00:00
Let's continue.
00:02
So we have here quickly
is an EKG.
00:05
I'm going to show you
what components of this EKG
would be the most important so that
you can interpret it properly.
00:12
Ready?
Now, we have the x-axis and y-axis.
00:15
X-axis is what we're going to be
paying attention to, is that clear?
The x-axis,
it represents or will show you
the different types of waves,
either positive deflection
and negative deflection.
00:27
Before we go on,
I wish for you to take a look at
a little bit of math up above,
so that you clearly see
as to the difference between
a little box and a big box, okay.
00:37
A little box and a big box.
00:40
A little box is 1 millimeter.
It represents 0.04.
00:45
Memorize that
if you haven't already.
00:47
You see that little box right there.
That little box represents 0.04.
00:51
So in from henceforth, whenever I
talk about little box,
I'm talking about 0.04.
Is that clear?
A big box is five little boxes.
01:03
Okay, so a big box
is five little boxes
can I be anymore dramatic.
01:08
So if you take five of those
little boxes,
what is your time?
Take a look.
01:14
0.2 seconds.
Is that clear?
And that you want to memorize.
01:19
So so far, a little box 0.04,
a big box is 0.2
Why is that important?
I want you to take that math
that we just did, please.
01:29
And I want you to come down.
01:31
And do you see where it says
PR interval.
01:33
I need you to memorize
if you haven't already,
that that PR interval,
the maximum amount of time,
normally speaking that a PR interval
should exist is 0.2 seconds maximum.
01:45
What's the minimum?
Is 0.12.
01:48
Okay, so if you take a look
at the PR interval,
what is the PR interval?
The PR interval
are the beginnings.
01:55
What does that mean Dr. Raj?
The PR intervals are the beginning
of the P wave
to the beginning of the QRS complex.
Is that clear?
The PR interval represents
what in your head?
The PR interval,
your thinking represents
the time that it requires and
impulses to begin at the SA node
making its way
down to the AV node.
02:17
Is that clear?
Why is that important?
Well, we could talk about how
if your time of your PR interval
is greater than how much?
0.2 seconds
which is the maximum time,
you got a problem.
02:31
Is that a WPW?
Or is that going to be
AV nodal blocks?
Do you see how we've taken the math
that at some point,
maybe it frustrated you
and even thought to yourself,
"Why do I need to know this?"
I'm telling you why right here,
clinical application,
So, if you find your 0.2 seconds
to be greater for your PR interval
then that is obviously
AV nodal block, right?
Because things are slowing down.
02:55
And we'll talk about that upcoming.
02:57
Whereas, if it's less than
0.12 seconds,
that brings us
to a very, very, well,
important diagnosis
known as WPW
now, that's only one component.
03:07
But do you see as to how that time
becomes very important for us?
And how the little box
and the big box
will play huge roles.
03:14
Let's continue on our x x,
the P wave we all know means
originating ever SA node
that took the activity
you tell me
and we mentioned this
a bunch of times,
what goes to the heart first?
Electrical activity
for by the mechanical activity.
03:31
What is the P wave represent
for mechanical activity?
The A wave.
03:37
Are you seeing it?
Take a second.
03:40
Okay, you saw it
in your head.
03:42
P wave represents A wave.
03:44
A wave represents atrial kick.
Correct?
That's a mechanical activity.
03:48
What's that part of again?
One more time?
Late diastole.
03:51
Good. Let's continue.
03:53
So now we have our QRS complex.
03:54
We just discussed pure interval.
03:57
That QRS complex represents
all, all while not excuse me
strictly represents
only the ventricle depolarization.
04:05
All it represents is
ventricular depolarization.
04:08
Now, if you're talking about
ventricular depolarization,
then what are we referring to?
Thats the fact that we have
remember an actual potential
way back basic concepts
of physiology for cardiology.
04:20
It's the fact that you have
0, 1, 2, 3, 4
Okay, 0, 1, 2, 3, 4.
04:24
You tell me with phases
0, 1, 2, 3, 4,
which one of those represents
a ventricular depolarization.
04:32
It is obviously
phase zero, right?
Phase zero.
04:36
What is phase zero mean to you?
So I'm really, I'm really,
having you review
your basics right now.
04:44
So that phase zero,
and how important is this?
Really important.
04:48
Alright, so if you're not
good with this,
I highly recommend
that you go back
and take a look at your
action potentials for the heart.
04:55
And here specifically,
I am doing my mechanical activity.
04:58
Okay.
04:59
Why is this important?
In a little bit,
in a lecture series,
we'll go into antiarrhythmias.
05:04
And if you haven't understood this,
things are getting complicated.
05:08
I don't want you to get frustrated.
05:09
It's about really building upon
your information.
05:12
Okay, so that
voltage-gated sodium channels
what that is
at phase zero
is a voltage-gated sodium channel,
isn't it?
and you have an MNH gate
and giving you more detail
stuff that you already should know.
05:22
So that phase zero is your
voltage-gated sodium channel.
05:26
It represents
ventricular depolarization.
05:28
How's that represented on your EKG?
QRS complex.
05:31
We will go as far as that
right now.
05:34
We'll go into further detail as
we go into phase one, phase two,
which is plateau,
and phase three.
05:42
Right now, we're focusing upon
phase zero,
voltage-gated sodium channel.
05:46
It has an activation gate
and inactivation gate.
05:49
This is represented on your EKG
by the QRS complex
ventricular depolarization
Now, let's move on
to the next portion.
05:57
The all important ST segment.
06:00
The ST segment a bunch of things
we've talked about.
06:03
If I told you non-STEMI,
non-ST-elevation
myocardial infarction,
give me some differentials, please.
06:10
If all that you see
in a stem of a question,
or an attending tells you,
"Son, or daughter,
tell me about non-STEMIs."
You're going to step up
to the plate,
and you're going to tell them what?
You're gonna say,
maybe just maybe
there is subendocardial type
of myocardial infarction,
What kind?
Subendocardial
myocardial infarction
or this was a angina? Correct?
What kind of angina,
is the attending asking you?
You're not going to tell the patient
vaso,
or not gonna tell the attending
that it's vasospastic angina.
06:42
More likely, you're referring to
stable or perhaps unstable angina.
06:48
Right?
And there you had
ST depressions.
06:51
You had ST depressions,
those were your non-STEMIs.
Is that clear?
What if it was ST Elevations?
About ST elevations,
the differentials would be
transmural type of
myocardial infarction,
or maybe vasospastic.
07:06
Now that attending or licensing exam
is asking you,
"Well, how can you distinguish?
How can you confirm?
You're looking for cardiac enzymes.
07:14
Cardiac enzymes are present, then
you know your patient for sure
had some type of
myocardial infarction.
07:19
If not, then your differentials
are a little bit more.
07:23
So ST segment,
we spent a lot of time there,
you know that normally,
it should be isoelectric.
07:28
And then we have the T wave.
07:30
Let me about that T wave.
07:31
Well, that T wave represents
a ventricular repolarization.
07:35
So a ventricular repolarization,
that you tell me
if you're referring to
actual potential,
and this could be a tricky question,
if you haven't properly studied,
if you haven't properly understood
your pathophysiology.
07:49
The T wave represents
ventricular repolarization.
07:53
If it's an actual potential
of mechanical type
that I'm referring to,
meaning phase 0, 1, 2, 3, 4,
you tell me what phase
of the action potential
is represented by your T wave.
08:06
Phase zero, we already talked about
what's QRS depolarization.
08:10
Phase two is plateau.
That's your calcium influx.
08:13
And that actually
is your ST segment.
08:15
Is that clear?
How can you remember
that? Plateau, phase two.
08:19
ST segment, flat.
08:21
Here is phase three.
08:23
Have you ever put that
into context?
I hope you have.
08:26
Because, you know,
this is a beautiful thing.
08:29
So if that potassium is
effluxing during phase three,
Isn't that repolarization?
Of course it is.
08:36
So that is your T wave.
Wonderful.
08:40
Finally, we have a QT.
08:42
That's important, isn't it? Why?
I just got done talking to you about
torsades de pointes.
08:48
What did I say was a predisposing
factor to torsades de pointes.
08:52
It was a prolonged QT interval.
08:55
So if that QT interval
was prolonged, what caused it?
Maybe drugs, more commonly.
09:00
Antiarrhythmic, such as your
sodium channel blockers class one,
or maybe it was antibiotics,
maybe antipsychotic
so on and so forth.
09:07
Then also inherent, such as
Romano–Ward, Lange-Nielsen and such.
09:14
Well, if you have a prolonged
QT interval,
you're predisposed to
torsades de pointes.
09:18
These are some of the most important
points of this EKG,
You're paying attention to x-axis.
09:24
Everything that I just
went through here
is just to give you
clinical application
in the subsequent lecture series.
09:31
We will dive into details further
further and further.
09:35
But it all begins
with knowing the foundation.