Chapters Transcript Video Conduction System Pacing Alright so um pacemakers has been the standard of treatment for our patients with symptomatic bradycardia. And for half a century we have been using our V. A. Pickle pacing for these patients. It's been widely used. We've known them it's established pacing that we've done in the past. However as more studies come about we we saw how it causes a lot of electrical and mechanical. The synchrony here is an example of an echocardiogram with speckle tracking strain analysis. And on the middle panel you would see patient in sinus rhythm and the B. Panel, you would see someone whose RV A. Pickle pacing. So these are the segments of your L. V. And you see how synchronous is in the L. V. Every time someone's RV a pickle pacing. Of note you can see the peak there and one arrow versus the other of the anterior septal versus the posterior lateral branch of your L. V. With a big discrepancy as long as 130 milliseconds. So with this we've seen in a lot of studies show that RV a pickle pacing puts our patients at increased risk of hospitalization either for heart failure or for arrhythmias. So there has been alternative RV sites whether it's septal RV outflow tract but there is no proof that's not proven data that they are superior to our V. A. Pickle pacing. So pacing induced cardiomyopathy is what about 10 to 40 patients per cent of the patient population with our V. A. Pickle pacing would have. And um the patients who are at risk for this would be those with baseline that are low and for those with high percentage of RV pacing. And with studies they have shown that about more than 40% RV pacing has been shown to put someone at increased risk. So what do we do if our patients develop this pacing induced cardiomyopathy? So our options are the standard of care of a bi ventricular pacing, putting in a CS lead, if patient is going for surgery then we refer them for an epic cardia lead. We have an L. V. N. Dakar delete. But this is just part of like experimental trials And the next relatively new kid on the block which is the most physiologic one about the past 10 years we've been studying them is the conduction system pacing. So um it's a gamut of pictures but the biggest picture on the left you would see are his Perkin G system go back there and here is the his if you would um the his bundle area is sitting by the tree caspit analysts and that it projects from the RV to the L. V. In the member Nous part. And um it's a very small area. It's only about um the length of it is only about 20 millimeters and the diameter is about four millimeters and then it branches out to your right, the branch of the right bundle and the left bundle. And as you can see here the left bundle system is a larger area that we can target. And here the picture you would see in the R. A. View the locations of their hiss bundle lead and the left bundle lead and below is the different areas of the park in the system that we target for pacing. So his bundle pacing has shown in our diagram of our hispanic energy system was the most physiologic pacing because it preserves you know the synchrony between the RV and LV and it's a simultaneous activation. So um a lot of studies show that it has become a rescue or first line alternative to see its lead in about 91 to 89% with an improvement of the E. F. And um RCT is his alternative trial which shows a similar echocardiogram echocardiogram response between the his pacing and by ventricular pacing. However in this study there's a big the big limitation is the high crossover of the patients with his bundle pacing because of the high thresholds in this location. However, there's a lot of studies which show the benefit of his bundle pacing and as you can see in our current guidelines of 2018 guidelines that his bundle pacing has made it to the guidelines as an alternative to C. R. T. It's just so with his bundle pacing. As I told you the small target area, it's technically challenging um about 56 to 95% success rate and histological lee the hiss bundle is in case an electrically inert fibrous tissue. So what does it mean? So that's why we have high thresholds. It's unpredictable how these thresholds would be. And at the location of the his bundle you can have low our waves. It's inherently going to have low are waves. So we will have a problem of over sensing your atrial or you have under sensing of your RV signals. So and there are times when your hiss pacing will not correct the distal conduction block if it's a left bundle disease. And there's a concern again because of the high threshold in terms of the battery life. So because of that we with our knowledge of the conduction system wang in 2017 has showed um how to do left bundle patient in a patient who has a heart failure and the it's less technically challenging because anatomically you have a bigger area to target the success rate is as high as 80 to 97%. So unlike the his bundle which is in case in an electrically inert fibrous tissue, it is in case in a dense muscle and you are able to preserve the synchrony of your left ventricle, you have stability parameters. Your thresholds are good and you can base pace beyond the conduction site. So these are the different the current different delivery systems for our pacing lb pacing. So there's just a quick, you know, introduction of the procedure of how we go about left bundle pacing. So we start off in an R. A. View locate the distal hiss and that's where the red asterisk there and then when you locate the hits with a signal. So what do we need for this procedure? Um Obviously from Flora Skopje, we have to have the 12 lead E. K. G. And our patients are recording the recording system. So once you locate the distal hiss we advance it forward. Um And this will be 1.5 to 2 centimeters advancing to the ventricles. So we're going to the muscular basal septum and then we start at and you know, prove if this is the ideal location we connect our lead and do uni polar pacing. And it will be here and see the unit polar pacing will have a specific morphology. So we'll look at V. One which is that it has a W. Pattern. And then we look at the A. V. R. And A. V. L. The discordance there and the R. Wave of to lead to would be it's not 383 more than the three. And then once we know we are at the right location, we fix it. Um 1 to 2 rotations and we do another unit polar pacing. And then we advance the sheath, make sure that we counter clock so that we are perpendicular to the septum. So this will be around one o'clock in our a view in 2 to 3 o'clock in L. A. Oh so from D. To E. To F. This is as we advance the tip of the lead about 4 to 5 rapid rotations. And then we again check with our unit polar pacing and we look at the morphology again in V. One and you look at um if it became a right bundle or an incomplete like a Q. R. And at this time as we are doing our rotations, the impedance rises and then it gradually falls by around 100 ohms. And studies show, multiple studies show around five it's the final and we look at the left bundle potential. So here if you would see the panel E and E. For the E G. M. S. You would see how narrower it got, the more you advance and then you change the mythology of your V. One to a Q. R morphology. And aside from that that we check are the septa graham in an L. A. O. Location. So here is just a picture of all the E. G. M. S. Or the of the 12 lead that we look at knowing if we are already at the left bundle. So again in the A. Is like looking at where the hisses and then um we look at our optimized location which is in C. That W pattern in V. One and then when we go forward forward and in D. Um from the left going to the right, you would see their left bundle potential and what we call an LV activation time where we measure we. So basically an L. That is when you measure from the pacing stimulus to the tip of the Q. R. S. And V. Five and V. Six. And that is just a measure of the L. V. Free wall activation time. We measure it at different outputs from a high output of six and eight um here at what's shown here and you would see um here in the middle to the other um Panel, you would see a standard um l that time. And then if you are still not, some studies show 80 others. 100. But if you are still not in uh in less than 80 then you can advance forward. And this is a step program that was done in an L. O. L. A. O. View. You would see the tip of your lead there. So the tip of the helix is about 1.8 millimeters. And from the going to the a note or the ring is about 9.8 millimeters. So it's also helpful if you know the thickness of the septum of the patient. So what are the associated complications that have been reported? So the most common are septal perforation about 3% for the acute septal perforations. And the clue would be during the procedure there will be a definition of the R. Wave, an increase in the threshold or the sudden drop of the impedance and the thrombosis embolism is at the theoretical risk of the exposure of the helix to the LV cavity, right bundle. So there is um for some patients where they have a left bundle, the the sheet that we use the can injure the right bundle. So they have recommended that if you're if you're worried about this then you can have a backup pacing in the RV during the time that you're doing this process. If you're really deeply embedded into the septum, there are some cases of septal arterial injury. So the recommendation will be to go a little bit more distal beyond the more than 10 beyond the hiss and that probably dislodge mint. So as I was mentioning earlier about the different criteria that we look for as an evidence for the direct left bundle capture. So first would be the pace morphology of a right bundle pattern. Alright. And usually it's hard to say that and use that as the sole criteria because there are different reasons why it won't be a typical right bundle because you can capture retrograde lee the hiss. Um There could be an inter particular conduction problem. So that's not the only criteria we look at the second criteria would be the presence of the left bundle potential. You could in the first um E K E G. M. There you would see that the one with the arrow on the left side, the left bundle potential there, the L. V. Activation time. That one that I was discussing earlier when we measure from the stimulus to the peak of the R. Wave in V. Five and V. Six. And you can see the it's the same whether we change our output and whether um the last one is if we can show whether it's a selective versus a non selective left bundle pacing So now that we know that this is good because it simulates the closest to our physiological conduction. So what about using this as a means of re synchronization? Because we all know the standard by ventricular pacing there's about 20 sometimes 30 and some data 20-40% incidence of percentage of patients who have poor response. And because of gamut of reasons first would be there's not not enough lbd synchrony there's just too much non viable myocardial. Um There's a severe RV dysfunction which could be worse with pacing, failure to re synchronize because we as we know in in the bi V. Pacing its we are slaves of the CS anatomy. You know sometimes it's hard to calculate it and there's not enough branch. Um And sometimes it's inadequate programming and arrhythmias can also interfere with pacing but if you come to think of it it's really non physiological what we do with by ventricular pacing because we have a CS lead that is doing an epic Ardell pacing from the left and then an RV that's endo cardinal. So this is not physiologic. What we're just seeing is just we're trying to fuse to wave fronts. One is epic cardio endo cardinal when we know our conduction system is purely and cardio. So with left Bundle pacing there they've seen that there's a rapid synchronous ventricular activation which is a greater electrical re synchronization, a shorter LV activation time. As I told you that some studies was less than 80 and then larger hemo dynamic response compared with by ventricular pacing. So there were a lot of of observational studies that show how feasible left bundle branch pacing is how it narrows the Q. R. S. I'm not going to go through each one of them. But there's a lot of data showing how it narrows the Q. R. S. In patients with left bundle, how it is better than our V. A. Pickle pacing. Um Because of of what I mentioned earlier. But so far up until last month there has been no randomized control trial. Um That has compared the l the left bundle pacing compared to the by V. So this just came out last month wherein it's a randomized control trial comparing left bundle pacing to a bi ventricular pacing for CRT. So what they got the population will be the included patients are 18 to 80 years old in sinus rhythm with a complete left bundle. With the criteria Strauss criteria where it's 1 40 milliseconds for men and 1 30 for women. E. F less than 40 and class of 2 to 4 exclusion if it's ischemic if it's not left bundle persistent aphids or pregnancy. And the primary endpoint is to to see if there's any difference with E. F. Improvement and the following are all the secondary endpoints. So after excluding you know those patients with ischemic you know not left bundle we had 40 non ischemic patients and they randomized them 1 to 1 to those getting the left bundle pacing in the bi ventricular pacing 20 each. The to cross over from the left bundle is because one they can't advance the lead because of scar in the septum. And it was proven by the M. R. I. And the second one is that they cannot achieve the other criteria for left bundle pacing. As I told you before there's several criteria they were only able to achieve the right bundle criteria part in the bi. V. Part the group you can see there's a higher crossover about four patients. And the reasons are first because of the CS anatomy they can't get into the CSR second the thresholds are high and the third will be some patients that that one patient had a frantic stimulation. So um with, okay so this is just a sample of the um EKGs of the patients who had C. R. T. In the left bundle in the middle in the left and left side and the baby and in terms of the procedural related data you can see the success rate of left bundle as high as 90% by v 80%. And you can see the narrowing of the Q. R. S. Year which is almost the same for about 131 136. So the most important part of this study is the primary endpoint where they were able to, even with a small sample size they were able to achieve power to show the primary endpoint where in here you can see in the intention to treat analysis and both of that analysis, the per protocol analysis, you can see that in the left bundle pacing which the blue line um the what I call this the blue line, there's a greater increase in the E. F. Compared to the left to the sea or the bi ventricular pacing. Sorry. And for secondary endpoints they did not find any statistical difference in terms of the E d v E d d, six minute walk test in the N Y H. A functional class. But in other aspects of the secondary endpoints, you can see the difference in those graphs like in the change of the E S. V and in the QRS duration, both in the intention to treat in the per protocol analysis and here you can see also in the and the last right lower graph you would see that in terms of the change in the f they're similar more than 5% increase in the eF. Also with PSV decreased by 15%. But you can see the difference of the super responders which is defined as more than 15 changing the ef or more than 50 as an EF. So this is very promising because it has seen that that there's a better ef improvement in L. B. B. C. R. T. Compared to the baby pacing, favorable reduction and all those endpoints. And um what it tells us is that left bundle can be an effective and complementary re synchronization strategy for our patients who need C. R. T. The main limitation of this study however being being a pilot study that it is a short follow up time, the sample size is small and the primary endpoint did not include the cardiovascular mortality. So this is just an example. We started doing left bundle pacing here at Sentara this year, early this year around january for eric. Um And it has for me I've done I'm not I haven't done a lot but for me I've done it for as a bailout every time. I could not calculate the CS. So this is a patient of mine who had complete heart block, had a dual chamber in 2019 and developed pacing induced cardiomyopathy of 35. She was very symptomatic. I couldn't calculate the CS. Um And I resorted to left bundle pacing and as you can see here from the top her pace. Q. R. S With R. V. A. Pickle pacing was around 1 60 then an follow up she felt significant better. Unfortunately her echo is going to be it's not yet done. So I can see it can say what the EF is but she's much better and her cue our restoration is not down to 123 milliseconds. This is another one that did did recently for also he couldn't go to the C. S. Because of the anatomy and with the intrinsic QRS of around 1 91 92 it has come down to 116 milliseconds. So there's a lot of hope with a left bundle pacing. If we could just have more uh you know refinement in their technique and tools. Long safety profile. You know the one thing that we're worried about is how about extraction because the tip is definitely embedded deep into the muscle and the lead integrity because you have the tip in the deep muscle that's just you know moving. And maybe in the future we can tailor to each patient. If someone has the left bundle branch block we can do left bundle pacing right bundle maybe do his pacing and then I. V. C. D. Maybe um you know our regular dive pacing. Thanks Tanya Published Created by Related Presenters Tanya Geronilla, M.D. CardiologyInternal Medicine View full profile
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