ST Elevation – EKG / ECG Interpretation Case 12 (STEMI, MI, ACS)

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

well welcome to another MedCram lecture
we’ve got another EKG that we want to go over and with this case this is a
patient that presents to the emergency room via ambulance for chest pain that’s
been going on for about 45 minutes and this is the EKG that is done in the
field you quickly review it and you notice that there is a report from the
field of a ST segment depression here in the precordial leads now this was done
about 10 minutes ago the patient is quickly moved into another room and an
EKG is done and here is the EKG that you get let’s go through our evaluation as
we go through this remember our five-step process here the first thing
that we want to look at is rates we can pick the easiest place to look at which
is the QRS complex here for instance we’ll look at these two and we can see
here clearly that we’ve got one box two boxes three boxes and then four and
maybe a little bit extra again let’s look at another one up here we can look
at the tier one two three four and a little bit more so as we’re looking at
that remember we go through the counts the first box is going to be 300 the
second box is going to be 150 the third box is good to be a hundred the fourth
box is going to be 75 and so this is going to be somewhere between 60 and 75
so we can come up with something for instance 70 now if we look over here on
the other side of the page we can see clearly if we count it through that
we’ve got one two three four five boxes so here it’s going to be 300 150 175
and then finally sixty over here on this side so whereas over here it’s probably
around 70 over here it’s probably more around 60 and it looks as though
something happened right about here where there was a change now remember
that the entire strip is about ten seconds and so if we count up the number
of QRS complexes and multiply it by six we’ll get how many complexes there are
in about a minute so let’s take a look here we have 1 2 3 4 5 6 7 8 9 10 so
multiply 10 probably and a little bit more here times 6 and we’re going to get
a little bit more than 60 somewhere between 60 and 70 which is exactly what
we come up with so for us the rate is somewhere between 60 and 70 beats per
minute all right next let’s go on to rhythm so the best lead to look for
rhythm is Roman lead 2 and that’s this one down here usually it’s the rhythm
strip and that’s aptly named that way so we’re going to look for each QRS complex
here and we’re going to look to see before the QRS complex if we see p-waves
and we can clearly see P waves before each QRS complex
here’s another QRS complex here’s the P wave QRS P wave we don’t see extra P
waves although there is this little extra beat here and you probably can
figure out what that is that’s probably a u wave sometimes associated with low
potassium but clearly we see here that there is P waves before each QRS complex
and so we’re gonna call this sinus rhythm great next let’s look at axis so
again like we talked about in previous videos you can look at these leads here
and see which one is the most positive and the highest in amplitude and in this
case the one that we’re looking at here is Roman numeral lead 2 you can see that
it’s the highest in amplitude so remember the direction remember 2 is
going down sharply in this direction whereas 3 is going down sharply in this
direction AVL is going to the left hand side and so it’s going to be going up in
this direction a VF of course is going straight down Roman lead 1 is going
straight across and AVR of course is going off at that type of an angle so if
we see that the highest one here is going in this direction then that’s the
closest to where it’s going now the other way of looking at this is to see
which one is the most isoelectric and we can see here with lead 1 that that seems
to be the most isoelectric so it’s gonna be very perpendicular to Roman numeral
lead one because it’s isoelectric but it’s going to be going almost parallel
to Roman numeral lead 2 and so in fact the probable way that this is going is
in this direction now if that’s the case it should be positive in lead 3 because
it’s going almost in the same direction and that’s the case since it’s going
almost parallel to a VF it should also be positive and in fact it is now
because it’s going almost in the opposite direction to a VL this is going
down and this is going up it should be negative and it is but it should be the
most negative link compared to a V R because it’s going almost in the
opposite direction and that’s where you have the biggest negative discharge so
the overall axis if we consider that this is 0 degrees here somewhere between
60 and 90 degrees and that takes care of access let’s move on to hypertrophy so
again the big things that we’re looking for for hypertrophy is the right atrium
and for the right atrium we look at Roman numeral lead 2 but we could also
look at pre quarter lead v1 and we’re looking at whether or not there is a
large up and a small down or whether or not there is a small up and large down
the big up remember is the right atrium and the big down is the left atrium and
of course we’re not seeing that here we don’t see that in lead 1 so let’s start
from the beginning right atrium should have a peaked P wave we don’t see that
there right atrium should also have a large positive component in the P wave
in lead v1 we don’t see that so right atrium is a negative let’s go on to the
left atrium as we mentioned the left atrium should have a large negative
deflection we may be seeing that a little bit here but it’s got to be
bigger than a box so we’re not seeing that much so no on the left atrium now
the right ventricle we also look at lead v1 and in lead v1 we should have a R
wave the positive component of of this that is bigger than the S wave and that
is actually looking like we might actually have that if we measure this
out we can see that the R wave may be slightly larger than the s wave so we
may have some right ventricular hypertrophy here it also looks like
we’ve got a little bit of a bundle branch block pattern here as well now
let’s go to the left ventricular criteria now for that we need to look at
the S wave in lead v1 and here it’s about 5 millimeters and we also need to
look at the R wave in lead v5 and here we’re looking at 5
10 15 20 so that’s 5 times 1 2 3 4 so here we have about 20 so we add the 20
millimeters and the 5 millimeters together and we come up with 25 however
that’s still not enough for the criteria of 35 which is what the criteria is for
left ventricular hypertrophy so after all of that we have some questionable
are the hypertrophy good now let’s go onto st-segment I think we can all
clearly see that we’ve got some ST segment elevation in the precordial
leads whereas before when the patient first came in to the emergency room
there was some ST segment depression now there’s ST segment elevation if you
look back at the first EKG you’ll notice something that’s really interesting in
AVR specifically ABR is a very specific lead and it’s important in that it looks
directly at the endocardium notice here very carefully that you actually see
some ST segment elevation although it is mild this ST segment elevation usually
means in AVR that myocardial injury is insipid it’s coming it’s an ST elevation
mi precursor if you will so if you see this ST segment elevation be very very
concerned and you can see here that this is kind of giving it away in the sense
that you’ve got precordial leads with ST segment depression and you’ve got this
AVR with ST segment elevation now be aware that if you see ST segment
depression in AVR that along with tachycardia is usually going to mean
pericarditis but that’s not what we see here we see ST segment elevation and now
on the second EKG notice in addition to our ST segment elevation that we already
talked about look here again AVR with significant ST segment elevation and
this in the appropriate clinical setting which is
we typically see is consistent with and concerning for an ST segment elevation
myocardial infarction so generally what you want to see is two contiguous leads
with greater than 1 millimeter ST segment elevation the criteria actually
for v2 and for v3 is actually a little bit more stringent and for men that are
40 plus the criteria is actually 2 millimeters and for men that are less
than 4 it’s even more stringent at 2.5 millimeters for women it’s actually just
1.5 millimeters and here depending on where you draw the baseline there is
maybe not quite 2.5 millimeters but certainly on its way to being that in
this patient and if you look at some other criteria here with v1 and also
what we talked about with AVR this is highly suggestive of myocardial injury
now because these are in the precordial leads we’re looking at right ventricular
precordial and anterior left ventricular notice we don’t see them going over to
the lateral leads here and so the answer here is yes there is elevation and that
is consistent with a ST segment elevation myocardial infarction okay
let’s briefly talk about the management of this because this patient has a
myocardial infarction the patient needs reperfusion therapy and this can come in
two different ways one is through what we call pci percutaneous catheterization
otherwise known as percutaneous coronary intervention and the other is
thrombolytics and this should be considered if the
patient doesn’t have any contraindications and if the patient’s
been having chest pain for less than 12 hours now you should know that PCI is
considered to be the superior technique now there’s two different options number
one is that you have PCI at your facility and the other option is that
you don’t have PCI now if you have PCI the goal is to get your patient to the
cath lab and have them inserting the catheter in ninety minutes that is a key
number that you should be aware if you don’t have a cath lab then you need to
get them there within 120 minutes that is another number that you should be
aware of is the 120 minute number the reason why this is important to
understand is that if you cannot do this if you cannot get the patient to either
your cath lab in 90 minutes or another hospitals cath lab in a hundred and
twenty minutes then the other alternative to do is thrombolytics now
you may still have to transfer the patient for rescue percutaneous coronary
intervention but in terms of primary PCI you need to know those numbers because
that is the treatment for this and be aware of the contraindications for
thrombolysis which we won’t get into in this lecture thank you for joining us if
you thought this was helpful I encourage you to come over to Meg cram comm for
our EKG course if you understand the key foundations of how the heart works it’ll
be much easier to learn and remember the nuances involved with the EKG that we’ll
cover later in this course so we’ll start with the anatomy and physiology of
the heart depolarization repolarization and then on to leads and specifics about
EKGs paper and how a tracing is captured next are specifics on EKG tracing the P
wave the QRS complexes the QT interval the our da our interval etc we’ll cover
the impact of our nervous system and neurotransmitters on the heart then on
to rate rhythm axis escape rhythms PVC bigeminy tachyarrhythmias ventricular
tachycardia and the key differences between ventricular tachycardia and
paroxysmal supraventricular tachycardia with aberrancy
the QT C and the potentially life-threatening Prasad’s the points
atrial fibrillation and flutter widened QRS complexes and the various types of
heart blocks using precordial leads to hone in on certain areas of the heart
atrial enlargement and ventricular hypertrophy acute coronary syndromes
myocardial infarction and pericarditis we’ll talk about two ways ST segment and
T wave changes that we see with ischemia bundle branch blocks and vesicular
blocks and then at the end we’ll put it all together and teach you how to
systematically read an EKG we’ll go through a normal one first and then on
to a variety of abnormal EKG is like sinus tachycardia atrial fibrillation
multifocal atrial tachycardia first second and third-degree heart blocks
atrial enlargement ventricular hypertrophy x’ hyperkalemia rare
anomalies and many many more abnormal EKGs

20 thoughts on “ST Elevation – EKG / ECG Interpretation Case 12 (STEMI, MI, ACS)

  1. How can science bring the youth back to the old man?
    How can young people be brought back to the elderly?
    . We need to invent drugs and treatments to remove signs of aging
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  2. QUESTION: If a doctor writes 0 stemi on EKG does this mean there are no signs of a stemi or does 0 stemi means the same as nonstemi?

  3. The initial tracing shows a very small but distinctly abnormal posteriorly directed initial vector of ventricular depolarization in the horizontal plane. In the absence of LVH, this likely reflects scar in the LAD distribution. There is reinjury in the same coronary distribution, as the second tracing shows. The development of (I?) RBBB is consistent with the process and is further evidence of proximal obstruction to blood flow. Of course, the vectors of right and left atrial depolarization normally separate with advancing age. I do not clearly see an atrial injury current (which would be ominous) but my computer screen isn't great.

  4. 5:25 Using the isoelectric method to determine cardiac axis, why would the most perpendicular one to Lead I not be Lead aVF, but Lead II?

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