In 15 minutes, I'm going to talk about all of supraventricular arrhythmias and brain arrhythmias. So, we'll see how it goes. But I want to focus a little bit on epidemiology and why we should care about this in ICU. Develop a framework for differentiating it, and there's only three steps for that. Then talk a little bit about pharmacologic therapies. If we have time, we could talk about slow heart rhythms as well, and then review treatments for that. All right, so why do we care about this? These are very, very common in ICU. All of you have seen this there. It's probably due to increased adrenergic drive, the fact that they're all on telemetry, the fact that they're sicker, their hearts are irritated. Whatever the cause is, there's a higher rate of death if you have supraventricular arrhythmias. This is one study where the odds ratio is almost two. So, something to worry about, and it definitely increases ICU length of stay, especially for atrial fibrillation, which increases about a third. In general, when you see a patient with a supraventricular arrhythmia, the way to think about it is, number one, is the patient stable or not? If they're not stable, then you have to do ACLS or other interventions to get them stable. If they're hypertension, you also want to treat them urgently. Those things require treatment first, and then you want to figure out the arrhythmia cause. What's causing, what's driving the arrhythmia? Why does that matter? Because you want to prevent future episodes of these arrhythmias. But while you're thinking about what the arrhythmia type is, you still want to be managing a patient acutely. Alright, so let's go talk about, here's just a case presentation, just in the interest of time, I'm just going to skip over it. This is a classic patient that you present in your ICU. This is their ECG over here, heart rate's 120. So this is considered a narrow complex tachycardia. So here, the QRS complexes are narrow, and so what you want to do is you want to follow this algorithm here. I don't know if you can see the, I don't think you can see the arrow here. Alright, so the first question, whenever a heart rate is fast, is it wide or narrow? The wide one will be in the next 15 minute talk, but for this one it's narrow. Then the second question is, is it irregular or a regular rhythm? And then if it's irregular, you go down one pathway. If it's irregular, then you administer adenosine or vagal maneuvers. Those are the three things. So just to get, let's get everybody involved, let's make this more interactive. What's the first thing you look at? Wide or narrow? And then if it's narrow, what's the second question? And then the third question, if it's regular, what's the response to adenosine? That's it. You don't need to be an electrophysiologist and go through short RP and long RP tachycardias, because guess what? Unless you're an electrophysiologist, you don't care. I'm a critical care cardiologist. I don't care what it is in the ICU. I just want to get this patient out of this rhythm and prevent them from being in it. Alright? So let's go back to this patient. In this patient's case, it was a narrow, complex rhythm, and it was regular, right? So we've answered two of our questions. And then the third thing is, what was the response to adenosine? What happened here? What was that? The rhythm slowed down. The rhythm slowed down. It didn't break. And so then you can see here that these, it slowed enough where you see these gigantic P waves that are showing up. So this is actually sinus tach, alright? Sinus tach, I don't really need to talk to you about sinus tach and what that means. It's the most common rhythm, right? But it's just one of those things where it can be hard to differentiate sometimes, and sometimes you have to do things like giving adenosine to figure it out. This is another case presentation. Let's just go over the ECG here. Is this narrow or wide? By the way, they're all narrow in this talk. Is this regular or irregular? Alright, so let's go to this thing. This is what happens when you give adenosine. What do you see? I blew, I, it's flutter waves, right? Like if you look at this one, now it's obvious that this is flutter waves, but it can be tricky to figure out this is flutter, right? I mean, maybe you can see the sawtooth and the inferior leads, but it's hard to. But here, you can clearly see it with adenosine. Now, sometimes adenosine can be super effective because it blocks the AV node, and you can, oh, I missed it. You could block it for a period of six seconds, but in this case, it just slowed it down. Alright, how do you treat atrial flutter, or how do you suspect it? Whenever you have a fixed heart rate of 150, if you have sawtooth patterns in the inferior leads, those are all consistent with flutter, and if you give adenosine, you'll have flutter waves. Treatment for flutter is hard because the AV node is, it can only block so much, and so if you give a calcium channel or beta block or digoxin, you might have trouble slowing the heart rate down, but it should help a little bit. You can also consider amiodarone or rhythm control if the patient's unstable. Once the patient's out of the ICU, ablation tends to be the treatment of choice. It's 95% effective, but we don't do this in critically ill patients. Atrial flutter has the same risk of stroke as atrial fibrillation, so if you're going to do any kind of rhythm control therapies for flutter, like considering amiodarone, you must put the patient on anticoagulation, or at least consider it. Alright, here's case number three. Okay, you know, what is it, wide or narrow? Alright, is it regular or irregular? Alright, so let's see the response to adenosine. Do you see a difference? I have it highlighted. It's back in sinus, but look here in this one. Do you see the lead two, the P waves are inverted? So this is not a sinus rhythm, but here, because it broke out of it, this is an atrial tachycardia. There are two types of atrial tachycardia, but both of them are characterized by repetitive tachycardias, and all of them have like a slight speed upramp of heart rate for the first five to ten seconds before becoming more stable, and there's two mechanisms for this. One is where there's just some part of the atria that wants to beat fast. Those, if you give adenosine, it won't terminate it. The other kind is where somebody's had previous heart surgery, maybe an atrial ablation or something else, it's basically scar tissue in the atria, it's basically V-tach of the atria, so it's atrial tachycardia there. That if you give something to block it, like adenosine, it will terminate the arrhythmia. Oftentimes, it's triggered by premature atrial contraction. For either type, you want to be using the same medications that you could use for things to block the AV node, beta blockers, calcium channel blockers. You could give adenosine, but that's only going to work for six seconds, and you could try other rhythm control agents. All right, next one. This is still narrow, by the way. The QRS complex is below 120 milliseconds, but is it regular or irregular? It's still regular, right? Then now we have to see, what's the response toward adenosine? Well, there's a slide that's deleted, apparently. What I wanted to show you was when it went into sinus rhythm. So that slide's deleted. All right, anyway, either way, this is probably the most common arrhythmia that's a narrow complex regular tachycardias. Either one's initiated by a reentry tachycardia. They're both initiated by a PEC, and the medical therapy's the same. You want to basically break a conduction through the AV node. Adenosine's 91% effective, but again, it only lasts for a short period of time. So if the patient has lots of salivos of this, you want to consider something else like a calcium channel blocker, beta blocker, or other antiarrhythmics. The problem is some of these medications also drop your blood pressure, so you're probably not going to give you verapamil to a septic patient. But you could try other things like amiodarone or flecainide. Ablation is curative for these arrhythmias, but again, you won't do this in a critically ill patient. Let me go over the two different types of this. So there's AVNRT or AVRT. So who here feels comfortable diagnosing the difference between these two arrhythmias in the ICU environment? I don't. So you can't tell. And again, do you care? No. Because both of them are treated the same in the ICU setting. But let's go over for AVNRT. What happens with that is that you have basically a re-entry circuit near the AV node and basically sends down signals down the ventricles and sends signals back in the atria. There's two different forms of it. One's slow-fast, one's fast-slow. It doesn't matter. They're both hard to detect on the ECG in the ICU. And another kind is AVRT, in which case the circuit is, there's a bypass track somewhere between the atria and the ventricles, not near the AV node. That's it. Here's an example of a, this is actually a young woman, 19 years old, came in in shock, developed this arrhythmia. Again, can you tell the difference between AVNRT and AVRT here? You can't. This is what happened after we gave her adenosine. She actually has intermittent delta waves. This is AVRT. But this is rare to find. Let's go to this one. This is not a narrow complex tachycardia. I know it's a narrow complex tachycardia. But this is an example of AVRT where it's going down the bundle of CANT rather than the AV node. And it's basically something that you see in patients who have a WPW syndrome. This one is treated just like any other narrow complex tachycardia, except it's not narrow. You treat it the same way. Let's go to the irregular rhythms. We have about five minutes left. I want to focus on the irregular ones. This is the most common one, which is AFib. All of you know how to treat AFib. Beta blockers are probably the best medications if they're not in shock. You could try calcium channel blockers, again, if your blood pressure can handle it. And then digoxin. Digoxin tends to be less effective in ICU because it works through vagal mechanisms. And most patients in ICU don't have heightened vagal tone. They have hyperadrenergic tone, right? But you could try it. In all these patients, you want to be thinking about anticoagulation. This is the most common arrhythmia in the ICU. Depending on the ICU, like a surgical CVCU, it's almost like 43% of patients. In a less acute ICU, it might be 1.7%. But either way, it's associated with badness. If you want to try rhythm control therapy, if you can't control their heart rate, if you can't keep them stable, then you could try pharmacologic conversion. The go-to choice, in most cases, is 150 milligrams of amiodarone over 10 minutes, and then you start them on a drip. You could consider ibutylide. I've used it once in the last 15 years. And that is rarely used because it causes torsades in about 4% of patients. Alternatively, you could shock the patient. If you have time, if the patient's stable enough, you should give them amnestics and analgesics. But otherwise, you could just shock them and then treat them later. But either way, if you're doing rhythm control therapies, you have to consider anticoagulation because it's a higher risk of cardiombolic stroke. Here's the next one. This is a multifocal atrial tachycardia. This is an irregular rhythm, but you see P waves, and three different types of P waves. Almost always, this is associated with patients with pulmonary disease, either COPD or asthma. If you see any question on your board examinations that has the word theophylline in it, this is the answer. Because theophylline causes multifocal atrial tachycardia. What do you do about this? Most patients are fine. Their heart rates are 120, 130. But if they can't tolerate that heart rate, you could try beta blockers or magnesium or calcium channel blockers. I have about two minutes left, so let me just talk about bradyrhythmias. And for bradyrhythmias, there's really two problems. Either the heart doesn't want to beat and doesn't want to beat anywhere, or something is blocking conduction. That's it. When you have a differential diagnosis for this, it's basically very broad, so you have to take a good history. But there's a number of different causes for it. Let me just go over a few things here. This is just an example of a lady who came into the cardiac ICU because she had an intracranial abscess. Now, why is she in a cardiac ICU? I'll tell you in a second. So here, if you see this ECG, what does it look like to you? Just sinus bradycardia, right? So nothing specialist. In her case, though, she was symptomatic. Her blood pressure was low with that heart rate. And so for any type of bradycardia, if you have acute bradycardia and the heart rate's not able to maintain blood pressure, you want to be considering, well, what is the cause of it? In her case, she had it due to heightened vagal tone and infection. And basically, you want to do something to speed up the heart rate. Considering if the patient's coding, atropine, epinephrine. But if they're not, then you could consider other medications like dopamine, epi, or aminophilin. All right. This is another patient came in, basically had persistently positive MRSA in their blood. And here you can see, I just highlighted with these bars, that there's a big difference between the P wave and the QRS complexes. This is first degree AV block, right? And then there's a number of causes for this. This is clinically usually asymptomatic. We don't care in the ICU setting. You've seen it plenty of times, except in patients with endocarditis. Because in those cases, then that means there's an abscess forming around the AV node. And in this case, what happened to him? Look at this ECG. What do you guys see? Prolongation of the AV node, right? So when you see this, this is basically a surgical emergency, the patient needs to go to the OR. Unfortunately, this patient that I'm showing you was not a candidate to go to the operating room because of other comorbidities. And so this is what it ended up having. And now you started having group beating. So you're having blocked beats. So the patient developed wanky block, and the next one was complete heart block. For all these things, the thing for any type of bradycardia is when. When do you treat bradycardias? Only if they're symptomatic. If the patient has a heart rate of 30 and they're doing fine, or they're sleeping, do you care about it? No. Okay, so that's that. That's 15 minutes of arrhythmias of this. I should probably tell you about this rhythm here. Rhythms that are fast and that are slow. Ever hear the term tachybrady? This is it. So basically what happens is you have a period of sinus arrest, where there's no electric activity in the atria, and nothing transmitted to the ventricles. And then you have other periods of tachyarrhythmias, where the atria are fibrillating. That's the tachy portion of it. So one's called sick sinus syndrome, when you have a period of sinus arrest. And then the tachy part is the AFib with RVR. This is the most common reason to get a pacemaker, because for the AFib with RVR portion of it, you need to give them beta blockers, calcium channel blockers, or digoxin, which further slows down the heart rate and causes longer pauses. And so then you have to give them a pacemaker for that time. All right. That's it. This is a classic one, digoxin. I don't know how often you see digoxin. It's becoming less common, but I feel like it's still a common board question. Because it has a narrow therapeutic window, the classic description is somebody who comes in, altered mental status, green, yellow, halo, nausea, and vomiting. Oh, by the way, they have a funny-looking ECG that looks like this. Does this look recognizable to you, other than it's black and white? Not really, right? It's basically, you have maybe a P wave somewhere, maybe something, and then you have a wide QRS complex. And so this is basically paroxysmal atrial tachycardia. So all you want to do is basically get rid of the digoxin. Sometimes you consider the digoxin antibody.

supraventricular arrhythmias

ICU treatment

pharmacological therapies

Advanced Cardiac Life Support

atrial flutter