Interpreting the ECG | The Advanced EM Boot Camp

okay so with that let's talk about why we're here EKGs right so you guys are the only ones awake this morning and not still you know hungover or drunk right so welcome to being the nerdiest people in Las Vegas I have no disclosures except for the story I just shared with you all right so let's let's talk about EKGs in terms of Y right and why it's important and it's more than just the squiggly lines and that number that Rick told us about in terms of how many we have the chance to read in our daily practices sometimes it feels like it's like a hundred percent of the patients right are getting EKGs that you're having to read let's talk about where EKGs come from so back in the day before they had iPhones and you know Alexa right people did science they actually did things to understand about the body and about physics and chemistry and biology so Luigi Galvani and his assistant are skinning frog legs they're trying to understand the various kind of humors as I used to call them of biology and he takes his scalpel and he sets it down and the assistant picks up the scalpel and as he is moving the scalpel over he happens to touch an exposed nerve on the Frog that they've been dissecting and the leg twitches right which good thing that wasn't me because I would have twitched myself right out of that room I don't do frogs very well so the the leg twitches and it's the first time that people understand that perhaps muscle movement is related to electric movement right electricity is creating muscle movement in a body fast forward about 200 years and so here's eindhoven with the machine we all use and love now except his machine was actually 500 pounds and took five people to move it and was in a different building than where the patient actually was right so it being transmitted almost by radio frequency and you can see one foot is in like a bath which doesn't seem like the safest thing to tell a patient to do like secure foot with this Troad in this bucket of water and let's see what happens to it right so we've come a long way from the 500 pound model to what we have today so in terms of the EKG this is it guys right it's it's really just as simple I think we make it more complicated than it needs to be there's electricity and it's moving in a direction and technically in the correct physiologic pathway that electric axis is starting somewhere on the right side and it's moving towards the left arm and down towards the left leg and that is technically how all the vectors in a normal path of physiologic state should be working and moving and flowing all right so let's start with placement of electrodes right which you're looking at me for those of you I can see without the light in my eye up here and you're thinking why do we need to know this so why do you need to know this because when you get handed in the EKG and something about it doesn't look right whether the something about it that doesn't look right is a true positive there's something really not right with the heart or it's just that the technique was wrong you need to know the difference right so you need to understand how that EKG was acquired so if there's a problem with it then you can troubleshoot that problem and get the EKG you actually want to take a better look at the patient so assuming that you're the right arm is is the white lead right or the snow lead snow sits over grass which is green so the green lead goes on the right leg on the left arm being the black lead or the smoked lead right smoke sits over fire so the red fire goes on the left leg right so it's no grass and smoke fire right it's for the colors luckily the rest of the pre cordials have v1 v2 and they usually have colors on them so you can you know where to put them but understanding again where those lead placements go right so that v1 is going to be on the right side on the precordial wall of the chest somewhere around the sternal angle right between ribs one inch vitu goes directly across from it then you put v4 down then you put me six down and you put B 3 and B 5 in between those two okay so that way you know that the EKG was obtained correctly this is roughly what it looks like right with the looking at the right arm and the left arm and the right leg and the red leg left leg in terms of the colors on the electrodes sometimes we just do a 5 lead right we have the initial 12 lead then we want the patient to be monitored continuously so we have a 5 leads is what the 5 lead placement looks like where instead of all of those precordial slices that we take we just drop the chest lead on there or the brown lead all right so we have a rhythm and it conducts right it squeezes there's the polarization there's a contraction and then there's repolarization again simple right something simple at the heart is doing that produces a wave on your EKG code P waves where do they come from they should always come from the sinus node right the normal P wave comes from a sinus node there's a depolarization there's an atrial contraction which is short enough then it conducts down into the right and left ventricles you have a full squeeze every polarization that gives your full EKG as you look at it on the grid paper how long should a P wave last on the little piece of grid paper so less than point one right so if you're looking at your EKG grid that big deep those big red lines in between those are 5 little tiny boxes and each little tiny box is about point 0 4 so the P wave should really be about 2 of those little tiny boxes maybe partly into the third one right but that's about how much a P wave should be in its width so let's talk about P waves technically speaking the right atrium does squeeze just before the left atrium does but that millisecond fraction is so small that we just kind of see it as a P wave right so when you're looking at the I put it in two colors of the righty gym going first and the left atrium kind of by cell to cell fires immediately and you get this nice little P wave morphology or axis I don't think the mouse is going guys so again when you're looking at that grid paper you see the the big square grid lines and within that box are five little tiny boxes right which are each point 0 4 so you see that that P wave technically takes up about two of those little boxes okay which is what it should when it's normal when you have right atrial enlargement and we'll talk about why it's important to recognize this on an EKG what you get is a right atrium that squeezes and makes a tall p wave okay so you get a P wave that is taller than normal as you see here in front of you okay so it's a little bit taller than two boxes tall in left atrial enlargement what you get is a wider P wave okay because the right one squeezed the left is working on it but it's taking it a little bit longer because the left atrium is stretched so that goes a little bit wider than normal why does it matter what if you did have right atrial enlargement on an EKG what would that tell you that when that right heart has been squeezing all of those years right it's squeezing against some kind of resistance that has made it stretch okay so maybe there's right ventricular hypertrophy maybe there's pulmonary hypertension okay when there's left atrial enlargement what does that tell you same thing right that left chamber is floppy and it's dilated and the question is is why did it become dilated so maybe there's LVH maybe there's regurgitation that's flowing back into the left atrium okay now I know all of you in this room love rushing in to talk to your patients right because we're such captivating people right but if you could piece together a lot of their puzzle before you walked into the room you see how much more you'd have with you when you walked in and you could kind of focus their history or you could focus your line of questioning to make it more convenient for both you and the patient in that room not to say it's not great to spend you know 30-some minutes talking to somebody in the ER right but if you could spend three or four and get really great information before you walked in because you had all of this in your head already for a differential that's the purpose of the EKG so you're some p-waves right at the very top you'll see there's normal which just looks like a nice normal kind of upside-down u ish shape always upright in lead to again when you're looking at your limb leads and the placement your p-wave should always be positive deflection and lead to in v1 which is that right-sided precordial lead you may get a biphasic fluctuation right because again as we talked about the vectors they're positive on the right side and they're flowing right words and downwards so you may get that little kind of biphasic v1 notch as you see there we talked about right atrial enlargement where it's a taller wave and we've talked about left atrial enlargement where it's a wider P wave and then you have the really pathophysiologic heart where you have both RA e and la e and then you get a tall and a wide P wave okay but again looking at that now you already have in your mind a lot of differential for what is going on in that patients heart before you ever walk in that room alright so SA node right fires we've just talked about the P wave and that depolarization part of it hits the AV node down into your bundle of his Purkinje fibers big squeeze and the ventricles repolarization next cycle of the heartbeat so QRS complexes are meant to be narrow Rick at the introduction talked about wouldn't it be nice if the EKG could just actually tell you something accurate about the patient so my personal bias is the following bet EKG when it spits out at you those numbers at the top those are great numbers I can't do that I mean I can't do that kind of math right can you do square roots and division that quickly with those little tiny boxes no but the computer is very very good at doing that for you that is what you should be using the computer for all the other stuff it tells you yeah that's nice thank you for the suggestion computer I'm gonna make my own interpretation of this EKG the computer can be useful for the those mathematical numbers like the Qt see that it gives you the the p-wave with that it gives you that part is good from the computer spit out so QRS complexes are meant to be narrow right and they can look in all kinds of different ways we'll talk about those as we go through our morning and more depth so in general when you're looking at the QRS complex it's narrow right so it's going to be maybe about two boxes wide in total so 0.06 2.10 seconds wide the little boxes on your EKG the Q wave is going to be particularly the skinniest part of that little deflection where it's going to be just about the width of that one of those little tiny boxes everybody just kind of collectively go oh right okay because here's the access part so the the schematic at the bottom the spokes at the bottom are what I feel like every cardiologist I've ever interacted with or even in in Physiology in med school they love to toss this up there right like I think it's like their job security of yeah I I can read the spokes okay that's cool oh good let me simplify it for you so we talked about the right atrium here firing left and downwards right correct yes okay so you see the little skinny man at the top of that screen I'm sorry the mouse is not working so again the vectors are going to go to the left and they're going to go down and you'll see up there there's R which is AVR there's L which is AVL and there's F which is av foot if you took those vectors and put them on the spokes at the bottom you will see again there's an AVL platform there's an AVR at the +30 and then there's an AV F at the plus 90 at the very bottom thank you all right the spokes are still there so let's make it a little simpler if we assume that lead 1 is a left-sided lead oh thank you very much then we look at a VF as that perpendicular lead to lead one and we make it our right-sided lead okay and that's how we figure out the access we're gonna look at one and a VF so we're gonna do some examples of this all right everyone take your hands out this is your stretch for the morning Rick and I talked about this room it's such a big beautiful room we thought we should do like yoga or something in the back you know anyway take out your hands right in front of you so what your hands are gonna be used for every single day now going forward looking at EKGs why do we have thumbs you would argue because we're humans no it's in fact so we can look at the axis on the EKG all right so here your thumbs correct you're looking at your EKG the QRS deflection is positive in lead one okay which is our left-sided lead sore left thumb is up and it is positive in AVF which is our right-sided perpendicular lead so we have positive and positive so our axis is we have two thumbs ups that's good right so it's normal okay so back to our hands now we're looking at the EKG our 8r lead one on our limb lead is positive that's our left lead okay and our foot a VF or our right perpendicular lead is negative what thumb is up please somebody say left okay good right so if your your left thumb is up that's left axis deviation so far so good okay so shake off those hands again now you're looking at your EKG okay you're eight you're lead one is negative so your left lead is negative you're 80 foot to your right perpendicular lead is positive what thumb is up you're right so what axis is this it's right access good now in the case where it's negative and negative either you are way right axis or your way left axis and then at that point the rest of the EKG will help you determine whether you have lv h or RV h or what else is going on or a paste rhythm etc etc good with the thumbs yes okay okay so let's look at this EKG right so we're just all we're looking at right now is the axis so we're gonna get out of little hands again a nice human thought poseable thumbs and our QRS deflection is positive in 1 yes they're right so we're upright in 1 which is our left and our QRS and AV foot which is our right-sided perpendicular lead is so what axis is this normal absolutely okay see it's literally just that easy all right another axis here is one right so the QRS is more positive than negative so we'll get that a positive in one here is F the QRS is definitely negative what thumb is up left okay so this is left axis okay now this one we will all do together from your seats right so I'll lead one the QRS is negative and in AVF the QRS is positive what axis is this right okay good class done why does it matter so that's great right we talked about P waves checked by right axis enlargement we talked about left atrial enlargement that's great why do you care this is why you care if you have right axis deviation right so when you're looking at your one and your F it's like this okay if right axis deviation and let's say you have a P wave suggestive of right atrial enlargement what can you now tell about the patient's heart potentially before you walk in that room look at this they might have an acute lung problem which is why they just showed up in your eg okay they might have that a QP e for from flying from Florida to Vegas and not getting up because the drink cart was in the way right they might they might have chronic lung disease so they have chronic lung strain that creates right ventricular hypertrophy that backs up to the right atrium that gives you a trill enlargement that creates a right axis deviation if they have left axis deviation so you're positive and one and you're negative and AVF on your cure s complex what is that going to tell you important things is there an inferior mi going on right do they have LVH do they have hypertension that nobody has treated for all these years until they just hit the door of your emergency department today so this is why you care it's not to be fancy and just run around go and look like and look at EKGs because guess what I think the iPhone or the iWatch right is coming out with some technology for afib so soon some Alexa was going to tell you what the EKG reads but this is why you want to know what that interpretation means for you and for the patient okay so moving on at QRS complexes anything look kind of jump out at you on this page so when I was a resident just a handful of years ago not really I had a cardiology attending edge I just loved him he won he was my height which I really loved him but - he was this really sweet man from Cuba and he would he would look at these EKGs like the one you're looking at and he would go Joyce Joyce look at this in these this is like the cousins are kissing it's a little dirty but the cousins are kissing like you would say this stuff all the time so what he meant was see these little cousins right here the S wave in the R wave and subsequently the S wave here and this R wave they land on top of each other right so here we have left ventricular hypertrophy so there are multiple criteria that you can use I should have said my disclosure was I'm really great at languages I am not great at math so this is the criteria that I like because it's simple so this is the Sokolov lion criteria you're gonna take your S wave in v1 okay and you're gonna add it to the number of boxes of the R wave in v5 or v6 you pick whichever R wave is more prominent and easier to see so if you calculate up the little the boxes right so if you imagine that each of this these big heavily lined boxes is five millimeters which it is so we start here --is-- so one two three four five what's 5 times 5 25 yes we're gonna add 25 which is this S wave and v1 we're gonna add that 25 - let's take this one so it's very tall we're gonna add that to let's see 1 2 3 4 5 boxes on the airwaves in v6 what's 5 times 5 25 what's 25 plus 25 50 ok moral of the story if the S wave and v1 added to the our wave in v5 or v6 totals more than seven boxes you have LVH make sense yes okay it's not complicated math because I cannot do complicated math so what's our axis here is your key RS up or down and one it's down is it up or down in AVF right and you have some kind of right bundle so it's severe right axis the point is here we have right axis deviation and we also have criteria for right ventricular hypertrophy where the are waves here in v1 is clearly much taller than the S wave and in v6 your s wave is much deeper on the other end then your our wave okay so R greater than s and s greater than R right ventricular hypertrophy right and again not it's it is important to know what these are electro physiologically but remembering we also want to understand the pathophysiologic why does the patient have rvh why is the patient here today what this is EKG telling us about their heart or their system that we can glean right now before we go in and talk to them the T wave is your repolarization phase it should always be upright and we'll talk about why it is not upright what that means for the patient lots of different ways to clearly look at T waves at the top you have normal and you have those kind of non specifics these ones down below and Fred is going to go into much greater depth here shortly about these these are the ones that you worry about this is why it's important to know what a normal EKG should look like so when something pops up that is not normal then it alerts you and you can start to see about the differential of that t-wave and what it is symbolizing for the patient the you wave is that being a little itty-bitty tiny deflection after the T wave which half the time you can't even see and it's not important here's when it becomes important when it's prominently up right then these are the conditions that it could symbolize severe hypokalemia which you will also have T wave changes with that right hypercalcemia right so the hypercalcemia of malignancy for example that patient will have a very prominent upright u wave which again if you look at any normal EKG you half the time that new wave is kind of buried along with the T and it moves on you never notice it so if you know what normal is then when you see something abnormal like a very prominent upright u wave now you can catch something potentially lethal for that patient and then of course here's our friend is which creates all kinds of troubles on EKGs because of its cardiac conduction physiology when the you wave is flipped same thing it's a it's notifies us that something bad is happening for the patient now assuming that if they're having an acute ischemic event you will see that reflected as a STEMI which you should but maybe they've come in at that very early phase before you have those big tombstone patterns right or maybe they've come at the end of their non-stemi event and they've had some ischemic event and you now have a very prominent deflection of a negative you wave the QT interval should be about 0.42 seconds right and that is where the computer is helpful to when you're looking at the QT see the computer is great for giving you a square root of some computation that part the computer is great at when you're looking at an EKG much like when you're looking at any diagnostic tool whether that be a chest x-ray whether that be a head CT whether that be your labs that you're looking at right you should always have a system why should you always have a system how many of you in your day-to-day work in the emergency department can sit quietly just think about patient okay so when you don't have a system and you don't do something the same way every single time you're going to miss something which is why I think we all we do it not realizing that we are doing it right but we do it we look at x-rays we do it we look in our at our labs maybe some of you always look at sodium and potassium first maybe some of us always look at the glucose for whatever reason first but we have a system of how we do that so we don't miss things right a heuristic pattern that we use same thing for the EKG this is the one that I like to use it does not mean that one that you should use but I like to look at the rate the rhythm I like to look at all of my waves the segments the complexes and then usually by then I will have already kind of glossed over and looked at the axis but if you want to put the axis before the rate that's fine too but just pick a system and use it every single time so the rate as many of you know you find the heaviest dark line you can find that darkest pink line right which signify is one solid grid of a box you find the QRS that falls on it and then you start counting downwards right so your next heavy dark line is going to be 300 150 175 50 and onwards okay again often the computer is great at telling you what the rate is sometimes it's not so great because you either miss counts or it starts a double count paste rhythms for example okay when you're looking at a rhythm wait who started the rhythm right like where does it come from is it sinus is it junctional is it ventricular what is the rate whoever started the pacing is that the rate that you expected them to pace this heart so if that rate is coming from the sinus node then does it likely follow a 60 to 100 feet per minute cycle or is it faster than you thought it was going to be or is it slower than you thought it was going to be how regular is it regularly regular right like scientist normal sinus rhythm is it regularly irregular is it irregularly irregular and that will help to tell you again in that heuristic pattern what that rates and rhythm likely are and who's creating that in the heart last but definitely not least is is this rhythm coming because it's an active pacing or because it's some overdrive that somebody took over for a pacemaker that had not captured properly these are in the book I'm not going to belabor this because again it's just the different intervals and what their rates and time should be but if you want to put this somewhere like snapshot to put in your phone look at it compared to what the EKG spits out for you this is a great tool to have alright so let's go through quickly a couple of EKGs so we're gonna interpret this one and since I'm standing in this box then we'll use my system right so what's the rate and I'm going to admit you get to this age first of all where readers are no longer optional I'm not really loving this age so much and then the light makes it hard to see that the light of the big grids but if we assume that that is a deep heavy line right there right then we have 300 150 100's right so we're just above 100 everyone agree with that okay so we'll say we'll say 100 for the rate what's our rhythm I hear sinus yes right so if you're looking here and lead to there is a P that comes before every cure s and why did I pick lead - because that's where you should always have it up right P wave yes so there's a P before every QRS so we will call this sinus tach right because we know that the rate of sinus we expect the rate to be 60 to 100 but it's actually a little bit over 100 so we're gonna call it sinus tach what is our do anything stand out to you in terms of P waves or cure s complexes ST segments so these T waves right are symmetrical but they're definitely inverted and you might expect an inverted T wave in v1 because that is a negative deflection away from the right side of the heart but you certainly don't really expect it to remain negative as you're coming down to the left side of the heart and oh the axis so the cure s is kind of isoelectric and one and it's upright in AVF they will call it little call a positive one so it's normal axis okay how about this one so here again our rate let's pick this line right here so 300 150 175 60 50 ish okay so our rates 50 what's our rhythm who's pacing us maybe I can came into there's a p-wave here right so we'll call it sign is Brady yeah because it's sign is paced but the rate is less than 60 so it's sinus bradycardia nothing really stands out I don't really see anything fancy about the p-wave the Kuras looks nice and skinny the t waves are up right when they should be nothing super bleep prominent happening here what's our axis we are negative in one positive and AVF so we write access so right axis sinus Brady and so we have write access can we say that we have our V H no not really all right this one here I'll let you tell me the rate because I really can't see any dark lines from up here 100 okay we'll go with that rhythm sinus rhythm at 100 okay P waves look nice and upright ers is to me here look skinny T waves look normal in there kind of normal range nothing else there stands out the axis up in one and isoelectric row down Navy F this will call left okay so we have left axis so what else should we look for if we look for LVH let's do that huh alright so here I'm going to say one two three boxes on our s wave and B 1 3 plus another 1 2 3 4 5 ish so three boxes here and five boxes here is eight boxes and eight boxes multiplied by five is 40 so it's greater than 35 so we also have LVH okay last three questions and then it's Fred's turn so you're looking at the axis on an EKG you're trying to determine it your cure s is up right in lead one it is negative and AVF the axis on this EKG is left is correct this EKG that you see in front of you has changes most consistent with which of the following problems I'll give you a clue there might be some cousins on this page certainly yes so it is LVH right if we were to add up these boxes here and let's pick v6 because there's just so many of them we clearly are more than 35 millimeters so left ventricular hypertrophy and last one here when you're looking at the rhythm you are specifically considering all of the following except do you want to know who started the pacing yes so you want to know the site do you want to know if the rate matches the site yes you do do you want to know if it's regular in its rates yes so by default the axis doesn't play any part in the rhythm okay I'll see you all shortly

Channel: The Center for Medical Education

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Length: 34min 38sec (2078 seconds)

Published: Wed Nov 14 2018