- Hi, my name's Jenny Sprengler.
I'm an RN with the cardiology clinic
at the St. Cloud VA.
Today we're going to talk about cardiac physiology,
or how your heart works.
The heart is a muscle,
it's about the size of your fist,
and it sits in the center of your chest
and a little bit to the left.
It's essential for life.
It receives blood that needs oxygen
and it pumps it to the lungs, where it's filled with oxygen,
and it comes back into the heart
and is pumped to the rest of your body.
The heart has four chambers.
There's two on the top that are called the atrium,
and two on the bottom that are called the ventricle.
The top two chambers are a light blue on the screen,
and the bottom two are a darker blue on the screen.
Blood comes in the heart through the right side,
through the superior and inferior vena cava.
It's then pumped through the pulmonary artery
into the lungs,
where it's filled with oxygen,
then returns to the heart through the pulmonary veins,
and it enters the left side of the heart.
The blood is then pumped through a large vessel called the aorta,
and it distributes oxygen-rich blood to the rest of the body.
As you can see from the previous picture,
there are four valves in the heart.
This picture gives us a little close-up of those valves.
There is a valve on each side of the heart
between the atrium, or the upper chamber,
and the ventricle, the lower chamber.
These valves help to prevent blood from back-flowing.
On the right side we have the tricuspid valve,
and on the left side we have the mitral valve.
When the blood goes to leave the heart from the right side,
it goes through the pulmonary valve,
and on the left side it leaves through the aortic valve.
How does the heart pump blood?
The heart receives blood while it is relaxed.
This is called diastole.
When the heart pumps, it is called systole.
This relates to your blood pressure.
The top blood pressure number
is called your systolic blood pressure.
This is when your heart contracts.
The bottom number is called your diastolic blood pressure.
This is when your heart is relaxed.
This picture shows some of the main vessels in your heart.
The vessels in your heart fill with blood during diastole,
or while your heart is relaxed.
These vessels deliver oxygen-rich blood
to the heart muscles.
When a vessel is blocked--
for example, when someone has a heart attack--
the blood to one area of the heart is lost.
This can affect how your heart pumps.
What causes heart attacks?
Heart attacks happen when
a heart vessel becomes completely blocked.
This prevents blood flow to an area of your heart.
The most common cause of heart attacks
is from plaque becoming unstable and breaking open.
In the picture, you can see the yellow area is plaque.
In the third picture over,
that plaque is broken open.
When that plaque breaks open, it activates our body
to release certain enzymes
that produce an inflammatory response.
Blood vessels respond to this and form a clot,
which completely blocks the blood flow through that vessel.
So what can we do about that?
There are many risk factors
to prevent heart attacks or coronary artery disease.
We have non-modifiable risk factors and modifiable,
and these are just a few.
Non-modifiable means these are things
you can't do anything about, things like...
You already had a cardiac event or a heart attack.
You might have a family history
and a parent or a sibling of heart disease.
Your age.
We know as we get older, your risk of heart disease increases.
The highest rate of hospitalization
for heart attacks are in those 85 years of age and older.
Your gender.
Heart attacks occur in both men and women.
For women, heart disease tends to happen about ten years later,
and heart attacks happen about 20 years later than men.
Diabetes is another risk factor.
Modifiable risk factors are things that you can change.
Tobacco use.
Cigarette smoking is the leading avoidable cause of death
in the United States.
This is the most single important
modifiable risk factor.
Lack of exercise.
High blood pressure.
High cholesterol.
I put diabetes on both non-modifiable and modifiable
because there are many things that you can do
to control your diabetes.
And stress is another modifiable risk factor for heart disease.
Our other presenters will get into
more things that you can do
to reduce these risk factors.
Here are some other heart conditions:
heart failure,
cardiomyopathy,
irregular heart rhythms,
and congenital abnormalities.
With heart failure,
49% of the cases are caused by untreated hypertension.
A common question I get is,
"What does the EKG tell us?"
First of all, an EKG or an ECG are the same thing.
They both mean electrocardiogram.
Besides a few squiggly lines on the EKG,
we can get information from this about your heart.
Above you'll see a normal EKG.
When we see changes on an EKG, it might mean nothing,
or it could indicate blockage in a vessel
or enlargement of the heart.
The EKG assists us with knowing what to explore further.
This is a picture of the electrical activity
of your heart.
This is what's shown on the EKG.
The electrical activity starts at the top of your heart
in the sinus node,
and it moves its way all the way through to the ventricles.
In summary, we've talked about the location of your heart,
the chambers of your heart,
your heart valves,
blood flow through the heart,
your heart vessels,
risk factors for heart disease,
and the electrical system of your heart.
So now that we've talked about heart function,
let's talk about ways that
you can reduce your risk for heart disease.