well welcome to another MedCram lecture we're gonna go over an EKG 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 ST 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 rate 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
anytime 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 if
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 a hundred and fifty 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 down 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 axis has to be most in line with lead
room 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 gonna 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 live for peaked t-waves in
Roman then we'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 purchased
you to look back at lead v1 and you're going to 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 going to 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 in 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 2 we're also seeing it 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