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The ECG Course – Paced Rhythms

June 12, 2019



hello and welcome back to the ECG course this is chapter 13 and in this chapter we're going to be talking about paced rhythms and we're talking about implanted pacemakers not transcutaneous fake pacemakers where we put the pacer pads on the skin those rhythms we know we're going to be paced and that's a whole different topic implanted pacemakers usually you'll have a patient that will hopefully be able to tell you that they have a pacemaker if not let's say they're unresponsive for some reason you can identify a lot of these patients a pacer pouch where you can actually see the device underneath the skin and that device is you know a little pacemaker and what it's doing is it's sending out a signal through a lead wire that's connected somewhere into the heart and that is creating cellular depolarization from outside means so our normal physiological pacemaker is typically the SA node right but if that for some reason is not working and the rest of the conduction system isn't working out effectively you might have a implanted pacemaker put in by cardiologist and there's different kinds you know you could have a lead wire to the ventricles you could have a lead wire that goes to the atrium and we're going to talk about those different types of pacemakers the first one we'll talk about is the H real pacer this is actually a very desirable type of pacemaker because you're using a lot of the normal physiology in the heart most of your conduction system is still working pretty effectively with this atrial pacemaker and the first thing you should probably be able to notice that's different on this rhythm than any rhythm you've seen so far that we talked about are these little spikes these straight lines before the P wave and it's going to be before the P wave with an atrial pacemaker you're going to see a spike just like that and that's creating a you know that first signal sent by the pacemaker to start cellular to polarization in the atria okay so that lead wire goes into one of your atrium your right or left atrium and it's causing the polarization to begin each time it sends that signal so that pacer is firing and it fires 60 to 100 ok pacemakers used to all be set around 60 now there's different rates okay so you're going to determine the rate and that rate of that the pacemaker set at is probably going to be the patient's heart rate okay the rhythm should be regular the P wave is present with an atrial pacemaker followed by usually a narrow QRS complex less than 120 milliseconds and then of course you have normal repolarization after that so this looks a lot like a sinus rhythm except you have those spikes before every P wave so ask your patient if they have a pacemaker if you see that the next one we're going to talk about is an AV sequential pacemaker it's not as desirable as an atrial pacemaker but it is another sort of backup system if the ventricles aren't the polarizing on their own so an AV sequential pacemaker is just like that a V stands for atrial ventricular so you have an atrial pacemaker and a ventricular pacemaker it's all coming from the same machine but you have two different lead wires one that stimulates the polarization of the atria that's why you get a P wave after that and then another little spike followed by a QRS complex because it's stimulating the polarization of the ventricles and you'll notice that when the QRS complex immediately follows the pacer spike that it's going to be wide you're going to have a wide QRS complex now think about the reason for that whenever something's wide it in EKGs it means it's taking longer to happen so when the ventricles the polarize and it takes a little bit longer for them to the bowler eyes you get a widening of the QRS complex and here's why that pacer wire is not starting that wave of the polarization in the normal lane of conduction so we talked about the normal Lane of conduction with the his bundle and the bundle branches ending in the Purkinje fibers and the ventricles that's your highway in the heart that's the highway the fastest way for conduction to travel but it can still go outside of that and travel from cell to cell to cell which takes a little bit longer so imagine it as almost taking the back codes instead of taking the highway and just like if you get off the highway in your car and you have to take the back roads and you start hitting stop signs and street lights it's going to take a little bit longer to travel right well same thing in the heart when it get when that Lane of depolarization or that wave of depolarization leaves that fast lane of conduction or that highway of conduction and it goes from cell to cell to cell it takes a little bit longer and that's why these ventricular Pacers are going to take a little bit longer so that's why you're a be sequential pacemaker is you got a lead wire in the atria and a lead wire in the ventricles and it's the polarizing and they're set to the polarized at that PR segment time so the atria will the polarize from the pacemaker and then it'll send out that next signal spaced out you know less than 200 milliseconds so it'll hopefully get that full filling of the ventricles using that sequence the ventricular pacemaker ventricular pacer is a little bit different in the fact that it's not the polarizing the atria okay so it's probably the least desirable of the three that we talked about so far because the particular pacer is not the polarizing the atria it's just the polarizing the ventricles in fact it's very similar to having a ventricular rhythm the only difference is is it's not happening intrinsically within the heart it's happening through that mechanism that has been implanted in the patient and because of that if the rate can be controlled so that rate again is going to be usually around 60 to 100 the rhythm will be very regular the p-waves will be absent you won't see any P waves because you're not having atrial depolarization occur before the ventricles and your PQRS ratio because you have no P wave so you have no PQRS ratio or no PR interval either and again your QRS complex is going to be wide because we're outside the normal lane of conduction with Adam and pacemaker it can be any of the ones we've talked about so far usually you're going to see this with ventricular Pacers they can be set to a demand mode okay so this example that we're showing here is obviously a ventricular Pacer you see a pacer spike and then you see the wide QRS complex immediately following it but then you notice right here in this area and right here our rhythm became a regular the pacer did not fire here or here so it didn't fire in this area or in this area and the reason that the pacemaker didn't fire is because the patients hearts decided to create its own pacemaker and kind of fill in the gaps there so what happened is the heart's conduction system or that you know the heart's automaticity still kind of effective in a sense here decided it's going to go ahead and depolarize well the pacemaker being you know set to Adam and mode and being pretty smart said that well if it the heart's already firing right here and it's already sending out a signal let's let that happen let's let the ventricles to polarize on their own and then we'll come back in if it takes too long to happen again so this patient's heart rate if the heart rate goes down below a certain number this pacemaker kicks in and kind of fills in that void so let's take a look here at a different pace rhythms we've already identified the many different kinds of pacemakers and here we could see we have what looks like a sinus rhythm right you see a pea way of a QRS complex you see a t wave all that T wave is inverted but before that P way we see big old pacer spikes don't we these are big gigantic pacer spikes so this here would be an atrial pacer it's an H real pacer let's move along all right here we haven't talked about this you see pacer spikes but you don't see QRS complexes or T waves or anything else this is a pacemaker that's not capturing okay so this would be what somebody would look like if they're in asystole asystole is a lack of any electrical activity but their pacemaker is still firing so those pacemakers they generally don't pay attention to whether somebody's alive or not so if somebody did die and they've been dead for a while and their pacemakers still kept firing this is what it would look like also could be somebody that's completely on a you know completely dependent of their pacemaker their wire could have become misplace or they could just be losing capture for some other reason hyperkalemia is actually quite a common cause for losing captured with an implantable pacemaker so this is a failure of the pacemakers capture and this should cause serious concern you may be doing CPR at this point okay here hopefully you're able to identify this one this here is an AV sequential pacer and this is an AV sequential pacer that is a demand pacer you notice that right here we did not have pacer pacer spikes because this is the heart's own beat going and taking over right there for that one single QRS complex the heart decided to send out its own beat in this pacemaker just filled the gap after that and kept the rate normal okay here we haven't seen an example of this this is a ventricular pacer okay you see a spike and then the QRS complex after that and then you see it over here as well spikes and QRS complexes but you also have failure to capture yet failure to capture here so this patient you would want to take in to a cardiac facility where they can see hopefully their cardiologist about their pacemaker and see what's going on I don't know what kind of tuning they would have to do but hopefully fix that and get them back to 100% capture this next example we have a captured beat a ventricular pacer with a captured beat and then this is almost like a fusion beat the pacer fired but it shouldn't have because we have this is obviously a physiological beat as well as this one and this one so this is the patient's own intrinsic rhythm it's a normal sinus rhythm and it appears that they probably have a demand pacemaker and that pacer spike still fired and of course it finally realized that it shouldn't be firing for some reason and then the normal sinus rhythm continued okay so this patient also you would want to have seen and if you were lucky enough to capture this EKG strip that could be shared with the cardiologist moving along to the next one here we have a looks like a pretty fast rhythm pretty fast rate for a pacer but it is in fact a pacemaker you notice how small those spikes are compared to the ones we've seen so far those little pacer spikes are in fact coming from the pacemaker you'll never see the heart itself just cause a straight line like that it always has a little bit of a slope even it's them if it's the most minut slope ever physiologically you won't ever see a spike come from the hearts conduction so this is a ventricular pacemaker and there are reasons where pacemakers will speed up the rate the underlying rate and the reason could be because sometimes patients will go into a rapid rhythm and the pacemaker will do something called over ride pacing okay and it will start to speed up the pacer rate to kind of override whatever the patient's underlying rate is so if they were in a heart rate they were having a heart rate of 160 and the pacemaker said that's too fast the pacemaker might speed up to 170 and then take over the rate and bring it down so watch out for over-riders sometimes called overdrive pacing a lot of times if people call it overdrive pacing okay here's another example and here we have a pacer spike a P wave and a QRS complex so hopefully you're able to identify that as an atrial pacer okay and then notice you do not see that here it may have been a failure to capture that by the monitor or that could be a failure to actually send the pacer signal okay but we do not see a spike before that one a lot of times you'll notice that when you have somebody with a paced rhythm and you look at it on the monitor and you print out an EKG you'll see pacer spikes and it seems like you can see them in some leads but not another lead always choose the lead to monitor where you could see them the most clear and that's kind of true for all rhythms pick the lead that has the biggest QRS complexes and you know the easiest to identify p-waves when you're trying to interpret those things don't use the hardest lead to determine the rhythm a lot of times lead to is not the lead you should be monitoring it although that is what most EKG monitors will default to you should often change that lead and see if there's another lead that could be better to identify your rhythm in here again we see those two spikes before every QRS complex it's really difficult to identify the p-wave here but there is a little tiny P wave following that first spike this is an AV sequential pacer notice the ventricular spike is causing that widening of the QRS complex so it's the AV sequential pace for this patient is 100% paced at this point moving along here we have another example of an AV sequential pacer again you have that atrial spike you have that ventricular spike and you have a widened QRS complex as a result and notice that this rate is different from the rate we just saw look at the rate here you can see it's much faster than the rate we're looking at again that's the very dependent on the pacer settings okay here we have a another example of a pacemaker we see widened QRS complexes that should always make you sort of assume that it's probably going to be a ventricular pacer and then you do see these spikes occur immediately before ventricular depolarization which tells us that this is in fact a ventricular pacer and since we did have one intrinsic beat that did not occur as a result of the pacemaker we can say that this is a demand pacemaker so this is a particular demand pacer and one final one we have another ventricular demand pacer we have a spike we have a widened QRS and we can see here we have a couple beats where we did not have a pace rhythm and then we went back to the pace rhythm so what happens is the patient's own heart rate came up so the Pacers stopped firing for this period of time here and then the patient's heart rate slowed down so the pacemaker decided to kick back in and that's what they're designed to do they're designed to keep the patient within a normal heart rate and that's it for now that that's it for paste rhythms they're really not that hard to identify as long as you get used to looking for that pacer spike and asking your patient if they have a pacemaker but remember that those pays respects are getting smaller and harder to identify so your monitor hopefully is calibrated to you know identify those but sometimes it will miss them if you want to go back and check out chapter 12 again on ectopy and aberrancy click on the image to the left here if you're ready to move on to the next chapter we're just going to talk about asystole and some artifact stuff you might already be familiar with a lot of that information as always subscribe to the channel because I'm always updating videos this is just the initial course so there's always going to be added videos on different topics I certainly am going to add some more videos on AV blocks and on Y complex tachycardias and narrow complex tachycardias to sort of kind of fill in the gaps of a lot of stuff I haven't talked about yet so make sure you subscribe so when those videos become available you can check them out

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20 Comments

  • Reply Sweet Life June 12, 2019 at 12:06 pm

    beautiful

  • Reply Marcia Grant June 12, 2019 at 12:06 pm

    thank you sooooo much

  • Reply Severino Arata-Ryan June 12, 2019 at 12:06 pm

    Im in my second semester of paramedics and starting to learn ekgs and I've been watching your videos non-stop and are very helpful. it looks like you havent posted in a while you should.

  • Reply nasma awad June 12, 2019 at 12:06 pm

    you help me alot thanks

  • Reply Irene Fung June 12, 2019 at 12:06 pm

    Very well explained. Thank you.

  • Reply Paul Rumbaoa June 12, 2019 at 12:06 pm

    Thank you for putting this together. I love your presentations. You're an awesome educator!

  • Reply Ana M June 12, 2019 at 12:06 pm

    My savior haha thank you!

  • Reply gnedelcu7 June 12, 2019 at 12:06 pm

    Thak you for this video.
    Bucarest, RO, UE

  • Reply Stacey Baack June 12, 2019 at 12:06 pm

    Awesome information for a paramedic! I'll use what I learned here to help me care for patients.

  • Reply Lilly 19 June 12, 2019 at 12:06 pm

    a thank you is never enough for these great videos..much appreciation for your efforts

  • Reply Saria Rahman June 12, 2019 at 12:06 pm

    Thank you so much for the clear explanation. Can you please also do a detailed video about abnormal pacing ?example: oversensing/undersensing? failure to sense/capture?

  • Reply waqas akhtar June 12, 2019 at 12:06 pm

    Excellent excellent execellent

  • Reply Yashvanth Shantharam June 12, 2019 at 12:06 pm

    Very informative

  • Reply MALISA WILLIAMS June 12, 2019 at 12:06 pm

    great explanation of paced rhythms

  • Reply jimbo cuttz June 12, 2019 at 12:06 pm

    can you get STEMI's that are stemi's with atrially paced rhythms….i imagine unreliable with ventricular pacers?

  • Reply 1fineRT June 12, 2019 at 12:06 pm

    Well done! This is the first of the series I have watched. Looking forward to checking out the others. Thank you!

  • Reply Alyce L June 12, 2019 at 12:06 pm

    This video was really helpful for me to understand pacing thanks

  • Reply juan perez June 12, 2019 at 12:06 pm

    My ilustrativo y asequible,just great!

  • Reply Basel Altoos June 12, 2019 at 12:06 pm

    These videos are great! Thanks

  • Reply Jamie Merlin June 12, 2019 at 12:06 pm

    You are awesome! Thankyou! I was struggling, but you explained the content very well. Much appreciated 🙂

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