ECG - QRS Complex in EKG - Nomenclature - Electrocardiography - Cardiology

today we are going to talk about QRS complex and Nomenclature of the component waves which make the QRS complex in a classical ECG we can see that this is QRS complex first of all how QRS complex is produced basically QRS complex q r s complex on ECG tracing is graphic representation of ventricular depolarization let me repeat it what is QRS complex QRS complexes a graphic representation of electrical activity of the heart when ventricles are undergoing the process of depolarization when the ventricles are undergoing the process of depolarization when ventricles are undergoing the process of depolarization certain electrical forces are generated those electrical forces when they are graphically recorded by ECG recorder machine on the paper or on the monitor screen that complex which reserves is called QRS complex now QRS complex may have one wave or two wave or three waves or sometimes more than three waves right now what is a wave wave is when there's deflection away from the isoelectric line all those deflections which are above the isoelectric line they are called positive waves and all those reflections which are below the isoelectric line they are called negative waves is that right what did we talk about that during ECG recording positive deflections are all the deflections which are above the isoelectric line are positive waves and which are below the isoelectric line negative waves but before we really go into detail we must know what is isoelectronic line what is isoelectronic line or baseline in ECG actually usually student answer in different way some student tell that isoelectric line is P R segment some student tell me isoelectric line is ST segment but really isoelectric line is this one this is T wave and this is next P wave isoelectric line is the line between the T wave and the and extending from here up to the onset of next P wave because isoelectric line is drawn by the pointer ECG recorders pointer draw the isoelectric line when there is no electrical activity in the heart when there is no electrical activity in the heart now this is a really depolarization this P R segment this represents when current is passing through AV node this is right then QRS complex represents ventricular depolarization very good and then ST segment represents the electrical activity in the heart then after the separate of the tubular depolarization there is plateau phase right and then this is rapid phase of ventricular repolarization but once at the end of the T wave and before the next cardiac cycle start the needle should rest in a neutral position and the line which will be drawn this should be considered isoelectric line so isoelectric line is basically T P segment what is the isoelectric line we can say isoelectric line is T P segment right now why I don't consider PR segment or ST segment as as I selected the reason being in certain pathological conditions in certain certain pathological conditions PR segment or ST segment may get elevated or depressed so they cannot be used as a reference the you get it again I will repeat for a reference if we have to use a reference point for positive and negative deflections we must use that segment which is mostly stable right so TP segment at the end of the one Cardiff cycle electrical activity of the one cardiac cycle and before the electrical activity of the next card each cycle start in between them when pointer of ECG recorder remains in neutral position without any deflection the line which is drawn is isoelectric line or baseline of ECG of course mostly or in healthy subjects PR segment and ST segments remain at the same level as isoelectric line but as I mentioned in different pathological conditions these two segments can elevate or depress but people segments remain stable at its neutral position once you know that now onwards when I will use the word isoelectric line right I will mean the level of TP segment let's go back when we are concentrating on the normal nature of QRS complex right we should know which component of the complexes deflected above the isoelectric line and which component of the complex are deflected below the isoelectric line because nomenclature depends on multiple factors number one nomenclature of QRS complex depends on direction of the deflection is it positive waiver negative wave secondly nomenclature depends on the position of the wave if there are three waves how their position and reference to each other according to that we will label the waves and number three degree of deflection this small deflection or large deflection again I will repeat there are three basic parameters on which we determine the unnormal Eicher number one is point a that we have to talk about the direction of direction of deflection deflection right point number one that is it directed upward above the isoelectric line it will be positive wave below the isoelectric it is negative wave second thing it also depends on the position of wave in the complex position of a wave in complex as I will tell you the initial negative deflection is given a different name but after the positive deflection if there is negative deflection that is given a different name is that right and third factor which is used and this is amplitude of deflection amplitude of deflection there if deflection is small then it is represented by a small letter if deflection is large it is represented by capital letter right for example it is small deflection and if I call it Q then it will be small letter and it's a large deflection if I have to represent by r it should be written in capital this is not right so there are three basic component that when we are going to name the waves we have to see their direction of deflection we have to see the position of deflection within the complex and we have to see the amplitude of the deflection right now let's start with very basic principles there are how we designate the different name number one these are the three factors these are the three factors which influence the nomenclature now we go to the principles of nomenclature the first principle of nomenclature is or first rule of the nomenclature is that in the complex the initial negative wave initial yes negative wave is labeled as labeled as q wave now someone from the student said it should be small q no it may be small or it may be large depending on the amplitude of the wave depending upon the amplitude of the wave so let's correct so initially deflection right in the complex if there's initial negative deflection that initial negative deflection may be called to wave if it is small or capital Q if it is large right am i clear then number two rule number two the first positive deflection in the complex is called R wave the first positive deflection is called R wave again it may be small R if it is small in amplitude or it may be capital R in uppercase if it is a large and amplitude is it clear third rule third rule is again first was initial in the QRS complex initial negative deflection is Q wave first what is that positive deflection is our wave and negative deflection after the R wave negative deflection which appears in the complex after the R wave that is labeled as S wave so what is this negative deflection after our wave either small or large after our wave is s waves if the smallest or largest depending upon this was Q and this is now this is the simplest form of QRS complex of classical Q R and s another way to to say the same rule is that in QRS complex if you find an upward deflection it should be labeled R and the QRS complex when you find the first positive deflection it should be labeled as R wave and anyway before the RS Q and any wave just after the RS as another way to mention these three rule is that when you look at the QRS complex first identify the R wave if it is there any negative reflection before the R wave is Q and any negative reflection after the R wave is s wave is it clear after these three rules then I will mention another situation but before I go for that let's compare this I was just developed two RS draw two QRS complex this is one QRS complex now let's invert it we already know this will be labeled as q r s what about this one who will tell me yes doctor very good the first positive deflection should be R it is a small R of course first positive deflection should be considered are but because it is small deflection I am writing it to lowercase is that right it means here the R is without you because there is no negative before da and then yes doctor what is this wave yeah this is negative deflection after the are wave so it should be as we have smallest largest largest very good and then what should be this yes okay let me tell you before you get more confused here now one more rule right the rule is that if you have second positive deflection within the QRS complex if you have second positive deflection within the QRS that will be labeled as R prime right so what is that second positive deflection within QRS complex first positive is our wave second costume is our R prime of course is a smaller large depending upon the deflection depending upon the degree of amplitude of deflection then now let's suppose I draw another complex here what is this now you will tell me yes doctor this is which wave they're following very good first positive reflection should be our but capital and this is there is s way very good and it is a large reflection and then there is our prime okay let me modify it further now how do you label this wave remember previously you know this was s wave and what is this wave now this it is another negative deflection and actually thus the negative deflection is after the R prime so it should be considered s prime s prime PR IM e prime so what I really wanted to put in your mind that of course it's very easy to remember just QRS this nomenclature is easy the first positive is our wave and any negative before the R wave is Q and any negative just after the our wave is as we're done then we came to know this thing that here what is there there is no Q wave because there's no initial negative deflection but first positive is our wave after that negative is s wave and after that it's still one more positive appears then it is a R prime then we go in further detail again first positive is our wave it is followed by a negative which is s wave again followed by a second positive deflection that is our prime and then followed by another negative after the R prime that is s prime so negative wave after the RS s an negative wave after the R prime is s prime is it clear any question no so once you have two what is the say a fourth principal here second positive deflection may be our prime small R prime R capital R prime and and of course then is that s and negative deflection after our prime is s Prime depending upon size I hope now you can identify properly now once you know these four principles now I will come to another thing I said simply that small deflections are small deflections yes small employ mplet ood small amplitude deflections are designated by small letters small letters like Q or R or s or R prime are s prime right and large deflections are designated by capital or uppercase uppercase letters that is either they are called Q R or R prime or of course in between that there should be s very right QR s and then there will be R prime or s fine I hope these rules are clear right some authors believe how do you define that there is small deflection or large deflection some authors believe that when deflection is more than three small square it should be considered large deflection and when deflection is less than three small squares then it is the amplitude of deflection is less than three small squares then it should be considered small deflections right now just for practical purposes I will draw some QRS complexes and you will rapidly label them right this is the classical what you see right what is this q r s complex then I will again repeat yes what is this r s capital R complex right then I made what is this our s our prime complex then I'm going to make one more is just for practice so if you find difficulty in labeling let me tell me please then we can make it like just what is this R as R prime right now you can see all of these complexes special ok start from here all of these complexes they have how many waves those three waves right all of these are having 3 waves so these complexes are called triphasic QRS complexes what are they called prime physik QRS complexes so these are triphasic now we come to another situation just for practical purposes put it here yes if this is now what is this this is Q and this is our complex and if I make it like both are large so what is this Q and now you get it so actually this nomenclature helped when you are talking one doctor is talking to other doctor and other doctor doesn't have Christine in front of his eyes and you are going to explain the QRS complex so if you say there is small Q and capital R this image should be produced in the mind of trained doctor right and if you say there's capital Q and capital R wave QRS complex is capital Q and capital R of course then it is so just both of them are called Q R and Q are complex but actually they are different so you need to mention it's a small letter or capital letter this is there right now we come to another arrangement what is this QN are now all of them are QR this is who are that if you are that is also QRS but here both of them are large both deflection negative and positive are large here negative to flatten Ischl negative is small and first positive is large here initial negative is large and first positive is small and then if deflection is like that what you will call it this is us very good small R and s or if I repeat it in a different way then what is it q as complex q as complex good so I think you are really learning Q are yes very right it means you have really learned very good Q ah right now I come to another set of complexes let's pose here what is this complex are s now you see RS is different than Q R and Q are negative deflection is before the first positive and RS negative deflection is after the first positive right then we make another arrangement what is this our small s and if we make another arrangement what is it small R and capital s now both of them are our s but when you designate which one is small and large then you can differentiate these complexes even by hearing on the telephone from other doctor this is that right and what is this one small R and small s there are small deflection positive deflection followed by one negative deflection is that right now note all these deflections how many waves are there in all these QRS complexes - so these are called biphasic deflections what are these called these are by visit QRS complexes right these are biphasic QRS complexes right sometimes you come across something like this you find just one positive deflection and before that there's no negative and even after that there's no negative what you will call it just start with very good or this will be capital R and what will be this small R right this lecture is dangerously simple isn't it yes you have Wow that is very good question excellent question he says here will we use the word qrs complex or not answer is yes will say there is qrs complex which is only our wave we will use the word qrs complex by convention having only are they well and of course you are very right this will be considered monophasic and now tell me what is this if you come across a deflection like that what is it is it - wave or a s wave it is a negative deflection now my intelligent doctors are going to tell me is it Q wave or s wave you think it's Q wave yes you also think you wave why do you call it Q wave because Q wave must be before the are wave is there any other ways it is initially negative but not followed by positive initial negative is the only initial word is used when it has followed by something so is it Q or s the problem is now concentrate to legal label a negative wave as you or as you must have ah but sometimes you come across a QRS complex which does not have positive deflection then what to do with the single wave actually because we cannot label as Q and we are not sure is it Q or so we become a little tricky so what do we do we just call it Q s wave we call it Q s wave is that right clear and of course and it's just little small deflection what is it you S wave now in this case again we will say here's QRS complex which has only one negative deflection or we can say QRS complex consists of Q s waves here QRS complex consists of just our ways remember one thing when we use the word QRS complex it does not mean that Q R and s all three must be there QRS complex is name given to any wave complex for reduced by ventricular depolarization it may consist of one wave or two wave or three wave or even more waves yes right so these are also QRS complex but these QRS complexes are having only deflection positive or negative so we call it monophasic urs complexes mono phase it QRS complexes right any question up to this okay now I will draw something here and you will help me to label it just as a test yes what will be this our and if it is small R small R and what is this large s and what is this R Prime and what is this s Prime right now well draw and more complex just I want to see how you label these there's a very unusual presentation but anyway what is this Q R what is this R Prime and if you draw the isoelectric line then it is going below the isoelectric line it is capital S and if it is a small one make it very good this is small s Prime so I hope you are clear about it is there any question ok once the nomenclature our QRS complex is clear right I will make it a rapid review QRS complex is a term used for the graphic presentations on the ECG tracing which represent ventricular depolarization done QRS complex may consist of one wave or two wave or three waves or more than three veils and as a either it is one wave or more waves it is still called QRS complex when there are multiple waves in the QRS complex how do you label the waves for that purpose you have to see that waves are positive or negative all waves which are above the isoelectric line are considered positive deflections positive waves below the isoelectric line a negative isoelectric line is basically a TP segment classically speaking more accurately speaking clearer then if there is a positive deflection the first positive reflection should be called R and any negative before that should be Q and nn- after that should be as clear then if there is small deflections they should be designated by small letters if the large deflections they are designated by capital letters right then if there is second positive deflection it should be considered R prime and if there is negative deflection after the R prime that should be considered right any question up to this then generally we can divide different types of QRS complexes depending upon the number of waves constituting if there are three waves involved in that we call it professor complexes if there are two waves involved we call it biphasic complexes if there's only one wave positive or negative involved it is one of is it you must remember if there's only positivity scars just are but complex is considered QRS and if there is only negative deflection it should be called Q S wave the reason being there's no R wave to help us to designate as Q or s so you call it Q s negative wave right any question up to this class dismissed yeah here I want to highlight one thing why I taught QRS comment later in such a detail because in future lectures the next two lectures one lecture will come QRS complex in the chest leads from v1 to v6 and the next lecture will come QRS complex in limp leads once we are done with these next two lectures then we'll go to the clinical side of the ECG no question class dismissed

Channel: Dr. Najeeb Lectures

Views: 448,626

Rating: 4.8888402 out of 5

Keywords: ecg, ekg, nomenclature, ecg leads, ekg leads, dr najeeb, dr najeeb lectures, cardiology, electrocardiogram, usmle step 1, 12 lead ecg, ecg interpretation, ekg interpretation, chest leads, arrhythmia, tachycardia, ecg axis, ecg reading, medical school, ecg waves, 12 lead ekg, electrocardiography, normal ecg, ventricular fibrillation ecg, precordial leads, ekg practice, qrs complex, paramedic, cardiovascular, ecg basics, ecg learning, ecg machine, understanding ecg, emt

Id: KUC_iDnEJE4

Length: 32min 30sec (1950 seconds)

Published: Tue Aug 15 2017