Atrial flutter & atrial tachycardia with 2:1 and 1:1 AV conduction is mistakenly called "sinus tachycardia" and is often missed. In this video, Dr. Joshua Cooper, Director, Cardiac Electrophysiology, Temple University Hospital, reviews how to find hidden P waves and use the heart rate trend to easily distinguish atrial flutter and atrial tachycardia from sinus tachycardia.
Please also see Dr. Cooper's other two "telemetry tips" videos, including:
Telemetry Tips: Mobitz 1 Block vs. Mobitz 2 Block
Telemetry Tips: Electrical Artifacts
Telemetry Tips: Sinus Node Dysfunction
This is Dr Joshua Cooper and this is the first in a series of presentations designed to help you interpret telemetry tracings more accurately. I decided with this first topic to review atrial flutter and atrial tachycardia because in my experience, this is one of the biggest missed diagnoses. Uh as people often will see the tachycardia and think that it's sinus tachycardia with an incorrect diagnosis. You miss the opportunity to anticoagulate somebody and reduce their risk of stroke and also slow the rate and control the rhythm and avoid tachycardiac cardiomyopathy and other symptoms that go along with a missed diagnosis of ongoing tachycardia. When somebody has atrial flutter on telemetry with a slow ventricular response. The diagnosis is pretty simple. You can see the flutter waves or the P waves if it's atrial tachycardia, which greatly outnumber the QR S complexes. Uh and therefore, are easily seen. One thing that people sometimes don't appreciate is that when you have uh a flutter wave or a P wave that falls on a QR S T wave complex, that P wave may go uh may be somewhat invisible because it's obscured, not a big deal if you have more P waves than QR S is because you see all of the rest and make the die diagnosis. Uh But if you were to have a 2 to 1 tachycardia, then imagine that these invisible P waves are present every other beat and you might therefore miss half the P waves and miss the diagnosis. They are in a 2 to 1 rhythm. Let's review some of those examples and how to not miss that diagnosis. Here are two examples of patients who were called uh to have sinus techo cardia. Uh one with a heart rate of 100 and two and one with a heart rate of 1 14. And in each case, the P waves were either not very visible as is the case with the top or, or in the bottom, it looked like there was one P wave for every QR S complex and the patient was misdiagnosed as having sinus tacho cardia. Let's review these examples in more detail in a few slides. The first trick uh in diagnosing atrial tachycardia or atrial flutter is to find the P waves that you know. So in this case, here are two P waves and humps that are uh more easily identifiable measure the distance with calipers between them, whether that's electronic calipers or manual calipers and then have the distance between them and see if you can see a similar looking P wave peeking out and hiding that you didn't initially notice. And here there is in the S T segment ha hanging off the end of the QR S, another P wave that looks like it's the same morphology, although half of it is hidden and then you can look at the rest of the tracing and identify that this is in fact a 2 to 1 atrial tachycardia or atrial flutter. Sometimes when you do this uh maneuver and you measure the humps of the P waves that you can see and you go halfway in between. It's really not clear if you're now seeing the end of the QR S or is that really another P wave? Uh But in this example, instead of looking at the peaks or the valleys of the P waves, uh notice that there are these sloped segments, normally the S T segment should be horizontal or flat and same with the segment after the T wave. But here we in fact, have a slanted downward slope of twice for every QR S complex. When you see this repeating slope pattern, you should think of atrial flutter. Another huge clue to the fact that you may be dealing with atrial flutter or atrial tachycardia is a very flat heart rate trend, sinus rhythm. And sinus tachycardia have variation through the day during sleep, during emulation, during pain fevers, whatever it is, you'll see the heart rate rise and fall even during sinus tachycardia. When you see a flat heart rate, that's railroad tracks straight all the way across that is just not gonna be sinus tacho cardia. When you look at this tracing, it's not initially evident that in fact, you're dealing with an L tachycardia or atrial flutter because the P waves are not tremendously visible. Although they're sort of peeking out there in the bottom of these three leads, you can gain up. The telemetry is one trick that you can use to see P waves and now they jump out at you in this MC L lead in a 2 to 1 pattern. And sure enough, this flat heart rate trend is indicating an atrial tachycardia. In this case, with 2 to 1 A V conduction here is the other example that I showed at the beginning where it looks like there is one P wave for every QR S complex. And again, this was misdiagnosed with a heart rate of 1 14 as sinus tacho cardia. But the moment you click on the heart rate trend, you'll see that it's absolutely flat and there's no way that this could be Sinus Tao Cardia with that flat heart rate trend. If you click on different parts of the telemetry, you'll see that the one P wave to one QR S appearance seems to be preserved and that's not very helpful when you look at a heart rate. That is the same. Here's a third place that looks identical, not very helpful. And here's 1/4 place where we click on the heart rate at exactly the same rate. And we see interestingly a slightly different appearance, maybe with a slight shift in the P wave to QR S timing. And in fact, now, maybe we see that double sloped pattern I referred to earlier suggesting the possibility of 2 to 1 atrial flutter. But it isn't crystal clear. Here's another very critical principle about looking at heart rate trends and where to click and look, notice that there's a place here where there's a lower ventricular rate, find that low point. What you're looking to do is get rid of the Q RSS and T waves as much as possible. So you can see the underlying atrial activity. So don't keep clicking on the same fast heart rate, but instead click on that low point. And now you're going to see a little separation between the Q RSS as reflected in that slightly lower heart rate and the flooder waves now jump out at you. You can see now uh two flooder waves in between the QR S is uh separated out a little bit further rather than having one buried inside a QR S complex. Uh and hiding it. Here's a patient with true sinus tachycardia. This patient was pretty ill and in fact, ran heart rates up into the one forties uh with true sinus tachycardia and take note of what this heart rate trend looks like with sinus tachycardia. Here's what the uh telemetry strips look like. And you can see uh one obvious P wave for each uh QR S here and you can do the halfway in between and you don't see anything obvious, but it's not really clear. But again, the heart rate trend is the tell there is a gradual acceleration of heart rate here consistent with uh sinus tachycardia and increasing rate with increasing cates and the rate changes sort of gradually. Uh and you have a whole range of heart rates without any abrupt changes. This is sort of the hallmark of sinus tacho cardia. In contrast, here's a patient with atrial tachycardia and look here how suddenly and abruptly you have changes in heart rate jumping up and down very suddenly. If you look here where we're at the sort of lowest rate where there's sort of a plateau that I'll talk about in a moment. Uh and look at the tele strip at this point in time, you'll see that there is in fact a 2 to 1 A V relationship with obvious negative P waves in the inferior leads two and three here. Uh again, in a 2 to 1 fashion with a heart rate around 80 or so. Uh And there is this sort of flat heart rate trend that I was referring to earlier that serves as a baseline from the, from which point you see it jumping off to higher rates and then coming back down to that exact same heart rate of 80. If you click on a different area where you have uh one of these little peaks uh at maybe a different uh heart rate um again, an abrupt up and down heart rate change. And now you look at the telemetry in this spot, you're gonna see sort of a 3 to 2 pattern at this point, uh a mathematical uh fraction of the atrial tao cardia rate. If you click on yet another higher peak, you're going to see um another sort of plateau at which some of these peaks uh arrive at before either extending further upward or falling back down to one of the lower plateaus. And the patterns that you might see at one of these sort of higher plateaus include a 4 to 3 pattern or a 5 to 4 pattern. I sort of clicked on a point of transition here and uh these are all very mathematical relationships to the atrial tao cardia rate and at the very highest plateau where you see these little flat peaks at times, presumably at times of higher catapult patient activity or otherwise, this is the fastest that this can possibly go. And it is exactly at twice that lower plateau at the bottom. This is 160 and you're now in a 1-1 pattern of the atrial tachycardia. So this jumping up and down with very discrete rates, sometimes with longer periods of plateaus at each of these lines is another clue that you're not dealing with sinus tachycardia or sinus rhythm. But instead an atrial tacho cardia or an atrial flutter with varying a V relationships. So the tips to remember in this module talking about A and a flutter include the fact that a flatt heart rate histogram is not at all suggestive of sinus tack. Think of arial tao cardia, think of atrial flutter with a 1 to 1 or a 2 to 1 relationship. The same thing A applies when you see abrupt changes in heart rate. Because sinus rhythm, sinus tachycardia will have a much more gradual upslope as CICS change, you're not gonna uh switch from one rate to another in a split moment and then look for the hidden P waves if you find ones that you can see and you're wondering whether there's a, there's a 2 to 1 relationship, uh use your calipers to find the halfway point in between and see if maybe there is a P wave or flutter wave feature that mimics the ones that you are more obvious. Uh And maybe the rest of the flooder wave or P wave is hidden by the, the T wave or the preceding QR S complex when you see parallel slope segments, that's another tell that maybe you're dealing with a 2 to 10 flutter um instead of seeing the peaks or valleys of P waves, and then lastly look at the patient, a patient with sinus tachycardia should be sick, whether they're in pain or having a fever or, or some other illness, um, if the patient's heart rate is 1 31 41 50 they'd better be pretty sick if this is sinus tacho cardia. So it's always important. And that really should have been my first tip to remember, correlate the heart rate with the clinical scenario. And that's a big clue whether you're dealing with sinus tacho cardia or something different. Hope you found this helpful.
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