00:01
So let's talk about amplitude.
00:03
Now, that is the height of the wave,
when you looked at it as a graph.
00:08
So the amplitude of an R wave
is measured in millivolts.
00:12
Well, that's convenient, right?
Because we know one millivolt
is how many millimeters?
Good job, 10 millimeters.
00:22
So amplitude is kind of
how far that wave
has moved the stylus
above the ISO electric line.
00:30
So the QRS duration,
we have that mark there,
the Q, R, S duration,
that's how long it took.
00:38
But amplitude is,
how much energy did it take
to move that stylus of that high?
So amplitude is always measured
from the isoelectric line
to the peak of the QRS
or the R wave,
the very peak of the QRS complex.
00:55
So take a look at this picture.
00:57
Before we go on, you see,
we have the isoelectric line,
what color is it?
Good, it's red.
01:05
And that is the flat part
of the ECG reading.
01:09
Now amplitude is measured were?
Correct at the very top of the QRS,
which is the R wave.
01:18
I want to talk to you about what
things kind of impact amplitude?
So let's start right in the middle
with normal,
always the best place to start.
01:26
So look at a normal amplitude.
01:29
That's going to give you an idea
or a reference.
01:32
Now, sometimes you have patients
with a high amplitude.
01:36
Now, this is if a patient
has cardiac hypertrophy,
they're most likely to have
this high amplitude waveform.
01:44
Now, think about that word
hypertrophy.
01:48
Why would that cause someone to
have a higher amplitude than normal?
Remember, that is the impulse
moving through the ventricle.
01:58
And if someone has cardiac,
meaning heart;
hyper, that's all a lot of extra;
trophy is growth.
02:06
So someone has an overgrown heart,
it's going to be a lot more
grown for it to be going through.
02:12
And that's why you'll see a
higher than normal amplitude.
02:17
Now, let's look at the one
on the left,
this is a low amplitude.
02:21
Now think about the leads
that we put on a patient's chest.
02:25
Usually, they're little stickers,
and they're attached to a wire
that goes to a monitor.
02:30
But those are trying to pick up
electrical signals
through the chest wall.
02:35
So anyone who has kind of a
think of it
as an altered chest wall,
it's going to be harder
for those signals
to be picked up.
02:43
That's why you have
a lower amplitude.
02:47
Higher, when you have like this
really big heart
that's hypertrophy.
02:51
You're going to have
a higher amplitude.
02:54
But when it comes
to a lower amplitude,
that's because something
has altered the chest wall.
03:00
Now, examples of what could alter
the chest wall, would be obesity.
03:04
If a patient has extra body mass
in between their
chest wall and the heart,
it's going to be harder for
that signal to make it through.
03:15
And the amplitude will be smaller.
03:18
COPD.
Ah, that should make sense.
03:21
Remember, COPD patients
get kind of barrel chested, right?
So that's an alteration
to their chest wall,
that could cause a low amplitude.
03:30
Now pericardial effusion is not
necessarily the chest wall, right,
that's extra fluid around the heart,
but it also is going to make
it harder for the signal
to make it through.
03:42
So we said,
any alteration to the chest wall
or something that makes the signal
more difficult to make it through
to the leads.
03:49
But the term for that is
increased resistance.
03:53
So someone who has extra body mass
in between the leads and the heart,
someone has COPD,
their chest wall has changed,
or somebody who has
extra fluid around their heart,
that's going to lead to increased
resistance to the current flow,
and that results in
a reduced amplitude.
04:12
Okay, before you go on
to the next one,
those are three examples.
04:17
Make sure you're clear
and when it would be normal.
04:21
Can you remember
why it would be high?
And try and give me three reasons
it would be low.
04:29
Do you wonder what you do
in an example with low amplitude?
The answer is
you just try to do your best.
04:36
Just try to get
the best leads that you can
and adjusting on your monitors
so you can get an accurate
ECG rhythm.