- So you're probably aware that we have
four valves in the heart,
and if you're not, that's completely okay.
And you can see in this handy little drawing
that I've placed on the left side of the screen
that you can actually see all four valves at once
in this picture, and that's kind of a unique view,
and it gives you a way to visualize
where the valves are in relation to each other.
So let me help you orient yourself real quick.
So the way I like to think about this is
as if I'm on top of a building,
there's me, a little stick guy,
and I'm about to drop this big water balloon
on someone down here, who's just kind of
minding their own business and reading a newspaper.
And if you're wondering,
I definitely would have dropped the balloon.
But you can see that this guy down here is facing this way,
and I'm up here looking down
basically at the back of his head.
And so, if I could look through his skull
and down into his chest,
I may come across a cross section of the heart
that actually looks like what I've drawn here.
And I can tell you that this is the pulmonic valve,
and I'll abbreviate that PV.
This is the aortic valve, AV.
This is the mitral valve, and this is the tricuspid valve.
So let's talk about murmurs for a second.
So if you've been in the hospital,
or you're familiar with cardiology,
or maybe your grandma or grandpa has a murmur,
maybe you've heard of some of the common ones,
like, let's say, mitral regurgitation
or maybe aortic stenosis.
Well, a lot of people get caught up with
the regurgitation part or the stenosis
and may forget what's actually causing
or caused these problems.
And so, let's take a look at some of the things
that actually cause valvular heart disease.
So some valves can actually become calcified,
and even though I'm drawing these little calcium ions
as if they're ions and in solution,
that's not really the case.
And these calcium ions kind of go together with
fat and cholesterol, and the last time you heard
all those words together,
unless you were talking about a Big Mac and a glass of milk,
it was probably in reference to atherosclerosis.
And so, the process of valve calcification
has actually been found to be very close to the process
that causes atherosclerosis,
and atherosclerosis is just the buildup of
fatty and, over time, calcific plaques
in the arteries of the body.
So another cause of valvular disease is valve degeneration,
and a lot of the times the degeneration
is associated with connective tissue disorders,
and all that really means is that you have problems
with proteins that normally make up
some of the structural components of the body,
and there are these structural components in valves
and some of the heart structures.
And so, that's why these valves can become dysfunctional.
And so, a classic connective tissue disorder
would be something like Marfan syndrome,
and the way I like to remember that
is with a picture of good ole Abe Lincoln.
Now this is not to say that Abe Lincoln had Marfan syndrome,
but he did have some of the very typical
outward features of Marfan,
such as being really tall and skinny,
having long fingers and a really long face.
So what else can do it?
Well, bugs can do it.
And when I say bugs, I don't mean an ant or a fly
but rather a pathogen or a bacteria or virus.
And so, these bugs can actually get into the blood,
and since all the blood goes through the heart,
then these bugs will actually see
the surface of the valves in the heart,
and they can either stick to it or cause an immune response
or a combination of the two, and as a result,
you could get problems with the normal working of a valve.
And so, if you'll notice where I've placed
all of these causes,
they're actually all on the left side of this diagram.
And so, if you bear with me for a second,
I'm going to kind of split the heart into left and right.
And so, here I've separated the left side of the heart
and the right side of the heart,
in terms of the valves,
and the reason I've done this
and listed all the causes on the left side
is because as a general rule,
left-sided valvular heart conditions
are much more common than right-sided valvular conditions,
and the reason for this is pretty easy to understand.
I like to think about it with a pair of shoes.
So I have this pair of shoes
that I love and wear all the time,
and those get really worn out quickly.
And then I have this other pair of shoes that I kind of baby
and I wear on the weekends or on special occasions,
and those never get worn out.
They last for a really long time.
And so, the left-sided valves are like
that pair of shoes that I wear all the time.
And so, because the left side of the heart
is the workforce that pumps blood
out to the rest of the body,
and it's pumping at really high pressures,
every time the heart beats and goes through a cycle,
blood is smacked up against these valves on the left side.
In the right side, blood splashes up against these valves
because it's at much lower pressure
and is performing much less work.
And so, to illustrate the last two major causes,
I'm going to come over to the right side of the screen.
And so, let me explain what this diagram is.
We're actually looking at the left atrium here,
the aorta here, and this whole thing is the left ventricle.
And so, for these two causes,
the same left-to-right rule,
meaning left more common than right, still applies.
And so, the first thing I want to talk about
is annular dilation.
So the annulus is really just this fibrous ring
that supports the valves.
And so, you can see I'm circling those in right here
for the two valves in this diagram.
And so, in a condition such as an aortic aneurysm,
which is really just a ballooning out
of the walls of an artery,
you would have something that looks a little more like this,
and as a result, it's going to pull the annulus this way.
And so, if we actually come over to
the other diagram for a second
and get rid of this line down the middle,
so we can see the aortic annulus,
I can actually show you what that would look like
in this view of the heart.
And so, instead of the annulus that I'm erasing now,
as a result of this aortic aneurysm,
now it's been dilated, and instead of the cusps
coming together nicely,
now maybe you have a situation like this,
meaning that the valve does not close fully.
And that circle that I'm drawing is the open area
from the valve not being able to close.
Now, how could you get annular dilation
in the other valve in this diagram on the right?
Well, what if the actual heart muscle dilates or expands?
Well now the annulus of this valve is being pulled this way.
And so, in a similar fashion
it's going to pull the valve apart.
And over here on the left diagram,
this would now look something...
Like this.
And so, now you can see that this space in the middle,
where my cursor is, is all open.
And so, you can imagine how that could cause problems
with blood flow in the proper direction.
And so, the last major cause I want to talk to you about
are ventricular attachment points.
And so, you'll notice in this diagram
that we have these blue things right here,
and these are called papillary muscles,
and this is actually part of the left ventricular muscle,
but they have a specific function,
and that function is to hold these white strings here,
which are called chordae tendineae.
And I'm not really a professional at language,
but to me that would seem to mean tendinous cords,
and these tendinous cords are attached to the valve.
And so, the papillary muscles serve as
a ventricular attachment to the valves
via the chordae tendineae.
And so, you can imagine that if we have a rupture
or break in a papillary muscle, or the same thing,
a rupture or a break in a chordae tendineae,
then this valve over here is kind of free
to float wherever it wants.
And so, that can be problematic.
And so, these are most of the major causes
of valvular heart disease.