Cardiovascular | ECG Basics

hi ninja nurse what we're going to do in this video is we're going to talk about the basics of ekg this is a really important diagnostic tool that we should use as clinicians it's important for being able to look for arrhythmias being able to look for possible myocardial infarctions so it's a great tool that we as clinicians should be able to understand in order for us to do that we have to really kind of dig in just to the the basics of the electrical activity of the heart talk about how that represents vectors talk about how those vectors are basically interpreted um and generated through a graphical representation that we see on ekgs so let's go ahead and first start on the cardiac conduction system all right so let's go ahead and talk about a little bit about the cardiac action potentials right so whenever we re in order for us to really understand how the electrical activity the heart correlates with the corresponding ekg we have to understand just a little bit about electrodes okay just the basics and basics on electrodes so let me give you an example of what i'm talking about here so in order for there to be like this graphical representation because that's what an ekg is it's a graphical representation of the electrical activity of the heart so the electrical activity of the heart is actually going to be transmitted onto specific electrodes and those electrodes will pick up that electrical activity and present it with either a positive deflection a negative deflection or it might just be like a flat line so let me explain just a little bit about that let me say here i take a piece of cardiac tissue here here's a piece of cardiac tissue and here's a piece of cardiac tissue okay what i'm going to do is let's say that this cardiac tissue is going to it has the ability to conduct electricity all right and what i'm going to do is i'm going to put an electrode on one end of the tissue let's say that here i put a positive electrode at one end of the cardiac tissue okay so here's a positive electrode it's linked in with this tissue here then over here i'm going to put a negative electrode on the other end of this cardiac tissue now what happens is let's say that the cardiac tissue right it has the ability to generate its own electrical activity and that electrical activity when it's generated it moves in a direction towards the positive electrode when the electrical activity of that tissue moves towards the positive electrode the positive electrode actually picks that up as a positive deflection so when electrical activity which is being conducted through a tissue is moving towards the positive electrode which are going to be these different things that we're going to put on the patient's body it is actually going to have a positive deflection okay so this will give you a positive deflection if again i do the same thing over here i put a positive electrode on this end of the cardiac tissue i put a negative electrode on this end of the cardiac tissue you probably already know where i'm going with this right so same thing let's say that the electrical activity that's being generated is actually moving from this side to this side so it's moving from the positive to the negative electrode well now if it's moving away from the positive electrode because that's who's actually picking up the electrical activity it's the positive electrode if the electrical activity is moving away from the positive electrode it'll actually produce a negative deflection so that's what i really want you guys to remember here when we're kind of just talking about oh this is a positive deflection this is a negative deflection this is a flat kind of line so that's the next thing well how do i know if something is just going to be maybe there is no deflection well that means that maybe that if you're having something like that it could be that the action potential is actually being conta so the electricity that is being conducted through that tissue is being conducted very very very slowly or another thing that can indicate a flat line is that you have an electrical activity that's moving perpendicular to the axis of this lead this electrodes okay so basic thing that i really want you to understand here for these ekgs is you have a negative positive electrode if the electrical activity of the cardiac tissue which we're going to use in this example is moving towards the positive electrode it's going to produce a positive flexion if the electrical activity of this tissue in this case we're talking about cardiac tissue is moving away from the positive electrode it's going to produce a negative deflection all right that's what i want you guys to remember for right now i just want you guys to trust me and we'll talk about all these different leads i just want you guys to trust me that we're going to be looking at each one of these hearts from one specific lead okay and that's going to be lead 2 and again we'll talk about what the heck lead 2 is i just want you guys for right now to trust me that this is going to be lead 2. so in order to make a lead right a lead 2 you're going to have to have a positive and negative electrode so lead 2 we're going to put the positive electrode here at the apex of the heart and we're going to put the negative electrode here at the base of the heart and now you have this this lead this axis of the lead which is going to be moving in this direction here okay now let's try to imagine that this is kind of a straight line right here okay so negative to positive electrode the electrical activity of the heart starts where it starts at the sa node which is up in the right atrium right when the electrical activity of the sa node is triggered it triggers action potentials that move throughout the atria but where is it moving towards it's moving towards the av node right so it could be moving all the way out this way it could be moving this way and moving towards the middle the mean vector of atrial depolarization is going to be pointing directly towards the av node so that's where the mean vector of atrial depolarization should be going what am i talking about let's make it very simple here let's say that i'm talking here's the heart okay here's just a very generic thing here's going to be the sa node let's say here i put the sa node here i put the av node okay here's my bundle branches and purkinjes very simple here electrical activity is generated and it might move this way it might move this way this way and this way if you take all of these vectors and develop a net vector the net vector should be directed towards the av node that's what i'm talking about okay so atrial depolarization starting from the sa node going towards the av node is moving this way moving kind of downwards and to the left where is it moving towards the positive electrode if the electrical activity of the heart is actually moving towards the positive electrode and again what lead is this that we're kind of using this example here for let's make kind of like a dotted line here this is going to be lead to again we're i just want you to trust me for right now that this is going to be lead to i'll explain what that means in a second but which way is it moving the electrical activity is moving towards the positive electrode so what should that produce on the ekg on lead 2 a positive deflection right so on lead 2 if we were looking at lead two here you should get a positive deflection well guess what that positive deflection is that's the p wave that's representing atrial depolarization so the p wave is indicative of atrial depolarization all right all right cool next thing we move on okay electrical activity was generated right sa node to the av node then what happens remember i told you that the electrical activity goes to the av node and remember this back from all the other physiology videos the av node is a slow conductor of electrical potentials so it has about a 0.1 second delay before it sends the action potentials from the av node into the bundle of hiss so what me what that means is that there's no actual vector that's being generated the electrical potential isn't moving if no electrical potential is actually being generated and moving is there going to be a direction of the electrical potential in other words i want you to think about like this the electric potentials was being generated from the sa node towards the av node the av node is now stimulated right so it's positive but it's depolarizing and it's conducting the action potentials through it very very slowly so it hasn't developed an actual action potentials to move down to the bundle of hiss yet it's stuck in that av node so therefore the electrical potentials the actual electrical activity isn't moving anywhere in this direction it's staying in the av node for about point one second so if there's no electrical activity being generated or moving imagine here your negative electrode positive electrode again here's your lead two there's no electrical activity that's moving from the av node to the bundle of hisket there's about a 0.1 second delay is there going to be any deflection no so this should actually be a flat line so this is your p wave again we already discussed that that was actually going to be atrial depolarization right and that's generated by this vector but now you're going to have this period where there's an isoelectric line in other words there's no deflection from this point this is actually going to be the pr interval and the pr interval is basically when action potentials are being conducted through the av node but very very slowly and because of that no action potentials and move from the av node into the bundle of hiss so there's no direction of the action potential why is this important the pr interval is important because when it comes to heart blocks in other words if someone has a first degree heart block what does that mean that means that the av node is taking a while before it's actually conducting action potentials down to the bundle of hits down to the ventricles if it's a second degree heart block sometimes there's action potentials coming down to the av node but it just doesn't send some of the action potentials and the third degree is the av node doesn't even have any connection anymore between the atria and the ventricles so that's why the pr interval is very important okay so p wave pr interval move on to the next one again sa node action potential to the av node av node is now going to generate action potentials that are going to move into the bundle of hiss and down these bundle branches right so what are you going to have here you're going to have sa node to the av node av node is going to generate these conduction but again it's a very slow conduction so it's not going to have a direction of the electrical vector yet then it's going to move down into the bundle of his and into the right bundle branch and left bundle branch well we have to depolarize the septum here's what's really interesting when electrical activity moves down the bundle of hiss and down the right bundle branch and down the left bundle branch the left bundle branch is the actual branch that depolarizes the interventricular septum so imagine like this let's come over here to this little diagram you have here your left bundle branch right so left bundle branch and over here you're going to have your right bundle branch electrical activity is going to be generated through the av node into the bundle of hiss and then down into these bundle branches when the left bundle branch is generating these action potentials he is actually sending these action potentials in the direction of the interventricular septum so it's actually going to be depolarizing the septum and it's going to be moving towards the right side of the heart so when you're depolarizing the septum it's only going to be from the left bundle branch okay so left bundle branch is actually going to be stimulating the interventricular septum moving this way so what kind of vector would that generate if you're moving this way you're going to generate that type of vector right it's a simple thing so again left bundle branch is stimulating the interventricular septum just remember the heart's kind of shifted two thirds of the left so it's going to be kind of at an angle moving towards the right and upwards so to go back to your lead system here lead two right negative electrode positive electrode and then here's going to be the axis of that lead which way is that actual action potential the positive um the the conduction of electrical potentials moving towards was moving from the left bundle branch towards the right bundle branch right but it's going to be going through the interventricular septum so that's moving in what direction the opposite direction so what should that generate that should generate a negative deflection okay so you're going to have your p wave which is going to be a positive deflection from the atrial depolarization your pr interval right there right pr interval which is going to be whenever the av node is slowly conducting action potentials but there's no net direction of an electrical vector okay then you're going to have this negative deflection and that's going to be indicative of interventricular septum depolarization what is this wave here called this wave is called your q wave now remember this there is pathological q waves and we'll talk about what these mean but all i want you to remember for right now is that the q wave in this normal qrs complex is indicative of septal depolarization okay simple thing here i just want you to remember that the q wave is indicative of septal depolarization okay so we got our p wave here right that's going to be indicative let's draw the net vector let's keep getting being consistent with this so where's the net vector going from the sa node to the av node it's generated like this okay so there's that vector then we have the period pr interval this is where the av node is stimulated it's conducting action potentials through it very very slowly then we have the net vector for the q wave where's that pointing it's pointing from the left bundle branch right towards the right so it's going to be pointing rightwards and slightly upwards now we're going to move down the left bundle branch down the right bundle branch so we've already depolarized the septum now what do we got to start doing let's have these action potentials that are now going to be from the bundle branches go to the purkinjes and from here we're going to start depolarizing like this it's going to move so imagine here i kind of took a tissue i took like a piece of tissue there imagine here i take this piece of tissue right and this is going to be the inner cavity this is going to be the outer wall okay so imagine here just to be simple here this is going to be the inner wall this is the outer wall inner wall outer wall imagine here you're going to have a bunch of cells right this is made up of a bunch of cells the action potentials are going to be generated moving through those cells okay so it's going to be moving through those cells so these action potentials are going to be generated they're going to start moving outwards like this okay so it's going to turn the negative membrane to a positive negative positive negative positive so the direction of the action potentials are moving towards the right towards the left and straight down let's think about this right ventricle is it thicker or is it thinner than the left ventricle left ventricle is pretty thick isn't it it's thick so if the left ventricle is thicker than the right ventricle who is going to have more electrical activity more of a larger magnitude of electrical activity the left ventricle so let's do this let's say that we get a net vector for the right ventricle let's draw it like this okay there's our net vector for the right ventricle but then you're going to have the net vector for the left ventricle and this should actually be have a larger magnitude so there's one vector there's another vector this is the right ventricular vector left ventricular vector why is the left ventricular vector larger because it's thick you got a thick left ventricle so now where is the resultant vector going to be between these two right but it should point a little bit more towards the left right why because the left ventricle is going to generate more electrical activity than the right side so if you're going a resultant vector just basic physics right you have here here one vector one vector the net vector is supposed to go between but it's going to be a little bit more towards the left so now the net vector here should be going like this okay so if the net vector is pointing down that way let's imagine this then what do we have here what do we have at this point down here we have our positive electrode positive electrode of lead 2. over here we have the negative electrode of lead 2. the mean vector which we're going to circle here let's circle this vector here in brown this is the mean vector between the left and right ventricle where is it pointing that sucker is pointing straight down at the positive electrode and it's going to be a big vector okay this is going to be the mean qrs vector right and it's pointing towards downwards towards the left hip right towards that positive electrode so it's going to produce a very nice large positive deflection okay the mean qrs vector which is the sum of the left ventricular vector and the right ventricular vector should point downwards and a little bit more towards the left y because the left ventricle has a thicker myocardium so it generates more electrical activity larger magnitude that's going to produce a positive deflection so again this positive deflection again what do we got here p wave then we have here this point is the pr interval then we have here we have the q wave negative deflection what's this big mama that big mamma jamma right here is going to be the r wave and the r wave is indicative of what ventricular depolarization right so it's indicative of ventricular depolarization now let's move on to the next step so you're depolarizing the ventricles you're you're basically flipping the membrane from negative to positive that's what this r wave is indicating all right so the net vectors are being generated now we go to the next step which is going to be this s wave okay so again keep going off of your vectors just to be consistent where's the the direction sa node to av node that's your p wave right that's the first vector then av node is becoming positive y is conducting action potentials very slowly but no net direction okay then the net vector from the left bundle branch stimulating the septum is going to be moving to the right and slightly upwards then you're going to have a right vector coming to the right ventricular myocardium left ventricular myocardium is going to be a larger vector when you sum the two up and get your resulting vector because the left is larger than the right it's going to be pointing downwards and slightly leftward okay let's keep her going then now we said that you were depolarizing outward right in this stage here where you were generating the r wave well now guess what happens as you stimulate outwards you then have to move where so you're going to have to move upwards and now the electrical activity is going to start moving upwards and as it starts moving upwards towards these actual bases of the um the ventricles where's the vector moving so imagine now i draw a vector this is moving upwards this is moving upwards towards the bases of the ventricles where is this pointing with respect to lead 2 here's your positive electrode here's your negative electrode and again here's the axis of that lead mama where is these guys pointing they're pointing in the opposite direction of the positive electrode so what does that mean if it's going in the opposite direction of the positive electrode it's a negative deflection so that's going to be our negative deflection right there and that is our s wave so again you have the p wave you have the pr interval you have the q wave r wave and the s wave what is the s wave indicative of it's indicative of the depolarization at the bases of the ventricles okay so it's the depolarization of the bases of the ventricles so the r wave is you were depolarizing the apex of the ventricles and then the base of the ventricles is going to be too polarized for the s wave okay all right so now let's think about this sa node you guys are going to hate me by the end but this is going to make sense right so this is the net vector from sa node to av node av node is depolarized afterwards it stays positive conducts action potentials very very slowly doesn't generate a net electrical vector left bundle branch is going to be depolarizing the septum and it moves from the left to the right and slightly upwards mean qrs vector formed as the resultant between the right ventricular vector and left ventricular vector for the apices is going to be slightly downward and leftward and then you're going to have after that after it depolarizes the apex it's going to turn around and go upwards towards the bases of the ventricles and you're going to get the depolarization of the right and left basal part of the ventricles and that's going to generate your s wave all right so now the entire ventricular myocardium is depolarized okay but there's no net direction it's just depolarized it hasn't repolarized yet so that is what our st segment represents so the st segment is going to be the period of time in which the ventricular myocardium is still depolarized okay it hasn't gone into a repolarization state just yet okay so that's what i want you to remember about the st segment the st segment there's no net electrical vector okay so that's why it's going to be isoelectric the entire ventricular myocardium is depolarized for that instant of time and it hasn't repolarized just yet that is the st segment okay we gotta go to the last part which is actually gonna be our t wave right so again if you guys remember the vectors right sa node to av node pointing downward here towards the av node positive av node due to conducting the electrical potential slowly septal depolarization pointing rightwards and slightly upwards right and then you have your mean qrs vector pointing downwards and to the left and then you have the base of the ventricles depolarizing because of the moving from the apex and upwards right then the entire ventricular myocardium is depolarized right so it's entirely positive now when you flip the charge right so it was entirely positive now it's going to go from positive and you're going to flip it to negative right when you flip the charge so now this entire ventricular myocardium imagine this entire thing on the outwards is positive i'm going to go positive flip it to negative positive flip it to negative so i'm trying to make my entire i'm trying to bring a negative charge moving back and upwards so that negative charge is moving away from the positive electrode and so what you're going to want to remember for this is because the negative charge is moving away from the positive electrode it's just going to give you a positive deflection okay so again here positive electrode here for lead two negative electrode here right here's going to be this axis of that lead again lead to if you guys are remembering the negative charges are going to be moving and it's going to be moving upwards right so negative charges are going to be moving you're going to be going flipping it from positive to negative positive to negative positive to negative because the negative charges are moving in the opposite direction of this positive electrode it's going to cause this deflection to be upwards so you're going to get an upwards deflection and that is going to be the t wave so to wrap it up for this part here p wave is going to be this part here again that's going to be the depolarization from the sa node to the av node pr interval is going to be the period where the av node is actually conducting electrical potential very slowly q wave is going to be the septal depolarization r wave is going to be the mean qrs vector generated between the resultant of the left and right ventricle s wave is going to be the base of the ventricle depolarization st segment is going to be when the entire ventricles are depolarized and haven't repolarized just yet and the t wave is going to be when the entire membrane flips its charge and it becomes from positive to negative okay that is going to be your entire ekg strip there now we've gone through the electrical vectors and correlated that with their corresponding ekg deflections what we have to do now is get a little bit more information on how these leads work okay what are the different types of leads and how all these leads make up a 12 lead ekg system that gives you a very very significant three-dimensional view of the heart in both a frontal and horizontal plane all right so now that we understand how the cardiac vectors that are generated from the electrical activity of the heart represent these kind of deflections positive negative or isoelectric lines on the ekg and we kind of just kind of bombarded you with this idea of oh you're only looking at it in this lead two system that's not true again that's one way that you can look at it so whenever you see ekgs you just see like a one component of an ekg usually it's a lead ii ekg and and again we'll talk about what that means but what i want you to remember is that whenever we're doing these things in a clinical setting they're usually 12 lead ekgs so 12 leads what does that mean that means that you have okay so we have 12 leads out of these 12 leads that make up the ekg three of them are going to be what's called bipolar limb leads okay and these are gonna be what we call one lead one lead two and lead three okay we'll talk about these first the next one is going to be three augmented we call them augmented unipolar limb leads and these were kind of derived from anchovies triangle by a guy named wilson he made what's called wilson central terminal and then another guy named goldberg he kind of modified that to where you got this really cool way of having an augmented unipolar limb lead and we'll talk about we'll talk a little bit more about that means but again this is going to be avf avr and avl and again we'll discuss this a little bit more the last thing is going to be your six precordial or we just chest leads okay or we can call them chest leads okay and this is going to be v1 all the way to v6 and again we'll talk about these here's one thing i want you to remember though the bipolar and the augmented unipolar limb leads they look at the heart in a frontal plane so if you were to imagine what that means a frontal plane is it's also another word for it called coronal so in other words you're taking a slice of me like this you're slicing me like this and you're putting me into an anterior and posterior piece okay so an anterior and posterior piece is a frontal plane that's how these are looking at the heart okay the chest leads are going to be looking at it in a horizontal or transverse so imagine you're cutting through me right in the middle of the heart and you're looking at the heart in that direction so a superior inferior piece is what i'm going to be in but you're looking at the heart in a transverse type of way okay transverse or horizontal sectioning so that's another thing i want you to remember all right so the first ones that we're going to talk about is bipolar limb leads bipolar limb leads is you're going to have a negative electrode and a positive electrode so there's two poles a negative electrode positive electrode what you're going to be doing is you're going to have three of them and they're going to need one electrode on one side one electrode on the other one and that's going to develop a lead okay so imagine here we have this guy he's coming in he's got to get an ekg we got to get him hooked up okay so we're going to apply the bipolar limb leads on him all right so the first thing we have to do is we have to take and put some electrodes on him what we want to do is we're going to put on his right arm so this is going to be right arm left arm left leg right leg on his right arm or right shoulder we're going to put a specific electrode here we're going to put a negative electrode on this guy we're going to stick that on his right arm okay then what i'm going to do is that's my negative electrode i have to put another electrode on the other side the left side and if it's a positive electrode that's going to give me one lead so this is going to be a lead right here there's one lead that's the axis of my lead this one right here is called lead one so i'm going to put a negative electrode on right arm a positive electrode on the left arm and that's going to create the axis of lead one okay that's the first thing i want you to remember then what we're going to do is we're going to take another electrode and we're going to put a positive electrode on the left leg so let's put a positive electrode on the left leg now i have a negative electrode from the right arm and a positive electrode from the left leg look that generates an axis here now i have an axis of a lead this is the axis of this lead this lead right here is going to be lead two so negative electrode on the right arm right so what i'm going to do is here i'm actually going to put another because i actually have to create i'm going to put a negative electrode another negative electrode on this guy's right arm and then i'm going to put a positive electrode on his left leg that creates this axis this is going to be the axis of lead 2. okay let me do another one i'm going to put another positive electrode on this guy's left leg and then what i'm going to do is i'm going to put a negative electrode on his left arm if i do that now i'm going to have another axis right here going from the left arm to the left leg this is going to be the axis of lead three now this right here is going to be my bipolar limb leads all right so now we're just going to take and kind of superimpose this on here right so very simply what do we have on this side right arm left arm left leg right right arm what are we going to have we're going to have a negative electrode here positive electrode over here that's going to give you lead one then we're going to put another electrode on the right arm positive electrode on the left leg that's going to give you lead two we're going to put a negative electrode on the left arm and another positive electrode on the left leg that's going to give you lead three all right so this makes up this triangle which is ein tovan's triangle and he has a law and tovan's law says that if you take lead 1 right and you add it to lead 3 it's going to equal lead two and this is just coming based off of the vectors we'll explain this very very briefly in a second here's what i want you to remember though the axis of this lead right you have a negative electrode and a positive electrode here okay that's going to be making up lead one the positive electrode is the exploring electrode here's the way i want you to think about this imagine the positive electrode is your eye okay imagine it's your eye and you're looking towards the negative electrode okay so if we were to kind of think about it like this this is me i'm on the positive end and i'm looking this way this is what lead one is doing it's looking at the heart from which way from the left side okay so that's the way you want to remember this is that lead one is looking at the electrical activity of the heart but from the left side of the heart okay that is important now lead two where is it looking from okay well the positives here remember i told you put your eye where the positive electrode is and look towards the negative electrode okay well he's looking from down here so now i have positive electrode looking up towards the negative electrode so it's looking at the heart from the bottom okay what about three three is doing the same thing he's just looking at a different angle but he's looking at the bottom of the heart looking upwards isn't that so cool so now what these leads are doing is is they're looking at the electrical activity of the heart from different angles so which way is one looking one is looking at the electrical activity of the heart from the we're going to say left lateral so left and lateral heart so it's looking at the left and lateral view of the heart what about 2 and 3 it's looking inferiorly okay and we'll talk about angles later this 2 is usually positive 60. 3 is actually going to be like positive 120 degrees and again we'll get into that stuff when we talk about axis but what i want you to remember is that two and three are looking at the inferior view of the heart why is that important because if someone is having a myocardial infarction in the inferior view of the heart which leads are you going to be wanting to look at two three and there's another one avf if you want to look to see if there's a infarction on the left lateral portion of the heart what are you going to be looking to one as well as another one we'll talk about avl and v5 and v6 so that is the significance of these leads that's what i want you to remember from this not all of the physics and stuff behind it and all the electrodes but really just to understand what is lead 1 doing and how is it looking at the heart what is lead 2 and 3 doing and how is it looking at the heart and again you should know where to put the negative and positive electrodes that should be important but know the axis of the lead and where the how you're looking at the electrical activity of the heart with respect to those electrodes okay so that's our bipolar let's go on to the augmented unipolar all right so now let's talk about the augmented unipolar limb leads so this guy named wilson he kind of developed this like different way again you don't really know all the history and background and physics behind it what i just want you to understand is augmented unipolar limb leads i want you to really know how they're looking at the heart what these electrodes are supposed to be doing okay which one's negative which one's positive in what direction the ekg machine is doing all of this really for you so you don't really have to know a lot about the physics and the electrodes on this one it's more just about the direction that this is looking at the heart that's what i want you to really understand more of so augmented unipolar limb leads what happens is the the machine the ekg machine it has this ability right to generate negative charges at two points right so imagine here here's going to be the right arm here's the left arm here's the left leg right let's say that the ekg machine so we're going to be having we want to look at the heart from a specific way let's say that we want to look at the heart from the right side okay so what it'll do is if we want to look at the heart from the right side it's actually going to take and put a negative electrode on the left arm okay it then correlates a negative electrode on the left leg now what happens is whenever you have negative negative this is going to have to be the positive electrode here at the right arm now the direction in which this vector is actually moving is between the negative electrodes right so now it's actually pointing which way it's pointing this way towards the positive electrode okay so now here's what i want you to remember then this right here right so the augmented unipolar limb leads you put it the ekg machine puts a negative electron on the left arm left leg and then it generates a positive electrode on the right arm okay what that does is is that creates a vector between these two negative points these two electrodes right because it can't you're going to have the net between this one and this one so it's going to be right in the middle there remember positive is looking towards the negative which is going to be in between these two negative electrodes so if you're looking how is the how is this electrode looking at the heart it's looking at it from kind of upwards so it's above it and it's looking at it on the right side so it's getting a view of the heart from the right side and a little bit above it this right here is called augmented unipolar limb lead right but we don't like to put all that crap so we just put avr augmented unipolar limb lead r so avr how is it looking at the heart again here's your eye you're looking at the heart from the right side and a little bit from the superior view so a little bit more of the upper and righter right of the part of the heart but if you want to be simple it's looking at the right side of the heart okay so that's the big thing there all right so now you want to look at the heart from the bottom right so again here we're going to have right arm left arm left leg okay what we're going to do is we're going to put a negative electrode on the right arm a negative electrode on the left arm and again the ekg machine is doing all of this and then it's going to generate a positive electrode here on the left leg where is the resultant vector going to be remember this is pointing this way this will be going this way but the resultant is going to be straight down slap dab in the middle right so it's going to be pointing this way towards that positive vector but again remember the positive electrode is going to be looking towards the negative electrode which is going to be smack dab in the middle so how is it looking at the heart it's looking at the heart from the inferior view the bottom so it's looking at it from the bottom so which one is this one this is going to be augmented unipolar limb lead foot we don't want to write all that so we just put avf so this one is actually going to be a v f so this is what i want you to remember avf looking at the heart from the inferior view avr looking at the heart from the right side of view so what do you think we're going to have left guys avl right so again let's come over here right arm left arm left leg so we want it to be obviously the positive electrode at the left arm and the ekg machine will generate negative electrodes on the right arm and left leg so which way is the resultant vector because remember it's moving from negative to positive negative to positive smack dab in the middle is the resultant so it's going to be pointing this way so now how is this one looking it's looking at the heart from the left and lateral view isn't that a beautiful thing so which one's this one it's augmented unipolar limb lead left arm so this is going to be a v l so here's what i want you to remember avr looks at the right side of the heart the av l is looking at the left and lateral side of heart and then the avf is looking at the inferior view of the heart that is really important all right so let's imagine here that we're going to be putting these chest leads on the chest wall right so what you're going to be doing is you're going to go in feel the patience chest right and right like about here you're going to have this little prominence a little bump okay called the sternal angle or the angle of louie you're going to palpate that then what you're going to do is you're going to kind of move over to the right when you move over to the right you should be at the level of the second rib and then what you're going to do is you're going to count down so right second rib second intercostal space third rib third intercostal space fourth rib fourth intercostal space okay that's where we wanna go first so right fourth intercostal space just on the right side of the sternum we're gonna put our first chest lead there and let's put on here let's do first one here so again first so second third fourth we're going to put v1 that's going to be our first chest lead okay it's going to be right fourth intercostal space on the parasternal side okay then what we're going to do is we're going to just go on the opposite side of that so just go symmetrically to the other side so now you should be on the left fourth intercostal space on the parasternal side right so now put your second chest lead right there okay then we're going to skip v3 for a second okay we're going to go to v4 v4 is gonna go to the fifth intercostal space okay but we're gonna have to make sure that it's kind of like right in the middle part of the clavicle so we're gonna do is we're gonna skip v3 we're gonna go from the fourth to the fifth intercostal space and we're going to go to about maybe right here and let's say that about right there that's mid-clavicular line we're going to put v4 v3 is going to go right between them okay so right smack dab in the middle here i'm going to put v3 so v1 right fourth intercostal space v2 left fourth intercostal base pair sternal line v3 hold on a second v4 mid clavicular line fifth intercostal space then put v3 right between it then you're gonna go to about the anterior axillary line and again fifth intercostal space you're gonna put v5 there so let's say that v5 we're going to put right here then after you go to the anterior axillary line you're going to go mid axillary line and that mid axillary line fifth intercostal space is going to be v6 so let's put that one a little bit over here this is going to be the placement of the chest leads okay now this doesn't do justice on how these are actually looking at them but here's one thing i want you to understand this is really really pretty pretty cool with the bipolar and the augmented unipolar limb leans you had negative and positive electrodes these are really cool because they're just a positive electrode so all that they are are positive so imagine like a little suction cup here imagine here we have like a little suction cup okay it's connected to a wire this right here is just a positive electrode that's all it is so it's picking up electrical activity to generate it by the heart it doesn't need a negative electrode it only just needs this one positive electrode that's pretty darn cool so there's they're they're actually picking up electrical potentials that are moving through the heart and into the chest wall right so let's look at this and let's imagine here that i take the heart right we're gonna take the heart out and then we're gonna slice it in half and we're gonna look at it and we're gonna pull it out like this okay so again imagine here i'm taking the heart like this okay and all i'm going to do here is i'm going to slice it and i want to look at this heart in a sliced view okay so here we're going to have the interventricular septum all right here's our interventricular septum this is going to be the left ventricle and this is going to be the right ventricle okay here's the apex of the heart and here's going to be the bases of the ventricles so if you imagine here let's put our first lead on here so again v1 is going to go about right here so imagine here we're putting v1 then we're going to put our next one here v2 we'll put our next one over here v3 put our next one over here v4 and then again we'll put over here v5 and then over here we're going to put v6 all right so how these work is again this is going to be positive electrodes here these are all positive electrodes they're unipolar what they're able to do is pick up electrical activity of the ventricles so v1 and v2 these ones are mainly picking up activity within the septum so here's what i want you to remember v1 and v2 is picking up mainly the electrical activity within the interventricular septum so we're going to put septum here v3 and v4 are going to be picking up most of the anterior part the anterior part of the ventricles okay so this is going to be the anterior wall and then you're going to have v5 and v6 and this is going to be picking up most from the left side of the heart the left lateral part of the heart so left slash lateral wall so whenever someone is having infarcts right you're going to be looking and depending upon where it is you can determine so for example if someone is having some changes in their st segment and v5 and v6 what would that tell us it would tell us that oh man this is maybe picking up some uh infarction within the left lateral wall oh it's v3 v4 well maybe there's something going on here in the anterior component oh it's v1 v2 maybe there's something going on with the septum or maybe sometimes v1 v2 it can indicate possible septum but guess what else it could indicate it could be a possible sometimes posterior mi and remember what you need for that one is sometimes what you'll see is you'll see st segment depression in v1 and v2 so sd segment depression t-wave inversion of v1 v2 you put on posterior chest leads so v7 v8 v9 and it should be able to pick up st segment elevation which could be possible for a postermi so that's something to also remember so look at v1v2 because it's also important for posterior wall so that's the basics of the the chest legs so again chest leads are picking up a view of the heart and i want to make sure that we write this down here it's looking at the heart in the horizontal plane so horizontal plane or transverse plane and again what i want you to remember v1 v2 it's picking up electrical potentials from the septum right and it also can tell us about posterior wall remember if you ft st segment depression t wave inversion anterior wall v3 v4 if you want to combine v1 to v4 it's pretty much all anteroceptal okay and then v5 and v6 is left lateral wall all right so that tells us about the chest leads all of this if you combine together you get an insane view of the heart your bipolars can give you a view of what from inferior it can tell you a view of what else from the left your augmented unipolar can tell you the right it can tell you the left and it can tell you the inferior view and v1 and v2 b3 v4 v5 v6 can tell you the entire horizontal plane from the left ventricle right ventricle and the interventricular septum as well as even the posterior part of the ventricles as well so that's an amazing thing that these ekgs are able to do so that's giving us everything we need to know about the basics of ekgs all right engineers so that covers pretty much everything you guys need to know about the basics of ekg boiling down to cardiac action potentials their electrical vectors how that correlates with the graphical representation on ekg mainly looking at it from a lead to position and then after that we talked about the multiple different chest leads v1 through v6 we talked about the augmented uni polar limb leads avf avr and avl and then we also talked about bipolar limb leads one two three and their significance in being able to get a very significant large view of the heart from multiple different planes including the frontal and horizontal plane i hope all of this made sense i really hope that you guys did enjoy it that's what we really want for you guys to understand this stuff i know it was a really long video i'm sorry i hope that you guys it's really able to help you guys if you guys did like this video please hit that like button comment down in the comment section and please subscribe also if you guys want to check out our instagram our facebook even our patreon account you guys can go down to the description box and check that out as well alright ninja nerds as always until next time [Music] you

Channel: Ninja Nerd Lectures

Views: 965,309

Rating: 4.9730883 out of 5

Keywords: ninja nerd science, heart, cardiovascular, EKG, electrocardiogram, ECG, EKG Basics, 12 Lead EKG, 12 Lead ECG

Id: ZwHCpl22tLU

Length: 52min 28sec (3148 seconds)

Published: Sat Nov 30 2019