- [Voiceover] The heart is a very beautiful organ
and here I have drawn a cross section of the heart
where you can see the various different compartments,
you've got the right atrium, the right ventricle
and the left atrium and the left ventricle.
And the right side of the heart
of course pumps blood to the lungs
which would be on either side of the heart
and this blood returns back
to the left side of the heart through the left atrium
and then blood is pumped again from the left ventricle
out into the system all the way down to the legs
and then up to the brain as well as the arms
through the aorta.
And of course, this entire process
is essential for life,
for delivering oxygen to the tissues,
delivering nutrients, all of that.
And so you would imagine,
failure of the heart pump
results in less output, less cardiac output
which means less tissue perfusion.
A patient would no longer be able
to distribute all that oxygen.
But what could cause failure?
Well failure of the heart can result from valvular problems.
So, for example if the aortic outflow tract
which is right here
is perhaps damaged or narrowed in some way,
it's going to make it extremely hard for blood
to be pushed out through the aorta
and out to the system.
So valvular problems can be a cause
of failure that leads to shock, arrhythmias.
Which means there's an issue
with the electric conduction through the heart
which allows it to function and pump our entire lines.
There could potentially be stiffness of the ventricular wall
or the wall of the heart
which prevents it from being able to contract properly,
and if the pump itself is so severely disabled
this can lead to shock,
lowering of the blood pressure
and decreased ability to
deliver the necessary oxygen to the tissues.
And I want to highlight that heart attacks
are the major cause of cardiogenic shock.
So, MIs, myocardial infarctions
cause decreased contractility.
So, what you'll see is
for example if we look at the left ventricle,
if blood can't be pumped forward it will back up
and it will back up into the left atrium.
And when the heart can no longer accommodate
all these fluid overload,
it's going to backup into the lungs as well,
each side of the lungs.
And as things gets worse and worse,
it will back up into the veins
and all the way into the right side of the heart
and it can be backed up
all the way into the system as well.
So this is really known as fluid overload
and there are just a couple of symptoms
that I'm going to point out.
So for example, pulmonary congestion.
Pulmonary congestion.
Like I said, blood is backing up into the lungs
and so that may make it difficult for patients to breathe
and they may have a cough that's productive
with a lot of fluid
and that's really the blood backing up into the lungs.
You may see something called
increased jugular venous distention, that's JVD
and jugular venous distention is basically
the jugular vein gets distended
because as you see here this blood backs up
into the venous system
and it can back up all the way into the neck.
And of course, you might see chest pain,
also known as angina.
As the heart is starved for oxygen
and then of course you may see
the different symptoms that you would see in other shocks
such as organ failure, organ dysfunction,
decreased urine output
and all of these is caused by decreased oxygenation
of those different organs and tissues.
And you will likely also see cool skin
as blood is being diverted away from the skin
and to more vital organ such as the brain
or the heart and the lungs.
So with these symptoms and these causes of heart failure,
how can we diagnose cardiogenic shock in a patient?
Let's take a look over here
so we can take a look at the diagnosis
of cardiogenic shock.
And so diagnosis will include of course your
typical labs such as serum lactate or ABG,
assessing the oxygenation
and the failure of tissues to utilize oxygenation
for their biochemical needs.
But also you're going to want to
look at different things that
might be causing heart failure.
So for example, you might want to look at troponins
which will show if there's any tissue damage
or damage to the heart
like in the case of a severe heart attack.
Or maybe you can look at a chest x-ray.
So here is a normal chest x-ray
with the clear lung fields.
You can see this diaphragmatic recess
so there's no fluid accumulation here
and here is a congested heart and lungs.
You can see this kind of fluffy fluid accumulation
where the pulmonary veins are.
So, over here on our little heart picture
the pulmonary veins are really congested
because of the backup of fluid
from the left side of the heart.
And you can also see this sort of blunting
of the diaphragmatic recess.
Here it's still a little bit sharp
but on this side you can see it's starting to blunt,
get blunted a little bit.
So you can kind of make out the outline of the diaphragm
and where it meets the chest wall
but it's somewhat obscured
as compared to the normal view.
And let me actually go ahead and erase that
so you can see it again.
You can see how it's still kind of obscured
versus over here.
Or maybe you might want to look at an EKG
for different signs of arrhythmias
or a heart attack or something like that.
Or take it one step further and get and ultrasound it,
echocardiogram to take a view of the heart.
This heart ultrasound will allow you to see
the contractility of the heart,
how well it's squeezing blood.
And so I highlight all of these really just to say
that you want to look
and see what's going on with the heart.
What is the problem that's causing this
cardiogenic shock or heart failure
so that you can potentially correct it.
But aside from these lab values,
two ones that are particularly important
in cardiogenic shock are evaluating the PCWP
which is pulmonary capillary wedge pressure
and the cardiac output.
So here we are, let's zoom back down
and take it over here.
And look down here
so we have a little bit more room to play around.
And again, I'm gonna raise it a little bit.
So first let's go ahead and tackle
the pulmonary capillary wedge pressure.
Now the pulmonary capillary wedge pressure
is determined by inserting a catheter
to go through the venous system
into the right side of the heart
and up into the pulmonary arteries
to essentially the capillaries.
And that's why it's called the
pulmonary capillary wedge pressure.
You wedge this pulmonary catheter
all the way into the pulmonary capillaries.
And the reason you do this is to assess
back pressure from the heart.
Remember in cardiogenic shock
fluid from the left ventricle builds up
and backs up into the lungs
and into the pulmonary arteries.
And so this backup of fluid actually creates a pressure
whereas the pressure is normally
less than 15 millimeters of mercury
in the pulmonary arteries near the pulmonary capillaries.
The pressure in cardiogenic shock
will be above 18 millimeters of mercury.
So this will be a way you can diagnose cardiogenic shock
when you're trying to figure out
what type of shock this may be.
And the second thing that you can
take a look at with the heart is cardiac output.
Now, I had mentioned cardiac output or cardiac index
and cardiac index might be a word
that you haven't heard before,
don't really understand what it is.
Well, cardiac index is essentially the cardiac output
over a patient's body surface area.
And cardiac index is really used to
standardize cardiac output.
The idea here is that patients come
in many different shapes and sizes.
They can be very tall like NBA players
such as Michael Jordan and Kobe Bryant
or normal sized,
a little bit smaller than a basketball star
or even shorter like children for example.
So, with different heights and weights of patients,
cardiac output varies
and that's why you can use body surface area
to really create a standard value
that can be used in place of cardiac output.
And cardiac index in patients with cardiogenic shock
will be less than 2.2 liters per minute.
So that's cardiac output over meter squared
and that comes from body surface area.
And the normal of cardiac index
should usually be between 2.6 and 4.2.
Now there are actually many different ways
to measure cardiac output
including pulmonary artery catheter.
You can also use an echocardiogram
to look at the heart
but it's important just for you to know that
cardiac output is an important measure
to obtain in a patient who has cardiogenic shock.
Now for the treatment of cardiogenic shock
I like to break it down into three different things.
First of all, remember in shock,
patients are lacking oxygen delivery.
So providing a patient with oxygen
will provide added support
so that their cells can receive the oxygen they need.
And number two, you need to provide
cardiovascular support.
So the cardiovascular system is in trouble
and needs a little bit of help.
So there's two ways to think about doing this.
First, you could increase the systemic vascular resistance.
So that means blood vessels
will be able to carry blood forward a little bit better
if the resistance is increased.
And this can be done with different medications called
vasopressors, norepinephrine, epinephrine.
They're all examples of vasopressors.
They allow blood vessels to squeeze down
to improve blood flow.
And another way to improve cardiovascular support
is through increased heart contractility.
If the heart can contract better
then it can squeeze out the blood.
In fact, that's the problem with cardiogenic shock.
Blood is not getting pushed out of the heart.
So improving contractility
and there's different medications for this as well,
but improving contractiility is
another thing that can be done
to treat cardiogenic shock.
And finally, the last
and probably most important thing to do
is to repair the heart
or whatever problem is causing the cardiogenic shock.
So for example, in a patient who has
occluded blood vessels in the heart,
there's a procedure to restore blood flow
by opening up those vessels
and allowing oxygen delivery back to the heart.
Or maybe as i said before, a valve is the problem
so repairing or replacing that valve
may be what helps solve the heart failure.
And in some very severe cases,
replacing the heart entirely,
performing a heart transplant
may be the only way to treat this cardiogenic shock.
So remember, in cardiogenic shock,
the issue is the heart itself is not pumping
and does not squeeze enough
to allow blood flow to go forward
and this results in poor oxygen delivery
to the rest of the body.