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Course: Health and medicine > Unit 3
Lesson 8: Myocarditis and pericarditisDiagnosis of myocarditis and pericarditis (part 1)
Created by Raja Narayan.
Want to join the conversation?
- What is the physiologic mechanism of increased ESR in inflammation?(2 votes)
- Increased amount of fibrinogen causes RBC's to "stick" together, giving them a higher density, which then causes them to settle faster. At least that's my understanding, I'm sure there is some other factors as well.(3 votes)
- Pericardial effusion is an abnormal build up of fluid in the pericardial cavity.
My question is wouldn't inflammation decrease the space in the cavity?(1 vote)- Your heart may need to pump harder to move blood between your lungs and your heart. As a result, the right side of your heart may enlarge. Fluid around your heart (pericardial effusion). Accumulation of fluid in the sac (pericardium) that contains your heart may cause your heart to appear enlarged on a chest X-ray.(1 vote)
- When you see an elevated ST segment in the ECG, how do you differentiate between pericarditis and ST elevation MI?(0 votes)
- http://lifeinthefastlane.com/ecg-library/st-segment/ I recommend looking at this site to gain a better understanding of the ECG and how to differentiate between different pathologies; it helped me out a lot!(1 vote)
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.