00:01
So who benefits from vasodilator
medications?
That's always the question you
want to ask yourself
when you're studying pharmacology.
00:08
What types of patients would I
give this medication to?
Well, hypertensive patients benefit
even if it's chronic hypertension,
they have it all the time,
or they're in an extreme crisis.
00:19
Patients with angina or chest pain.
00:22
Patients in congestive heart failure.
00:24
Someone who's had a myocardial infarction,
which is a heart attack,
or patients with peripheral
vascular disease.
00:31
Now, I know I went through that
list pretty quickly.
00:34
Don't worry. We're going to
break down the drug
through this and the other videos.
You'll explain why vasodilators
help each one of those specific diagnoses.
00:43
Okay, so let's review what happens
when your veins dilate.
00:47
Remember, we've got vasodilators that
go primarily after arterioles,
that can go after both.
00:53
And then we have those that go,
particularly after the veins.
00:56
So look at the first graphic.
00:58
They've got a heart there, and they show
you a decrease in volume.
01:01
That means there's less blood returning
to the heart, remember?
Decreased preload, "pre" meaning
before the heart.
01:09
When I have less blood returning
to the heart,
that means when it's coming up
to the right atrium
and the right ventricle,
there's less ventricular stretch
because there's just
less volume stretching out that ventricle.
01:21
Well, where is the blood? Remember,
when I give venous dilators, more of the
blood stays out in my periphery,
like my legs, for example. So, less blood
returns to the heart. That's
a decreased preload
and less ventricular stretch.
01:38
Now, I love this next picture, because look,
he's got a little nightcap on, you see the Z's.
01:43
The heart doesn't have to work as hard.
01:45
Because there's less blood coming
back to the heart,
there's less ventricular force
because it's not as full,
the heart doesn't have to work as hard.
01:56
Now, the heart also pumps out relatively
less blood per minute, why?
I have a decreased cardiac output
because I have less preload and
less ventricular stretch.
02:07
Now, before we go on, I want you
to stop for just a minute.
02:11
Think back through those list of diagnoses
that we talked about right before this.
02:16
Think through that list and see
how would less blood help a patient
with hypertension?
How would the heart not having
to work as hard
help a patient with congestive
heart failure?
How would the heart pumping out
relatively less blood a minute
impact a patient's blood pressure?
Now, I'm not going to tell you the
answers right now,
I want you to see what you can
synthesize and put together
as we're walking through this,
and we'll come back and summarize
the answers later on.
02:45
So, in a nutshell, we've got
less tissue perfusion.
02:49
Because less blood is returning
to the heart,
I have less cardiac output, and the
heart isn't working as hard.
02:56
Doesn't mean it's going to be detrimental, it
just means there's going to be technically
less tissue perfusion.
03:02
Now, what about those arterioles,
those tiny branches of the artery?
What happens when they dilate? Well, there's
our friend, the heart, with a nightcap on,
the heart doesn't have to work as hard.
03:14
Now, I want to make sure that
concept makes sense to you.
03:16
Remember, the arterioles, we're talking
about those right outside the heart,
what the heart is pumping against.
03:21
If I dilate those arterioles,
the heart doesn't have to work as hard.
03:28
That's why we have decreased
afterload after the heart.
03:33
Also, the heart is going to pump out
relatively more blood per minute.
03:36
You know, if I'm in the gym and you load
up my weights that they're super heavy,
I can't get it up very high.
03:43
But if you drop those weights off the
bar, I can pump a lot faster,
and I can put out more.
03:49
Well, that's what happens to your heart.
When it's not having to work as hard,
it can pump out a lot more blood,
which we call cardiac output.
03:58
So you have increased cardiac output
because it's not working as hard.
04:02
All that's accomplished with
an arteriole dilation.
04:06
So therefore, we have more tissue perfusion.
04:10
That was a lot of words.
04:12
Before we go on to the next slide,
I want you to see,
why does a heart not having
to work as hard
lead to more tissue perfusion?
Well, a heart that isn't overstressed
can just produce better, it can be more
efficient, and it can deliver
more oxygenated blood to your tissues.
04:29
Because that's the goal, right?
The blood that's coming out of the
heart has returned from the lungs,
goes into that left atrium,
the left ventricle,
and out to the rest of the body.
04:39
That's kind of our goal. We
want oxygenated blood
perfusing all of our tissues.
04:45
Now, let's go back through that list.
04:48
How would somebody on
a vasodilator medication
be treated for hypertension? Well,
the benefits are clear, right?
We have vasodilating of the arterioles,
we're going to have a lower blood
pressure. If we dilate those veins,
we're also going to have a
lowered blood pressure.
05:05
Somebody with chest pain can benefit
from the ways that vasodilators
make afterload lower. The heart doesn't
have to work as hard.
05:13
It's not going to need as much oxygen.
05:15
That's how a vasodilator
can help with angina.
05:18
Now with congestive heart failure, that's
kind of a floppy, mushy heart,
just isn't functioning super efficiently.
05:25
Maybe the patients had an
MI, it's taken a hit,
heart's just over, it's gotten
bigger and floppy.
05:32
We need to decrease the workload of a heart
that's experiencing congestive heart failure.
05:37
That's how vasodilators help somebody
in congestive heart failure.
05:41
Same thing with an MI, we want to
take the workload off that heart.
05:45
Vasodilators help us do that by
decreasing afterload and decreasing preload.
05:52
Now, peripheral vascular disease
is just another issue
of perfusion and that's how
they vasodilators
are extremely helpful in that disease.