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