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

Interpret ECGs with confidence – join Dr. Seheult for the complete ECG Clarity video series available at https://www.medcram.com/courses/ekg-ecg-interpretation-explained-clearly