two three yeah hey Katie what's going on
oh hey dr. camka just taking a look at
my patients EKGs trying to understand
what's going on in each of these leads I
don't even have 12 leads you know that's
a great question so we're looking at a
three-dimensional structure in 2d and so
the EKG represents a single snapshot of
the heart's electrical rhythm from 12
different angles oh so it's like a chest
x-ray when we look at the lateral and
the frontal plane if we look at one view
we might miss something you got it
exactly right and those 12 leads tell us
different portions of the heart the
anterior the posterior and so forth and
this actually leads us to our next
discussion so let's take a look at this
diagram here so we're taking a look at
the heart from 12 different angles right
and so we have two sets of leads we have
the precordial leads right here which
are the chest leads the purple ones that
are looking at the heart from the
horizontal axis and then we have the
green leads which are looking at the
heart from the frontal axis and we can
take this to take a look at certain
portions of the heart so we have two
three and Avia that are looking at the
inferior portion we have v1 through v4
that's looking at the anterior portion
of the heart and then on this side of me
we have v5 v6 and one an AVL they're
looking at the lateral portion of the
heart now let's take a look at how we
can use the leads to tell us about the
axis or the flow of electricity for the
heart so we hear a lot about axis what
is axis it simply represents the average
flow of electricity through the heart
your normal heart leans down and to the
left so it makes sense that the average
flow of electricity is also going to be
down into the left and we can take a
look at the EKG to kind of tell us which
direction the flow of electricity is
through the heart normal hearts are
going to be somewhere between 0 degrees
and minus 90 right axis deviation is
going to have the flow of the heart
between 105 to positive 180 degrees left
axis deviation is going to be minus 105
degrees to minus
180 degrees but it can get a little bit
complicated so my friend mark here is a
very simple method that can help explain
things yeah so I really like to use the
quadrant method I've heard about that I
like it yeah so the quadrant method we
mainly look at the QRS complex in two
leads please one in a Viet but what
about all the other leaves mark well
they're important too but we like to
keep it simple simple is always positive
so remember that lead one runs
horizontally and to the patient's left
and lead AVF runs vertically and towards
the patient's feet so if we have a
positive QRS complex and leads one and a
BF then we know our vector is somewhere
in between those two leads or normal
access that's pretty good mark let me
make it a little bit more challenging
for you so what if the lead is negative
in lead one and positive in AVF that
would mean that our axis is somewhere in
this quadrant we would call that right
axis deviation that's pretty good what
about if it's positive and lead one and
negative in AVF well though it means
that our axis is somewhere in this
quadrant and we would call that left
that axis deviation exactly right so now
that we have a better understanding of
how to determine axis let's practice on
a couple 12 lead EKG z' all right now
let's practice determining axis here we
have a complete 12 lead EKG which leads
do we want to look at when we determine
axis remember that when we talk about
axis we're talking about the frontal
plane so we want to look at the limb
leads so let's take a closer look at
those are which two leads were we
looking at when we were using the
quadrant method to determine access we
were looking at lead one and AVF we can
see in this EKG that lead one is
positive meaning we have at all our wave
predominance and AVF is negative meaning
there's a predominant s-wave positive
and one negative and AVF means left axis
deviation left axis deviation is
commonly seen in conditions like left
ventricular hypertrophy which we can see
in patients that have long
standing hypertension let's take a look
at another EKG now that you've got the
skills let's take a look at another EKG
this one has a different axis deviation
so just like Mark taught us we're going
to focus in on those limb leads so let's
zoom in on one and AVF so in one we have
mostly a downward deflection that
predominant s-wave and then in AVF
we see that it's mostly upright with a
tall R wave this is a right axis
deviation we see this most commonly and
someone with right ventricular
hypertrophy where the right ventricles
become bigger because it's pushing
against elevated pulmonary artery
pressure this is often an EKG that
you'll see in our pulmonary hypertension
patients you may have noticed that we've
mentioned hypertrophy twice now as a
cause of axis deviation but in fact
there are multiple things that can
affect our axis another important one is
ischemia the mean vector will deviate
away from the infarct right hypertrophy
ischemia and many other things can
affect our axis it's important to
determine the axis on every EKG that you
see so remember determine rate rhythm
axis on every EKG every time
you