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

great

Thanks!

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.

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…

Clear and understandable information. Great explanation!!!! More topics please.

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

so nicely explained axis deviation

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).

Nice

.

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.