- [Voiceover] So heart failure is a pretty broad disease.
It's essentially defined as this inhability
to meet the body's demands, right?
But, how do we go about diagnosing that
or how do we figure that out?
Well, there's a couple of ways that doctors can do this.
And the first group of ways is
just by imaging the heart.
Or, essentially just looking at it.
So what we might do is we might take an x-ray
or the chest area.
Now, x-rays use this electromagnetic radiation
that's blocked by certain structures more than others.
So, that's why you might see the bones
show up as white.
And then, other organs might show up as gray.
So, this lets doctors kind of visualize
the current state of both the heart and the lungs.
So, usually they're looking for
the outline of the heart, right?
And one thing they might look for in the heart
is any sign of enlargement where the heart
just looks bigger than it normally should.
Because remember, with both systolic and diastolic failure,
the heart can actually get bigger.
And this can sometimes be seen on x-ray.
And then another thing that doctors
might take a look at is your lungs.
Because remember with left-sided heart failure
you can have this congestion
or a fluid build up in your lungs.
And this fluid is sometimes visible on x-ray.
And this can give doctors a clue as to both
how severe the heart failure is
and also, whether is left-sided or not.
So that was x-rays, but another diagnostic imaging
technique that we sometimes use,
and it's probably actually more common for heart failure,
is the echocardiogram.
And so, if we take a look at
the first part of this word, echo,
it kinda clues into its meaning.
This diagnostic uses sound waves actually
instead of electromagnetic radiation like with x-rays.
Specifically you have this thing called the transducer
that sends out sound waves.
And then it waits for the sound waves
to bounce back or to echo.
And by knowing certain properties of the tissues,
like how fast the sound waves are gonna move through them,
we can get this image and even sometimes a real-time video.
And so since you can see the heart moving via this video,
this tests are super valuable for measuring
the heart's pumping ability.
Or your ejection fraction.
Which you know, if we remember, it's this percentage
of blood ejected from the heart with each beat.
And by measuring the ejection fraction
the echocardiogram is a super useful tool
for doctors to figure out
if its diastolic failure or systolic failure.
Because with diastolic failure,
remember that you can have a preserved ejection fraction.
Whereas with systolic failure, your ejection fraction
is typically a lot lower than normal.
Alright, so besides imaging techniques,
another thing we can look at is the blood test.
With a blood test we're looking for certain substances
that are secreted or associated with heart failure.
And one in particular that we're going to focus on
is called B-type Natriuretic Peptide.
And that's a mouth-full so I'm just gonna
refer to it as BNP.
So BNP is this really important indicator
because it's secreted by the heart's ventricles
in response to this excessive stretching of the muscle cells
and changes in pressure in the ventricles.
Remember that with heart failure
the pre-load or the pressure in the ventricles
tends to increase right?
Which causes the muscles to stretch more
and the heart to enlarge.
So when this happens, the ventricles secrete
this BNP into the blood.
So the more severe the heart failure,
the more stretch in the ventricles
and the more BNP that's secreted.
And so it makes sense that if we
take a small sample of blood
we might be able to analyze it
and see how much BNP is present.
So BNP levels below 100 pg/ml of blood
indicates no heart failure.
And this is a really small amount
but it's still measurable.
And BNP levels between 100 and 300 pg/ml might
suggest the presence of heart failure.
Between 300 and 900 it might be considered
mild to moderate heart failure.
And then above 900 pg/ml would indicate
a severe case of heart failure.
But beyond Imaging and a Blood Test,
the doctor will often use a couple of classification systems
to describe the severity of the symptoms.
Basically so they can get an idea
on how best to treat each individual patient.
And the first is the Stress Test
which is also know as
The New York Heart Association Functional Classification.
This looks at how well you respond to physical exertion.
Because we know that with more activity and exertion,
your body demands more blood right?
So depending on how well your heart can respond
to increasing demands by increasing this activity,
we can start to understand how severe the heart failure is.
So the doctor might monitor you
while you either walk or a treadmill
or ride a stationary bike.
And the first class or I is
no limitation to physical activity.
Meaning that this activity doesn't cost any
out of the ordinary fatigue, palpitations
or shortness of breath.
Class II is some limitation to physical activity.
Meaning that you might be comfortable at rest
but any normal physical activity
results in some symptoms of heart failure.
Class III however is a lot of symptoms
during physical activity.
But still no symptoms at rest.
Finally class IV indicates a complete inhability
to undertake really, any physical activity
without feeling no symptoms.
And furthermore those symptoms even occur at rest.
So the second classification system is
The American Heart Association Stages of heart failure.
And this one is more defined at the objective level
bye the amount of structural heart disease
that's present with each patient.
So with Stage A, the patient might be
at risk for heart failure.
But there aren't any structural changes to the heart.
So at this point it might be a patient with
maybe diabetes or high-blood pressure.
But there haven't been any changes to the heart in response.
And there aren't any symptoms of heart failure.
In Stage B, patients have some sort of
measurable structural heart disease.
So, like maybe their ejection fraction is lower
or they have an enlarged chamber.
But with Stage B, symptoms of heart failure
still haven't developed.
At Stage C, both a structural heart disease has occurred
and symptoms of heart failure are present.
And finally, Stage D indicates
and advanced level of heart disease
and continued symptoms of heart failure.
And this level usually requires
aggressive medical therapy and intervention.
So using these two systems together,
doctors can get an idea on how best to treat each patient
based on both their class and stage or heart failure.