Okay. So, let's look at nitrates.
This is the drug that most people have seen,
but I want to break it down for you, so
you become an expert in when,
why, and how we use it.
Nitrates are a vasodilator.
Now let me explain to you how
potent that vasodilator is.
When I was a baby nurse, we used
to squeeze nitroglycerin
paste out on these little patches,
and the doctor would order it by
1/2 inch, 1 inch, 1 and a half inch.
And I squirted it out one day and
I got some on my hand.
I didn't think it was a big deal,
so I just kind of brushed it off.
Well, actually, what I did is I wiped
it into both of my hands.
I woke up passed out on the floor of the
med room with a really bad headache.
So, this is a potent drug
and the nurses never let me
forget that I did that.
So, nitroglycerin is a potent
vasodilator. It clearly
dropped my blood pressure. I got really
dizzy and passed out on the floor.
Got a lot of attention that
I really didn't want,
but keep that in mind with
your patients. It can have
a pretty significant effect on people.
It acts directly on the vascular smooth
muscle, primarily the veins.
Okay, so, I don't want to brush
over that point.
Nitroglycerin is a vasodilator that
works primarily on the veins.
Okay, so when those guys vasodilate,
it ends up leaving a lot of blood
out here in my extremities and not
necessarily returning to my heart.
So that's why it decreases preload,
and we'll hit that concept again because
I want you to be very clear on that.
Now, we use nitroglycerine in stable
angina and unstable angina.
Remember, in unstable angina, if a
nitroglycerin doesn't relieve the pain,
then we try the morphine.
So the reason nitroglycerin decreases
cardiac oxygen demand --
it doesn't increase the supply,
right? Because it's not
dilating those arteries, it's
dilating the veins,
I want to walk you through that and
how that works, again. Remember,
when you decrease the veins, more blood
stays out here in the extremities,
and then what ends up happening is
not as much returns to the heart,
so the heart doesn't have to work as hard.
Decreased preload means decreased
demand on your heart.
Now, nitroglycerin is also used in variant
angina. Remember those spasms
for variant chest pain,
we use nitroglycerin and calcium
So, it releases or kind of prevents those
spasms in coronary arteries.
That's how nitroglycerin helps.
It also increases the oxygen supply.
It doesn't decrease demand.
Now, wait a minute. That seems backwards
of what we just talked about.
That's because we're talking
about variant angina.
We're talking about an angina or a chest
pain that's caused by a spasm.
Now, a spasm cuts off blood supply
because nitroglycerin will help
those arteries prevent those spasms.
That's why it increases.
Okay, side effects of nitrates. I think I
pretty much talked to you about that,
but I want to make sure you hit it,
particularly in patients starting
nitroglycerin for the first time,
they're going to end up with that
same headache that I had
when I woke up on the med room floor.
They have low blood pressure.
I definitely had that when I woke up
on the med room floor.
And they might have a reflex tachycardia.
Well, anytime your body's blood
pressure drops kind of quickly,
the body responds, the sympathetic nervous
system responds by making the heart
pump faster and harder. That's
where the reflex, tachycardia --
it's the body's response
to the drop in blood pressure
caused by the nitroglycerin.
So it's a reflex, tachy, fast; cardio,
heart rate. Reflex fast heart rate.
So your patient will be like,
"Whoa, I really felt my heart about
to pump out of my chest."
That will get better as they
take the nitroglycerin.
Now we've got organic nitrates,
which that's not something
you'll find at Whole Foods.
That's just the some other options for you.
They've got some really long names.
Isosrbide mononitrate and
The action's just like nitroglycerin,
I just wanted you to be exposed
to some different names.
Amyl nitrite is another one,
but it's an ultrashort-acting agent
and we use it to treat
acute episodes of chest pain
only. But either way,
these are all forms of nitroglycerin.
So let's walk back through nitroglycerin,
but I want you to pause for just a minute
and see if you can write down
in the margin of your notes,
how does nitroglycerin relieve chest pain?
Is it supply? Is it demand? What happens?
What's affected; preload,
So take a minute,
write your thoughts down before we progress,
and we'll check your work and
see how you did.
Okay, good work. I honestly hope
you struggled with this question.
That's a good thing because I don't
want you to get discouraged.
In the struggle comes the learning.
So, if you're having to work at recall
concepts, that's fantastic news
because that means your
brain is really engaged
and you're trying to learn and
understand these concepts.
So don't avoid feeling uncomfortable.
I promise, the struggle is where
the learning happens.
Okay, so if I have chest pain, and
you give me nitroglycerin,
the pain is decreased because you
decrease the need for oxygen.
Now, is it because you dilate
my arteries with the nitro?
It's because you dilate my veins
primarily with nitroglycerin.
So, I had chest pain, you gave
me nitro, my veins dilate.
Remember when I got really
dizzy and almost passed out?
Because that leads to decreased
venous return to the heart.
That means when you dilate these veins,
more blood stays out in my periphery.
Less blood returns to my heart.
The amount of blood that returns
to your heart is called preload.
So, with less preload,
I have less blood filling up my ventricles,
therefore my heart is not working as hard,
and that is why I don't need as much oxygen.
Okay, how did you do?
Compare your notes to our screen here.
Make any additions or changes you need to
to make sure you're really
solid on this concept
of how nitroglycerin
actually helps with chest pain.