well welcome to another MedCram lecture we're going to go over an EKG and I've
seen that so many of you are finding these practice EKGs helpful especially
those of you who have gone through the EKG course that's available on our
website that this is really just the cherry on top it's the icing it is the
practice that solidifies all of the principles that we learn in the EKG
class so I really encourage those of you who can to go over to the website and
look at the EKG course where we go through all of this what we're going to
do here is go through our methodical method of interpreting EKG so we can
pick up all of these things and make a diagnosis and as we all know practice
makes perfect so what we're gonna do first is we're
gonna go over the methodology here and that is this order of rate rhythm access
hypertrophy and looking at s t segments so let's first of all look at the rate
on this EKG so the first thing that I want you to notice specifically here is
at the bottom we can see here is the criteria for what is set the speed of
the EKG is at 25 millimeters per second which is pretty standard what's not
standard is the 20 millimeters per millivolt and you can see here that that
standardization box is about twice as high as it would normally be so just
keep that in mind and be aware of that
so the first thing we want to do is look at the rates now just by looking at this
EKG you can tell right off the bat that the spaces between the QRS complexes at
the beginning are different than at the end so there may be a rhythm change and
any time we're this sort of this irregularity remember that this is a 10
second strip so because there are six ten-second periods in a minute we can
just simply count these up 1 2 3 4 5 6 7 8 21 22 23 and multiply that by 10 so we
have 23 QRS complexes and we multiply that by 6 since there are 6 10-second
periods in a minute we're gonna get something that's close to about 138
beats per minute okay so that would be the average for the whole EKG now if we
go back and look a little bit more carefully we can actually do it a little
bit different methodology well look here at the beginning and you can see clearly
here that we're dealing with 1 2 3 approximately 3 boxes and you know that
the first box is 300 and the second box is 150 and third box is a hundred so the
distance between here and here would lead you to believe that we're dealing
with about a hundred about a rate of a hundred okay whereas over here you can
see that the number of boxes in between each is about two boxes and so what
we're dealing with here is about a hundred and fifty so 150 means that we
went from a hundred to about 150 and as you can tell as we'll get into a little
bit later we may have got into any regular rhythm but let's keep an eye on
that so I think here overall we went from about a hundred to 150 based on the
boxes but the average looking at all of the beats would be 23 times 6 which is
about 138 so that would be the average about 138 beats per minute so that's the
rate the ventricular rate okay let's look at rhythm next
so for rhythm we're looking at P waves and QRS complexes and we're also looking
at seeing how regular things are you can see here at the beginning things
generally speaking are pretty regular whereas here at the end we've got some
irregularity you can see here for instance the distance between here is a
little bit different than the distance between here there seems to be a
speeding up and I think what you may see here if you look very carefully is some
P waves there and then there may be some in here and also in here or it could be
just the end of the QRS complex if there is there's definitely a distance between
these two and it's almost getting to be a first degree heart block
certainly here one can make the argument about that either this is a speed up
here and this goes into like intermittent atrial fibrillation with
sinus rhythm here I think one can definitely make the argument that we are
definitely in a sinus rhythm here at the beginning but in terms of the rate you
can see here that certainly the distance here is different than the distance here
so we may be dealing with the intermittent atrial fibrillation versus
a fluctuating sinus tachycardia and I know that later after this patient have
this EKG the patient did go into atrial fibrillation so again I think what we
can say here is we certainly started out in sinus but it ended up going into
atrial fibrillation although it's not particularly clear on that okay next is
access so what I like to do with access and I'll pick a different color here so
you can see is there's a number of techniques that you can use one of the
techniques is looking at these limb leads and picking out the one in this
case it's Roman numeral one that is the highest positive amplitude and that's
going to be the one that is going to have the direction that most likely goes
along with the axis so because the vector Roman numeral one is in this
direction that's going to be the direction generally speaking of the axis
now that could also mean that since a VF is going
that it should be the most isoelectric and in fact that's exactly what we see
is here in AVF we're seeing the least amplitude so therefore the access has to
be most in line with lead Roman numeral one and perpendicular to
lead a VF since that has the lowest amplitude out of all of them so let's
see what that would look like it would look like then that the vector would
have to be going in this direction why is that because it's most in line with
Roman numeral one and it's perpendicular to a VF so if that's the case if we were
to look at for instance Roman numeral two or even three if the vector is in
fact going from left to right on the page but actually left axis deviation
because we're looking at the patient then it should be negative in Roman
numeral lead three and positive in Roman numeral lead to right because it's going
generally in the same direction as two but it's going the opposite direction as
three so let's take a look and see if that's in fact the case and sure enough
we see in Roman numeral lead three we have a negative deflection and in Roman
numeral two we have a positive deflection so that makes sense
we also see a relatively positive deflection in AVL now why would that be
again looking at this AVL goes in this direction and that's almost generally
speaking the exact same direction as the vector that we're proposing so I believe
here that some perturbation of this is going to be your axis going from
basically it's almost to the left axis deviation a slight left axis deviation
okay so we got rate rhythm and we got access let's look for hypertrophy now
hypertrophy is tricky as you'll know well let's look back here and there's
four chambers of the heart let's go through them there's the right atrium
the left atrium the right ventricle and the left ventricle so if we're looking
for right atrial enlargement the big thing that we look for is two things
number one we look for peaked t-waves in Roman
they're only two and we don't see that and also here in v1 we look for a large
upward deflection and a small downward deflection that would be right atrial
enlargement and we don't see that here the other thing that you'd see for left
atrial enlargement is a small positive and a large negative deflection in the P
wave if we don't see that either so we don't see any evidence for right atrial
or left atrial enlargement what about right ventricular hypertrophy so right
ventricular I have perjury member is you go to look back at lead v1 and you're
gonna be looking for an R wave that's bigger than an S wave clearly here the S
wave is bigger so there's no evidence of right ventricular hypertrophy let's look
at left ventricular hypertrophy and the criteria for that is the number of
millimeters here it's the S wave in lead v1 and here you can see that we're
talking about oh I don't know about six or seven okay we're gonna come back to
that later because we're not done with that number six and I'll show you why
it's a little tricky and then we're looking at lead v5 specifically for a R
wave and the R wave here is what five 10 probably 12 millimeters so 12
millimeters however remember don't get fooled it's 20 millimeters per Mille
volt we're actually really adding a millivolt so we really since worked
we're since we're stretching this out with this calibration we really need to
add this up and divide it by two so that would be 18 divided by 2 is 9 so this is
essentially 9 millivolts total is the S wave and v1 and the R wave in v6 and so
9 millimeters is far short of the 35 millimeter criteria for left ventricular
hypertrophy so we don't see any any of the 4 chamber enlargement we don't see
right atrial enlargement left atrial enlargement right ventricular
hypertrophy or left ventricular hypertrophy so we can check that off the
next and last thing we go to here is ST segments and I think that's really where
the key is for those of you who have kind of looked ahead on this we're
seeing big-time ST segment elevation here in - we're also seeing
in v2 we're seeing it in v3 we're seeing it in v4 we're seeing it in v5 we're
seeing it in v6 also in lead 3 we're seeing a bit of it
in lead AVF as well but not to the same degree we're seeing it all over the
place it's not in any one particular distribution so you've got to be careful
because when you see global ST segment elevation all throughout the leads the
one big thing that you've got to think about in this situation is definitely
pericarditis pericarditis is an important diagnosis to make because it's
very close cousin alternative diagnostically on the EKG is a
myocardial infarction now in some of these centres that can't do angiography
within 90 minutes they have to give TPA you don't want to give TPA to some with
pericarditis because if you've got bleeding into the pericardium that can
very quickly turn into tamponade which is obviously life-threatening and so you
want to give TPA to those that you think have an inclusion in the coronary artery
and you definitely do not want to give TPA to someone pericarditis both of
those will have ST segment elevation one will be global
as in pericarditis the other one will be segmental either 2/3 a VF or inferior or
it will be v1 v2 for an anterior or will be V for five and six for a lateral okay
so I think what we've got here is pericarditis with a heart rate of 138
sinus / atrial fibrillation with a mild left axis deviation and no signs of
hypertrophy and that is the EKG join us for more EKGs to go over as you know his
practice makes perfect thanks for joining us
you