Chapters Transcript Video Left Bundle Area Pacing Dr. Hedley discusses traditional pacing, the methods of physiologic pacing and concepts of left bundle area pacing. I appreciate this opportunity to uh talk about a very exciting um evolution in uh in E P um called left bundle area pacing. Um With respect to disclosures, I have no financial disclosures and there are maybe a handful, 22 or three slides that I've um adapted from some given to me by Metronic here because I thought they made good teaching points. So the objectives for today, we're going to uh touch on the effects of kind of traditional pacing methods. Um Then we'll do a short introduction to the concept of physiologic pacing. And then we'll dive into left bundle area pacing, talking about the concept, the techniques, the evidence um and then do a few cases um with traditional pacing. Um you know, the the ventricular pacing lead is is placed at the R V apex. So um this R VA pacing um has been studied for a long time and of course, it's done a wonderful job for many, many patients over the years. Um but there are, you know, a litany of um negative um or I should say suboptimal physiologic effects of pacing, the heart, um you know, from the R V apex um that we aren't going to go into um all of them in great detail today. Um But the one that is worth certainly going into great detail um today is is pacing induced cardiomyopathy. Uh And so let's spend a few minutes on that. Um When we talk about pacing induced cardiomyopathy in general, we are uh discussing the concept of pacing, the ventricular, the, the right ventricle more than 40% of the time. Uh And when we talk about the cardiomyopathy, we're referring to generally speaking, a decrease in the ejection fraction by 10% um to a value that is less than 50%. That's a general general statement about them. So, um fortunately, uh doctor Keel and uh doctor who was here not too long ago published uh the Cleveland Clinic experience with respect to um uh pacing induced cardiomyopathy. And they took 14 years of patients. Uh So 823 patients who were going for a pacemaker in the setting of complete heart block and all who had baseline efs of greater than 50% and used a rather stringent uh definition of pacing induced cardiomyopathy of uh developing an E F of less than 40% or requiring C RT upgrade. And whereas I would say maybe there are some who believe this to be uh you know, kind of a fringe diagnosis or a less common phenomenon. They actually found in that setting, there are 12% of all patients developed uh pacing induced cardiomyopathy, which given the number of patients who undergo uh pacemakers for higher pacing burdens. This is not a small number. Um And interestingly uh that, that concept of of the 40% burden, which seems like a lot. It pacing induced cardiomyopathy. In, in Doctor Keel's study was strongly associated with a pacing burden much less down to 20% which is not hard to achieve. So similarly, the P group um published their experience in this case, it wasn't just complete heart block, it was anybody who uh had R V pacing greater than 20% burden. And so their study included 1750 patients all again, uh E F above 50% at baseline. Uh and they used a little bit more traditional uh definition for the uh uh for pacing induced cardiomyopathy of a 10% decrease to a level less than 50%. Um And interestingly, the nearly one in five in their study met the criteria for pacing induced cardiom oath. Again, reiterating the fact that this is likely not a rare phenomenon. Um And they too noticed that uh 13% with a burden between 20 and 40% developed pacing induced cardiom, leading them to say that the risk of developing pacing induced cardiom likely begins well below the commonly accepted percentage of 40%. So naturally, we progress on to the meta analysis. Um In this case, a group from Australia and uh Cambridge published uh you know, a meta analysis of 26 studies of nearly 58,000 patients. Um admittedly a bit of a heterogenous group with respect to cutoffs and definitions which are kind of outlined here. Um But suffice it to say they came to exactly the same conclusion that uh Doctor Kiel did, which was that the incidence is roughly about 12% um when they looked at all studies. So again, a common phenomenon. So this begs the need for physiologic pacing. Um And by physiologic pacing, uh what we're referring to is utilizing the heart's natural conduction system uh to pace the heart, you know, uh basically hijack it, so to speak, uh and pace the heart in a more physiologic way. The most physiologic way that one could pace the heart is by way of the hiss bundle. Um And so that was uh you know, this is a well studied method at this point. Um You're screwing a lead into the area of the hiss bundle, uh functionally recreating the natural conduction system below the A V node. And thus, you can all but uh you know, recreate a sinus QR S um or your paste QR s, which when achieved is, is a beautiful thing. Um uh The only issue uh and this kind of ties into the anatomy um is that the his bundle principally lies in the membranous septum. And so, here's a beautiful image from Shi Kumar's um atlas of cardiac anatomy showing that if you place a flashlight on the other side of the septum, it is so thin in this area that you can easily trans illuminate it. Uh And this is sort of the area that you are targeting. And the point is made even more um distinctly by looking at the histology. If this is the inner ventricular septum here, then we're looking at the his bundle coursing through this remarkably thin membranous septum. And so this poses both technical and also uh you know, electrical complications for downstream, which we're gonna come back to uh later in the talk. Um But the next evolution of this is in fact, the topic of this talk, which is left bundle area pacing. Uh And this first kind of came, this was first reported by um Canella Bogan and his group uh back in 2017 where they kind of figured out that for patients who have left bundle branch block, it's not that the entire left bundle branch is blocked, there's some site at which it begins. And if you just go right past that, then you can then recruit the rest of the conduction system and paste the heart in a friendly way. And so it's kind of taken off uh ever since there are quite a few um benefits, some very um uh you know, uncommonly encountered risks. And we're gonna come back to this uh after we kind of dive into uh the procedure itself. So I would say starting with the procedure of left bundle area pacing, uh You kind of think of some preprocedural planning that you want to take into account before you get going. One. It's useful to think. Does this patient have a preexisting left bundle branch block because you're going to be messing about on the uh R V septum. And so it probably behooves you to drop your atrial lead uh into the ventricle and give yourself a backup in case you knock out the right bundle while you're doing this. So what is their intrinsic conduction using? Just echo? You can look at the in interventricular um septal thickness because this is where you're going, you're gonna be drilling into the interventricular septum and having an idea of what the substrate is for your particular patient. A being somewhere in the 0.7 to 1.8 centimeters. But of course, we see a wide array of, of patients, how thick is the septum. And also, and very similarly, do they have any cardiomyopathy that would uh result in a particularly scarred or fibros uh septum because um in order to screw into the septum, um I think, you know, for those of us who have done this procedure, uh encountering a very scarred septum be can become a very painful day. Um The right sided anatomy is very, very useful to look at before you get started because it'll inform your tool um choice and then making sure that you have a good laboratory set up uh with a full 12 lead ECG with uh with leads in the correct position, not just on, on the chest, anywhere is critical to the success of the procedure. Um In, in the case of my experience with um left bundle leads, um you know, whether it's been right or wrong, um I have limited it um almost entirely to a single delivery system. And the reason for that is in my mind, I was limiting the number of variables while I was exploring the technique such that anything uh that I encountered, I could kind of quickly hone in on what was was going right or wrong. I use the Medtronic 38 30 lead um which uh does not take a stilet and has been uh ST studied extensively again in, in his bundle pacing. And then principally, I'm using either the C 3 15 which is a fixed curve sheet or the three oh four, which is an adjustable sheet. But this is the setup that I've used. I'm definitely not endorsing it as the best. And in fact, I tell everyone who will listen that I think the tools stink at this point. Um And I'm excited to see what is um uh you know, evolving over the coming years. Um But this, I thought was a very nice slide. And so um if you kind of look at the uh the right ventricle um from an R A O perspective, where are we going for? So if you slice the right ventricle into kind of basal mid and a septum and then once again, anterior, middle and posterior, then you get these nine sectors basically. And what we're aiming for. Sector two is where we're typically going after hiss and distal hiss con uh pacing. But sec sector five is where we're looking for. So a lot of this in the early stages of, of the procedure is really just an atomic based. Uh And knowing where you're targeting, saves you a ton of time. It's extremely helpful when you get cases that have uh prosthetic valves in place and then it's painfully obvious exactly where you are and you have areas to target. But um you know, you can do it this way as well. Um Once you have selected your area of the heart, you're gonna perform high output unipolar pacing it. And so for some of the non pe P S in the room, I kind of wanted to do some very simple uh diagrams as to what we're trying to achieve here. If you pace along the right ventricular side of the septum in kind of a usual fashion, you're going to capture the right ventricular septum. Uh However, if you perform high output unipolar pacing, then you can from afar, begin to capture the left side of the ses the uh septum and uh the left conduction system. And so that's what we're trying to achieve. So you go to the anatomical location, you think is accurate, you pace along the septum and then there are various things you wanna look for, principally, you want to look for the L V activation time. What this is is, this is the time that is required for the bulk of the L V myocardium to have uh to have fired. And so, um you know, historically, a number less than 80 milliseconds is associated with success and I'll explain what that means. So if you paste the heart from the right ventricular side of the septum, then the impulse has to travel down across the septum and then to the left ventricle. Whereas if you have captured the left side of the sep septum in the conduction system, then the impulse rapidly uh depolarizes the left ventricle. And this may not seem like a big deal. But keeping in mind that in order for an impulse to only cross the inner ventricular septum can take 60 milliseconds in and of itself. So if you are seeing the time from the stimulus artifact to the time that the bulk of it, the L V has depolarized and it's only taking 72 milliseconds with all of this having taken 60 milliseconds, you essentially know you have captured the left side of the septum and the conduction system. So that is a nice way of quickly assessing whether you're in a reasonable spot. And so when you're doing the procedure with the 12 leads, set up having a team that's savvy and quick in measuring the quote unquote L L V T can quickly get you into the right area where you can then begin, um, trying to implant the lead. The other benefit of having a good 12 lead, uh, in the, uh, in the room is just using kind of E C G knowledge to assess whether you're in the right area. And this well published sign is what's called a V R A V L discordant. What we're looking for is when we're in the right area, then your impulse when your pacing is traveling away from a V R. So A V R is going to be negative and it's going to be traveling in large part towards A V L which again will then be positive. So the two of them are discordant and that's something you're gonna be looking for when you're assessing your site. If however, you've become too basal, too high in your initial sight, then you're gonna be traveling away from R and away from L and so both will be negative, they'll be negatively concordant and you'll say that that's not gonna be a good spot. And conversely, if you're too apical and too low, then you're traveling somewhat towards R and L and they're gonna be concordant positive and you'll know not to try that spot. At least not straight away. The other um, thing that you're going to see when you pace is this so-called W pattern. And in the beginning, I, I'm always loathe to kind of just um memorize patterns and whatnot. So it's worth discussing a minute or two what this means as well. But you can clearly see this W pattern and this is not, this is actually not something that's super rare and is only seen in studies. You, you see this all the time um when you're doing this procedure. But if you look at V1, what you are seeing in this w this this kind of upward spike in the middle of the W this is late R V depolarization. So as you uh progress more and more and more from the right or from the left to the right and more selectively engage the left conduction system, then the right ventricle by extension is going to depolarize later. So you'll see this little hump move later and later into the QR s. Uh And that's showing you that not only are you in a good spot, but it's proof that you are beginning to capture only the left side of the septum. And so that, that is actually a very useful tool. And, and something you get excited about when you see um when you're selecting your site, sort of a natural extension of that phenomenon is something that is very useful when you are, then screwing the lead into the septum and this is what's called fixation beat. So, one of the questions that comes up with this is how far do we screw into the septum? And so one thing that can be very useful, not only to tell you how far you're in, but also kind of, are you in a good spot? And when should you stop is what's called fixation beats. You're screwing into the myocardium that's irritating to the heart and can generate PV cs. And these PV cs can recapitulate that exact w pattern that then moves out further and further. Um when you are traveling, uh you know, across the septum. And so having this is a little bit difficult to do in the lab, you know, kind of um focusing on the, the lead itself. So if you have, um you know, some of your teams uh keep an eye out for PV CS, they can say, oh I see PV CS and then you can kind of um take a look and see whether you like the, the morphology of them. Um But fixation beats have been well studied and have uh very, very high sensitivity and specificity. The other thing that you do is um when you're beginning to screw in, you, uh you'll hear this conversation in the lab over and over and over again with every single lab uh or every single lead implant, make note of your starting impedance when you're on the R V septum. Uh what? And then with every advancement, what are the changes? Because as you're on the R V Septin, the, the impedance is going to be on the lower side. As you drill into the myocardium, it is going to go up. And what you're careful to do is then avoid a decrease on the other side. A subtle decrease is actually often accompanied by being in the, the proximity of the the the kind of uh left bundle or the proximal fast uh particular system. But a large decrease in uh in impedance often means that you are either on the verge of or have already perforated um the L V septum. So paying attention to impedance all the way across this, um I I is kind of continued extension of that same line of reasoning and is the transition sign. This is exceedingly helpful in the lab. So I wish the figure I I probably should have re reoriented this. But I hope, I hope this is um easy to follow. So when you are pacing high output, so five volts um at a half millisecond, high output and you have clear evidence of left conduction capture because your L V T is very short again. Well, under that 80 you would say ah good, we're capturing it. However, as you drop your output down and you're capturing a smaller and smaller area of myocardium, then what happens is at a lower output, you lose that same L V activation time. And so what was happening was when you were pacing high, you were reaching to the conduction system from afar, but you weren't quite there yet. And so at low output, you lose it. So that transition is very helpful. Conversely, if you are pacing high output and you have again, evidence of left sided uh conduction system capture nice short L V. Um And you come down from five volts to only one volt and yet you don't lose that vet. It stays nice and short. Then you could say, ah you know what I'm, I must be in that region. Um Because I'm never losing capture of the left bundle. And what can happen is and is often the case as you then go even lower, you are no longer capturing both the conduction system and the myocardium. But when you're low enough power, you're actually uh capturing only the conduction system. And the way you can tell this on an EKG is that if you look at the pacing stimulus, then there's actually this isoelectric period where there's no uh you know, bulk uh depolarization of any myocardium here. This is actually the time that it is traveling in the insulated conduction system en route to then beginning myocardial depolarization. So that isoelectric sign with a nice narrow QR S and a short L V T is signs that you have truly captured uh the left conduction system. And so you'll see that every time start high power and walk it down, walk it down, walk it down and you're looking for these transitions. Um And it's, it's quite easy to do and very informative. You can, you can deduce a lot of information from this. And so this is maybe just displayed slightly differently but is exactly the same um uh uh concept, but making one additional point. Um Maybe that isoelectric period isn't quite so uh evident on the 12 lead. Um But one thing you can look at is if you can see the E G M, uh then if you depolo if, if this is the pacing stimulus and you have uh the E G M directly following the myocardial depolarization uh directly following the pacing stimulus, then what, what's happening is sure you're capturing the, the conduction system, but you're also capturing surrounding myocardium. However, if you then go even lower power, then you have a pacing stimulus a long period until you have the E G M. And again, that's, that's uh that's a sign of selective left bundle capture without any of the surrounding myocardium. Um And so that's a very promising sign. There are some other things that I'm gonna just touch on extremely briefly but are are kind of outside the scope um of, of a non pure E P lecture. But I just think it is particularly clever. And so one is this um paper that showed that you can use program electrical stimulation to tease out whether or not you're in the myocardium or the selective conduction system. And what this is doing is leveraging the difference in kind of electrical characteristics of myocardium versus conduction system by pacing the heart and then delivering an early extra stimulus. And so when you surprise the myocardium or you surprise um the conduction system with an early beat, you can tell a lot about whether or not you're um selectively engaging um the uh the conduction system. And so there are various published responses to this where um you lose left bundle capture and only see the myocardium or vice versa. And actually, both are very helpful. So that, that's something that probably isn't going to catch on a whole lot because there's all, there's already enough um difficulty with the procedural times with this um with this approach. And so then doing basically modified E P studies is, is probably going to get some eye rolls, but it's clever. Um And, and it can be useful if needed. It's another arrow in the quiver. And then this is actually very simple. Um And I thought very some, very clever um in its simplicity, which is that um if you look at again, that um R prime in V one, again, that is the, that is the R V depolarizing very late. Um And so if you measure from where you would have measured your L V activation time, the peak of that uh R wave in V six, which is the bulk of the L V depolarization. If you measure the time from that to the R prime in V one, then you're basically saying I must have captured the L V side of the septum if there's such a long time between that and when the R V fires, otherwise the R V would have been firing simultaneously with the, the L V. And so I believe their number that they published was if there's a greater difference than 44 milliseconds, that, that's indicative pardon. Yeah, so the peak of the R wave in V six, that is showing that the bulk of the L V has depolarized. OK. And, and, and by extension, the, the, the terminal S wave that you see in V six is actually analogous to that R prime in V one, that's the late R V depolarization. But we, but what we use instead is go from the top of the peak in V six. That's, that's L V to the top of the peak of the our prime and V one, which is the R V. And if you have a long period of time between the L V firing and the R V firing, you must have fired the L V only first. And that's, that's the rationale and, and if that time is greater than 44 milliseconds, uh then that has been associated with selective left bundle capture. Mhm Yep. Um So, and, and again, mindlessly easy to quickly measure just like we do L V T in the uh in the lab. And so I, I've actually started using that only in my last couple of cases because this was only just recently brought to my attention. And I, I really enjoyed it. All right. So it's worth comparing his bundle and left bundle area pacing. And so one very informative study that I found was um a study looking at people who were undergoing a V notation. Um And uh this involved uh a cohort of patients who had left bundle area pacing performed. And then they were compared to historical matched patients that had undergone uh his bundle pacing. And so 86 patients were, were picked in both groups with baseline characteristics being um non statistically different. Um And so let's take a little bit of a a look um at how uh the two procedures um compared so naturally, no one would be surprised by the fact that from his bundle pacing, you can achieve a shorter QR S in this case, not a particularly different um duration, 122 versus 130, but certainly highly statistically significant. And that makes sense, you the more proximal in the conduction system, you can recruit, the more the narrower the QR S is going to be thankfully left bundle area pacing was uh faster uh than his bundle pacing, which um was known to be a longer procedure. Um And this is still not a, a tremendously quick procedure, but as the tools improve, hopefully it continues to get faster. Um One major difference is that um these patients, uh 42% of the H S bundle pacing patients required a backup safety lead. And that's because over time, the his bundle leads can um become less reliable. And if you've just ablated someone's a V node, you better have a backup plan in place. And so a safety backup lead was placed in um uh in a non insignificant proportion of the I S bundle um cases, whereas a very small percentage of the left bundle area of pacing, so then let's look kind of at the um the electrical characteristics because this is kind of uh shows the the traditional experience with his bundle pacing. So with left bundle pacing, you are baring deep into the septum and by and large, the um the pacing thresholds are remarkably low, generally speaking, well under one, if not under uh 10.5 at 0.5 milliseconds. Um And that was reflected in this study with the near nearly the entirety of the uh left bundle patients being under 11 volt, whereas there was a much bigger spread and higher uh thresholds in the his bundle pacing again, tying into a very thin area of the uh the heart um that uh the thin is uh subsequently prone to fibrosing. Um and not only does that affect the pacing threshold but also your sensing. So, sensing is traditionally poor in his bundle pacing. If you're in the area of not much myocardium, then you're not going to sense much. Whereas when you're deep into the inner ventricular Septin, you're gonna have great sensing usually, I mean, usually it's, it's greater than 20 on the, on, on most of the devices, but certainly, um upwards of 10 plus in, in almost all the cases. Um So this, this is electrically far more favorable for the duration um of the device's life. Um And, and that was shown in this study. So, but how about outcomes? Um So if you look at the improvement um in ejection fraction, the, the average in both the his bundle arm and the left bundle area, pacing arm at baseline was 40%. Both statistically significant had recover, you know, improvement of E F. But yet there was no difference between the two groups um which is reassuring both had substantial decreases in New York heart failure association symptoms. Um And um and then also decreases were seen in the, in the proportion of those who had both moderate to severe M R and T R. And this is a one year follow up and this exact same trend continued at two year follow up and a three year follow up. So over the life of the device, uh there, there was never any shifting um between the groups as to who outperformed who? Um So I thought that was quite useful. There's no difference as well in all cause mortality or heart failure hospitalization. Although there was a significant difference, um statistically significant difference in lead related complications that were, that's worth a little bit closer look. So, complications was defined as dislodgement, loss of capture perforation, infection or a threshold increase by greater than or equal to two volts at 20.5 milliseconds. And so it's worth noting that in this study, five of the patients who had his bundle pacing had failure to capture either the hiss at all or even the surrounding R V myocardium at um at at high thresholds at only six months age of the device. And so at that point for those patients that R V backup lead that was implanted in, you know, 40% of those cases had to be enabled for safety purposes. And so that that's not insignificant. Now, what about left bundle versus by V pacing? Now, this is kind of the first and really only study that begins to look at this uh this question um and it is admittedly small but it's, it's all we got thus far. Um And so what happened was they took non ischemic cardiomyopathy patients with an E F of 40% or less and who had a classic or Strauss left bundle branch block, just kind of what that means is just true electrical disease and not a left bundle that is otherwise due to lots of intramyocardial delay. And so they randomized them 1 to 1 and there was some crossover. So uh not unsurprisingly, people had unfavorable um CS anatomy or um you know, or uh you know, high thresholds or NIC captures. And so there, there was four that crossed over from the, um the C RT uh to the left bundle group and two that crossed over from the left bundle group to C RT. So the device setup would have been in the case of a left bundle C RT P, so to speak, they would have placed a CS lead and turned it off and paced only by way of a left bundle lead or with a defibrillator have a left bundle lead with a defibrillator lead as well. Um And then C RT uh P versus D in the usual fashion. And so, um so what was seen actually is there was a statistically significant greater improvement in L V ejection fraction compared to baseline in the left bundle group compared to uh the by the pacing group. Um This effect was seen both in the in intention to treat and per protocol analysis. And there was numerically um uh greater decreases in L V systolic volumes um in uh you know, in the left bundle leads versus biventricular leads. Um and um as well as decreases in PRO B and P. Um There was a decrease. Uh There was a, a narrower QR s achieved by left bundle pacing um in both analyses and a numerically greater response rate in terms of um E F recovery uh with left bundle. And so I, I don't put too, too terribly much stock into this study, but it's the, it's the first we have and, and um certainly needs a whole heck of a lot more um investigation. So I wanted to look at two different cases hopefully to illustrate some of the um potential benefits of this um this technique. Um And I tried not to cherry pick just the kind of, you know, the cases that you took home and showed to mom and put on the refrigerator. I tried to make some, some lessons out of this. Um So, so case number one, um this is a 76 year old gentleman who literally just had to um you know, a little bit earlier this month. Um And so, yeah, he had a nice result. He, he's a good ta result. Um His E F immediately jumped up um after his tar and he was feeling a whole lot better. But at baseline, he had for a long period of time, had a right bundle with sort of a borderline, left the interior fale block and a very prolonged first degree a V delay. Um And this, this is his baseline. So you can see the right bundle sort of beginning to be a left inter fast um in APR that kind of starts now and finishes around a half an hour later. Um And so, um what, what I we ended up, this is actually a tough case. Um This guy was a super kind of intelligent and ana analytical guy and he had no a V block after um his ta um but his pr did lengthen out 400 plus at this point. Um And he basically said to me, he said, you know, um I don't want to find out the hard way uh developing a B block down the road. And, you know, as far as I can tell, I'm very high risk for this. And so, um I would just like to take care of this now, whereas you could argue whether or not this person definitely definitely needs a pacemaker. And so anyways, I said, yeah, I, I kind of agree with you. Um So let's try a left bundle area pacing, but left bundle area pacing is very appetizing when the patient has a razor narrow QR s at baseline. And you think you're gonna go about trying to all but recreate that. What's interesting more to me is these patients who have intrinsic conduction delay. Uh And so what can we do with those people? So here is the acute result of uh L V uh L B left bundle area pacing. Um And if you kind of zoom in and, and compare the two. His intrinsic QR S is almost 100 and 70 milliseconds, whereas the paste Q S is 100 and 30 milliseconds and, and the point that I'll make here is that not only is this already substantially better. Um However, this reflects acute programming of the device. And so that's a little bit of a point worth talking about when you again, the lower threshold or the lower output that you can pace these patients, the more likely you are to get just selective left bundle capture. However, safety reasons, you have to program them with higher outputs right after the device is put in just in case something shifts and you don't want to uh to lose capture. Uh And so you're almost by definition going to have nonselective capture on anybody that you put these devices in until they come back a couple of, you know, weeks or months down the road and can have optimized settings with much lower um outputs. And so uh these acute Q RSS are actually only going to get better. So for him, this was a very good result. Um I thought electrocardiographically, I don't have any follow up. The guy just got his device the other day, but he um he's doing well. Case number two, this was another challenging case. So this is a 69 year old gentleman who had very difficult to control um heart failure with chronic hypotension that required midodrine uh and really kind of couldn't do any medical therapy. He had horrifically, um, severe T R and his E F um, was noted to drop from normal uh to 45% late last year. And in this um context, he developed intermittent high degree A B block. And so because of his very severe T R, you know, I thought a very clever idea for him was to try to do a device for his A A B block that involved only A CS lead not crossing the tricuspid valve further worsening the T R very, very, very reasonable. Um However, this is the paced QR s that we get from that um device and it is obviously very wide and following the the device, his E F further drops from 45% down to 20%. And so we say, OK, we need to try to do something different here. Should we try uh left bundle area pacing a acknowledging the fact that yes, we are gonna have to, to traverse the the tricuspid valve. And so we did um and this is the pacing result that we get instead um from the left bundle area pacing. And if you compare the two from almost 260 milliseconds down to about 100 and 20 milliseconds. Um The difference was substantial, I will say in full disclosure, this was a very sick guy after the pace after the, the pacemaker was implanted, he said instantaneously, he felt better his hemodynamics began to improve in the IC U and unfortunately, he died several days later. Um And uh it's not exactly clear why he did. Um But um but this, this shows promise of what can be achieved. Um And if you do this in enough people and you have enough time to follow up, I I suspect we're going to see um very promising results. Uh-huh. No, no, I didn't use it. It, What that does though. And I did not think it was, it was necessary for this talk today. Is there, there's, there's lot C RT which basically what that is is um pairing a left bundle um area pacing with a CS lead and then fusing from those two vectors which already there, there is already evidence there that that looks very promising. Um But um yet yet another evolving technique um so that you might see that that again, lot C RT or uh left bundle optimized um C C RT. All right. So in summary, pacing induced cardiomyopathy is common probably more so than many of us thought roughly 12% and likely occurring uh at, at a pacing burden that is lower than what we traditionally believed. Physiologic pacing is a promising solution. And logistically nowadays left bundle area pacing is generally preferred to his bundle pacing for the reasons that we discussed um that this is uh an an atomic and E C G guided approach um to implant is generally met with high procedural success rates and favorable device indices, um future directions and research. So absolutely, we need more and larger R C T S uh regarding left bundle versus C RT as well as the combination which we just alluded to uh the lot C RT, we need bigger studies to, to truly suss out the the long term effects. Um And we need to know a whole heck of a lot more of the role in left bundle area pacing in those who have ischemic cardiomyopathy or diffused conduction disease. Because again, if your idea is to recruit or bypass, um you know, the conduction system and more proximal disease. Well, what if the whole ventricle is diseased or what if the distal left bundle um is diseased, then, then you're maybe not achieving the same thing. But that, that I believe is probably where lot C RT is going to come into play. Um with respect to technology. Absolutely, we need better tools we're using basically bastardized tools from the his bundle area and they're not optimized for these um these procedures. And so it gives people a lot of anna to to go through these um procedures. Um but they're, they're rapidly coming out. Every single manufacturer is, is hot, you know, hot after uh tools that will then become the most used um left bundle area pacing with I CD leads is certainly needed and is underway. Uh That way you are talking about a single R V lead system and not implanting both a defibrillator lead and a left bundle uh lead that that's never going to be favored. Um And of, of course, the, the, the end all be all would be leadless left bundle area pacing, which I think is in its infancy, but being um research that would be particularly exciting. Uh And I believe that's all I've got. So hopefully time for questions and discussion. Published March 30, 2023 Created by Related Presenters Jeffery Hedley, M.D. Sentara Cardiology Specialists View full profile
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