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I'm doing. I'm very I'm like the same as an FMI, so I'm a S h o and I'm currently working cardio thoracic surgery. And it's it was a pleasure, actually. To be asked by an offend me to do this presentation on pacing mainly. I know the title is pacing and arrhythmias. The focus of the talk will be on pacing And given this a Saturday, I'll try. And I thought, I'll keep it a bit shorter, and then we can focus it on something that you probably know less about. We'll touch on arrhythmias because it naturally does coincide with this. Can you see my slides? Yeah. Excellent. And we're recording. Pardon me, and we're recording. Excellent. I'll just plug my charger in and then we'll be good to go. Okay, Let me see. Yeah, I just want to get the list of who's here up because I tend to ask questions whilst I do these kind of talks. Oh, that one second, uh, you can literally see my screen. OK, Answer. We'll just go ahead and do it without that. That's fine. Cool. So epicardial pacing? No. So I'm gonna go through why we pace. I'll go through the different types of pacing, talk a little bit about heart block and then go specifically into different pacing modes and pacing issues. So does anybody feel like they could answer this initial question? What is pacing? So pacing essentially is, I describe pacing as there are two components. Pacing is the continuous measurement of the underlying rhythm of the heart and, where necessary, the delivery of electrical stimuli in order to elicit depolarizations of the heart at an adequate heart rate. So there's two main aspects. It's measuring the heart rate and then delivering electrical stimuli to stimulate the correct heart rate if the rate drops below a preset threshold. So whatever we do anything in medicine, I always like to know why we do it. You know, we can get very caught up in the life on the ward. I know some of you guys are medical students. Some of you are junior doctors, and for me it kind of went in this direction. I kind of learned about pacing in the pacing box, but then it was a bit later on. Someone really explain to you why we pace. So the role of the heart is essentially to circulate blood around the body in order to perfuse tissues perfuse organs and mean arterial BP is an excellent surrogate for your perfusion pressures. Now, if I was in a room with you, I'd ask somebody to try and tell me what the equation for me. An arterial pressure is, uh but I'll bring it up for you and I'll spare you the trouble. So mean arterial pressure is the product of your cardiac output multiplied by your systemic vascular resistance. Why is this important? And how does it relate to pacing? Well, when we look at the cardiac output component, we can see that one of the main contributors to cardiac output is your heart rate. So if we were to keep all things equal and significantly dropped the heart rate, that would result in a reduction in mean arterial pressure. In real life, the body adapts and the body compensates for things, of course. So, initially, if heart rate was to drop, the body may try to vasoconstrictor in order to maintain pressures as it detected a drop in mean arterial pressure. But if you're severely bradycardic as some patient's, maybe post operatively, then you will reduce your perfusion pressures, and that can have dangerous consequences if left untreated. So that's the bottom line. We pace to maintain pressures in patient's, unable to maintain an adequate heart rate. And to be clear, everything I'm talking about today is specifically in the context of the cardiac, surgical patient and the patient POSTOP. So within cardiac, within cardiology and within pacing. In general, there are three types of pacing. Epicardial pacing is the type that we use in cardiac surgery, but for your reference, if you want to go and read more, there's also endocardial pacing and transcutaneous pacing. Epicardial pacing is called epicardial pacing because during cardiac surgery, whilst the heart is exposed to the surgeon and usually after the main steps of the operation have been completed, the surgeon will stitch into the epicardium So the surface of the heart they will stitch the pacing wise directly into the muscle of the heart, and those are then essentially fed out through the chest wall. And that means that at the end of the operation and a few days later, once a patient is deemed fit to have the pacing wires removed, they can just be pulled out directly. So in case you're wondering what epicardial pacing is now, in terms of the delivery of the electrical stimuli to the heart, this is done via what we call bipolar leads. Unipolar leads are an alternative that exist, but for everybody here for our purposes in this presentation, I just want you to focus on bipolar leads. So when they place pacing wires, each set of pacing wires actually contains two leads the an ode and the catheter, and they're placed very close to each other. And it's the current generated between the two leads that stimulates the heart to then generate its own electrical activity. So you can see here in this diagram the bipolar epicardial pacing. So this is this is how the circuit is set up. In reality, the two points the two electrodes are actually next to each other. So in this diagram, the distance has been exaggerated, so you can see that it is two leads to deliver a current. So when it comes to pacing the heart and in the context of epicardial pacing, there are broadly speaking two ways to do it. You can either pace the atria alone or you can do dual chamber pacing, which is where you would pace both. You would place pacing wise both in the atria and the ventricles when you place the pacing wise in the atrium, the ventricle. Practically speaking, you only place one set of bipolar leads in the atria and one set of bipolar leads in the ventricle, usually at the right ventricle. Now there may be I'm I haven't seen Biventricular pacing, pacing wise, placed into the left ventricle in theater. That doesn't mean they don't do it. But as far as my experience and I've seen a fair few operations now they I've usually seen them place right ventricular pacing wise when they do pace the ventricles. So the main decision that surgeons will make when they are placing pacing wires is Do we just pace the atria, or do we paste both the atria and the ventricles? And the factors that would influence this decision are, firstly, what is the operation? And secondly, does the patient have any pre operative conduction issues that may increase the chance that they all suffer a heart block? Heart block really is the name of the game. When we think about pacing heart block being a disruption between the conduction system connecting the atria to the ventricles, the atrioventricular node. If you have a patient with complete heart block and you do not pace them, then you risk them becoming severely bradycardic as the ventricular. The intrinsic ventricular rate is very low, and if the intrinsic ventricular, if the patient's ventricular rate dropped down to the thirties, then you will run into that issue the thirties or the forties. You will start to run into those issues where they become profound, profoundly Braddy car, prana, bradycardic, seriously hypertensive, and in some cases they may even arrest. So in patient's, where there is no intrinsic connection between the atria and the ventricles after an operation, that is where you would want to have access to pace both the atria and the ventricles, the Converse situation would be in a patient where there's a very low risk of damage to the atrioventricular system. In that case, you may consider just pacing the atria, because by definition, if you have an intact atrioventricular conducting pathway, then each pace contraction in the atria should lead to a corresponding ventricular contraction. So you may be honoring. Okay. What, What, When, when? What operative circumstances would predispose and want to be at risk of a heart block. Aortic valve surgery is the second most common type of heart surgery that's done. The most common is coronary artery bypass grafting. The second most common is aortic valve replacement and the risk of complete heart block. It quote. The generally quoted rate in the literature is 5% and I'll show you this diagram of the anatomy to help you understand why that's the case. The when they do an aortic valve replacement to keep it simple, they basically cut the disease valve leaflets out. They clean away all the calcium and all the the gunk in the area usually classified deposits, and they will then place sutures in the annual assess, which is the anatomical plane within which the leaflets normally sit demarcated by the red line. Here they will play stitches into that plane, and those stitches will then be placed into the prosthesis, which is then secured at the same plane that the original valve was in. So if you can pick you for those of you that haven't seen aortic valve surgery that may be hard for you to picture, but to keep it simple where I'm pointing the cursor now, they would be placing stitches here. Yeah, and those stitches can catch the conductive pathway which is here demarcated in green. So you can see how delicate these operations are and how you know the margin for error is not that is not that big. And that's why if you do enough aortic valve replacements, you will have a certain proportion of patients that, unfortunately will have this complication so you can damage the conduction pathway. You could also just have edema from the trauma of surgery. Small amount of bleeding postop can cause it, uh, these are things that can damage the conduction pathway and lead to a third degree heart block as this takes us back to the function of a pacemaker. So the point of the pacemaker is to read the heart's rhythm and respond according to the inputs that we have put in the pacemaker settings. Yeah, so pacing thresholds, where now kind of before we go into pacing thresholds, I want to just double down on this point here. So if you were deciding two paisa patient, you're making that decision in theater. The consultant is making that decision in theater, and it will be basically determined by the type of surgery they're having. So if they're just having coronary artery bypass grafting the steps involved in that procedure are less likely to cause damage trauma and impact the conductive system. And they will therefore more likely to be paste atrially. Whereas patient's who have, you know, multi vial surgery. Really? Any valve surgery? Any surgery involving the aorta, the aortic root. They're more likely to be paid. The surgeon is more likely to choose to do. Bye bye. Sorry. Dual chamber pacing. So pacing the atria and the bedrooms? Does anybody have any questions at this point? And can you still hear me? Come on. Someone needs to tell me they can have you. Yeah, we can hear you. Oh, good. Where have you gone then? Oh, no. I've lost my I lost my window. Uh, sorry, guys. One second I had to borrow someone's laptop. I didn't realize they had so many tabs. Everything. Whilst I'm doing this, Someone asking me a question because this might take a minute. Oh, it's okay. We're back. We're back You can still ask you a question, but we're back. Yeah, cool. So we we've spoken about the rationale behind the different approaches to pacing. Cool. So now we're going on to the pacemaker itself and how the pacemaker works. So the pacing threshold, this is if we go, can we go? I think I had an image of the pacing box at the start somewhere. Let me see. Uh, here we go. So this is this is a painting box right here. This is the one that we these are the ones that we use on I awards. I'll see if I consume it. Can you Can you see this? This image. Okay, you can see here that there's the, uh, ventricular section, the atrial section. This. So let's go through this top to bottom. So this is the pacemaker box. So if you're on the ward me, me and the family when we're on the wards and we have patients that are paste the way that we would control the pacing is using this pacing box. Okay, So the first thing is the pacing mode, which I will tell you a bit more about later, but the pacing mode is essentially the way that the pacemaker is reading the heart rhythm and responding to it. The rate is the minimum rate that we want the heart to beat at again according to the settings that we have put in. So this is the minimum rate. This is the mode, then the These are the key component. This is one of the key components. Is this right hand side here? The the threshold. This is called the pacing threshold. Okay, so what? The pacing threshold is the voltage, the current that we have to deliver with the pacemaker in order for the heart to respond with its own deep polarization and subsequent contraction. So what this means? Conversely, what this means is we were if we were to give the heart if we were to deliver. Let's say we have a pacing wire in the ventricle. Yeah, and we were to deliver a very, very small electrical stimulus. This would not result in a ventricular depolarizations and subsequent contraction. So the way to imagine us testing that on a patient is if you imagine that the mode is set to VVI. I know I haven't explained what the modes are. But for the sake of speed, VVI essentially is a ventricular backup mode where the pacemaker is only looking at the ventricular heart rate. So when we and it will kick in and start trying to pace the ventricles, if they are not depolarizing at the rate that we've set here, that's what VVI is. So if we set the pacemaker to VVI and set the rate and the patient's and before we switched the pacemaker on the patient's heart rate, let's say was 50. We switched the pacemaker on. We set it to VVI, and we set the rate to 80. The pacemaker is going to try and pace the patient's ventricles at a rate of 80 BPM, because it's detecting that the ventricular heart rate is below the setting that we've put into the pacemaker. Yeah, so it will start delivering stimuli to the heart. The voltage of the stimuli that are being delivered is set by this dial here. This dial right here, this is the ventricular pacing voltage. And if you were to turn this all the way down to the lowest setting and attempt to pace the heart essentially, what would happen is you would deliver these tiny stimuli, but the ventricles would not respond by actually depolarizing and contracting. Then what you would do practically speaking is slowly turn the dial up, increasing the voltage, the current that you're delivering to the patient. As you increase that voltage, you will reach a point. Were you notice that after each spike, eat after each thresholds, After each stimulus sent by the pacemaker, there is a QRS complex. Once you reach the point where there is a QRS complex. After each pacing spike, you have achieved what we call capture. Yeah, So when you achieve capture, you have essentially found the patient's pacing threshold. You found the voltage at which each delivered stimulus results in a corresponding deep polarization. And then all you do is you just turn it up to maybe about double that just to be safe. So the rationale there is. Okay, I know that at three volts I'm going to get a ventricular contraction. However, just to be safe, I'm going to deliver a little bit more. The reason you do that is because as days pass and the pacing wires stay in the heart, there's a little bit of you can imagine a bit of fibrosis, a bit of gunk around the area. You know there's this constant and energy being delivered. They they don't conduct as efficiently, and then you. You therefore need to give a little bit more voltage to achieve the same output. So when you find the threshold initially, you usually will double the amount you'll double it so that you know you're safe for the whole time that the pace and wires are in the patient. Great, so that's threshold threshold is very important. It's very, very important because it's about it's about that's about being safe, You know, if you if you if you think you have set the patient pacing, you think you've set it, but they haven't. They're not being paste at or above their threshold. Then you'll be lulled into a false sense of security, and it could be unsafe for the patient if their heart rate does begin to drop. So if there's one thing that you want to sort of take away from, this talk is to make sure that you have a good, adequate understanding of the pacing threshold and what that means. Does anybody have any questions about a pacing threshold about how to find it, where, how to set it. Anything to do with patient threshold. Yeah, Okay. I'm hoping that you're all experts now, then pacing thresholds. Good. So talked about the different types of the different approaches to pacing the risks of heart block after surgery, we've talked about how to determine the pacing threshold. We're not going to talk about the common pacing modes. And these are things that really if you're working on a cardiothoracic award, you must know what these pacing modes are. And it's helpful to understand the rationale behind them. I won't go sort of too much detail. I'll just make sure you get the concept. So they are really as far as I'm concerned and on my an award, too. But there are three types of pacing that you're likely to see if you're in a cardio thoracic ward. Ventricular backup pacing, atrial backup pacing and D d D. Which is a sequential dual chamber backup pacing. And I'll get into what these letters mean Now when you have a pacemaker setting, there is a specific nomenclature away, a method of describing a pacemakers function so the good pneumonic to remember the order of what each letter means is PS A. This stands for pace sense, Axion. So pace Which chamber of the heart is being paste? Are they being a truly paste, ventricularly paste or both? Which is deep sense. Which chamber is being sent now? You may be wondering, What does sense mean? What? What? What does this word mean sensing is It takes me back to the beginning of the talk when I told you that a pacemaker has two functions that are taking place simultaneously. The pacemaker is reading the current heart rate and then it's responding to it. Okay, when we say it's reading the heart rate specifically, we mean it's reading the atrial rate, the ventricular rate or both. So that's what sensing means. What inputs to the pacemaker determine its outputs. And then Axion stands for trigger inhibition or neither. Now, with Axion essentially, the way you think about it is like this. If you set the pacemaker, the pace the pace maker wants to pace. Think of it like this. The pace maker wants to pace. Yeah, so when you set it to V. V, I and you put the number 60 the I stands for inhibit. So inhibiting what? Inhibiting the pacemaker from pacing. That's the point. So the pacemaker will inhibit itself from pacing if the minimum heart rate is reached, which is the rate that we set on the pacemaker. If the heart rate that is being or specifically let's say, it's set to VVI. If the ventricular rate is below the number that we've put on the pacemaker, then the pacemaker will not inhibit itself from pacing and it will pace right up until it reaches that heart rate, and then it will maintain that heart rate. It will be inhibited from pacing at a faster rate. I hope that makes sense. There is this option here for Oh, which is not something you should ever see on the wards, and I will touch on it later. D is what's really it's It's dual chamber, and this is what's used in sequential pacing and again, that will be that I will explain that in a bit more detail and one of the next slides. So now you understand that painting nomenclature It should make sense that VVI and a I are what we are what we call ventricular and atrial backup pacing. So in the ventricular case, what it means is the pacemaker is just looking at. The rate of the QRS complex is okay, and we've set the number. Let's say 2 60. It's detecting. The rate of QRS complex is 45. It's now going to deliver electrical stimuli until it detects a QRST polarization rate of 60. It will then stop itself from delivering stimuli to faster rate. That's VVI atrial backup Pacing is exactly the same. But instead of looking at the QRS rate, it's looking at the P wave rate. So again it's measuring the rate of the P wave. If it falls below kicks in, brings it to the level that we need. I think that's fairly easy to understand, and and hopefully I hope that that's kind of come across the The kind of painting the painting mode that I found a little bit harder to understand initially was D D D. This is called sequential pacing, and essentially, this is a pacing mode. Where the heart is paste kind of in order is a way to think about it. It's trying to maintain the most physiological cardiac cycle where the atria contract, you have your delay to allow for ventricular filling and then your ventricles contract. By contrast, when you have VVI pacing, you're pacing the ventricles irrespective of the atrial rate rhythm. You're just pacing the ventricles now. The reason D D. D is a very good mode to pace in is because you retain the atrial kick. This is the contribution to cardiac output made by the atria. Contracting in sync with the ventricles relaxing and this is this makes up a significant contribution. Makes a significant contribution to your cardiac output. And if you maintain an atrial kick, that will have a significant impact on your pre load sufficiently so that you'll get a 20 to 30% increase in your cardiac output. And if we remember why this all matters going right back to the beginning, that first equation mean arterial pressure equals cardiac output multiplied by systemic vascular resistance. So D D D is a good way to pace, and the the way that it works is the pacemaker will begin. By looking for a P wave, it will begin by looking at the P wave rate. Yeah, so if it finds that the P waves are either not there or the rate the the gap between them is greater than what we have set the desired heart rate to be. Then it will attempt to pace the atrium. Yeah, it will attempt to pace the atria. If, however, the atrial rate is okay, the P waves are there and there at the rate that we've set or above. Then the pacemaker will not pace the atrial. It will leave the patient's intrinsic atrial rate to proceed. It will then look for a ventricular depolarizations after the P wave. Crucially, the amount of time that the pacemaker gives the patient to generate a QRST polarization is something that we can set in the pacemaker. We can set that we can. We can give the pacemaker any quote unquote a V delay that we want. And if the pacemaker does not see a Q. R s deep polarization within that period of time that we've set, it will kick in and paste the ventricles, and what you can see here is this means that there are a number of different potential outputs that you can get with the D. D. D pacing mode. So the first one is the case of the patient whose heart rate is normal. The P the atrial, the rate of the P waves is normal. The rate of the QRS complex is are normal. So the pacemaker does nothing. Yeah, The second possibility is okay. The patient has a problem with their atrial rate. So the pacemaker kicks in and it paces the atria. But whenever the atria are paste, the ventricles respond within the period of time that we set. So then you essentially have an atrial atrial pacing. The pacemaker is pacing the atria. But in doing so, the atria are conducting the that impulse is being conducted down the IV node and we're getting a good ventricular response. So the pacemaker does not need to kick in a pace. The ventricles. Yeah, you could have a situation where the pacemaker paces the a trio and then finds that there isn't a ventricular depolarizations, so it will kick in and pace the ventricles. Conversely, you could have a situation where the patient has a normal, decent atrial rates. But the QRS complex is are not following the atrial depolarizations. And that is where the pacemaker would then kick in to pace the ventricles after the P waves. And you may get that, for example, in a third degree heart block where the Sinoatrial node is working fine. The atria are generating their own intrinsic rhythm, which is good. But because there's a complete disconnect between the atria and the ventricles, the ventricles do not respond after the P waves, and that's where de de de mode comes in. Great, because it basically allows you to sync them up. I'll just show you back at the beginning, on the pacing box again, where that is on the pacing box. I appreciate it's a bit small, but on the pacing box there's usually a setting like this. Yeah, a V DeLay, and we know that are normal. PR interval is not 0.1 to 2, not 20.2, uh, seconds or 1 22 200 milliseconds. So what you can do is manually set it so sometimes what consultants will do if a patient is recovering from surgery, they may. They may come and say, Okay, increase the IV delay a little bit, and as you increase the IV delay to a little bit beyond what you would consider normal. You notice that actually, the patient is able to generate their own QRS complex is they just need a bit more time to do it? And then sometimes they'll accept that and say, Okay, as the patient recovers, Will will allow them to sit in their underlying with them because at the end of the day, so long as the rate is okay, that's the most important thing. And then over the coming days, things often improve, and then they can start to reduce the AB delay. So here's where we got to said that the the old section is something I wanted to touch on asynchronous pacing. Asynchronous pacing is where the pacing box is basically just firing off electrical impulses with no regard for what's going on in the heart. No attempt to sink, know, attempt to read nothing. It's just doing its own thing. Yeah, now this is really only something that should be used in theater. As the patient is recovering, it's sort of the chest is open. Uh, the patient may be on bypass, and they're attempting to to take the patient off bypass. Then, in that case, they sometimes they they will use this. They'll use this setting to just fire. Stimulate the heart to just get it going. Yeah, outside of that environment, unless you're dealing with an extremely specialist cardiologist or you know someone in I t u I don't think from speaking to my colleagues, I don't think this is a setting that's really used. If you see this setting, you should alert somebody and ask questions and considered, you know, quite quickly ask questions because it can be dangerous. Yeah, and this is why I want to look at this bold part here. If you're trying to send a depolarizing or trying to send an electrical stimulus to the heart whilst it is itself Repola rising I e. When it's in, it's t wave. You can actually precipitate ventricular fibrillation in in a patient. So the risks and the stakes are high. And this is something that I always say when we're when you're dealing with the heart, remember, the stakes are always high, and this is something that I think especially on where s a chosen were new and we're getting used used to a new system and we're just getting our heads around things in the middle of everything. Sometimes you know, you just need to remind yourself everything is high stakes. You know, it's not like putting a cannula in if you get a pacemaker setting wrong if you get the voltage. You know, for example, with the pacing threshold. If you don't really know what it is, you got to ask questions and make sure that it's set properly because if it's not set properly, the patient could suffer severe bradycardia or because we didn't turn a knob up a few more notches. The same thing is true here. Now I want to tell you, I've told you about asynchronous pacing. So right now I'm going back and forth a lot to the start of it. But I want you to look at the pacing box here. You'll see that the there's the There's the D D D mode and the D 00 mode. The D. D. D is one of the most commonly used mode D. 00 is a mode that you should not use stupidly, these boxes are some like, for example, this box here and some makes are designed like this, where the D, d. D and the d o oh, they look really similar. So just make sure if you're setting it to D d. D, that you don't accidentally set it to D 00. And then there's some common pacing issues. So, uh, if you if you're not, if you're not getting pacing spikes. If the pacing doesn't seem to be working at all, just explore the connections. Make sure that the, uh, you know you have the leads connected and tightly secured in the pacing box. If you get failure to pace, there's, you know, it's possible that. So, for example, when I when I described to you earlier, the the bipolar leads are inside the myocardium inside the heart that stitched in. If one of those leads sort of fibrosis off or comes away from the myocardium completely, then you don't have You're not going to be able to pace because you know you don't have to leads to generate a current between them. So in that case, it's hard to know that's a diagnosis of exclusion. Um, I don't want to go into that too much to confuse you, but just be aware that that's a possibility. And if that's the case, usually something a registrar will will try and solve by placing another lead. The theory is they'll they'll place another lead to the skin, attach that skin lead to the pacing box, and then you'll pace the heart by the current between the skin and that lead, which is, would be a bit similar to transportation spacing and you need to You would need to deliver a higher voltage of energy. But just be aware that something that can happen have it in your head. The thing with D D. D is if a patient goes into a F that's going to cause problems on the d d d setting because the D D D setting relies on it, reading the P waves and responding to them. Whereas if they're in a F, sometimes you won't have a P wave, you won't be able to see the P wave, and you won't be able to pace accordingly. So essentially, if you see if a patient is not being paste properly and they're in d d d. Then just chase into VVI. Um, and what you what can happen? Uh, with a lot of patient's post cardiac surgery, Is there can go I/O of a F as the heart recovers from the trauma of surgery for a variety of reasons. Patient's that they didn't have did not have a F before can go into AF after surgery and usually a lot of the times it resolves with the correct treatment. However, just be aware it's a question. If you're on a water and as an S H O, the patient is paste and they've gone into a F overnight. Just have a look at the saying If it's d D D, you don't necessarily changing yourself. But just say to the Reg, Oh, you know, look patient Wasn't Sinus there an a f that set to D d D. Do you think we should switch it to be the eye? Um, I think it's a good question to ask Ross of capture, so this can happen over time if a patient has had the pacing wires in for so usually with a patient. If they have a smooth recovery, pacing wise will come out by, for example, the fourth day after surgery. But some patients have heart block. Some patient's have, uh, they require cardioversions, uh, and because of a new onset af. And if a patient is going to have a cardioversion, you wouldn't take the pace of wire out. You'd leave it in as a backup in case the cardioversion goes wrong. Then we've got a direct connection to pace the heart. Yeah, so there are a few reasons why the pacing wires may remain in for longer than expected. In those situations, you would want to. You make sorry you may lose capture because again, as I say, like the fibrosis around, the pacing leads over time. You know, 567 days that can happen. And then you need to deliver more of an electrical stimulus to result in a response from the heart. So just the thing to think about lots of capture, basically, to keep it simple. If your pacemaker, if you have a patient who was previously being paced and you're now having failure to pace and there bradycardic one of the first things to do is look at that voltage. I just whack it all the way up to the maximum level that might solve the issue. Just deliver the most electrical stimulation that you can. There's no risk. There's not really a risk that's going to over stimulate the heart. It doesn't work like that. The main concern is you're under stimulating the heart, and you need to deliver more a voltage to get a response. Sometimes you can have oversensing, which is where the so sensing is the opposite of the pacing threshold. Sensing is essentially the pacemaker, uh, what it's reading on the E c G strip. So you think of it as a patient, for example, moves around or whatever that's going to cause small deflections in the in the e c g strip that are artefacts. If the pacing, if the sense if the if the sensing threshold is it's too low and it's looking and it's interpreting everything as a P wave, for example, that you're gonna over pace the patient. So you just need to consider to turning the sensing down a bit. Sorry, increasing the sensing threshold of it. That's basically it guys, To be honest, ask that basically everything that I have for you today. So, um, if anybody has any questions about pacing about heart surgery in general, General, from the perspective of, uh, of an S H O. Uh anything that I can advise anyone or help anyone without. Are we more than happy to try and help? Come on, guys. Give me something. Can we get the slides? Yeah, No worries, man. You can get the slides, Tina. That's not a question. Guys, listen here. I want you to make sure, please. They fill out the feedback forms because that's the That's the only that's the only currency that matters in the NHS, Unfortunately, is feedback forms. So, uh, if you wouldn't mind, be honest with your feedback, please. But yeah. If you could get get me this feedback forms done. I'll be very, very grateful to you all. Um so no questions. Send us the link and we can provide the feedback. Let me see now for me to treat you. Don't forget them, Terry. Do you know about this The way that works or No, I'm just finding out for you now. Yeah, How I can send you the link. Just bear with me. Please. Don't go. Mm. But, I mean, if you just like the Here we go. Thank you. Oh, amazing. Who's done that? Please take a moment. There you go. Guys. There's your feedback link. Um, final final call for questions. Anything about anything in applying for jobs in being anything, literally. All right, guys, peace out.