- In the next couple of videos, we're going to talk about
two disorders that are often discussed together.
One is called myocarditis, myocarditis,
and the other one is called pericarditis,
and they refer to two different diseases
that are inflammatory reactions
of certain parts of the heart,
and I think you may have guessed that
just because both of them use this part, card,
meaning cardiac, and perhaps you also recognize
that anything that ends in itis, itis like that,
means that that's an inflammation or
an inflammatory process of whatever it's coming after,
like cellulitis is inflammation of the skin.
Optic neuritis is inflammation of the optic nerve.
So, myocarditis is inflammation of the myocardium,
which is the muscle of the heart,
and pericarditis is inflammation of the pericardium,
which is the outer layer of the heart.
So, I've started throwing some fancy terms at you.
So, let me define them.
So, when we talk about the myocardium and the pericardium,
where do they sit in our structural cardiac anatomy?
So, let's start from the very core,
and I'll draw a simplified heart.
Of course, you know that the heart
isn't really shaped like this,
but there are three layers to the heart.
I've drawn one right here, and then there's another layer
on the outside like this, so let me just draw
this layer out here, and I'll color this layer there,
and then we can start to label things.
This inner layer right here, and that also involves
everything that's on the inside, is the part of the heart
that makes contact with blood as it's pumped through
to the rest of the body.
This is called the endocardium, the endocardium,
and we're not going to talk about endocarditis in this video
but that's definitely a significant disorder to think about.
So, that's the endocardium.
The next layer, this meaty red layer that's on the outside,
is the muscle of the heart.
This is the myocardium, so that's the myocardium,
so let me label that there and this is the part
that's affected in myocarditis as we're going to discuss,
and then this outermost layer
that's all the way around here,
it's sometimes called the epicardium, so the epicardium,
but no one really calls it that.
The term most people refer to it as is the pericardium.
So, it's the pericardium and in fact, that does refer back
to what we were initially setting out to discuss.
Pericarditis is an inflammation of this layer,
but the pericardium isn't just one layer.
This layer that I've drawn here that goes like this
and wraps around here will come back
and reflect up that way.
So, let me draw it going all the way around.
It comes down here, flips back this way,
and then it comes and meets back up there,
and notice that this lining was coming in right here.
It flips here, and then starts going that way.
So, in a sense, it's a continuous lining,
but it forms these two layers,
and I'll color this portion inside here.
This is going to be its own little cavity
or this space here, and we refer to this
as the pericardial space.
This is the pericardial space.
All right.
So, I've set up these two layers right here
of the epicardium or the pericardium,
and, in fact, the layer that's here that
touches the myocardium and the inside of this
outer layer here, has a special name.
It's called the serous, the serous pericardium,
and some anatomists will make distinctions.
This is the visceral layer of the serous pericardium,
and this is the parietal layer of the serous pericardium.
I'm not going to write those down
because I think that's too much detail
for what we want to talk about.
Just know that there are two layers to the pericardium here,
and there's pericardial space,
and then finally on the outside,
this outer layer of the parietal layer of the
serious pericardium has a lot of fibrous tissue,
or fibrous tissue on it, and so I'm just going to
go around and just draw that, and all that means
is this outer layer is kind of rough,
and so, remember, the inside part of this lining
is called the serous pericardium.
This outer layer that's a little more rough
is called the fibrous.
It's the fibrous pericardium, okay,
and the fibrous pericardium is what you would see
if you were to dissect out the heart in a cadaver lab
or when you're doing surgery.
So, now that we know all of our different layers
for our structural heart anatomy,
I can tell you that the myocardium, as we discussed,
is the heart muscle, and so any disease of the heart muscle
will then undermine the ability of the heart
to pump blood to the rest of the body,
and so myocarditis is an inflammation of the heart muscle,
which can then lead the heart to dilate or this wall
can become thicker or the chambers can become enlarged,
making it difficult to actually pump blood out.
On the other hand, the pericardium, the serous pericardium,
which is the main thing we talk about here,
is the outer lining.
It's the outer lining of the heart,
and if there's an infection
or some other inflammatory process of the pericardium,
that would make it even more stiff,
and so what that means is that
when the heart tries to fill with blood that it receives
that's deoxygenated or doesn't have any oxygen
and it wants to send it to the lungs to get oxygenated
or send it to the rest of the body,
it's not able to pump a lot of blood out
because it can't collect it in the first place.
So, if the pericardium becomes inflamed,
it doesn't allow blood to return to the heart,
and functionally, that's the same problem here.
If you don't get enough blood back to the heart,
you can't pump it outside to the rest of the body.
All right, so I think we have an idea
of why it's so troublesome to have myocarditis
or pericarditis and we've talked about the card part
of where they exist in our anatomy,
but let's talk more about the itis.
Let's talk about inflammation and what does that mean.