in this video I'll be talking about the pathologic cue wave and the reason I'm calling it pathologic is because we obviously see a cue wave in a normal EKG and then there is a pathologic cue wave which we see during MI so before we understand pathologic cue wave we first have to understand what exactly is the normal q wave and then we'll talk about pathologic q wave so let's get right into it so almost all of you are familiar with the normal QRS complex this would be our Q this would be our R this would be our s the Q is a negative deflection the R wave is a positive deflection and an S wave is a negative deflection as well now this is what I want you to remember the Q wave is the first downward wave of the qrx QRS complex okay it's the first downward displacement of the QRS complex you might be wondering at this point is that don't I know that it is the first downward displacement of the QRS complex why am I putting so much stress in it the reason I'm putting so much stress in it is because sometimes in fact most of the times you might not even see a Q wave or a first downward don't downward displacement of the QRS complex you might end up seeing something like this a lot of the times okay Q wave often does not show so and that's not pathologic that's normal so in this kind of scenario is this the Q wave is this the R wave where is the S wave what would be your thought in it what exactly are we looking at here now this is what you have to remember if there is any upward deflection in a QRS complex that appears before your QE it's not a Q wave okay so by conveying this would be an hour wave the positive deflection and this would be an S wave and the Q wave we can't really see in this particular EKG okay so what about if the if the EKG looks like this after a P wave this is all you see what is going to be this wave is it going to be well we know that both Q wave and s we have negative deflection what kind of wave is this one so for this particular wave it is a little confusing right I mean we don't know which one is which so I mean you we have two negative deflections Q wave and an S wave therefore this kind of wave is called a Q s wave okay and if you are looking for a Q wave then you take this as a Q wave if you're looking for an S way you take this as an S wave S wave okay so what depending on what you are looking for you use it to your advantage if you're looking for a Q wave this is what you interpret if you're looking for s wave this is what you interpret in a Q s wave so now that we have a little bit of understanding what a normal Q wave looks like what would be a pathologic Q wave look like so in a pathologic Q wave usually what happens is the Q wave is relatively quite large okay usually Q waves are so small that sometimes you can't even see it it's a the first deflection in the negative direction but if the Q wave is really really large if the first negative deflection is really really large then you are talking about a pathologic Q wave now the Q wave is often going to be accompanied by an ST segment elevation and which usually we see a pathologic Q wave in case of an MI now here is a question for you do we see Q wave as soon as we have in mind is it the first thing that is going to be evident on an EKG when a person is going through MI absolutely not in fact Q wave develops later it usually takes several out several hours two days for a Q wave to develop often Q wave is the proof of an earlier mi so you might be looking at an EKG for a person who is completely healthy now but you look at a Q wave and you can tell that this person had an MI in the past it just means that there is a gap or a hole in electrical activity in that part of the heart which got damaged during an earlier mi now does this mean that we are not going to see Q wave in an acute MI no that is not true we will see Q wave in an acute MI but really the first thing we are going to see is ST segment elevation and a couple of hours later six to six to eight hours later then we're going to be starting to see a Q wave formation now my next question to you is once a person develops Q wave does it ever go away from the EKG well let's say you you have a patient who's going through an MI and the person developed Q wave but you you get to catch early on you Reaper fuse the patient and the patient does not have that much damage to the electrical activity of the heart and you can you can get rid of the Q wave yes so it is possible to get rid of the Q wave if Yuri perfuse the patient very very early on in the mi but for most cases once you have a Q wave if the damage is significant then you're going to have that Q wave indefinitely showing you that there has been an MI and it's just a is just showing lack of electrical activity in terms of a scar tissue so when when the electrical activity is passing through the scar tissue it's not showing that negative deflection it just means that you know there is no electrical activity in that part of the heart okay so we're looking at an EKG strip now before we interpret this I just want to say that we're going to start off with you know a normal P wave QRS and then T wave right this is the normal one when a person is going through an acute MI the first thing we're going to see is our ST segment is going to be elevated like that okay and then eventually we are going to start seeing Q wave and an ST segment elevation okay so this is a typical acute MI first we are going to see the ST segment elevation that's the first thing we're going to see in an EKG and then after six to seven to eight hours we're going to start seeing a key wave along with an ST segment elevation okay so let's see if we can recognize this in a in an actual EKG so the first thing that jumps to me from this EKG strip is that okay look look pqrst pqrst these are pretty nice over here but as we move to these lids we can see that P wave sorry Q wave Q wave Bay Q wave okay so this is where it's quite obvious that these are pathologic q waves because we don't even see you know R and s or T wave anything like that kind of here though we start to see that there is a ST segment elevation over here right over here so that tells us that this is not a old this is not an old mi this is a recent in mind because we're starting to see ST segment elevation as well another picture of EKG and this one is a lot more obvious because we can see Q wave here and look how beautifully we can see an ST segment elevation I know there's nothing beautiful about this ST segment elevation because the person is going through a lot of pain but I mean for our understanding for our purpose of Education this is a very beautiful Q way followed by an ST segment elevation picture to understand our pathologic Q wave okay so let's look at another example so we're going to be looking for a Q wave followed by an ST segment elevation so we can see here that this is more of a q wave as a segment elevation q wave ST segment elevation same here Q wave as a segment elevation Q wave ST segment elevation we also see that see the same thing in lead AVF we see a Q wave followed by an ST segment elevation now we're not considering these because we can see PQ PQRS normally so these ones doesn't qualify we only look at the ones where we have a Q wave followed by an ST segment elevation so in this circuitry this is again a huge picture of a Q wave and an ST segment elevation there is no substitute for examples right so we could never get sick of it so now that we kind of understand what Q wave and ST segment elevation looks like now let's see if we can interpret EKGs a little bit more so we know that one two three AV are AVL and AVF those leads are the limb leads right and then v1 to v6 those are the chest leads so we can see here that in our chest leads it's quite obvious we have Q wave as a segment elevation Q wave ST segment elevation Q wave ST segment elevation Q wave segment elevation and the same here the chest leads are showing obvious signs of Q wave and ST segment elevation this is a beautiful diagram now even in limb lids we can see Q wave a little bit of a segment elevation here right this is a diagrammatic picture this is not a real EKG so that's why things are so strikingly obvious we can even see it here Q wave as a segment elevation a little bit so it's easier to interpret these than real EKGs okay so now let's look at this EKG we see that we are starting to see Q wave here so lead to lead 3 again in lead - okay anywhere else we see Q wave that's pretty much it but it's not followed by an ST segment elevation so this is a typical example of an old infarct we see the Q wave because of lack of electrical activity there but really there is no ST segment elevation so don't be alarmed if you see it in a patient who walks in for a regular checkup they're just having a normal Q waveform from an old info because once you have a q Q if it will never go away unless we profuse them immediately okay again let's look at another ECG we see that do we see any Q wave here by the way what are these these definitely looks like u waves right but they're not why why are these not Q waves because what did I say Q wave was the first negative deflection sometimes we don't even see Q it this is we don't really see Q wave here this is r this is really S wave so don't get confused whenever you see a negative deflection Q wave has to be the first negative deflection so is there any Q wave in this picture or in this ECG at all yes we do look at this lead lead 3 what is Li treat these are one of the limits right look the Q wave is almost as big as the R wave and it should not be this way because the Q wave should be really small but this one here we can see that the negative deflection is as big as the positive deflection so this is definitely a Q wave here this is this is an old infarct again I'm showing you all in fact a new influx so that you can pick it up faster again we see a Q wave just as big as our R wave and where do we see it we see here as well the key wave is quite big showing that this is an old infarct because this is not followed by an ST segment elevation the the big Q wave kind of starts from the two so you can see a significant drop here right because this is an ECG where the pictures are kind of small and cuboids are really really small so we start seeing it from leety lead sorry they too but it becomes really big in lead 3 and ABF it's quite big and prominent in this ECG so this is our last example for our Q wave we can see that lead to they're starting to build our Q wave lead 3 whoa look at how big this Q waves are again an old infarct and we should also see that in a VF so whenever we are looking forward Q wave I usually look at 2 3 and AVF but we also see Q waves in other portions depending on where exactly the in fact is in this particular video I'm only talking about how we can recognize a Q wave in the subsequent videos I'll be talking about okay when we see a certain Q wave in a certain lead we have to determine where exactly the in fact is in the heart but let's take one step at a time in this video we can see that the Q waves are building up in two more and three and we can also see that in a beef