00:01
Now let's talk about that vagus nerve
is kind of a cool thing, isn't it?
I remember one time I was
with my brother and my dad.
00:08
And something was so funny.
00:10
I don't even
remember what it was.
00:12
But I was laughing so hard,
I passed out, you know what happened?
Well,
I stimulated my vagus nerve.
00:21
I was out for just a second.
00:22
But when I came back,
I was a little woozy.
00:26
Because the vagus nerve controls the
parasympathetic response of the heart.
00:31
So stimulation of the vagus
nerve will lower the heart rate.
00:34
In mine,
it lowered it all the way down.
00:38
Now in healthy people, parasympathetic
tone from these sources are well matched
to the sympathetic tone so it
doesn't usually cause a problem.
00:46
But hyperstimulation of a
parasympathetic influence
promotes some Bradyarrhythmias,
that's what happened to me.
00:55
I went all the way out.
00:57
But the minute I went
out, my body kicked in,
that sympathetic stimulation kicked in,
and I was right back with the world.
01:05
But when it's hyperstimulated, the
left vagal branch predisposes the heart
to conduction block,
right at the atrioventricular node.
01:14
I remember that the we've
also called that AV node.
01:18
So should this be a problem
without hyperstimulation?
No.
01:22
And if the person is
relatively healthy,
then they've got a good balance between
their parasympathetic which is, you know,
think of that, like after you've
had a big thanksgiving meal,
you're moving kind of slow,
versus the sympathetic,
which is that fight or flight,
when you're all fired up.
01:40
There's usually a balance
because our bodies are amazing.
01:45
But if that vagus nerve
is hyperstimulated,
your heart is going
to slow way down,
which is why it can sometimes be helpful
with supraventricular tachycardia.
01:58
Now you've got a right
and a left vagus,
the right vagus nerve
innervates the sinoatrial node,
which is going to give you
a very slow heart rate.
02:09
Before we go on, stop for just a
minute and look at this drawing.
02:14
Now I know we're talking
about the vagus nerve,
you see those beautiful
golden nerves, right?
Right down there that the
artists have created for you.
02:22
But stopping orient
yourself to a picture.
02:25
Don't waste these
beautiful pictures
for helping you keep oriented
and learning in more detail.
02:33
So look at everything that
they have labeled for you,
look for your trachea,
look for the esophagus,
where are the carotid arteries?
Look at the other words,
and make sure that you understand
what those structures do in your body.
02:49
Yes, I know we're looking at ECGs and
we're talking about SVT, and vagus nerves,
but you can always reinforce information
that you already have in your brain.
02:59
And that is a winner winner chicken
dinner, as we say around my house,
because you're using this as a form of
spaced repetition and you're studying.
03:09
Anytime you do that,
you're telling your brain,
"We've got this, we've got
this, we've got this."
And the more you make
connections between information,
exams are going to be much
more successful for you.
03:21
But even more important is you're going to
be able to be a proficient and safe nurse.
03:27
So how do we stimulate
the vagus nerve?
Well,
you do the valsalva maneuver.
03:32
This is what you do,
you follow the steps in order.
03:34
So you could pinch your nose
closed, close your mouth,
and try to exhale as if you were
trying to inflate a balloon like this.
03:44
I don't think you're
doing this with me.
03:45
So I'm going to need you
to really experience this.
03:49
So pinch your nose,
close your mouth and try to exhale.
03:54
It's what a lot of us do
when we're on an airplane
and our ear feels
like it's popping.
03:59
That's one way to do
the valsalva maneuver.
04:02
Now, here's another way it's
not so socially acceptable,
but you're going to bear down as
if you're having a bowel movement.
04:09
Now, be careful. I don't want to
know what else happens in there.
04:11
But you want to do that
for about 10 to 15 seconds,
that will also
stimulate that nerve.
04:18
So let's talk about
the treatment of PSVT.
04:21
I'm going to focus specifically
here on medication.
04:25
Now we've talked about
the valsalva maneuver
or we're stimulating
the vagus nerve,
those aren't medications.
04:32
What I want to talk about here
are two types of medications.
04:36
One category is an
antiarrhythmic agent.
04:39
The other category is a
calcium channel blocker.
04:42
So let's go through an
antiarrhythmic agent column first.
04:45
Name of the medication
is Adenosine IV.
04:48
Now it takes just under two minutes
to convert the patient out of PSVT.
04:54
What's our conversion rate?
Hey, that's like a mid-range B
86.5%, that's pretty good.
05:01
Now what's the likelihood
that the patient
who's received adenosine
might relapse into SVT?
Well, it possibly you say the
words they're possibly more common.
05:13
Could we be more
vague than that?
Well, it is not unusual for
someone to relapse into SVT
after being treated
with adenosine.
05:23
Now, the side effects.
05:24
This is not fun for the patient.
05:26
They usually don't like
receiving this medication,
because they get chest pain, flushing,
it's really uncomfortable for them.
05:34
Now a kinder gentler option could
be a calcium channel blocker.
05:39
Now that might be Verapamil
IV or diltiazem IV,
but it's going to take a little
longer for that PSVT to convert.
05:47
Remember,
adenosine was under 2 minutes.
05:50
Calcium channel blockers
is about 6.5 minutes.
05:54
But look at the conversion rate.
05:57
Yeah, it's 98%.
05:59
Now we think that
compared to adenosine,
they're less likely
to relapse into SVT.
06:06
Now they can also
have some hypotension.
06:08
Remember,
anytime you give a medication,
you have the risk
of a side effect.
06:12
But practitioners will be
looking at the risks and benefits
of both of these groups of medications
and see which one is more appropriate.
06:22
It would depend on the severity of
the PSVT, how often they're having,
but most people would prefer the
experience of a calcium channel blocker
over adenosine just speaking as a
patient receiving that how they feel.
06:39
Now here's one important
caveat, as we say,
Wolff-Parkinson-White
or WPW and medications.
06:48
Because both of the
medications we just discussed
like the adenosine or the
calcium channel blocker,
both of those groups of
medications are contraindicated,
meaning you should not
give those medications
to a patient who has
a diagnosis of WPW.
07:05
Now that's a
pre-excitation syndrome.
07:08
So Wolff-Parkinson-White or WPW
is a pre-excitation syndrome.
07:15
That means it has
a really short PR,
it's delta wave,
got some polymorphic atrial fibrillation.
07:21
At this point, you're saying,
"What are you saying?"
Well, I'd really focus on
this got that super short PR.
07:28
And this can be problematic for a
patient who has Wolf-Parkinson-White
to receive adenosine or
calcium channel blockers.
07:39
We'll talk more about Wolff-Parkinson-White
in a future presentation.
07:43
But either one of these
medications in WPW can lead to
yeah, ventricular fibrillation.
07:53
That is a life-threatening,
life ending dysrhythmia
if we don't treat it
effectively, and quickly.
08:01
Look at what's going
on in our graphic.
08:04
How does that appear different to
you from what we saw in sinus rhythm?
So let's wrap up
why this is PSVT.
08:14
So you look at the heart
rate, overall it's over 100.
08:18
The rhythm is regular but you can
see this reason it is shortened.
08:24
Now the P wave.
08:26
Yeah, you can measure it
before the sinus beats,
but you can't measure it
where it kicks into PSVT.
08:33
Now the PR interval.
08:35
Again, I can measure
that for the sinus beats,
but I cannot measure
it where it's PSVT.
08:41
QRS is even the sinus
beats and the PSVT beats
are within normal
range less than 0.12.
08:50
Thank you for watching this
part of our video series.