ECG Interpretation Made Easy – How to Read a 12 Lead EKG Systematically!

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

Welcome to EKGs explained clearly. By the
end of this course, you’ll have all the skills needed to competently interpret
EKGs in a systematic way. You’ll understand the electrical activity
represented on EKG paper that allows this process to happen: The heart to beat
and cycle blood through our lungs and bodies, this is the final product. Whether
or not you have experience with EKG interpretation, I think you’ll find this
series of videos very useful. If you understand the key foundations of how
the heart works, it’ll be much easier to learn and remember the nuances and pitfalls
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 EKG paper and how a tracing is captured. Next
are specifics on EKG tracing, the P wave the QRS complexes, the QT interval, the
R2R interva,l 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 QTc and the potentially life-threatening Torsades
de Pointes, 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 T waves, 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 EKGs like sinus tachycardia, atrial
fibrillation, multifocal atrial tachycardia, first, second, and third
degree heart blocks, atrial enlargement, left ventricular hypertrophy, hyperkalemia,
rare anomalies, and many many more abnormal
EKGs. So let’s begin with anatomy, this is an animation here of the heart beating,
and there’s a number of things that I want you to see so you’ll understand
this when we talk about the conduction system of the heart and the EKG. So the
EKG as you know, is a way of looking at the electrical activity of the heart and
it’s really the electrical activity of the heart that is responsible for what
we’re seeing here right now. Just for those that don’t know the anatomy of the
heart, we’ve got the right ventricle here on this side. We’ve got the left
ventricle here on this side and these areas up here are the atria so this is
the right atrium here and the left atrium is over here interestingly here
what we’ve got is the tricuspid valve this is a valve that allows blood to
flow in from the right atrium into the right ventricle and then gets pumped out
through the pulmonic artery and this is the pulmonic valve here the semilunar
valves as you can see and then what you can’t really see very well is the aortic
valve which is here at the top and this is where the left ventricle is pumping
out into there now one of the things that I want you to notice first off is
if you look carefully you’ll see that the right atrium here beats before the
right ventricle right atrium right before the right ventricle and you’ll
also notice similarly that the left atrium beats right before the left
ventricle now this is because of the anatomy of the conduction system there
is an electronic conduction system in the heart that is not made up of nerves
but instead of modified specialized myocardiocytes. Up here is the
sinoatrial node (SA) which because of its relatively quick activity is the
pacemaker for the whole heart it then goes to the atrial ventricular node
which is here and then goes down this conduction system here called the
His-Purkinje System and as you can see it goes up and it basically conducts the
electric signal to the myocardium now we’re gonna talk more about this in
detail but I wanted you to notice that it’s this conduction system that
basically makes this movement that we’re seeing right here like a perfectly well
timed symphony. It depends on the analogy that you want to use there are several
different analogies that you can use the conductor that is conducting a symphony
and you want to make sure that the violins and the cellos and the flutes
and the viola and the timpani they’re all acting all at the same time so you
get the maximum effect in other words everything is working in concert the
other way of looking at it is a little bit more destructive you know that if
people are trying to demolish a building they will have certain areas of the
building that are drilled out and weakened with sticks of dynamite and
when they activate that dynamite it has to be activated in just the right order
in just the right fashion so that the building comes down right on top of its
footprint well this is kind of what’s going on here with the heart this
electric conduction system the sinoatrial the atrioventricular and the
His-Purkinje system is activated in such a way that the electrical
conduction goes and stimulates the heart in concert so the electrical conduction
starts up here and then goes to the ventricle the reason for that is so that
the atria contract right before the ventricle the purpose of that is to get
the blood from the atria down into the ventricle to increase the size of the
ventricle right before the ventricles contract that causes an increase in
preload and allows your cardiac output to be improved that’s happening on both
sides so you can see that the atria are contracting first and then the signal is
placed down here to the His-Purkinje System it travels down very quickly down
this His-Purkinje system and then up here into the myocardium so the effect
is is that essentially the myocardium is contracting all at the same time and you
want that to happen instead of having contraction occurring
from the top down you want contraction occurring all at the same time because
of this very unique conduction system this is going to look very unusual
or look very unique I should say on an EKG what is an EKG it’s a way of
measuring current you know that when you take a battery and you place it on a
voltmeter if you put the positive end to the positive meter and the negative end
to the negative meter you’re gonna move the dial up so that you see that there
is a difference in the voltage when that voltage starts to move that is when you
have an electric current and so what an EKG does is it sees how is this
depolarization or this movement of positive charges that’s going down the
His-Purkinje system how does it look from the electric vision if you will in
other words if I have an ultrasound machine I could see if there is fluid or
fluid moving on the ultrasound what an EKG does is it does exactly the same
thing except instead of fluid moving and objects that you could see you’re seeing
electricity moving and so that is what we’re going to look at today atria
contract first then ventricles contract second but they’re contracting in
concert and then what happens is everything resets back to normal and you
have the same contraction happening again the next series that we’re going
to talk about is we’re going to break things down to the smallest level and
then we’re going to build it up so that we can finally see how we get back to
this point again okay so zooming in a little bit more now
in terms of where we were let’s pull away all the muscular activity here and
let’s look specifically at this conduction system I want to be very
clear the thing that you’ve got to understand that these are not nerves
okay these are modified myocardial cells that conduct electricity very quickly
and we’ll talk about how that happens so the first one that you’ve got to know is
the sinoatrial node it is at the very top and the reason why it is there and
is the pacemaker is because its intrinsic activity is the fastest and
since it is the fastest it’s going to cause depolarization to occur all the
way down and everything else is going to have to be in concert so this is kind of
the conductor of the concert now there are different pathways to get to the AV
node you can see here that the SA node can
to the AV node now the AV node is right here and it kind of holds things up it
kind of delays things we’ll talk about that in another lecture so that what you
have here is you have the sinoatrial node saying okay it’s time to contract
and we’ll talk about how that happens and the atria contract and then the
electrical conduction gets down to here and it holds up what that effectively
allows the heart to do is to pump blood from the atria down into the ventricles
and allows it the time to pump it member this happens so quickly
SA node to AV node then when the blood is in the ventricle the AV node then
conducts this depolarization that’s occurring into the His-bundle system and it
travels down and around so quickly so very quickly that essentially the entire
myocardium that this innervates or that it penetrates basically depolarizes
almost all at the same time so that again is sort of a map of this cardiac
conduction system and really it’s this cardiac conduction system that allows
the depolarization to occur in such a nice and timed way now on an EKG when
we’re actually looking at the electrical depolarization are we actually seeing
the electrical movement down this conduction system the answer is no this
is such a small amount of electricity that it’s almost imperceptible on an EKG
what is it that we’re actually measuring what we’re measuring is the
depolarization of the muscle the depolarization of the muscle is very
large and amplitude and that is what we are picking up on the EKG kind of like
if we are demolishing a building what do we see on the video do we actually see
the electricity going into the wires to the dynamite no we’re actually seeing
the dynamite blow up and the building coming down that’s in other words what
we’re seeing on the EKG even though there is electrical conduction going
down this what we’re seeing electrically on an EKG is the depolarization of the
actual muscle cells okay so just be aware of that okay so to
get a little bit more of the insight about what’s going on let’s go down to
the microscopic level and I want to show you a myocyte here now the thing that
you should know about a myocyte is just like any other skeletal or smooth muscle
cell it has a collection in it called the sarcoplasmic reticulum we’ll call
that SR, and the SR is full of calcium and the reason why it’s full of calcium
is because this calcium can be released into the cell upon depolarization of the
cell we’ll talk about that and that’s gonna cause contraction of the striated
muscle so we’ll just put a bunch of muscle cells here that’s going to
contract okay and if you were to look histologically at the areas of the
myofibrils that are in cells you’ll see how muscle cells work but basically
calcium is what’s gonna activate them to contract and they’re made up of troponin
and all of these other things that we won’t get into the key here though is
the sarcoplasmic reticulum causes calcium to be released and that’s what
triggers it the question is is what triggers the sarcoplasmic reticulum well
what happens is as you may know on the cell surface of these cells you have a
sodium potassium pump and the purpose of that is to pump sodium out of the cell
and as you know sodium has a plus one charge and at the same time pump in
potassium and potassium has a positive one charge but it pumps out three sodium
for every two potassium and so what ends up happening is is there’s a very high
concentration of sodium okay one plus outside the cell and there’s a very high
concentration of potassium inside the cell now as it turns out the cell is
very important so sodium stays very high outside of the cell a way of thinking
about it is because three are going out and two are going in there is a negative
charge on the inside of the cell okay negative charge on the end
of the cell and there are positive charges if you will on the outside of
the cell. We’ll ignore those for now because the outside of the cell is very
very large and the inside of the cell is very very small so as a result of that
there’s a far more negative charge that we see here now the other thing that’s
important to know is that the cell while it is very important it is very
permeable to potassium and as a result of that potassium leaks out somewhat now
as it leaks out it’s losing a positive charge so that even makes it more
negative and as a result you have a very negative resting potential on the inside
of the cell now with that basis of history let us go
forward here in the next lecture and talk about why this interior negative
charge is so important to the electrical conduction that we’re going to talk
about here in our EKG course thanks for joining us

58 thoughts on “ECG Interpretation Made Easy – How to Read a 12 Lead EKG Systematically!






  2. See the entire EKG series (40 short videos and quizzes) and many other courses at

  3. I've been in practice 15 years, preparing for my board recertification. In the past I prepared by re-memorizing the rhythms and 'key' ekg findings. I have never truly understood so clearly, the reasoning behind every part of the EKG, and felt so comfortable and strong in approaching every line and why it all happens. Put it this way. I put my 12 year old son to watch with me, who is just learning the very basis of molecules and electricity. He followed along the first 7 videos (about 2 hours), with minimal need for me to explain some anatomy. He was able to answer the quiz questions and showed clear understanding. Really amazing, well done. Pay more money than you think you should, and when you're done, you will feel you made a good investment. When you sign up for an account, they will likely send a small discount code as well, but even full price, completely worth it.

  4. Bad ass video, this is literally how my brain works. i read my text book over and over and drew pictures ….still was stumped. watch this video and all my notes came together perfectly. this video was the missing puzzle pieces . loved it. sharing with all my classmates as well as my instructor so she can learn how to teach a course correctly lol

  5. I am in nursing school. I love the simple explanations here that reinforce what I am learning. Thank you very much.

  6. This video is so great. Thank you for it. I am able to understand the basics. I wish I could watch more. I went to the site to sign up for a free trial, thinking I could watch the rest of the EKG videos and I couldn't. Your course is too expensive for a lot of medical students. It would be better if you considered a monthly subscription option. I would be able to afford paying 15 dollars every month instead of paying 500 USD at once. I barely have enough for my rent, I don't know where I could get that kind of money.

  7. dude amazing job but just a quick note on the side people who need these courses the most aka 3rd world countries with their shitty education system get pain around 100-300 dollars a month as doctors. so do you think the course is a bit over priced?
    I can't and non of my friends can buy such a course unfortunately. I understand you are doing this as a job not as a volunteer but still these prices should be directed to universities not students who are barely making it.
    guess we need to find good free 3rd class courses and lectures. Thanks anyways.

  8. Thank u so much these lectures they are helpful indeed…the explanations are simple and wellsummarised..

  9. The video is explained in such a simple way as to make it easy for a newbie to understand. Great job!

  10. Best ECG course on the internet. I am so glad I ran into this video. They also provide CE certificate for RN's in California at 10 contact hours for all the video. I'd recommend you watch the whole thing. The price is nice and if you work in the Telemetry, this is a must. Will take it every year. They should advertise this! Anyway, Dr. Seheult has great voice for learning and the videos explain everything! lol. He is perfect for teaching this complex material. Kudos!

  11. Ok but before I start, why do Americans call it EKG? Why is it necessary to change the C to a K? It is to avoid confusion with some other acronym that's also ECG? Does it stand for something other than electrocardiogram? Or is it just because it's cooler?


  13. Would you please post the link for the 2nd lecture about EKG? I cant find it. your videos are absolutely amazing. I have been studying with your videos support and really helps. Thank you

  14. I did electrical muscle stimulation exercises last week for the first time. My head and eyes have been drowsy since. My eyes have a flickering with each heart beat. Blood pressure and heart rate are normal. Can the EMS system have caused a change in my EKG heart beat causing lack of blood flow to the brain.

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