The ECG Course - AV Blocks

hello and welcome back to the ECG course this is chapter 11 on AV blocks atrial ventricular blocks and the first thing I want to mention is that AV blocks themselves are not a type of rhythm or arrhythmia they are simply a interruption in the conduction okay so your underlying rhythm could be sinus tachycardia with a first-degree AV block okay so it your underlying rhythm will still occur but there's some sort of interruption in that rhythm and I'll kind of explain what I mean here a V stands for each real ventricular so there's a block on the conduction between the atria and the ventricles and typically we when we're talking about AV blocks that the AV block will occur around the AV node just like a junctional rhythm the pacemaker is around the AV node or the AV junction with an AV block you will have a block in this conduction pathway between the atria and ventricles in that same area but you could still have a sinus rhythm beating you know depolarizing here from this sinoatrial node and it's just getting delayed once it makes it to that block okay there's just a delay right here somewhere that's slowing things down or causing an interruption in that conduction so here's the first example the first-degree AV block and this one's the easiest one to remember it's the same as a sinus rhythm it you just have a prolonged PR interval a prolonged PR interval that is the only difference so you your underlying rate will be whatever your rhythms rated so this was a normal sinus okay we'd say this is a normal sinus with a first-degree AV block your P waves are present there's no dropped beats you have a one to one ratio you have 1p waves for every Flores complex the only difference is this PR interval is long okay notice that that PR interval is greater than one big box in length so it's greater than 200 milliseconds or 0.2 zero second the QRS is still should be narrow now we're going to get into the tough ones all right the firt the the next type of ad block is the second degree type one it's also called mobitz one or sometimes winky Bach phenomenon winky Bach phenomena okay your second degree type blocks you have two second-degree AV blocks you have second degree type one and second degree type two second degree type one is also known as mobitz one and second degree type two might also be called mo bits - so if anybody says it's a mobitz they're saying it's a second degree AV block so again you're going to identify the underlying rate rate okay the rhythm should be regularly irregular it's going to have some sort of pattern now these winkie Bach or mobitz one type rhythms are typically transient they don't last a whole long so for a long time they're either going to go away and your underlying rhythm is going to return or they're going to progress into a worsened AV block so it's a transient rhythm it doesn't really last very long usually your P wave is present your PQRS ratio is variable I believe this is the first time we've seen that and what I want you to note is that you have P waves that don't conduct QRS complexes we have a drop to be here all right you have a P wave but there's no QRS complex now all the other ones we talked about before that had dropped QRS complexes such as sinus arrest or sinus flop those didn't have P waves present they had a flat line there that isoelectric line here we have a P wave present so that's what makes this different there's some sort of block between the atria and the ventricles where the atria depolarized but the ventricles did not follow okay and then the pattern that makes this a second degree type one is what we call only going gone but what I want you to recognize is that the PR interval gets longer from one beat to the next so it's how much longer that PR interval got so we went going going gone no QRS complex here all right and this could this be going going going gone it could be over three or four beats before you have a dropped beat but that's typically the pattern the way that we would remember it the QRS width should be narrow should be less than three small boxes wide let's take a look at the next type of AV block this is a second degree type two or a mobitz - okay a mo bits two AV block it's the next one down the line again you're going to identify the underlining rate your rhythm could be regularly irregular or it could be regular depending on your ratio of blocked beat your PR interval all right should stay consistent it should be normal and here's what I mean you have this PR interval here should be the same as this PR interval here which would be the same as this one over here and that's what we hear notice you do have dropped beats okay so this P wave occurred right where it should've but the QRS complex is missing now the difference here between mobitz one and mobitz - this is mobitz to is remember that the mobitz one had the going going gone pattern where the PR interval prolonged let's take another look notice how this PR interval is getting longer before the drop beat and with mobitz to your PR interval stays the same where it exists so everywhere you have a PR interval it's going to stay consistent moving on to the worst type of AV block third-degree AV block now these can be narrow or wide so remember we talked about ventricular rhythms and how they're wide in nature well a third-degree AV block very similarly may be wide and we're going to show some examples of those later off the atrial and the ventricular rate will both be different and here's what I mean if we look down here we see there are P waves here we have many more P waves than QRS complexes many more P waves and QRS complexes that means that a chart of polarizing at a faster rate than the QRS complexes and then if you look at the P waves your P to P interval let's find two P waves we could see clearly alright put that right on the top of them your P to P interval should stay consistent so you'll find hidden P waves all right you're going to find hidden P waves within the T waves and the QRS complexes there's no marriage between the P waves and a QRS complexes so they don't care about each other all right they're not that the atria are not conducting the conduction is not traveling from the atria down to the ventricles without there's a complete block there all right so sometimes third-degree AV block is called a complete heart block both the rhythms will be regular your atrial rhythm will be regular and your ventricular rhythm will be back regular okay but they are not associated with one another even if you see a P wave before the QRS complex you'll notice that it's just continuing throughout its pattern that just happens to be a coincidence that it fell right before it the PR interval there is none there's no pattern to PR animal alright so here's the easy way to remember these or to be able to identify them and this doesn't fit all of them there are what we call non-baby blocks but you'll know that that's an on type will AV block because it doesn't fit in this little pattern here so you're going to present yourself an EKG strip and you're going to say alright it looks like I have some kind of heart block here there's something going on with the PR interval first question you're going to ask is the PR interval a constant length if yes you come over here do I have a dropped QRS complex if you don't have a drop QRS complex it's probably a first-degree AV block if you do have a drop QRS complex it's a mobitz to a second degree type - coming back to the top we're going to ask again is the PR interval cause of length if it's not constant length we're going to say do we have a p-wave for every QRS complex if you do it's a mobitz one a second degree type one if you don't it's a third degree AV block third degree B but because remember even though we have dropped beats with the mobitz one we still have a p-wave for every QRS complex that exists I would ask you to write this down or draw a piece of paper and try to use it as you look at different types of AV blocks alright here's our first example again this is a first degree AV block let's go through our list though the first question we have is the PR interval a constant length and if you look at this you will see that the PR interval is staying consistent throughout there's already lines there to show us what you have an consistent PR interval the second question we have since yes do we have dropped beats do we have drop your s complexes and if you look at this there's no P waves that that don't have a QRS complex okay so we can come back here and we could say you know we don't have any drop beats so we have a first degree AV block first degree AV block look at another one again we have a PR interval the constant length there are no dropped beats however we have an extra beat okay and I will tell you that this extra beat has nothing to do with the underlying rhythm this is a normal sinus rhythm because it's a normal rate with a first degree AV block force agree heart block this is ectopy that is ectopy and we're going to go over that in a future chapter here's another example that now let's ask the first question is our PR interval a constant length well if we look at this and we said this was a PR interval you can see that that is definitely not the same as the next one so no it is not a constant length and then if we go back to that chart again our PR interval is a constant length well we have to ask do I have a p-wave for every as complex if I do it will be a mobile to one if I don't it'll be a third degree so let's go back and take a look and while there is a p-wave in front of this QRS complex and viewing them from this view s complex there's a peeling from this QRS complex that just happens to be coincidence they are not the same okay those P waves are not causing those QRS complexes in fact if you took this P 2p interval and then you took exactly half of that you will see you have varied P waves in the T waves and what's happened is what we call complete AV dissociation in fact this is where you would find your P 2p interval use that P 2p interval to identify where the hidden P waves are so there's one in there and if you go this way there's one in there so we have what we call complete AV disassociation so this is a third-degree heart block remember I said that those can be wide those QRS complexes are wide that can happen and that happens because this underlying rhythm is a ventricular escape just look at it it's got a rate of 1 2 3 40 beats per minute it's wide it's a ventricular escape rhythm and you have a third-degree heart block there let's take a look at this one first question is our PR interval consistent and where we have a PR interval yes it's consistent we have a consistent PR interval for these three beats here and it's the same as this one over here and our next question would be do we have drop eats and yes we do have dropped beats you can see clearly here you look away without a QRS pop let's of people ate without a QRS complex here so this is a mobitz one a second I'm sorry mobitz to a second degree type to a Vblock second degree type to mobitz to looking at the next one okay the first question again is our PR interval a constant length so take a look here that's our PR novel there looks like it probably is pretty consistent and now we have a question do we have dropped feet and looking at this I don't see any drop beats and I'm not going to assume that there are any drop beats because our PR will staying pretty consistent so this would be a sinus bradycardia with a first-degree AV block and that is a very prolonged PR interval all right here's our next one first question is our PR interval a constant length and you can see clearly it is not a constant length it is changing that PR interval that PR interval it's not constant and then the next question do we have drop beats do i or do I have a drop B here yes let's go back to our algorithm it's been a while since we've looked at it so we said our PR interval is not a constant length and then we're going to ask if we have a key wave for every QRS complex if you have a P wave for every QRS complex it's a mobitz one if you do not it's a third degree AV block so let's go back to that one we were looking at spend so long since I looked at the algorithm after going through all these that I forgot what happens when you have a change in your interval all right so here's that one we're talking about again do we have a P wave for every QRS complex oh yes for every QRS complex that's up there we do have a P wave in front of it and also I want you to identify that this is that regularly irregular pattern where we have three beats and then we have a drop beat and then you'll see that that happens again if you printed this out for a longer strip and you'd also identify this going going going gone going going going and it would be gone again so this is Winky Bock second degree type one for mobitz one all of those being the same thing to second-degree AV block type one type one moving on oops skip one all right first question is our PR interval a constant length I think you'll see that it is a constant length where we have one second question do we have drop beads and yes we have drop ETOP wave here with no qrs people here who adhere this is a second degree type to mobitz to second degree type - all right let's ask those questions again is our PR interval a constant length you can see clearly that this is way longer than this we're not even going to going further than that and then we're going to say uh do we have a P wave for every QRS and these are not associated these are not associated you can clearly see that the pita peas are just marching out if you just go from there they're the pita peas are marching out there's a hidden one in there you see it bottom of the S wave there and your QRS complexes will stay regular your r2r interval this will stay regular so this is a third-degree AV block because you have complete AV dissociation your pita peas will be the same your r2r will be the same but they are not associated with each other now if you look at this previous one here feel to this previous one notice that your pita peas okay your PR intervals will prolong your pita peas still say the same for it to be a p-wave that always remains true okay your peas will always march out but notice how your R two R's change got this and then you have no our way of there because I've dropped beat that's a clear way to tell the difference between a complete heart block and anything all right looking at the next one all right first question is our PR interval stay at constant length and it does not you can clearly see that that PR interval that one and then we don't even see one here all right and if we want to try to identify that hidden p-wave because I bet you're guessing that there's a hidden key wave over there let's do this P to P and sure enough there is a hidden P wave in that t way remember T waves are never notched for anything other than the fact that there's a hidden P wave in there you also had a hit have a hidden P wave over here so we we asked the question is our PR interval constant length it is not and then you're going to say well do I have a P wave for every QRS and you do have to wait for every QRS all right you also notice you have that going going gone pattern going going gone pattern this is a winky bar a second degree type one AV block type one also known as mobitz mobitz one all right let's look at another one it's important to look at a lot of examples of these because they're more difficult than pretty much any other arrhythmia all right first question again is our PR interval staying the same right P right over there there and there I would say yes that's thinking pretty consistent the second question is do we have drop beats and yes you do those are P waves there all right and you have obvious drop beats again if you want to find the hidden P waves find the two closest P waves that you can see and then you just March those out March those out and you can find the hidden ones in there it's important to do so we would call this a second degree type to AV block second degree type to AV block and it's got a three to one ratio three P waves for every QRS complex so it's also called it 3 2 1 AV block so again just want to review this when you get over to this side here as you can see there's a little bit you know a little bit more you got to look for yellow for that going going gone pattern and look for the R to R regularity if you are to our regularity is not staying consistent it's going to be this one because the third-degree AV block is typically very regular okay that's it for this chapter and again I don't want you to think that that's everything there is to know about AV blocks there's a lot more to know we're going to discuss that later that's just an introduction to AV blocks if you want to go back and you want to look over the tricular rhythms in chapter 10 click on the left image there and you're ready to move on and learn about ectopy and aberrancy click chapter 12 on the right there and as always don't forget subscribe to the channel

Channel: The Resuscitationist

Views: 201,302

Keywords: ECG, Cardiology, Paramedic, EMS, Prehospital, EKG, 12-lead, arrhythmia, clinical, emergency, emergency medicine, EMT, advanced life support, ALS, P101, paramedicine101, meducator, ER, CEU, CME, drug math, clinical education, medicine, ambulance, trauma, medical, electrocardiogram, ETCO2, capnography, premed, med student, medical school, physician, axis determination, meducator01, adam thompson, EMT-P, nurse, RN, LPN, CEN, board review, education

Id: nCZI_NY501Q

Length: 20min 51sec (1251 seconds)

Published: Sun Jan 05 2014