I know you would never want to miss
anything that could affect patient care
EKGs can tell you a ton about a
patient's cardiopulmonary status exactly
and you don't have to memorize anything
by the end of this series you'll be able
to tell whether your patient is having a
new heart attack an old heart attack or
something entirely different
the first step to good EKG
interpretation is to understand the
waves let's get started here we are next
to the electrical activity of the heart
let's pair this with our EKG tracing the
EKG tracing starts about 40 milliseconds
after the SA node fires this begins with
a P wave the P wave represents atrial
contraction next you get ventricular
depolarization through the QRS the QRS
represents the electrical activity
running first through the AV node then
through the interventricular septum and
finally to our ventricles this is
quickly followed by the ST segment the
ST segment represents the end of an
tricular contraction in the beginning of
repolarization and the whole thing ends
with the T wave which is the electrical
reset of the heart and it's preparation
for the next cardiac cycle whoa that's
fast let's take a closer look at each
wave all right here we have a 12-lead
EKG where should we look at our P waves
well normal P waves should be upright in
leads one two and upside-down or
inverted and lead AVR let's take a
closer look at lead to a great lead to
look at P wave morphology here we have a
normal QRS complex with a normal P wave
normal P waves should be smooth
monophasic and less than 120
milliseconds now let's look at to
abnormal P waves remember that when we
look at P waves the electrical activity
in the atria takes longer to travel
through larger atria so if we think
about a right atrial enlargement we
would expect our P wave to be taller
conversely if we think about left atrial
enlargement we would expect our P wave
to be longer
hey mark what are you looking at oh
we're just looking at some P waves yeah
looks like you're looking at some right
atrial enlargement yeah how'd you know
well you know how right atrial
enlargement is usually caused by a
problem in the lungs yeah
my favorite pulmonologist oh it says you
never sit on a pulmonary problem ha good
one it's pointy I get it maybe we should
move on from this atrial talk to the
heart of the matter let's talk about
ventricular contraction in the QRS
complex the QRS complex can look very
differently depending which lead you're
looking at in fact you don't have to
have all three components to make up the
QRS complex the Q is the initial
downward deflection this is followed by
an upright R it's always has a positive
deflection that's the thing to remember
about the R wave this is followed by a
downward deflection or the S wave now
let's take a look at how differently
they can look let's pull up another
12-lead EKG so here you can see that
their variety of QRS complexes depending
where you look so a lot of people want
to know what's the best lead to look at
the QRS complex I like to focus in on
the precordial leads in v1 through v6 so
let's pull those in and take a little
bit closer look okay in v1 and v2 you'll
see that you have a very small art wave
that's that upward deflection and then a
large deep s wave all downward
deflection afterwards then you move on
to v3 and v4 where the are wave and the
S wave are about equivalent finally in
v5 and v6 you see that it's mostly just
R wave and sometimes you don't see any Q
wave at all that's okay it's still the
QRS complex hey Katie
what's a migrate are we at progression
through your P cordials how long should
a normal QRS complex be less than 120
milliseconds or else I really start to
worry that we're seeing interventricular
conduction delay that would be like a
left bundle branch or a right bundle
branch block all right we'll talk about
how left bundle branch blocks and right
bundle branch blocks affect our QRS
later yeah
for now let's move on to the ST segment
and the T wave sure let's talk about all
the heart gets ready for its night next
cardiac cycle
say about the t-wave then you said whoa
that was fast
okay so I don't say any for some reason
in my head I was like what are you
supposed to say about the keyway but
it's nothing no because I took that over
so that we were balancing the knowledge
yeah I know you don't want to miss
something that could affect your
patients care EKGs are can tell you a
ton okay
Yura can see the electrical activity of
the heart let's tie this together with
our EKG tracing let's start with the P
with sure the P wave represents atrial
contraction
next comes the q RS the QRS represents
the electrical activity bring through
the interventricular septum and then to
the ventricles next is the ST segment
the ST segment represents the end of
ventricular contraction and the start of
repolarization and the whole thing ends
with the T wave the T wave is when the
ventricle electronically resets before
the next beat man that was fast
I think each of these waves have us more
of a story to tell I think you're right
let's start with the P wave yeah okay
what are the three things you're gonna
list the coronary blockage huh AV block
okay and just a pinch it's a scar or
should I say like whether they are
tissue you're right look image to know
if there is actually an actual inversion
versus just a scar tissue okay yeah do
you think that's better than just think
yeah I think listing the three things is
awkward yeah yeah I think maybe if you
just say like yeah whether this heart
attack yeah or or essentially in having
a heart attack right now yeah yeah so is
there a schema ongoing or did it already
happen something like that you could say
that right if you want to
is not the word ischemia okay then study
pathology maybe I don't know okay you
wanna use like a heart attack too and I
use the things that patients will use
okay you'll be able to tell even if the
heart attack were even happened and it's
old or even a new one it's actually
ongoing simple thing you could say is is
this an electrical problem or it's a
plumbing problem
yeah I like that nothing