Alright, now, speaking of which, how important is
this? Really important clinically and these
are pictures that you're seeing over and over again,
but the number of things that we can walk
you through here. Let us begin. First and
foremost, I want you to take a look at the picture
in which we find left ventricular pressure,
that green line and then you comparing this
to the red line, which is the aortic pressure.
At that first point, where we have just completed
diastole, at the bottom of the valley and then
you are moving up that curve, what is that
called? Isovolumetric contraction, isn't it?
Of what? The left ventricle . And the left ventricle
is building up pressure. Would you tell me how
much blood is in your left ventricle right
now? It is the fullest that it can be. And
it is building enough pressures so that it
can do what? Open up the aortic valve. That
is my problem and on a question they can actually
put A, B, C, D, E on this graph and ask you where
is not pathology located for aortic stenosis?
It would be at that point where the green
line intersects with that aortic pressure
and is trying to open up, but it can't. So
what does the left ventricle have to do? It
has to continue building
that pressure. How is that represent? You
see that shade underneath that curve that
peachish shade, that's a pretty color, isn't it?
The peachish shade that you see underneath
that curve represents the increased pressure
of the left ventricle lifting up weights so
that it can overcome the afterload of the
stenotic aortic valve. Is that clear? How
are you going to represent this? Well here
is S1 and there is S2. You see them. Now S1
is going to represent what? Closure of the
mitral valve. S1 is never opening. Actually,
no heart sound is created by opening. Is that
clear? We have talked about that a few times
now. So where is my mitral valve closing?
At the bottom of that valley. At the end of
your diastole, right before you begin isovolumetric
contraction. And so therefore when the mitral
valve closes, you're building pressure, crescendo.
Aortic valve opens, decrescendo.
It is a diamond in the rough. That is a diamond
between S1 and S2, the crescendo decresdendo
the type of murmur. Welcome to aortic stenosis.
How is the patient feeling? Tell me. Tired,
fatigued. Now you guys feel motivated right now.
You want to learn more. Your are thirsty for
knowledge. Let us continue. So you have crescendo
decrescendo type of murmur.
Next, let us take a look at the pressure-volume
loop. Well we will take a look at two here.
One is going to be the blue curve. You see
that solid blue curve and that is going to
be normal. Listen to what I am saying. That
solid blue curve represents normal pressure-volume
loop. Now with that, you begin at a point
where it is a diastole. The X-axis represents
volume and the Y-axis represents pressure.
to be pressure and so now you begin increasing
volume. You increase your volume,
what do you do now? You close your mitral valve and
you move up the Y-axis, which means what? You
increase the pressure. You see that. Now this
is the pressure-volume loop that you also
comfortable with and the blue line represents normal
and you move up that pressure and eventually you
will open up that aortic valve. When you open
up the aortic valve, you go directly into what
is known as your rapid ejection. Which way
are you following the pressure-volume loop?
You are following with counterclockwise, not clockwise. That
must be understood. So that is the only way
that you get this right. I want you to compare
that point where aortic valve should open and
compare that to the dash line. That dash line
continues to increase pressure, why? Because
the aortic valve doesn't want to open. Is
that clear? So any time that you find a curve
in which it is much more increased in pressure
compared to normal, then that you automatically
should mean what? Aortic stenosis and now
I may ask you something. If that aortic valve
doesn't want to open and by the time you finally
do,then would you tell me what is stroke volume
equals. Close your eyes. Stroke volume equals,
when is your heart or ventricle the fullest,
at the end of diastole or end of systole?
Take your time. You got this. At the end of
diastole is when the left ventricle is the
fullest, isn't it? From this, you subtract
your end systolic volume. What is that going
to give you? Stroke volume. Is that clear?
So how does that represent?
On the pressure-volume loop, the area between
the curve or area underneath the curve represents
the stroke volume. So now in aortic stenosis,
how do you open up the aortic valve, systole.
As you open up that aortic valve and once
you do so, the blood is being ejected. How
much blood is left at the end of systole?
It is the least that your left ventricle contains.
In aortic stenosis when the aortic valve doesn't
want to open, then at the end of systole,
how much more blood you have left in your
left ventricle? A little bit more. You see
that dash curve and so when you follow it
with kind of clockwise, you will notice that
end systolic volume is actually increased.
Is that clear? When your end systolic volume
is increased and in the equation where stroke
your end systolic volume, with an increase
in end-systolic volume, what have you done
to stroke volume? You have decreased it. These
are types of questions that you are going
to get integrated with pathology and physiology.
If you're weak these particular areas,
I would highly recommend you go back and
take a look at your physio so that you are
perfectly clear with every single one of this
clinical points. We must continue.
Aortic stenosis, pathophys. As the valve
area decreases, the left ventricle must work
harder. What is the left ventricle going to
do? Increase thickness. It is going to increase
the demand for oxygen. It could or could not
be met. If it is not met, then we have issues
with what is called as angina. And in response
to the increased workload, what kind of effect
is the left ventricle undergoing? Hypertrophy.
What kind of hypertrophy is this? It is the
fact that sarcomeres are going to do duplicate
in parallel. It is
called concentric hypertrophy. Take a look
at these hearts. It shows exactly
that when you are walking through this. You
see the normal heart. You see where is LV,
left ventricle. That is the normal left ventricle.
"But Dr. Raj, it looks thickened." Yes. It is
supposed to be, normally. Left ventricle has
a heck of a lot of responsibility of supplying
blood to the entire body. And so therefore it
has to have increased pressure, 120/80. You
know that right. Now I want you to compare
the thickness of left ventricle of normal
versus which you are seeing here with concentric
hypertrophy. Concentric hypertrophy, you have increased thickness.
What caused that? Increased pressure. In this
case, by whom? Aortic stenosis. The left ventricle
was lifting weights and it underwent hypertrophy.
You tell me once again, what happens to
stroke volume here with the aortic stenosis.
It decreases. Why? Because of increased end
systolic volume. Why? Because at the end of
systole, there is more blood left in left
ventricle because of that stenotic aortic
valve. Is that clear? Make sure it is before
you move on. Or otherwise you want to make sure
you solidify that point forever more before
take a look at any other issues. Now in terms
of concentric hypertrophy that is exactly
what we just talked about, that bigger left ventricle.