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Video transcript

In this video we're going to talk about how to diagnose myocarditis and pericarditis. Both diseases are somewhat similar in terms of where they happen and the fact that they are both inflammatory processes, so a lot of the labs we'll talk about are indicative of both disorders. But as we talk about more and more invasive tests we can do to determine what's going on, we'll see when we can discriminate and say "This is myocarditis'" or "This is pericarditis." Let's start by talking about certain labs that you can order. Or things that you can analyze in our blood. Let's say I've got this vial, and there's a green top on this vial. And here's the rest of this vial as it goes down here and curves right back up. This guy is going to be filled with blood. There are a couple of things we can look at. First of all, there's the white blood cell count. And this isn't very specific, it's increased in all types of inflammation, so this could be inflammation from an infection, it could be from an autoimmune disorder, or if you're in a car accident, a traumatic injury can also cause inflammation and an increase in your white blood cell count. Other than that, you can also look at the erythrocyte, I'll write this out, this is the erythrocyte, which you might recognize as the term for a red blood cell. The Erythrocyte Sedimentation. Sedimentation is the process of blood, or some fluid, resting after it has been spun in a vial, it sediments down. So, Erythrocyte Sedimentation Rate. That's also referred to as the ESR, the Erythrocyte Sedimentation Rate, the ESR. This has the same feature of being increased in inflammation. So it's not specific to myocarditis or pericarditis versus other types of inflammatory processes. There's also another marker we look for that's called C-Reactive Protein, which is a protein that's made in the liver. I'll just write, CRP, that's what you'll see it's called on a lab results sheet, CRP. It's produced in the liver and also non-specific. It's also increased in inflammation. Let's get to more specific labs. We can order what's called a creatine phosphokinase level. A creatine phosphokinase level, it's an enzyme. That's what anything that ends in "ase" refers to. Creatine phosphokinase, the CPK level. We're looking to see how much of this enzyme or protein has leaked into our blood stream. And this is more specific because it's increased in our bloodstream when there is damage to the heart, brain, or some muscle. Heart, brain, or muscle damage. Which means that if a person has myocarditis, or if a person has just run a marathon, you wouldn't be able to tell the difference just by looking at the CPK level. They'd both be elevated. But perhaps one of the more specific, or the most specific lab you can order is what's called the troponan level. A troponan level, which you might recognize as a protein that's responsible for contraction of muscle, and it's present in the heart if you look at certain isomers of it. But a troponan level will be elevated when there is heart tissue damage. So it's very specific for some cardiac process and this is one of the first labs we'll ask for when we suspect someone's having a myocardial infarction, or an MI or a heart attack. This can also help us distinguish between myocarditis and pericarditis, because you can get an elevated troponan level with acute, or fairly early myocarditis. because you have damaged the myocardium, the heart muscle, which is where you store your troponan. Or you might see it in late, relatively later, pericarditis. Because the preicardium is not a muscle, it lines the muscular layer of your heart, and so if the pericardium is compressing on the heart, perhaps you'll have troponan leak from the heart eventually, but that will have to be late pericarditis, or more advanced pericarditis. So these are all the labs that we would order. Let's move on and talk about how we can use an electrocardiogram, which you abbreviate ECG. But because this is something more of a German term, we call it, oftentimes, an EKG, which you may have heard of more commonly. An EKG can be helpful in diagnosing whether a patient has myocarditis or pericarditis. I think I showed you this animation earlier, where you can see here that there's an initiation of a signal that comes down and is spread downwards and then comes back up through this myocardial wall. And as this is happening, there's a signal here that's being made, and it starts with a "P" wave, a "Q", "R," and then it's gone, "S" and a "T" wave. I'll draw that again in a minute, but these all happen. First the P-wave, as you have contraction of your atria. So see, when this pumps here, we'll have the "P" there. Then you have this QRS complex, it's called together, when the ventricle contracts. So you see now, the red was where the ventricle was contracting and then this T-wave at the end is when the ventricle relaxes, and you can see the redness going back upwards, signifying that the ventricle is relaxing during this time. This is what we look at in an EKG. This is the electrical signal of the heart that we're studying by putting some leads or stickers on someone's chest. Let's get rid of this thing. An EKG helps us to study the electrical signal in the heart. The electrical signal of the heart. And we have different leads, or different snapshots of the heart based on which direction we're looking at it from. A normal EKG would be flat, like this, and then we'd have a bump here, referred to as a P-wave. This is where you atria would contract, and then there's a Q-wave down here, there's a spike down, and the spike up right after is referred to as the R-wave, and then we have this spike down again, and that's the S-wave. We usually refer to this together as the QRS complex. And then we have a flat line here before we get another wave, and this is our T-wave. This segment in between in known as the "ST" segment. I know that's a lot to mention right now. I'm not expecting you to memorize everything about EKGs, but these are the letters I'm about to refer to. We see some fairly classic, or characteristic changes with myocarditis versus pericarditis. First, I have this EKG over here that we're trying to figure out, and this is going to be classic for myocarditis. With myocarditis, all we see is what's referred to as Tachycardia, and it's specially called Sinus Tachycardia when we're looking at an EKG. When we have the correct rhythm but our rate is a little fast. As you might recognize, in this lead right here, as we follow through for this guy, we have our P right here, there's the QRS squeezed in there, and we've got the T right there before we start up with another P, which is right here. And so we've got all of the right wave forms that we need, shaped as they're supposed to be. But this is kind of a fast rate to have, and so we've got sinus tachycardia with myocarditis here in this patient. Now another EKG we could look at here has some more specific changes that we can note and this is what's associated with pericarditis. In pericarditis, what you'll see is diffuse ST segment elevation. As I told you in our perfect EKG drawing, that I did over here, this ST segment is flat. If you look for the ST segment down here, notice that this is our baseline, but the ST segment is elevated. If we look at the other leads as well, so this is flat on this dark red line, the ST segment is elevated right there as well. So it's elevated here, and in all of the leads we're looking at. These are flipped over, but this one, this lead right here, shows that we've got an elevation as well above this solid red line. So we have ST segment elevations. I'll write an increase right there, because it rises up. When you see this for pericarditis, it's classic, and you can actually diagnose it straight from here you don't need to move forward, you can start treating right away. For myocarditis, sinus tachycardia is not a very characteristic finding on EKGs, so we'd have to do other tests. Let's move forward and talk about some other tests. Another test that we can order to look at the function of the heart is something referred to as an Echocardiogram. Maybe the "echo" part of it gives it away, but we call this an "Echo" for short. The echo part refers to the fact that we are only using sound waves, or ultrasound, to look at the heart. So, I'll make these important notes here: We're using sound waves to look at the heart, which is great because we're using no radiation, which you might recall is actually a cause of pericarditis. So you'd want to avoid using radiation. And the other thing about it is we study the function of the heart with an Echocardiogram. We're looking at an actual moving image, and this can help us differentiate between a patient that may have myocarditis or pericarditis, as we'll seein these videos right here. This is an echocardiogram of the heart, and this is a four-chamber view right here. This is the right atrium, the right ventricle, the left atrium, and the left ventricle. This is a patient who has mild myocarditis. The way you can diagnose that is to look at the right ventricle here, look at how much compression you have here. This is really acute angle that closes whenever the heart beats, relative to that over here in the left ventricle. We say this is hypo-kinetic, because it's not contracting the way it should. This is one of the things you get with myocarditis, where you have a dilation of the chamber and an ineffective ventricle that should be pumping blood out to the rest of the body. Now here's an echocardiogram at a different cut of the heart. You'll notice up here that there's a lot of fluid that's sitting between the heart and the pericardium. That's the pericardium that's sitting up here. This is because we have what's referred to as a Pericardial Effusion. It's an unusually large amount of fluid that sitting in the pericardial space, and it's compressing the heart. It's preventing it from beating the way it's supposed to. It's preventing it from filling with as much blood as it would like to, to pump out to the rest of the body. And this could be dangerous, because then you get hypotension, or low blood pressure, and other averse effects that are associated with it here.