Before we move on, let us take a look at some
S3 and S4 issues. First and foremost what does
S3 mean to you? S3 is always going to take
place after S2 and that is nice because chronological
order. So take a look at the picture down
below. Then you will notice that there is
a little red line with S3, you see there? And that S3 right
there is following your S2. What is exactly
happening here? How are you referring to S2
as? S2 is a diastolic heart sound because
you just close your aortic and pulmonic valves
during diastole. And in the mean time what
happens afterward? The mitral valve opens
and blood is gushing into left ventricle.
Are you picturing this? You have to picture
this in your head or otherwise it is just
bunch of words that makes no sense. So all
of this blood is rushing into the left ventricle
during diastole, the mitral valve has opened
and if the left ventricle is too large as
it may occur with pathology such as congestive
heart failure. Could occur physiologically?
Sure. Really, what kind of patient? A patient
that is a well-conditioned athelete. Isn't
their heart a little bit more efficient in
terms of increasing preload and having increased
contraction? That is why they are athletes.
They are able to properly have enough blood
and oxygen being supplied to the skeletal
muscle. "So Dr. Raj, you're telling me that S3 could
be found in normal individuals?" That's exactly
right. Who are these individuals? Athletes,
may be pregnant ladies. What happens to plasm
volume in a pregnant woman? It increases up
to as much as 50 percent. That is a lot of
volume in your plasm I am telling you. And
what may then happen to left ventricle? Well
that left ventricle might then become overwhelmed
with fluid during diastole and you may create
an S3. Hope that is clear? So it could be
found normally in children for the same reason,
athletes, reasons we just talked about
and pregnant woman. An S3. However, in the
United States a 35-year-old who is obese, hearing
S3. That is pathology. You are thinking
about left ventricular dysfunction, a systolic
dysfunction. That is what happens with congestive
heart failure? What is the most common cause
of congestive heart failure? I am throwing
a lot of information at you, but that's okay
because this is how you are going to learn.
You are going to feel overwhelmed. You are
going to take what I am telling you and you
are going to digest this and trust me anything
that I have been talking to you about throughout
this entire lecture series, it is not the first time
that you are going to hear it nor is it the
last. Guarantee you are going to hear these
a hundred different times. So congestive heart
failure, the most common cause would be a
myocardial infaction, would be an ischemic
event. Therefore, causing death of the myocardium
resulting in perhaps congestive heart failure.
Resulting in what kind of dysfunction? Sytolic
dysfunction. Are you with me? Good. Now is
it possible that you might then create an
S3? Of course. Take a look at that chest X-ray
in your hand with congestive heart failure.
Tell me about that apex. Where is that apex?
It is not where it should be. It is not at
the midclavicular. It is laterally displaced.
You feel good? I hope so. Is this information
setting in? It will, have faith. Let's continue.
There is athletes. S4 is a little bit of a different story.
It is regrouped. So S3 could be found in normal
individuals, yes. We are going to hear S3 after S2.
What is an S2? An S2 is a diastolic heart
sound. What happened at S2? Closure.
Closure of whom? A2, P2, followed
by mitral valve opening, left ventricle is
too large. You create an S3. What about S4?
Take a look at the bottom picture. You've an S4,
where is it? It is before S1. Regroup, tell
me about S1. S1 is a sytolic or diastolic
heart sound? It is a systolic heart sound.
How do you know, Dr. Raj? Because during systole,
you have closure of the mitral followed by
closure of the tricuspid. Welcome to S1.
What happen right before S1? It is the fact
that you are at late diastolic. Think about this.
I am asking you what happened at the beginning
or right before closure of that mtiral valve.
Late diastole, what does that mean to you?
Atrial kick, right. SA node depolarized the
atria kicks. This is part of diastole. Is
that clear? Atria is going to kick. It is
acute part of late diastole and is kicking
the blood into left ventricle. What if the
left ventricle is thickened? What if it is
stiff? Like what? There is something called
hypertrophy. You've heard of that before. You
have heard of hypertension. You've heard of that
before. That's a lot of pressure on your
left ventricle and at some point left ventricle
is then going to respond physiologically.
It is going to go through an adaptation process.
What is that called? Hypertrophy. What kind?
Concentric, we will talk about this. Not to
worry. Over and over again, a concentric hypertrophy
is when the sarcomeres are going to duplicate
in parallel. Why? In this case, it is pressure
overload. What caused that excess pressure?
Hypertension being the most common. Later
on, we will talk about aortic stenosis. But hold
on, let me just give you what is happening
with S4. So here is hypertension, huge problem
in the US, metabolic syndrome. What is the
cut off point for hypertension? 140/90. Our
discussion earlier took place with the difference
between urgency and emergency? Do you remember that?
If you haven't, make sure once again you go
back and review to see. It's not that information
is difficult. It is the volume of information
and so, therefore, it is important that you
keep going back and review. Trust me. It will
work out. Trust me, it will. Just stick with
me. So with all that pressure taking place
in left ventricle undergoing concentric hypertrophy,
a thickened left ventricle wall. Tell me about the compliance
of this left ventricle. Take your time. Tell
me about the compliance. It is decreased,
right? Decreased compliance, what does that
mean? It has becomed stiffened. Now during
that kick, the blood is having a hard time
getting into left ventricle. What are you going
to create? You are going to create an S4.
Look at the term bolded here. Always abnormal
S4, what does it mean? Indicates a stiff left
ventricle. Example, hypertension. What's another
one? A pressure type of overload on left ventricle,
aotric stenosis. What kind of hypertrophy?
Concentric. What does that mean to you? The
sarcomeres are duplicating how? In parellel.
Causing what? Narrowing of the left ventricle. I'm
going to take you one step furthee, you ready? Of course,
you are. You are born ready. So that left
ventricle on thickening,
this is a diastolic dysfunction. That chamber
becomes very small and if that chamber becomes
very small you can’t fill it up doing diastole,
is that clear? That is the diastolic dysfunction.
What then happens to left atrium, please?
You see the last line right here. This is
dilated what? Left atrium. How come? The left atrium is having
a hard time kicking left ventricle. Therefore
left atrium is going to do what? It is then
going to get dilated. So what does S4 mean to you?
Always pathologic. What does it mean to you?
It means that you have a stiff left ventricle.
Now is it possible for you to have congestive
heart failure in which blood remains back
in left ventricle? Think about what I am just
saying. Congestive heart failure, you have
a dying heart. Blood then remains back in
the left ventricle. Are you with me? So you
are creating what kind of issue? You are creating
an issue where the blood is contributing to
stiffnes. So could you have an S4 with congestive
heart failure? Sure you can. That is not a good sign though.