this is intro to a method and rate and rhythm in this video we'll talk about a couple things we'll talk about why it's important to follow a sequence of steps each time you read an EKG I mean really is it really that important to be systematic I'll answer that question for it we'll also talk about how to figure out the heart rate and we'll talk about how to assess the cardiac rhythm so let's go ahead and get started so the first question is is it really that important to be systematic when you read EKGs and this one is easy to answer well we like to tell you to be systematic with the way you go about a lot of things the EKG is unique in that if you don't have a systematic way of looking at your patient's EKG chances are good that you've missed something I give you an example Q waves which indicate myocardial necrosis are often seen on the EKGs of patients who have had a prior mi that you can also see them with acute MI if you don't have a step where you ask yourself hey or their QA is on the ckg then when Q waves are there chances are pretty good that you'll miss them so for example this seemingly low-risk patient you had scheduled to go to the operating room might actually be higher risk than you think or this patient you're evaluating for atypical sounding chest pain might actually have ischemic heart disease and Q waves are just one of a number of abnormal findings you can find in a 12-lead tracing the more you look at EKGs is the more you'll notice just how many abnormal ones are out there for that reason it's really important to have a sequence of steps each time you read an EKG where you ask yourself questions like hey are there Q waves on this tracing how about LVH how about rvh is your left atrial enlargement here how about right atrial enlargement simply because these things are so easy to miss and so my recommendation is that you memorize the sequence of steps that you go through each time you read an EKG and you practice going through EKGs until you get the hang of it I'll show you the method that I use but really you can use any method that works for you as long as it's something that you practice and you're comfortable going through it each time you read an EKG so this is the method I use it's adapted from Dale Dubin and you can see the general categories of steps that I go through first I look at the tracing and I ask myself does it look regular and then I figure out the rate and the rhythm I take a look at the intervals then I look at axis then I look for signs of chamber abnormalities okay so this step is really important and so for each of these I ask myself are there signs of LVH are there signs of rvh do we have evidence of left atrial enlargement how about right atrial enlargement how about low voltage and then finally I get to the step called infarction which really looks at a lot more than just infarction okay and so I go in alphabetical order looking for Q waves which are signs of prior MI and then I look for an S wave and lead 1 and which if it's there then I look for an S 1 Q 3 T 3 pattern which can be seen with right ventricular pressure overload syndromes acute or chronic we'll talk more about that later then I look for ST segment abnormalities T wave inversions and then finally I scan the precordial leads for u waves which can be found in hypokalemia again we'll talk in more detail about these things later so let's start with a rate so there's a couple ways to figure out the heart rate one method is known as a box method where you take the number of large boxes between consecutive QRS complexes on an EKG and you take 300 and you divide it by that number it's important to note that the box method you can only do if the rhythm is regular in other words if the QRS complexes are evenly spaced when you're dealing with an irregular heart rhythm such as atrial fibrillation you can't use the box method because you'll have two QRS complexes that are close to each other and then you might have the next two that are farther away from each other so let's try it with this EKG so we can see here that this rhythm is regular or the you can see that the amount of space between each consecutive QRS complex is the same I'm going to zoom in over here so we can see over here these QRS complexes are about three boxes away from each other I just found a QRS complex on the line and it counted the number of large boxes before I got to the next one and we can see over here there's about three thus our heart rate is 300 divided by 3 or approximately 100 beats per minute let's say we had 4 boxes between consecutive QRS complexes well in that case our heart rate would be 300 divided by 4 or 75 beats per minute and if you had 5 large boxes between consecutive QRS complexes then your heart rate would be 300 divided by 5 or 60 beats per minute trust me I'm going somewhere here with this so an easy way to figure out the heart rate is to simply memorize the numbers 300 150 175 60 50 these numbers are derived from taking the number 300 and dividing it by 1 2 3 4 5 and 6 large boxes so all you have to do is recite these numbers as you tick off one large box between each consecutive QRS complex and you'll come up with a heart rate let's try it with a zkg so we see here this QRS complex is on the line and we simply count off 300 150 175 as we can see here our heart rate is somewhere between 175 beats per minute but it's much closer to 100 so I'll just go ahead and say our heart rate is about 90 beats per minute let's try it on another one so this tracing you can see is also pretty regular you've got a similar amount of space between each consecutive QRS complex so we can use our box method so let's go ahead and find a QRS complex that's on the line this one looks like it's about on the line and we'll just count off 300 150 175 60 50 so we can see here our QRS complexes some are between 60 and 50 so I'll go ahead and say our heart rate here is about 55 beats per minute if you want it to be even more precise instead of taking number 300 and dividing it by the number of large boxes between consecutive QRS complexes you could take the number 1500 and divide it by the number of small boxes between consecutive QRS complexes because we're bored let's just go ahead and try that five 10 15 20 25 26 27 28 we have about 28 small boxes between consecutive QRS complexes so we can go ahead and take 1500 and divide it by 28 which gives us our heart rate of does someone have a calculator all right hang out let me find my calculator fifteen hundred divided by 28 okay so it appears that our heart rate is actually approximately 54 beats per minute I was close so besides the box method or the 300 divided by X or if you're totally OCD the the 1500 divided by X method there's another way you can figure out the heart rate pretty easy and that just requires you to look at your 12-lead EKG as a whole and consider the fact that the entire 12-lead tracing lasts for 10 seconds and duration so all you have to do here is count the number of QRS complexes on your tracing and multiply it by 6 so over here we can see we've got 1 2 3 4 5 6 7 8 9 QRS complexes 9 times 6 is wait let me get my calculator no just kidding I don't need it 9 times 6 is 54 the nice thing about this method of figuring out the heart rate is you can have a tracing that's irregular such as the EKG is someone with afib and you could still use this because the QRS is don't have to be the same amount of distance between each other let's go ahead and try it with one more this is the EKG is someone with atrial fibrillation you can see here that the rhythm is irregular and so to figure out the rate I can simply count these QRS complexes and multiply by 6 so let's go ahead and do that we get 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 to QRS complexes on this ten-second EKG tracing that means our heart rate is 22 times 6 or 132 beats per minute okay now I'm just showing off enough about rate now let's go ahead and talk about rhythm so the normal cardiac rhythm as we talked about is normal sinus rhythm it's characterized by an impulse that starts in the sinus node before it makes it down to the AV nodes and then connects to the ventricles because the impulse starts in the sinus node we get an upright P wave and lead to and then a brief AV conduction delay before the impulse is transmitted to the ventricles so to figure out the cardiac rhythm I ask myself the following questions first is it regular in other words are the QRS complexes regularly spaced next I ask myself is there a P before every QRS and a QRS complex after every P wave next I ask myself are the p-waves normal so for example with normal sinus rhythm you get an upright P wave and lead – so let's try it on a couple so here we can see that it's regular we have a consistent amount of space between consecutive QRS complexes similarly we can see that there is a P wave before every QRS complex and a QRS complex after every P wave and finally we can see that the P waves look normal they're upright and lead to thus here we've got normal sinus rhythm if the rate was a little bit fast let's say over a hundred beats per minute then we'd say we have sinus tachycardia and if the rate was slow let's say less than 60 beats per minute then we'd say we have sinus bradycardia let's try another one so first let's ask ourselves is it regular so you can see over here it's not regular at all it's totally irregular this is an example of an EKG of a patient with atrial fibrillation atrial fibrillation is characterized by poorly defined irregular atrial activity and a very irregular ventricular response we sometimes call it irregularly irregular the heart rate can be fast moderate or slow and there's a number of things get that can predispose patients to developing a fit because the focus of this video is to go over a basic method of reading EKGs we'll go in more detail about afib and other with me as later now let's go ahead and look at another EKG I just want to know one thing what's the rhythm so here we can see it's pretty regular we've got a consistent spacing between each consecutive QRS complex but we don't really see good normal looking sinus P waves this EKG is an example of atrial flutter if you look closely you could see these sawtooth flutter waves down here and if you look even more closely you'll notice that there is a flood wave buried at the end of each QRS complex that means that there's only one box separating each consecutive flutter wave giving us an atrial rate of 300 beats per minute meanwhile our ventricular rate is 150 beats per minute because our AV node can't conduct that quickly we'll talk in more detail about atrial flutter and other arrhythmias later but this is just to give you an idea of what it looks like

## 6 Comments

Where did he get the 1500 from? i dont understand

Thank you π so much this video meant a lot

Thank u ππ

It's extremely helpful. I have never felt closer to understanding ECG π

each box is 100?

Thank you for this !