Sorry. Hello, everyone. I'm Patty Larkin. I'm the product manager for the EP Device Impairment Registry. Thank you all for coming. This is going to be an excellent talk. It's going to be very informative. Remember to ask any questions at any time through your mobile app. Go down to the presentation at the bottom. There's a Q&A button. You're probably most familiar with that. So I'm going to introduce Dr. Matthew Olson. Hello, everybody. Too loud. I'm kind of a loud talker. I probably don't even need the microphone here. So I'm one of the electrophysiologists at Minneapolis Heart Institute up in Minnesota. I wanted to talk, I was asked to talk about left bundle pacing, conduction system pacing. I'll start out by saying I can confuse myself amongst all of my colleagues, amongst cardiologists, electrophysiologists, et cetera. This is going to be an exciting but difficult topic moving forward over the years to come. How do we apply it? How do we apply quality to this? How do we actually measure is it appropriately done or not? It's going to be pretty hard. And I'm going to dig deep into the weeds. You know, if you need a quick breath of fresh air, just raise your hand and I'll stop talking for a while and we can digest some of the things. But that being said, my goal here is to kind of delve pretty far into this topic, understanding that I'm not expecting you to have a deep comprehension of exactly what we're doing, but to make you aware of some of the things you may see and some of the things you may hear. Disclosures, I do consult for Medtronic in our research and development, faculty only. I was an engineer in a prior life. I call myself a recovering engineer. So I do spend some time with the R&D team kind of enjoying some of those design and product development aspects. So what we'll cover today is some anatomy. And believe it or not, anatomy is going to be essential for nomenclature, for understanding what we're doing, et cetera. How do we do it? How do we put this lead into place? What do we look at? What are some of the complications of that? And I think one of the things and probably the hardest thing to comprehend, hardest thing to also, we don't have a great answer for yet, is what are the absolute and relative determinants of conduction system or left bundle pacing? Is it a home run? Is it a triple? Did you strike? Did you strike out? Like, how good is it? And that's really the question that the field needs to answer yet. We don't have. Is this a third? Did you get a triple? Is that good? Is that good enough? Do you need to hit a home run? Where do we need to be? And then finally, some of the clinical data and a brief discussion on future direction. All right. So I'm going to start with a case just because I think this illustrates, you know, Danielle, she has to suffer through my commiserations when we go through our quality data. But I grabbed this because it illustrates one of the things in the field we run into with, do we take out an LV lead? We get slapped on the wrist, right, because we took an LV lead out because it wasn't, we put it in or we couldn't. I should say this. We as proceduralists like to succeed. So if we take an LV lead out, that falls into our inability to deliver an LV lead. And we all are A students. We all want to get 100%, right? So there's that challenge here. But I'm going to present the case where the data is to be determined, but I have my feelings. But anyway, so pretty classic 80-year-old gentleman on goal-attractive medical therapy, non-ischemic myopathy, EF 40%. Class 3 symptoms. So he meets pacemaker indications independent of his heart failure. He has intermittent high-degree AV block, left bondole. The plan was for a CRTP. So underlying EKG, wide left bondole. In some things you'll see is that the left bondole, depending on how sick the patient is, et cetera, can vary by 20 milliseconds. You might see one in an ECG where it's 140, the next day it can be 165, et cetera. So this left bondole width varies, which is why sometimes I worry about getting the ECG the day of the procedure when you have one a week prior that's longer, because if someone just looks a day off and it's 142, and you're like, well, what are you doing? You don't technically meet guidelines. So that's just where we're at here, 160 to 170, pretty clear left bondole. I want to show this picture to have you understand kind of what are we looking at. This is the right ventricular lead, which you all see. And then we have to gain access into the coronary sinus. We have to inject contrast into the coronary sinus, illuminate the coronary sinus, and find a vein to put this lead in. We are beholden to your God-given anatomy. We don't get to choose where this lead goes. It goes where there's a vein available. The main downfall of left ventricular synchronization pacing. So you can see there's kind of some funny anatomy, but there's one vein. There's only one vein that I can use. And it was actually somewhat difficult to get into due to some valves, et cetera, required a couple techniques, but I was able to deliver the lead. So get the lead into place, pace. We have phrenic stim way above threshold. So any pacing threshold, we've got head phrenic stim on leads two and three, which are the middle two here. And then leads one, electrode one and four, have high thresholds, okay? I tried to pull the lead back, didn't capture it all. So this is the only place we can put this lead. The high thresholds, we're talking about three volts at a millisecond, which is a lot. You're talking three to four-year device longevity. So I have this really nice conduction system lead in place. I have this kind of, so what would be acceptable? We would always take this seven years ago. Should we take this now? What should we do? What's the best thing for the patient? How are we getting followed for our quality? What is considered a good result, right? So I left it, and we'll go on to why I did. And lo and behold, clinic follow-up one week. You have to trust me on this, but we're actually not even capturing the LV lead, all right? Beautiful looking QRS. So if you look really closely, this ugly wide spike is what we call unipolar pacing. That's when we apply the most energy to single. This is what you'll see when the device is saying, oh, crap, things aren't working, and it ramps up power. You'll see this wide spike. You don't really see anything, and then after this, you see this little spike here. This is actually the conduction system pacing lead capturing. So you have to ignore all the black marks, and as you can see, a pretty narrow QRS. The QRS is about 130 milliseconds. So what I did, oh, here's the data. Brand new device, one week out, 2.2 years of longevity, okay? And this is not, unfortunately, it is, it's not common, but it's not uncommon, right? Nothing makes you feel worse than saying you got a nice device, but you're going to need a gen change every three years for the next 15, you know, for 25 years. That's a lot of risk. I always say for gen changes, this is technically the easiest thing I'll do all day, probably the highest risk thing I do all day, okay, because of your risk of infection, complications from infection. This is a horrible long-term outcome for the patient. So I just turned off the lead. I left the conduction system pacing lead in place, 12-year longevity, all right? In the retrospective scope, I should have just put in a dual-chamber device, cheaper device, less flow of time, faster to put in. But we're in this gray period, and this is one of the things that I brought this case up because we don't have the right answer. Let's say that was a great LV lead. Is that what we want to do? Do we want to optimize a CRT lead and the conduction lead? There's a lot of questions here. So moving on, anatomy. The conduction system, it's a pretty graphic, but just a brief background on conduction. As an electrophysiologist, we have the sinoatrial node. I call it the timing belt of the heart, and for a normal heart, it essentially sets the heart rate. You are beholden to the autonomic inputs, hormones, et cetera, that drives your sinus node. It's a beautiful thing. That's why you can go from sleeping to running down the hall in seconds, and your heart rate adapts appropriately. The AV node, the most invisible structure in the heart. Can't actually see this thing. We can record electric potentials everywhere. We can't record the AV node. You can only record what you put into it and what you get out of it. It's invisible, but it works really well. One of my mentors, I like to say, the AV node exists to stave the ventricle off from an atrium gone wild, right? So it's essentially there as a regulator to keep the ventricle from going so fast. And then finally, the conduction system is broken down into the His bundle, which you guys all have probably been looking at, His pacing, right? So the His bundle. And then it bifurcates into the right and the left bundle, and then further into some more complicated aspects of the mid-to-distal conduction system. So we'll go into that a little bit. Purkinje fibers. So let's go back to Purkinje fibers. Why does this work well? Speed of activation. This work was from 1970, which is pretty amazing. I wasn't even born yet. I wasn't even thought of being born yet. So two to three meters a second conduction, right? That is very, very fast. That's one of the fastest conduction speeds in the body. And the myocardial, so a cell-to-cell, which CRT does, it doesn't activate any conduction system, 0.3 to 0.4 meters a second. So very slow versus lightning quick. The conduction system isn't something that we randomly just discovered. 1906, Tawara has this beautiful dissection and hand-drawn graphics of what he thought the conduction system looked like. And what you're seeing is the proximal part. So to get into anatomy, how this penetrating bundle goes from the right atrium, which is technically the hiss on the other side of the heart, to the proximal left bundle, which is right here, and then injects itself into the ventricle. I always tell patients, how amazing is it that within 80 milliseconds you can activate every single myocyte in your heart in 80 milliseconds? That's amazing, right? It is truly incredible. And it's done through the Purkinje system. And it was figured out 1906, which is, I think, it's withstood the test of time. Every electrophysiologist knows this picture from the good work done then. All right. So here's where it gets interesting for us. I'm not going to spend too much time. There are multiple variations on how this conduction system breaks out. Hiss is the proximal. Just remember, hiss sits in the right atrium. Once you get into the left ventricle, it is game over for knowing what you're going to be dealing with because the nerves go everywhere. It's kind of like the veins in the CS. They are where they are. But for the most part, the majority, there is a broad, wide breakout. Occasionally, you get these narrow bundles. And why does that matter? Because one of the rare things in cardiology, this is more of a horseshoe and hand grenade approach with conduction system pacing than throwing a dart. Because if you get something in here, it's going to get into that conduction system pretty quickly. Where, unfortunately, the rare ones like this, if you put a lead in the middle, it's not going to be as effective. But this is one of the few things where being close enough is good. And by close enough, capturing the conduction system. So here is what was drawn. You can see there's, we're not going to say there's type 15. We don't really look at delineating these. But this is just to illustrate to you that anatomy and complexity. One of the optical maps, which I really like this picture, what it shows is when you activate the Purkinje system, this is what it looks like in real life. So you can see it's high variability and distribution is broad. Okay. Implant technique. Any questions yet so far? This is, we're going to get into a little bit more of the weeds here. But without that background, it gets a little hard to do that. So I will say that Medtronic equipment is what allowed this to originally be pioneered. And I would say it's probably the safest. All the other companies are developing techniques. The challenge is the lead, all right? So this 3830 lead is very small. It's 4.1 French. It's roughly half the size of all other pacing leads or two-thirds the size. And so it's hollow body. What that means is that there is no helix that goes into the heart muscle like a corkscrew and extends back. Most leads, you extend the helix like a line opener, you twist out, and then you can twist it back. This lead is fixed. You actually twist the lead to advance it. So there are some benefits to what we call tunneling through the septum. So it's 4.1 French or 1.4 millimeters. And when you're used to working with big, beefy ICD leads, the first few times, these are like working with angel hair posture, right? That's actually about as close to what this is. And then the distance, and this is what we use a lot, is this spot here is the radio-opaque ring electrode. The ring is the proximal part of the capture. You've probably read bipolar pacing in reports. What the heck does that mean? It's a disorder, which my wife says I may or may not have, but also it's pacing from the tip, which is the helix, is the one part of the... So this is the red part of your battery, okay? And then the energy, it sinks to the ring. So that's bipolar, meaning you're trying to capture a more finite, a broader region. You get this arc of electricity that polarizes the myocardium from tip to ring, or bipolar. Unipolar, which you saw earlier, that big, ugly spike on the ECG, that is taking just the tip. So this is a really small helix. It is roughly, it's about a couple millimeters in length, okay? And you'll pace from the helix all the way back to the can, whichever can it is, if it's a pacemaker or an ICD. What that does is it creates a very focal spot within the myocardium that you're activating, just the very tip. But the sink portion, when it accepts the energy, is very broad. And so it's a big antenna, it creates a big pacing signal. So if you can, for the most part, see that pacing spike, it's unipolar. Then finally, what are our delivery sheets? So unlike all other pacemaker leads, you put a small catheter onto the myocardium and you hand turn this lead in. So that's one of the key things to understand when you get to complications is, my turn is not your turn, is not your turn, meaning how much each rotation, how do you standardize that? I do three turns, well my three turns is your five, your two is my one. So that requires a learning curve, right, as to what your rotation, and on top of that, that one turn doesn't translate into a singular rotation of the lead in the muscle. Unlike the fixed helixes, that actually, when you turn, it goes out a fixed amount, comes back a fixed amount. This is much more operator dependent, and you have to understand some of those implications. So moving on, maybe, there we go. So this is just a picture of the lead. I just grabbed this to show the nice thing you have in aortic valve that kind of gives you some idea. I use contrast, and most people use contrast just to inject a little contrast to make sure you're on the septum, right? This is the right ventricle's thin. If you're in the wrong spot with this lead and you twist it, it's going to pop right out of the free wall. So you really have to be conscious of that. And on top of it, what I'll tell you, and you can see actually a little faintness right here, that is a left anterior descending artery. In this view, the left anterior descending artery goes right here, okay? So if you're in the wrong spot and you screw it in, it's actually, ACS is one of the rare, very rare complications, is not knowing where you are, tunneling lead in, hitting the left of the artery. It's very rare, but you gotta know about it. So, this is, the Europeans just came out with a very nice update. I'll reference it a fair amount because it's, I think, the most comprehensive and has some nice graphics in the process. Well, nomenclature is a real bugaboo right now for what we're doing. So what you'll see most commonly people is left bundle pacing, all right? But that's actually a pretty broad, broad topic. So, what we've all, what's been around for longest, the grownup on the block, so to speak, is his bundle pacing, right? No one likes it anymore because it's high capture thresholds. It is prone to entanglement. It's higher dislodgement rate. It's a bugaboo to take out, a bunch of those things. So, I would say about four years ago, since then, I haven't put in a HIS lead, all right? There's, no one does this purposefully, but maybe there is a right bundle, so this lead could be screwed in just the right bundle. The most common thing, which I suspect we'll use the most, is left bundle branch area pacing. Like I said, it's a hand grenade, right? We're not, the precision strike, we're more determined by the ability of the myocardium to take the lead, the support of the catheter. This cath, this is, you're screwing a lead through the heart muscle. You have to utilize a lot of different techniques to be able to give that type of support to do it. So, you really are dependent upon the tools available to exactly where this can go, in terms of how it ends up in the proximal left bundle. This, I would say, we can control. So, there's left bundle pacing. This is the original work that was done by Dr. Wong in China in 2017. I remember being at Heart Rhythm Society when he presented this, and everyone was walking out of there like, this is crazy, no one would ever do this, this is nuts, this is not gonna work. And then, six years later, I would say it's the most exciting aspect of pacing that we've had in 25 years. You'll see left ventricular septal pacing. Notice how it's close, but not quite into the conduction system. And then, there's left fascicular pacing. The left bundle breaks into the posterior fascicle and the anterior fascicle, and I'll be frankly honest with you that the majority of the leads are probably right on this border of fascicular pacing versus true bundle pacing. Anything involving the conduction system is considered a conduction system. Pacing, the bundle branch and posterior fascicle, this is the sweet spot. That's where you want it to lie. This is really what you're shooting for is rapid entry into the conduction system. And then, there's this guy that nobody wants to agree that they've ever done, which is you put a lead deep in the septum and you don't actually capture any conduction system. No, no, trust me, that is capturing the conduction system, right? Because you have to work at this. Sometimes, you try to advance the lead and it doesn't go anywhere, and then, okay, how many times can I do this? How can I rotate it? You run into highly fibrous tissue, non-ischemic cardiomyopathies. You get that mid-septal stripe, which can be all scar. How do you get through that, and how do you do it safely? So, that's where left ventricular septal pacing hopefully is good enough. We don't know, but that'd be really nice if that's good enough is good enough, which is the opposite of what my seventh grade high school science teacher would say. So, this is a picture of a case that I did. What you may see if you're looking at kind of a bigger picture when you're extracting and looking at some of the quality stuff, echo can be exceptionally misleading. What do you think's going on here? You're like, that's in the ventricle. You've perfed, right? You see that, and that's the first thing. When we first started doing this, and we were getting a good understanding of it, you'd get a phone call from your echo lab. There's a lead in the left ventricle, and you're like, no, it can't be, because of a couple different parameters we'll talk about. I've done some work in the visible heart lab where we definitively replicate this, and the apical floor, which means you're sticking the probe out in the apex of the heart and shining it towards the atrium, the lead is perpendicular. Ultrasound waves bounce off metal in a perpendicular fashion, so what happens? What happens with that imaging artifact, right? It rings, if you look here, you can almost see how it's in a perfect beam, almost in alignment with the echo probe. So you will get phone calls. I help teach some people the technique, and so you will get phone calls, but if you, which we'll go through in a second, if you've met these criteria, and you're safe in implant, and you're capturing everything's unchanged, you haven't perforated, but it may look like it, okay? And that's one of the things that we'll get to in a second, that is, here is actually, before we get to that, here is a picture, this is from the, one of the papers that were written a few years ago by Dr. Vijay Raman out of Geisinger, and this is, you can see that lead is pretty far in here, but if you look here in what's called the cross-sectional view, it's in. What I wanted to point out, what I like about this, is you know we talked about is 10.8 millimeters from the here to here? Look where that contrast is shadowing. That's a long way into the muscle, all right? You're a centimeter in, all right? So as this technique gets broadened, being cognizant of this is really, really important, because in expert hands and high-volume implanters who understand what to look for, it's fine, but you can only imagine if you don't know where you are, I liken it to drilling a hole to hang a picture frame or a big TV, right? You might wanna know if there's a water pipe behind there, you might wanna know if you're drilling through an electrical, you might wanna ensure you're putting it in a stud, right? Those are important things. It's the same kind of process here. All right, not only that, implanting this lead, remember, you're turning it. You can't see at all what you're in contact with, at all. You can only base it on feel and electrical signals. So let's say I get a nice contact, all right? I start out, let's say I start out, I put the lead in, and I turn. But instead of advancing, you're drilling, I call it coring, you're essentially spinning the lead in the muscle, and it's 1.8 millimeters long. It's not very long, right? You spin, spin, and all you end up doing is denuding the local myocardium, and you're not advancing, okay? Then what happens when the patient coughs when they stand up? Pops out, right? This is the most common. It pulls back, all right? You go from beautiful left bundle pacing to wide. It almost looks like it's an old school pacemaker. No one would ever put those in anymore. But yeah, just joking aside, but it would look more consistent with what you would have done with the extendable helix leads. You put it in, okay? And when you slit this lead, you unwind a lot of built-up torque because it's not a, the catheter and the lead, the catheter's bigger than the lead, and as you twist that, there's built-up helical torque, and when you slit this lead, you get, I call, I guesstimate about a turn and a half. You gotta count for a turn and a half when you slit this lead because if you're here and you give, and that torque is released, you can pop through. And when you pop through, you've all that hard work. If you're in the right spot, you can, it doesn't hurt the patient because it's in the heart, right? It's bleeding into itself. But it's not, it's definitely not ideal. Even worse, there are very small septal papillary chordae that connect to the tricuspid valve in this area. By far the most uncomfortable feeling. You have to recognize it quickly based on impedance, based on torque feedback, based on inability to penetrate. You've gotta recognize it, that you're entangled. If you keep going, you're gonna wrap that thing into that helix, and you're going to dislodge chordae. All right? So, that is, having had a small, those are very small chordae. There is some evidence that it can impact the tricuspid valve, but those are the challenges of implant, right? You just gotta be fully aware of all of these. We watch thresholds and electrogram characteristics and current of injury, et cetera. So, this is an example of a case I did. I'm not, I don't want, you don't have to, this is for electrophysiologists, but the key thing here is what we see is what's called current of injury. It kind of looks like a MI here that's cut off because there's so much injury. And we look at the impedance increasing, 900. So, impedance is resistance. And as you go through the septum, it gets more resistive to pacing and then less. So, impedance lower, higher, lower, meaning you're up, mid, and through, poking to the other side, all right? The injury current, so what looks like how much you're injuring the myocardium, the less and less myocardium by the tip of the lead, the less injury current you see. If you don't see injury current, you're through, all right? Other things, you know, I should have blown it up, but you can see a far-field left bundle potential here. That means you're right on the left ventricular endocardial surface, no further, right? If you go one turn more or there's a lot of torque that you don't release, you can, and I've unfortunately done it, all of a sudden this electrogram, the current of injury disappears, the electrograms flip because you're now in the blood pool instead of the endocardium, and you're like, oh, that's not good because it takes time to get to this, and you don't like doing that. So, are you ready for the fun part, right? Because if I haven't confused you yet, buckle up, here we go, okay? So, there are four possible outcomes. RV septal pacing, consider this what you would any other pacemaker lead, but positioned more proximal in the septum. Deep septal pacing, that's what we had kind of talked about, that was that red circle, all right? Then we get to left ventricular septal pacing, which I didn't put on here, you're not in contact with the conduction system, but you're on the left side, and then the two things you'll see mentioned frequently, non-selective left bundle area pacing and selective, all right? This is similar, who remembers selective and non-selective HISS stuff, right? That was the same type of process here. What does it mean? Non-selective, actually is my preferred, is that you're in contact or capturing both the muscle and the conduction system, right? You're only getting one, you're getting both, and then you get selective, which means you're only capturing the left bundle, all right? And honestly, at the outputs that all these devices are programmed, it's very rare to get selective left bundle capture only. It actually worries me if you do, because I think you're too far. Most of the time we get non-selective left bundle, but the reason we need to know about this is how do we know where we are? How do we know it? Since you get a centimeter of, if you pace a pacemaker lead, you get about a centimeter of activation, right? So it can activate in a pretty broad area. Are we capturing the conduction system? Because all of the outcomes, all of the clinical data is predicated on left bundle or conduction system capture. And one of the keys, strength-duration curves, if any of you have been to look at, you're gonna have some chills thinking about this, but all I'll tell you is that at higher outputs, it requires more energy to capture muscle than conduction system, all right? More energy to capture muscle than conduction system. And the reason being is that if you're in the conduction system, it's the only way something can depolarize quickly, right? It's gotta take a little bit of energy to go really fast. Cell-to-cell has to take a little bit more energy. So more energy, muscle, less energy, conduction system. And we utilize that differential in the process. All right, not expecting you to, if you guys wanna take a nap, pass out, that's fine, but this is about what this, this is where my reflection shows up in front of me when your eyes are all glazing over, right? But here is, when we're in the EP lab, this is what the EP nerds like myself really like about, if you would've told me eight years ago when I was training that I was gonna love pacing, you'd be like, no way. Like, you don't have to think, you don't have to look, you don't have to, you're not an electrician, you're just a, you know, a stent jockey. You just essentially go put a lead in, you don't have to, there's not much to it. But now, we actually have to be electrophysiologists to do this, so that's where I think a lot of our excitement comes in. What you see, now, remember we talked about higher output? This is the same lead position. High output, you're capturing muscle in the conduction system, and then, as we decrease the output, you see this pause. Why is there a pause? It's like, are we failing to capture? No, it's the time it takes to get into the conduction system, you don't see it. And then, it goes from the conduction system out to the rest of the heart, through the conduction system, and the myocardium depolarizes. So, this is what we would call non-selective to selective left bundle capture. And the other thing we're doing as we're doing this threshold test is starting here is high output, right? We wanna look at something, what we call the left ventricular activation time. How long does it take when you pace to the top? If that stays the same as we're pacing, you know because you're capturing the conduction system always. You're always, always capturing the conduction system. The amount of myocardium you're capturing is changing. So, your activation time in V6, why do we look at V6? That's kind of like the all roads lead to Rome. It's the tip of the heart, everything comes towards V6. It's the most consistent lead in the ECGs in the body, and so one of them, and so we use V6. So, that's a constant time from pace to peak, no matter what the output, is consistent with left bundle capture. And then the other funny thing is, if you were to say which one looks more narrow, excluding the pacing spike, this or this, it actually gets wider, not narrower as you decrease, which doesn't make a lot of sense until you start thinking about the fact that you're capturing muscle and conduction system to just conduction system. So, it's, when we're reporting these things, right, it's extremely subjective. It's very difficult, and there are so many parameters with each individual patient, rotation, et cetera, that can strongly affect all these different issues. So, something called extra stimuli testing. This shows the same function where both conduction system and muscle, which looks really nice, to conduction system only. Again, that's consistent with left bundle pacing capture. So, here are the ones that I think people like, like myself, like the most, because it's easy. How long does it take to get? What I'll just say, you don't have to stare at these. This is, it'll make you sick if you do. But what it essentially is saying is that regardless of when you pace the heart, when the heart gets activated, when that activation starts to the very top of V6, the V6 R-wave peak time, if it's less than 80 for, you know, this, actually, these numbers here, don't hold onto these numbers too much, but that's gonna be where the debate in the field lies. How long it takes from when the muscle starts to get activated, not the pacing spike, because you can have a delay to capture and a couple other things, but once the muscle gets activated to the top of lead V6, if it's under 80 milliseconds, you have conduction system pacing, or so we think. And how they did this is they put leads definitively in the left bundle, and they tested all this stuff over and over. It's empirically derived, okay? And you can see the R-wave peak time, selective left bundle, or non-selective left bundle, you can see where it's falling in the 70. If there's a left bondo branch block you get a little bit more leeway because of the intrinsic conduction system disease But our way of peak time is something that I tend to report a lot because it's more consistently reliable to measure You can look at an EKG afterwards and you can measure it, right? It's pretty nice This is a little bit more to wrap your head around but this one's easier to measure in the EP lab Which is the V6 V1 interval difference. So pretty much what we're looking at is The right bundle V1 is a manifestation of right bundle branch block appearing or when you're pacing the left left Conduction system it comes over to the right like a right bundle branch block because we're pacing the left It looks like a right bundle. How wide is that right bundle is The more selective you are it makes sense, right? If you're kind of in between you're capturing a bit of the right bundle and a bit of left bundle You're not gonna see a wide right bundle as we get close to that left bundle we're gonna capture none of the right bundle and you start seeing more and more right bundle and And we just got done talking a little bit about V6 is gonna consistently be the same so V6 activation time pretty much doesn't change and then as You selectively get to from non-selective to selective you're getting closer and closer to the conduction system That right bundle gets delayed and delayed and delayed and the difference between those activations time Is what we can measure This is these these two are really variations of the same theme But appear to be a little bit more reliable and measurable And then here's here's the real question And I think this is where the field has to do a lot of work What's probably and is it good enough, right? Those things we just talked about I was saying 75 and 80 is 85 and 100 good enough we talked about 44 for a left that was a Interval peak time. Well, is it greater than 33? Is that good enough, right? And then there are some things we won't get into Threshold threshold propagations and things along those lines But you can see if you're not in the lab and you're not doing this day to day Right it is. How do you how do you police this? How do you you know say someone? Yep. That's a left bundle That's not a left bundle. It is exceptionally difficult All right, here's our fun part complications So How do you become an expert in the field? One of my senior colleagues who did lead extractions a lot He said you when I just started goes, you know You only become an expert in the field by learning from all the complications that are possible to make right? Unfortunately, but that is we're all human and errors occur. So septal perforation Yeah That's rare now that we've developed some of these current of injury. I it's rare Yeah, I would say in my case is a probably two per two out of a hundred roughly. I you'll go through right bundle branch block Complete heart block. So the thing about these leaves is you're right by the conduction system. I Have for sure cause complete heart block by just touching that part of the heart, right? These are sick conduction systems. You'll look at it You know, it's like that on the poorly built the hundred ten-year-old house. It hasn't had any upkeep Tornadoes come and blows everything over right the same thing here. You touch the conduction system with these catheters heart block dislodgement ACS we talked about, you know putting this lead into the coronary that's from where it's from fistulas Hematomas septal hematomas. I'm going to show you a picture of that. I think this is probably pretty common Is it a problem clinical problem longitudinally? I don't know the big bugaboo is How much does it affect the tricuspid valve versus normal leads Normal leads affect the tricuspid valve a lot. Is this worse better or the same? We don't know all we know is that tricuspid valve impingement by leads for the most part don't have clinical implications Long-term in outside of rare events, but they do lead dislodgement We talked about and then loss of left bundle capture. We thought these leads can pull back All right Swine model not a but you can see here This is now this is like the worst-case scenario. They screwed it in and out screwed it in and I mean they made Swiss cheese out of a septum for a nice picture, but the point being is you can see the Interceptor hematoma and you can see where these leads come out the other side That being said having done this in a visible heart model the University, Minnesota It's doable, yeah, this is certainly if you weren't careful and you said I'm gonna get this I'm gonna spend four hours I'm gonna put this in nine different locations. We're gonna get this you can do this to someone So, all right, where is a clinical data? I'm not gonna go into all of the case There's mean two main studies, I think That have been done that are of the highest quality very small this one essentially Normal CRT Versus the left bundle in Not ischemic patients with a kind of though just similar to the patient. I presented earlier 20 in there the key things about this how successful are we in the experts who develop this technique? Only 10% and CRT or a 10% were able to 10% were not able to be Conduction system paced and 20% were not able to get CRT. All right that being said there is a significant improvement in left ventricular injection fraction heart failure, etc in CRT pacing immune in conduction system or left bundle pacing compared to traditional CRT Now what we haven't analyzed and this is what I struggle with is left bundle optimized CRT Do we need to do it? Should we do it? The data isn't strong enough yet for me to say that I shouldn't do it. I don't know I don't know the long we don't have long-term outcomes on left bundle pacing. We got so much data on CRT It's like mind-numbing right? We that's like no one ever questions it. So for the most part my partners and I Will look and if the CRT is reasonable and it looks like a good quality lead we'll put it in place You know, the thing is is you'll get pace complexes of 100 milliseconds if you time it, right? It's pretty amazing. You can take someone with 175 millisecond left bundle pace them at 110 100 milliseconds And it's truly remarkable Synchronization, so this is one study the next study just came out in May Retrospective case control multi-center for the trial periodist garbage, right? But it's the best we have we don't have a big randomized Long-term trial there. It's in the works, but it's not there yet. This is CRT versus left bundle. All right Barring aside all of the issues we talked about substantial difference in this study of Biventricular pacing versus left bundle area pacing there is a reduction By 8% by hazard ratio for death and heart fail hospitalization and that's on the right mortality heart fail house like Very rarely. I just remember when the paradigm trial came out They were looking at the you know in Trestle. This is a biggest trial, right? This is huge for heart failure, but you're talking to what two three percent one if this holds true prospectively It's a huge difference that we have to take seriously All right. Finally, we just talked about that large control trial long-term follow-ups. We don't know this was first done six years ago What's a probable left bundle capture? What's probably good enough? What is this safety wise? In the real world and then in just to make your minds even more complex to throw a wrench in there There is actively developed in testing a ICD lead Identical to the pacing lead same French same everything So what do we do in and what what I'm trying to help figure out and working is how do we put an ICD lead in that's effective safe and conduct and captures a conduction system probably more posterior fascicle, but What do we do then? I just as you guys look at analyzing this quality and Analyzing these things understand the nuances understand that there's a lot to be learned in I will say good centers You'll start seeing their LV lead success rate should be 70% what I'm getting at is it's not like if it's a hundred percent. They're not actually looking at the best thing for the patient in my opinion because at this point in time if you can get 12 years out of a device and get the same effective synchronization as Someone I could leave a CS lead in the vein of shame We'll do zero work for the patient my numbers will look great, and I've done a disservice to them So that's my opinion there. You know that's certainly not We wouldn't want that to be a standard practice, but anyway Lots of things to come exciting area. Hopefully I didn't bore you too much We took a deep dive and now we're back up for air All right questions No Supposed to be already Okay there you go great all right yes, we do have a number of questions, so if 3830 lead implant results in deep Septal pacing ie there is no evidence of conduction system pacing is the pacer a registry eligible device so that actually goes into our Data collection form so that's not something. I believe that you wouldn't Good question so there was a brief period of time when the Lead was considered MRI conditional and then Medtronic came out for about three months and said technically right now. It's not MRI conditional And so some people were labeling these as deep septal pacing From an MRI conditional standpoint it's all MRI conditional But I don't think no like you should not deep septal pacing with no conduction system capture whatsoever you know the you can RV peak time of 110 QR s a 170 with a wide right but Right bundle morphology and no other evidence. You should not put that in the registry. No it might still be good, right? We should be following these these are the clinical data. We need to understand, but in terms of conduction system pacing no Thank you Okay, another question. We have been going back and forth on if we enter the pacemaker as a left Bundle branch most of the time they say they have captured the LBB But when they say they place the lead deep septum or septal Would you consider that as a LBB P and enter that well into the registry? Yeah might be similar to the you know that I mean that's probably more consistent To what most operators put right I'll just be honest That's most consistent with some of the terminology I use for my reports right the problem is if you are Putting so let's put it this way if we wanted to go through all of those exhaustive testing and had that Requirement for a lead you could take an hour just of testing this lead to see if it meets Crate all crosses what criteria cross-up usually people use the activation time Bundle potential etc so in you can see those aspects, and you say oh, I've shortened my QRS substantially This is a left bundle area pacing lead but You don't see a left bundle potential. So where are we right? We kind of talked about that I don't know the answer to to that specific question because if you're capturing some of the conduction system It's left bundle area pacing, but that's a It's not a well-defined term What are we going to consider as true left bond are we going to have the hand grenade approach and kind of throw everything in? That basket I would argue. We don't because then we're gonna pollute the data It's just like CRT data you have a really bad CRT lead location But you put it in successfully it pollutes all of our outcome data right and then you don't get that Important to term so I would say why we're looking at quality outcomes. We keep the definitions tight Original and then as we understand as a field to then expand it further But I wouldn't be wanting to be analyzing anything other than what I felt was a home run left bundle Because then you're polluting our data on what we're actually doing Great. Thank you. If the LBB lead paces both ventricles in Replacement of a CS lead. Is there any reason to put it put an L put an RV lead? Oh great question so I've done this in patients who Let's say you have an 89 year old female a fib with RVR into the 170s hypotension hypotensive, right? We don't we don't have any other options pacemaker AV node is shown to improve mortality in these patients. So That is a time when I do a backup lead because we talked about some of the dislodgement rates some of the loss of capture And I don't like making a patient dependent on anything I put in their body But I'll do it if I have a backup lead that's usually when I put an RV lead in some people are trying to Capture the right bundle and the left bundle. There's a field Dr. Roderick tongue is looking at biventricular synchronization So should we capture the right bundle and should we capture the left bundle for patients with pulmonary hypertension and bad heart failure? Maybe but routinely no Sometimes in certain situations. Yes Great, thank you. What do you think of? Sorry, I just lost the question What do you think of putting the LBB lead in with the ICD RV lead for? CRT D Instead of putting in the CS lead great question That second trial I showed that case control actually that was two-thirds of the patients. All right So very good question certainly harder, I'll tell you the bigger boggier hearts and Schemia, etc. It's a little it takes a little bit more work, but honestly The fluoro times for left bundle lead versus an LV lead substantially lower I Think longitudinally, I mean this is you know, it's always dangerous to predict anything It's always dangerous to predict anything But I think the left ventricular lead will be the bailout For the inability for us to place a conduction system lead in the future at least that's what the data is looking like now I don't we have to you know, there's a lot of things we have to prove for that to be the case But that's what I think just looking at you know You have a conduction system lead and you have 12 years with a sink with a much simpler device I mean if we can do that with an ICD lead alone and just got a dual chamber device Oh and the more wires More things go wrong. So yes, it's a viable alternative we still use that in our lab as the left bundle bailout and Danielle knows one of my partners is a perfectionist and we'll take both out and I'm like you're killing our numbers You took the LBB lead out and the CS lead killing me, dude, right? And but he's doing there he is doing the right thing, you know And that's one of the things that as the operator you hate that F on the report card Understanding that it's he could have left either of those in right and we got a you got an a but it's is it gonna Help the patient. No, right and that's where the internal day because this is published data. These guys suck at this, right? I mean who would ever have their mom put this device in with that bad of a report card, right and it might be Because they're actually doing the right thing for the patient Those are the questions that we have. All right. Thank you so much. This has been very informative for us Just before you go I just want to remind you for the purposes of purposes of the EP device and plant registry It is a device based registry. So Regardless of how it functions or lead placement or lead Removal if that patient leaves the lab with the device it is included again, and also there was another question it had to do with the It's a device Registry, so if a patient leaves the lab with a device in place Implanted regardless of how it functions You're going to capture that device So if a patient is has a CRT D or CR TP implanted But they are only there that third lead is not placed. You are going to capture that as a CR TD or CR TP regardless of how it functions

left bundle pacing

conduction system pacing

heart patients

synchronization

variations of left bundle pacing

complications of left bundle pacing

effectiveness of left bundle pacing

traditional CRT pacing

long-term outcomes