EKG / ECG Practice Strip Interpretation Explained Clearly – Case 10
23
August

By Adem Lewis / in , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , /


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


11 thoughts on “EKG / ECG Practice Strip Interpretation Explained Clearly – Case 10

  1. my favorite doc,

    just wanted to let you know ever since I first watched your videos over 2 years ago, I am now a 3rd year medical student and still watching your videos on occasion.

  2. Type A aortic dissection can give diffuse ST elevations, as well, when the initma dissects all the way back to the coronaries. While it is an ischemic cause of the ST segment, again TPA would be disastrous.

    Always correlate clinically…

  3. Thanks for watching! Just so you know, our entire video collection is at MedCram.com

    Our videos include:
    – Enough relevant anatomy/physiology to allow key concepts to stick and be remembered (not memorized)
    – Simple illustrations (rather than overpacking slides with info)
    – Topics that are relevant to your medical education and career.

    Hope to see you soon at www.MedCram.com

  4. Thank you so much for great and very helpful videos! Here is a helpful rhyme: Heart blocks: If Q is far from P then you have a first degree; @@@ 2nd degree: Long, longer, drop, then you have a Winkenback(type 1); If some of the Ps don’t go through, then you have a Mobitz 2; 3rd degree: If P and Q don’t agree then you have a 3rd degree(divorced heart syndrome).

  5. If you look closely, you can also make out the pattern of electrical alternans caused by the swinging of the heart. The amplitudes slightly increase and decrease as the heart swings closer and further away from the EKG leads in the inflamed paricardial sac.

Leave a Reply

Your email address will not be published. Required fields are marked *