roof of the coronary sinus, and this extension from the new station ridge and underneath the tendon of Dodaro, right up to where the member in his septum. So this triangle obsessed to approximate where this compact maybe note is located. And then we use pleura skah, pick or electrical landmarks to identify these structures and then say this is where we would like to avoid damage while the blade, another couple of useful ways to think about this region is in the L. A. Oh, projection. The projection. You'll notice the inter atrial septum is actually a very small structure where it's truly a septum. You spoke on one side and you're out to the other everywhere up anterior as we go up towards the head. Interior lee and superior lee. You see there is no septum, it's a separation of the right and left atrium with pericardial space and tissue in between and then inferior lee. We see a similar kind of an X shaped deviation, except here on the left side. We've got the roof of the coronary signs and on the right side we move away the television valve region, you stationed rich and free while of right atrial. So septum, when we talk about septal pathway, we talk about conduction system on the septum, it's a very restricted region of the heart. one of the things that's also useful to point out that unlike the infra asian conduction system, where we have specialist conduction tissue in the atrium Cherokee, there is no specialized conduction tissue. You often see a figure like this. It's from an older concept where it was thought there were into international tracks. There aren't any anything that we look at preferential conduction in the atrium is just the fibrous, the muscular architecture, the way in which the microscopic fibers are, and just a These myocardial fiber arrangements in the atrium are based on whether they are all in one direction vertically or there are horizontal or slightly oblique variation, the most reliable ones that we see in the atrium related to this christa termine Alice, and to a lesser extent this vertical ridge in the left atrium between the pulmonary veins and the atrial appendage, and this horizontal connection between these vertical ridges, which is Bachmann's bundle. So just a kind of early introduction for us to help preface some of the questions that you had and we hope you have to share with us. And we'll go back when needed to one of these figures or any that you send to us or like to bring up to us to talk about the conduction system. So maybe we'll start talking about questions. So uh I know that we'll answer them as they come in real time. Feel free to also send any that you have through the chat messaging or email any of us for these questions as well. So start with, one question that we had was um what are the locations during ablation other than heavy node reentry our septal pathways where we mean injure the conduction system, So not A V and R T where we're sort of used to thinking about it, but where else could we injured the conduction system? So maybe I'll ask uh any of our panelists here, would you like to comment on where in other abrasions, where you worry about this phenomenon of inadvertent injury to the conduction system. So what do you want to make a comment? Sure. You know sometimes when we're doing a PVC ablation or VT ablation very common to the his Birkin G axis. Like a bleeding in the costs. We have to be careful about injury to the imprecision system. The other situations where you should think about conduction conduction system issue is when you're doing a accessory pathway in the venus system, like in the middle cardiac rain. Um and then sometimes when you're doing ablation in the mitral isthmus area where you have arterial supply to the sinus node, sometimes you can cause sinus arrest with that. Thanks to this. So maybe I can just expand a little bit. Uh huh. And then um if we if we were to look at the doctor Marlboro brought up a couple of points first was the sinuses of el salva. So we know that the junction between the right sinus and non coronary sinus. This is posterior, this is anterior sternum will be here. This junction is where we have the history. And if you remember the triangle of cock, the compact they be known is posterior to the this money is closer to the spinal column. So the place where it would come as a risk is if we are a blading saying the non coronary sinus and we didn't realize that the catheter had slipped in the commission or we perforate the non coronary science, then we can have risk to the conduction system there. So that is one area that it is important to think about. Uh Civil also brought up the issue of the accessory pathway in the post roe septal region. So this is a little counterintuitive and maybe a and go back to the slides here to kind of show what the issue is. So if we think about, if we think about this region, it should be that when we're in a bleeding by the post roe septal space or in a middle cardiac vein, we're actually extremely far away from the compact baby. No, we really are not. Even in the slow pathway region with even more inferior and posterior. But the issue is the compact Evie nodes. Blood supply. The artery to the A. V. Known travels up into the septum and actually is what separates the right and left slow pathway inputs to the avenue. So if we are in the post receptive space and in the venus system and our catheter is pointing up work trying to get my cardinal content, it's possible to injure the artery to the Even now I should. Ah The third. The third scenario that is inadvertent injury because of when trickle attack of cardiac ablation. The way that can happen is if we're a bleeding in the ventricle of the left ventricle, we already have understood that the compact even known is atrial to the trickiest advance and all electro physiologist. This is kind of Bread and butter to us to know that if you stay ventricular um you will not injure the 1800 if we stay ventricular, you won't injure the home. But that's only true on the right side. But because of the separation where the mitral valve inserts more separate than the trick has been involved in the normal heart that region, the A. V nodal region. When we look opposite on the left ventricular side is underneath. More ventricular to the mitral valve. So if we were, for example, a bleeding, a mitral business VT and we took the catheter up under the mitral valve, it is possible to injure injure the even more. I think that was some of the main main questions that we had related to inadvertent injury during during ablation. Now. Um any other questions that have come up now that or anyone would like to come up, please let me know as your, as your answering the questions. I think I think when some people are putting through a few questions, if I could make a couple points, so I agree. I agree with him completely. Pvcs for sure. Especially one thing to be aware of, especially the patient is a right bundle. Branch black is when you're even crossing or prolapse in the valve, you could bump that area between the right and non corner. Custom penetrating journalists and get complete heart block. I think that's one of the other thing is some people are doing interior micro length with the interior micro lines. If you're too close, maybe you're too close to that left sided inputs into the A. V. Note. Mhm. Yeah. And I think uh I think that's that's the key to kind of picture in our mind where the normally we notice located and work from there. But we should also keep in mind that there are times where baby note isn't located in that region. So the most important uh in those areas is that we think about this aerial view. Mhm. And we have the strangle of coke heavy note here. This bundle here and the membrane is septum. We know that when there's a membrane it's septal VSD the his bundle justice deflected either downwards far away from the VSD. So it's still intact. Now, the BSD or the type of defect that takes away the strangle of coke region, there's a primary SD or an A V. Canal complex. So in those cases we will never find the contract they we note in this location and it's typically found in the floor of the coronary science. So here also it's important to keep in mind person, intuitively, we say the lower we stayed or less likely we'll get a be damaged. one issue we talked about this arterial damage. The second is sure that comes up is in some genital disease where we have in unusual location for where they noticed gave me notice located. We have a question from the panel SAm asking how likely is it to see sinus node injury with while we are a plating an upper loop flutter. We're mapping an upper loop flutter. And we're we create a lesion set to interrupt that flutter. You know, what are the precautions that we can take to prevent the sinus node injury? Sure. Yes. So if we uh now does the doctor who have that question want to come up to talk about it? Yeah. Okay. So first of all, just a little bit about what is upper loop uh reentry or upper looks better. So lower look, we know ibc cable tray, hospitals miss try caspit bam. And a type of flutter that will use the mic Ardian posterior to the I. V. C. And anterior. That is the cable dry conspiracy thomas. This is our lower loop reentering lower loop reentry. If we have laid a standard flatter line cable trick this christmas, it translates this critical tissue for this type of re entry and that's why we rarely think about mapping or blading lower loop reentry separately. Cable trackers christmas will take care of lower loop reentry. Now, upper loop reentry is a type of circuit that does not occur in the normal heart. The reason for that is we don't have an inferior boundary for upper look reentry. So we have muscle behind the posterior part of the S. P. C. A. R. E. Junction and then we have the sinus node region and the right atrial appendage junction region in front. And this whole cylinder is got my according. So theoretically we could get re entry that just goes around the spc. But the reason it does not happen in the normal heart is we have the crystal termine Alice and Maya Cardi. Um that's completely posterior and inferior to the spc. So it's impossible to restrict the circuit. So to answer that question about how do we avoid avian order? Sinus, no damage. We'll have to bring up the issue of why that particular person actually got re entry related to the upper loop. So if I just bring this up here. So how do we do then? How do we get re entry around this site? It is very important question. You almost certainly would worry about damage to the sinus known, but the only way this happens is if there is scar inferior, so Hyperloop reentry, we run into the syringe me in. People who have had can you elation or a right a tree? Autumn. So if we have here an inferior skull that can restrict the circuit then we get upper loop reentry. It's possible to get a blueprint. But the same scar now gives us a way the same scar now gives us a method of trying to anchor two the scar and avoiding the sinus node altogether. So we would then go from the sbc to wherever that scar is. And anatomically remembering where the sinus node is located, we skirt around it and blade and we would be able to anchor the legion and get rid of a for loop reentry with really zero risk of uh damaging the uh the science. No. So does that does that get to the uh The Doctors? Question seven. Yes. I think so. To make a point here that sometimes, you know, we talk about the right atrial flutters, but even while updating left atrial flutters, we can get profound uh sinus, we can probably damage the sinus nor artery when we are waiting on the roof of the left atrium to terminate roof flatters because sometimes the sign is not large brick and travels around the roof of the left. A treatment certainly that can be damaged during that. I can show you a picture if you want. Yes, that would be great. Why don't you bring that up for us? Can you see this? Can you see a picture and screen? So for example we have done our vodkas and then the roof line is being done. But you can see this sinus nodal artery goes around the roof of the left atrium. And as we are a plating here, we could certainly obviously terminate the flutter but sometimes can also damage this artery and cause profound sinus bradycardia or even junction bradycardia, sinus arrest. So this is the artery and post population. You can see this artery completely going away on getting a bladed. Great. So we have another another question about understanding this conduction system uh anatomy and where it is located from a peacemaker standpoint, where exactly do we pace too? Capture the conduction system? This bundle facing left bundle facing conduction system facing. Uh So where do you have some comments on that? And then I can show some slides as well. Sure. You know, conduction system pacing these days is being popular and many people are doing it to restore synchrony and and even using you using it instead of by ventricular pacing. So initially pacing the conduction system was mainly the proximal his bundle or the distal part of the A. V. Node. But there because the leaders in the member and a septum the thresholds tend to go up with time and the few has evolved to do the deep septal pacing, trying to target the conduction system on the left side of the septum. And some it do you have so maybe we can like happy to share a slide to. Okay. Why don't you do that? Okay, so here this is an aria of you. This is a patient. We're not sharing your screen right now, are we? Okay? I don't see. Not yet. Not yet. Or I have a slide here to that and then you can you can help me look through this. So this is I think a key kind of you mentioned for all of us to keep in our mind when we're thinking about pacing for the conduction system. So um first of all, there's lots of terms in terms of this region, membrane is septum his bundle region atrial ventricular septum facing conduction system without crossing the tricolor, spit down. And I think this simple images and this one to kind of think through. So if we remember this strike a spit valve has got like a free portion moves back and forth Sicilian diastolic. And this kind of pasted down portion, this line of attachment on near the analysts and partly into the atrial ventricular symptoms. So everything that's proximal to this line of attachment is not going to be the hiss bundle. It's either compact, every no, or it's going to be the transitional zone or trigger zone as the A. B node moves forward to become the hispanic. But once we cross this, we're on a member of this septum part of the ventricle and there we could get we get the actual this bundle and we also get the separation to the right and left bundles. Now, if we take a section through here and look at it, what will notice is that his burden? Because the member this symptom is a fairly thin structure when it lands on muscles, is his bundle when it comes and hits them, in particular. Seven. That's when it's going to separate into the right and left Mondays. one thing that's worth noting here is the separation acts actually occurs relatively left work. The left bundle is the natural continuation and then we have the right bundle that will partly traverse through muscle and then come out on the end of cardio service. So when someone says his bundle pacing, so what what's your guests most commonly like cases you've done or you've reviewed? What's your guess what it is that we're most likely to stimulate your cap? Well, most likely the distal A V node is where it kind of transitions into the hiss bundle because it's hard on the membrane. A septum to exactly capture the hits. You know, such a thin structure. I think most people are getting the distal A V. Node or maybe more distantly the proximal part of the right bundle. So so if not right on the member. Ernest septum it's going to be either the end of the his or as you said, possibly the beginning of the history. Were really approximately we're getting some sense to atrial electro grams. There it could be something close to here. The only difference between actually screwing and then lied in this apex of the ventricular septum, the crest of the ventricular september and left bundle is really just distance. If that screw reaches right up to here, that's distilled this. If that screw reaches up to hear the distal part of the healings, the cathode reaches up to here, that's going to be left handed person. Another kind of useful image to try to keep in mind. I know the questioner had some follow up questions about examples and we will devote some of these sessions just focused on special aspects of facing. And we'll come back and ask those as well. I have another question, I believe it's dr Lewis uh sort of uh related to this topic but feel free to ask questions about any topic during this time as well, sample while we're on this topic, you know, Dr Rutland is asking a question when we are pacing for for for his bundle or conduction system facing, is it better to do it more on the atrial side or do we cross the vow to do it some uh silva, maybe I'll just take a shot at that. Um so let me bring this back. So it's kind of one of those, six of one, half a dozen of the other. So if we target this region, the nice thing is we're not messing with the troika spit valve, a dog. So that's a plus. The other nice thing is that we don't have to go through a thin part of the septum, like the member in his septum. So it's probably a bless. We have probably a little bit broader target, but the downsides would be that the more approximately you come, the more likely you're going to sense atrial electro grams. And if those are large, they're going to mess with the timing site. So certainly all of these have been observed both ways. And if we come really approximate, it's definitely possible to capture and get a very narrow QRS. But we might now start having some detrimental tissue between are facing site and the ventricle because we're now not really in the transitional zone, but more actually in the compact. Even know. On the other hand, if we pick a site like here, crest of the inter ventricular septum, this area has got a nice broad landing zone. And if we miss, in other words, We're not exactly capturing one tissue. It's generally all good in this region. If we've gone all the way to the left bundle, not bad because left bundle is getting stimulated and we can have a retrograde wave front coming down to the right bundle in most patients. If we miss that and we're getting the distal part of the this one, we're probably okay if we're getting the right bundle and there's no left bundle branch block, we're probably okay. It's the narrowest Urs. And if we only get myocardial tissue, it is septal my carding. And you'll remember that the septum in this region, the fiber orientation. Like if we look at these fibers here, they're all parallel and very similar to the left and right bundle orientation. So even though that's technically muscle, the muscle is oriented in a way to mimic the way in which the conduction system leaves this region of the heart. So those would be all plus points. But the minus points that we would have in this region would be we definitely have to cross the trekkers program. So that's one of the main reasons we're doing this, That wouldn't work so so well and if someone has a high stepped of infants then we would have a narrow zone where we would be able to get this cap. Anything else you'd like to add to that object? I think this is fantastic. Even your panel be actually kind of off topic. But you know why people get complete heart block after tower. You know, one of the things is if you have a low seated value in the L. V. O. T, you know, one of the reasons why they have complete heart block again would be your compressing on that structure, on a lower from the lower side of the valve and which can cause complete heart block. Which you can see from Panel B. I think Panel B also two shows you not only is it really hard to get to that hiss like when people are saying true hiss, but if you're at that member this septum and you screw in you'll end up in the L. V. It could be. It's interesting that that hasn't been reported. Which also makes me think we're probably putting it into muscle otherwise out of guests would have seen quite a bit of that. Now is this another question here? Uh That the question is from dr lewis about premature atrial bees premature. It will be it's anything about locations that tell us there is a predisposition to atrial fibrillation. What do we know about natural history of PFCs and likelihood of getting atrial fibrillation of the shape? You want to take a shot at that one? Sure. So we know that the majority of the triggers for atrial fibrillation start from the parliamentary events and if you look at how, if it gets initiated a lot of times, it is the Pcs or non sustained attack which could potentially set off metal fibrillation. Now, the question is, is there an absolute ph burden which we should be aware about for setting off metal fibrillation? I'm not clear about an exact number, but there have been epidemiological studies which have been performed which have looked at various pieces burden, but a general, if it is about more than five or 10 based on some studies, then there is a risk of having it real or at least those patients may have. It'll fibrillation, but again, it'll fibrillation as we all know is so complex be beyond the trigger. It is also a vascular disease. It is a substrate based disease. So there is a lot which will go into it for genesis of fatal fibrillation. Right. Thanks appreciate. So another question here about is we've shown the A. V. Node but the question is left side input to the baby. Known, where do we look at for the bleeding? The left side input to the north. Maybe I'll take a quick shot at that and we'll use this bigger that we saw a little while ago. So just to kind of understand like concept of these inputs to the every known A V node is going to be a septal structure. But notice if any Mile Kardian wants to reach the final, whether it's anterior inputs or posterior inputs to the every known we have to start off the symptoms and then eventually encroach onto the septum to reach the arena. And this is the an atomic basis of discrete inputs to the avenue. Heavy notes on the septum but not much else safe. So any other way we get in there, we're going to have to have an input rather than just any non spark getting to the So specific question here is about the left inferior. So this is where we are imagining the be known. We see right my accordion. This can encroach up here region of the coronary sinus osmium and come on the left myocardial, left atrial myocardial can also come up to that region. But because this septum separates out at the criminal space and because the A. V. Node artery is coming right in the middle here we don't have a single posterior input. Today we know we've got a right inferior important and we've got a left inferior. How do we a blade that left inferior input? Well one option is to get into the coronary sinus, go towards the roof of the coronary science, staying away from the septum which means staying away from the ecosystem of the coronary science and pointing atrial that would give us uh ablation of this extension of the air in order to receive the left inputs towards the. Another option is to get to that same location but trans septal and then getting our catheter down to the street. Some folks my own preference in cases where it's clearly that's what needs to be insulated and by that I mean that's the retrograde limb that was mapped or the anterograde limb that was mapped. What with entrainment. To show that that's where we need to have played is to do both. Both the C. S. Approach as well as the approach mint. Uh hopefully that answers the uh that question. Uh any other questions that any of you have seen that you'd like to highlight or if someone would like to come up here to uh to ask one of the attendees was interested in, you know, if you could explain the A. V conduction system access in C. C. T. G. A. Okay, sure I can do that. And then let's see, maybe I see another question here about um damage. I believe what the question being asked is damaging the left bundle easier then the right bundle. I think asking like 100 branches if we were to a plate, is it possible to a blade? Is one easier than the other? So maybe while I'm pulling up a figure about conduction system in C. C. T. G. A. Maybe server, Do you want to take a shot at that question about damage to the infra radiation conduction system? Yes. So in books we, when we look at the pictures, the left bundle is commonly depicted as just to two branches downstream. Usually it's a very simplified explanation of that and it's the imprecision system on the left side is far more complex and you have multiple branches in general. The right bundle structure after it after it traverses away from the member and a septum is a little bit more superficial structures, thinner structure and once it is subir Gokarn real that area we could potentially even it caused transient block by pressure in the right bundle region compared to the left bundle region. Left bundle at least approximate left bundle is a thicker structure, bigger structure and his southern do cardio. Potentially you could blade the proximal left bundle. ah a part of the proximal right bundle can be intra muscular and could be difficult to a blade. Sounds good. Um So you know, let me use uh a just a diagrams appeared to talk about CCTV to and we do have a special session that will give you the dates or shortly where we'll have one of our cardiac pathologist dr Melanie. Boys will be a guest Panelist and we'll have actual king congenital heart disease specimens to look at the common issues for electro physiologists. And the boys will have a C. C. T. G. A heart. We'll also have a post mustard heart in a post Fontane heart for session one later in the year will focus on tetralogy of fellow in some of the Bt Congenital heart disease. But to give a quick answer to uh the question that was asked. So, first of all, a couple a couple of things. So when we think about the normal heart conduction system, we had a tv note here, we had the his bundle here. So single his single lady note connection. One access to get down Now in C. C. T. G. A. We could can get a second a be known with its own his bundle and potentially linking up with this to produce like a sling or a monkey bird slink. Now one of the things the clues and C. C. T. G. To anticipate a second conduction system access is if the right ventricular outflow, the infanta bilham is small, smaller the infanta bill um of the right ventricular inflow, the more likely you are going to find this situation. And this can make SPT ablation in CCTV quite confusing because it's possible to get a V. N. RT Related to either of these a vinals or possibly both with slow pathway input to one and exit through the fast pathway to the other rules of thumb, once you've recognized it, his first try to define which a V. Node is conducting really well. So we identify his, we identify another his we face the atrium and see which tends to block first. The idea is to understand in our own minds if we a blade one of these A B knowns, are we leaving the better conducting if we know the law. So that's one 2nd is with induction of tactic cardia to have multi electrode catheters on both his bundles. So we have say 4441 proximal distance. And if we see conduction that's going approximate two distal in one of the users And distal to proximal and the other one. Then we do have a sling type attack cards. But if on the other hand, if it's a proximal to distal and both, then that's not it. It's not enough to just a blade one of the nose. We've got a super ventricular tachycardia, possibly. Maybe not reentering. That's just using this this tissue as a bystander. Like in ah living Audrey entries going from proximal to distal. So we'll have to a blade the A. V. Node reentry either with our standard approach or mapping and train mint mapping to find out a key part of the circuit and M. Blatant. The other difference to keep in mind with C c T. G. A. And for that I'm just to uh share here is to understand that the non coronary sinus. So if we look up at this bigger here. So if we notice here this is a very beautiful dissection from dr Damian Sanchez quintana and it shows this central location of the hieratic bam. So we use this aortic valve as our land months, non coronary sinus versus right coronary sinus, this bundle and we know sometimes anterior inputs to the every note can be a blatant, say from the non coronary science, several reports now and something recognized some years ago with anecdotal cases in C c T G. A. We should remember that this well, the central valve in the heart, it's not the biotic bell but the harmonic them. So the central valve is the harmonic value and that's why in tough baby in our T and c c t G. A. Some of the ablation that's successful is in the posterior RV. Okay, because the posterior our bot and harmonic well, is the equivalent of non coronary sinus of ourselves ablation in CCTV. So I don't know if you're chatting with the person who asked the question, Siva. But does that kind of give a brief answer to that question and then we will have a special session for sure. And maybe if we could bring up doctor uh cannon to just comment also about unique issues of C C T. G ablation, particularly in the context of avoiding conduction system damage. And would you be able to do that for us? Russell it? Yes, he said no brian uh anything uh and uh had to, so it was just uh we will definitely do a focus session later, but just this specifically for C C. T. G. A stuff that you keep in mind when thinking about conduction, system location, pulmonary valve, pulmonary outflow. Yeah, I mean it's it's an excellent question. I think before you do any ablation on a congenital heart disease patient, you should try to figure out where the A. V. Note is and a couple of things is typically Baby Note will run posterior, but in C. C. T. J tends to run more anterior. In addition the no because of its position around the DST and around the valves tends to be not quite as stable. So they actually incidents of 80 block is about 2% per year. So you have to be very careful when a blade because the Xavi nodes are not strong and a lot of times they don't function well. As you mentioned, the other thing is that the septum instead of being activated from left to right is now activated from right to left. So actually one of the clues that you may have congenitally corrected T. G. A. Is you'll see a Q. Wave and lead the one rather than be six just because of that opposite activation of the septum. But these are patients are at risk for accessory pathways. It's one of the higher incidents, but sometimes you have to make sure before you played the accessory pathway that the A. V. Note is actually there because they can have a V. Block underneath and some conduction is better than no conduction. So that's my couple of comments. Thanks and great. Uh So you know, maybe maybe I can just draw a little sketch about the E. C. G. Issue that brian brought up. So this is a normal symptom without ventricular inversion, just the normal right ventricle, left ventricle, we have right bundle here, we've got left bundle here. Few of the things we remember about right and left bundle that's slightly different is the right bundle in addition to taking that little intro. My accordion course we talked about is also slightly longer in terms of its insulated portion before it breaks out to ventricular muscle. So because the left bundle is the natural continuation of that is wonderful because it's slightly shorter to segment that it has installation and you wind up exiting on the left bundle earlier than the right money. So as a result you're normal conduction across the inter ventricular septum is left to right. This is the normal heart, and as a result, we have the so called physiological or septal Q waves In V five, V 6 Activation, moving away from the five should also be noted that from the exit of the left bundle of the usual exit of the left bundle on the posterior massacre fiber orientation is slightly angled from inferior to superior. So not only do you go left to right, but you go from posterior to anterior go higher. And that gives the small Q waves that we see sometimes in the inferior leads, especially in heavier and and sometimes all the inferior with small septal cubes. So brian's point is when to suspect ventricular inversion, just from the electrocardiogram is when in C c t G. A. The ventricles are inverted. And when the ventricles are inverted, we also have in version of the conduction system. So right bundle is now on this side, left bundle being on this side. Now this is shorter. This is winning the race and we're moving this way. So now we lose our septal q waves and be five visits. In fact, if we had right sided leads, you'll see the septal Qiwei there and in those leads uh for this. So just E C G variation in uh C c T G conduction system. So if we know what we talked about sling multiple A. We know potential for pathways and then this natural difference in the radiation conduction system. Now I see one more question here in the chat. Any others that any of you would like to bring up shake? Uh Chris I was just pulling up by, we had done in a patient with C. C. T. J. To show the small acute marginal veins, but I'll just bring it up and then show you in a minute. Here. Sounds good. That would be great. So that's another question that comes up sometimes when we think about C. C. T. D. A. Is not only the conduction system itself and but the veins the ventricular means. So it's right ventricle which is on the left side of the body. And we know the coronary science keeps time with the atrium, the annual list of them. So coronary sinus is normally located. But what about the ventricular names? What do they do? Ventricular veins go with the coronary sinus. So will they be left ventricular veins or because they're draining the right ventricle? Will they be right ventricle events? Very small, small marginal vessel? And the answer answer, bishkek is going to show us is even though the CS is normally located, the veins keep time. They go with the ventricle. So it's right ventricular things very small, tend to be very small. On the other hand, the septal veins are still like normal. So the anterior inter ventricular vein and the middle cardiac thing are like the normal heart. So if we just have to get a lead in a vein, we tend to target one of the symptoms because it can be tough to get a lead out in one of the small things. Have you shake you wanted to share example with us? One thing I will put it up, put it on a slide. Give me one more minute. I'll do it. Okay So maybe while while you're pulling that up I'll just make a little sketch on what we're going to see here. So we see a coronary angiogram. Mhm. If coronary venus and your grand or a lead position the proximal part of the C. S. Will look normal and then we'll see a rubbed tapering and then small marginal vessels and then coming back more towards the symptoms. Sometimes an anterior intra ventricular vein that's fairly normal size. So approximately us middle cardiac vein will be okay but lateral veins will anticipate being significantly smaller than normal. Do you have that big rub shake? Okay so talk us through what we're seeing here. This is an area of you were trying to do an angiogram of CS venogram to put in a. C. S. Lead and here you can see as we engage the coronary sinus. These veins are quite small very very small branches. Um You know so sometimes lead deployment is difficult. Sometimes thresholds are you know very high impedance is very high because of the smaller tributaries and smaller branches. Sometimes the question also becomes can be completely re synchronized this ventricle which again is going to be very difficult to do this. So at least what I try to do is try to find an opposite factor. Maybe get the lead somewhere higher up and then see if we can you know base that way. Great thanks adam. Uh Other other questions that anyone has their otherwise I have one more here to address. Let me know if there's someone who wants to come up and ask a question. Uh So question here is a bit of a bit of a difficult question but specific areas in the infra asian conduction system prone for arrhythmia, the word parking G. Or infrared vision conduction system. So maybe I'll start with just a slide of what it is we mean by infra radiation conduction system and I'll ask maybe dr DeSimone too. Have a nice slide to show to show if you want to take a peek. Um Yeah well first let me just. Yes. And so just first of all, it's important for somebody to remember that the infra radiation conduction system is far more complex than we normally consider. It's not like, you know, here's the money, here's the left post later festival, here's the left inferior septal classical. It's really a network and that network is relatively discreet towards the annual list towards the historical region but gets very very intricate in the mid septal region at the level of the papillary muscles, and then gets a little bit more discreet as we get towards the apex. So in other words, the chance of getting very complicated circuits, circuits nonetheless re entering but highly complicated circuits is possible in this mid portion of the ventricle, whereas more distinct particular type tactic. Our ideas more proximal or occasionally when much more disturbed. I think also important to kind of remember here, the whole is the region of the membranes septum is that there's a difference when we just say infra asian collection system, there is distal filigree like Kinji network which at any point can connect to the ventricles any point. There's no installation. The only reason we see distinct signals in that level of the conduction system is the orientation of these specialized fibers, whereas more approximately we're seeing this kind of insulated portions where distinct circuits, relatively larger circuits are possible. Whereas here almost impossible to define what are the components of the circle circle there chris you had some questions, some comments you wanted to make. Yes. I just wanted to share the screen. That's exactly actually the figure you show. Okay. And then any comments that you have one that please go ahead and then well I say there's a couple more questions that came, including one by the meal, will definitely address. It, will kind of go over it and added to youtube. Bring it up when we start our discussion next week. So chris go ahead and we can finish up with that so everyone can see what I'm showing. Yes. Okay. So I guess lower down that you said. One thing to mention is this false tendons where connection system could be running through these actually. So I really like this picture shows that it's not really an easy system as we go From proximal down, two more distal and absolutely things like vesicular Bt or this prick, Kinji PVC triggered BF could be around these areas. But I think the question that was asked is a tough one and maybe we can even devote a longer nice discussion too is any area in this conduction system? It's more a written majestic. I think what's being meant is more likely to give malignant arrhythmias like via maybe we'll keep that as a dark, we'll try to discuss that a little more fully and add that to the youtube along with one other question that I see uh just come up there but thanks thanks everyone for joining and please keep the questions. Feel free to ask any manner. That's good. Send an email to any of us. If it's something you need urgently addressed before the next webinar will address it to you directly through email or give you a call. If not, please submit them online. More cases that you have questions from your own practices uh nicer than it will be. Uh dr Majumdar your question as well. We'll make sure that we get addressed in the add on which will post on Youtube thanks to them. Okay, so we have a few questions that we didn't quite get to and will give brief answers. Some of these will discuss in more detail in subsequent sessions. So the first question that came up was related to where can we damage uh, the conduction system while doing transept of function and maybe I'll take a shot at that. And the other two questions were just an extension of the for Kinji. I read more Jenness city and uh also about uh the tab asian vessels to be seen vessels while we are trying to uh trying to Kanye late in C. C. T. G. So let me start with the issue of trans septal puncture. I think the key view to kind of try to appreciate transept er and damage. He's probably looking at a real sort of like this. So what's really dividing the fossil Vallis which we see here? Kind of a natural continuation of the abc? And the conduction system. Triangle of coffee is the station lynch. So conduction system compact, every node is going to be ventricular and inferior to the angle of the station rich, whereas the fossil Vallis transept of puncture side is going to be atrial away from the ventricle and superior and cranium to the station bridge. So that's going to be a safety for understanding. When will I not damaged the conduction system. So how does this wind up happening sometimes? So the times when you get conduction system damage during transept of is with an older technique for transept of today, all of us go up to the spc and then come down on the I. B. C. S. P. C. Axis, engage the faster and do the transept of. An older technique was actually to place the shape and disengaged needle towards the ventricle and using clockwise torque to fall into the fossil various. And while this technique definitely works and some people have done thousands safely using that technique. If we haven't talked enough, if we haven't brought it all the way back here, say we're looking at an empty rather than an aerial view and it's possible we wind up trying to puncture here. The other situation where this can happen is a conditions where the youth station reaches vestigial, very small in almost all normal hearts. Thing station ridges prominent. That's what kept mothers oxygenated placental flow in the fetus, directed it towards the patent foramen new volume. But in conditions where we actually want blood flow to go to the right ventricle. So this is situations where the right ventricle is the systemic ventricle. They're the bigger the U. Station ridge, the more difficult it is to maintain the flow into the right ventricle. So conditions like double outlet, right ventricle. Indeed, G. A. In double inlet, right ventricle. In situations where we don't want the station ridge, often it's man developed. So in those patients after correction or if they have a trail of indians and we're trying to engage, we don't have this natural safety and we can go towards the conduction system. Now, if we have successfully done transept and were specifically trying to have laid on the surface if after we have done the transept, er if the ablation categories in the same plane is where the transsexual is done, we're okay. But if we're on the symptoms, but the plane is more interior, closer to the ambulance, then we're going to be opposite the conduction system. So maybe I'll draw a quick picture here before we go to our next question is the key view is going to be the barrio view. So, in the L. A. Of you, what we already saw is we're here by the faster and we've crossed and we just see the catheter curling back towards the septum. We don't know if we're in the same plane as the transept er meaning saved or we're in more interior plane being unsafe. So we could know this by looking at how big is our ventricular electro graham and rule of town is the ventricular electro grand If it's any bigger then the atrial electro graham. We're not in the plane of the fossil various. But this also depends on how biggest the ventricular tissue. How healthy is the atrial. So we can also be very sure by looking at the aria view. If that curled catheter is in the same plane is where we cross the plaza. In an R. E. O. View where the CS is coming right out at us approximately 30° are real view. We're probably safe. But if we see the catheter more ventricular then where we do the transept um And in the L. A. Overview we have it going back onto the symptoms. You can be sure there's conduction system nearby. So for example, napping and left mid septal pathway. If we see the pathway potential leo here, are you here? The only way you're going to a blade. There is either with test trial or with the patient already consented for a basement to combine use and understanding the rolo views Fossa versus you station rich versus conduction system. You can usually make that mental correction. So maybe we'll go to the next question here and we'll save the question about for Kinji arrhythmia. Maybe for a more detailed discussion uh next time. But I'll ask dr decision to address this question about tab asian veins and Kanye elation uh for uh patients with C. C. T. G. I believe that was the question. Is that right of the ship? Are you muted a vision? Yes. Okay. Maybe show us that. Maybe we could start by showing us that venogram that you had that you briefly showed us during the main session. And let's see an example of a vein that we're not used to seeing. And try and say if that's the vein that we need to consider. And then maybe you can show us some examples from the literature of the busy in vain calculation. Sure. So this is again the aereo view which we are trying to show and let me just make sure that I can see it perfect. So run that you ensure us the vein of interest as you're showing the tools. Yes, So this is the area of you. We are engaging the main body of coronary sinus. These are the marginal veins which are going towards the right ventricle. But if you see here you will start to see some branches which are coming more. Or I wish you can see these branches more. eight. Really, this is a little bit better seen in the L. A. Overview where you can see these small branches more on the superior aspect. Which could certainly be the veins which we may want to target for pacing. So I be chic. Maybe it will be good to say something about like definition wise. What do we mean by the busy in vain? So sometimes we just fall into vein that's not in the coronary venous system. And we hear different words like to busy in vain prominent atrial vein intra my cardio vein or these remnants of the cardinal venus system. Direct l wrecked labour retro atrial cardinal vein, extra retro. It'll cardinal vein. So you know like among all of those, what would you what's your guess on what that means that we're seeing in the C. C. T. G. A patient? So this in this picture at least you can see it is going kind of very superior early. I initially thought this could be the division win but certainly could be the vein which you pointed out. Which could be following the left sinus nodal artery going around the roof of the left atrium. That is certainly possible. Yes. So maybe I'll just draw a quick figure here for those definitions. So if we if we look, you know what we mean by the busy and things is that my cardio veins that drained directly into the cavity. So they're not actually draining into some epic arterial venous system but they're going straight into the cavity and a lot of the right ventricle actually drains directly into the cavity. So those are like physiological busy and things. Everybody has this. But one of the things about the television veins is they're not really longitudinal things. So they're really myocardial veins like sinus sides that then just rain into the cavity. Sometimes we get a catheter wedged into one of these veins. Sometimes are pacing lee looks like it's perforated or gone deep into the my accordion. And we're probably engaging hey to busy and being there. But when we see a distinct waiting like a vein that's not just opening into the muscle but then goes for a distance and then drinks this portion is to be easy in the sense that's not an if the cardio vein coming and joining with the coronary science but these often in high pressure or winter, other normal venus system is not developed well could be normal veins like veins like the vein that accompanies the sinus nor the red. We also have these cardinal vein remnants that connect with each other either in front of the heart of behind the heart, liver retro atrial or extra retro atrial cardinal veins. These are causes of physiological shunting and these can also be very large when left side of venus pressures are learned. Now the question is can we use these veins or any of these veins to actually put a facing region. So maybe we'll go back to dr dish milk and you have some pathology specimens. Some examples of mm veins like this. Talk us through this movement. Can you see this? Yes, this is the right atrium. We have cut it open and you can see these prominent orifice is here which is basically the television veins. And we could certainly calculate these veins accidentally or by design certain places where we would consider doing that would be saying patients who have significant valve regurgitation and you don't want to cross the valve. Certainly if you are able to engage into these veins then certainly the ventricle can be potentially paste another example here you could see sometimes they can be quite small that it might be difficult to engage them. But a lot of times you might find some you know some veins which might be large enough to accommodate a pacing lead. So here also I think it's useful to say like truth a busy and veins we're not going to be able to track the lead. But if you have a normal vein that has to be easy and drainage that is it's not connecting to the rest of the venus system. That becomes option. Now. Some people would call these as aberrant venus Greenidge. So instead of that vein draining into the C. S. Just training directly into the cavity. Or we could also say a normal vein with a busy and range. But how will we know that these are them? If we wanted to use to target or placing and big any anything said about any tips for finding these wings for us to be able to candidate if we wanted to. Well, you know one way is um if you can use intra cardiac echocardiography, if you see like pits, you could try to Kanye late and you can visualize the catheter going in. The other clues are the areas where you have a prominent ambition main. Usually there won't be an epic cardio venous drainage. So that's something that you can consider ah in those patients. Yes and maybe allowed a couple of things today. So you know this venus drainage and it's coming into the cavity. So one technique has been atrial or ventricular and geography. The problem with just doing a right atrial angiogram are uh right ventricular angiograms. Most of it is going to be back. So it is possible though to do right into angiography. And just temporarily balloon include the S. P. C. I. V. C. Or both. Just very temporarily. So we can see that backflow into the wings. Another technique and maybe I'll draw that is to do CS and geography. But with an end whole catheter and balloon occlude the proximal Sears. So here we inject here we have very few branches and you're forcing to see where these aberrant veins or venuste real television drainages. Another technique is to do coronary angiography, Look at the venus space but do the injection with balloon including of the coronary venus last. So you're kind of mimicking the venus base and geography and patients with coronary sinus increasing. So you see what are the other ways in which the myocardial veins can drain. And then you save in a biplane floral where that asked him looks like it is and then think about trying to calculate their but great questions. It's really nice to get these questions and we'll do our best to answer these, either directly to you or in these small and on sessions. Thanks a lot everyone. Published February 3, 2021 Created by Related Presenters Samuel Asirvatham, MD Cardiac Electrophysiologist View full profile Abhishek Deshmukh, MBBS Cardiac ElectrophysiologistCardiologist View full profile Christopher DeSimone, MD, PhD Cardiac Electrophysiologist View full profile Siva Mulpuru, MD Cardiac ElectrophysiologistCardiologist View full profile
