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Atrial Dysrhythmias: Atrial Fibrillation (Nursing)

by Rhonda Lawes

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    00:01 Hi, welcome to this video in our series on the electrocardiogram.

    00:06 In this one, we're going to learn about atrial dysrhythmias and specifically atrial fibrillation.

    00:12 So we're always going to start with normal.

    00:15 So why is this ECG normal sinus rhythm? See if you can review in your mind the criteria that caused this strip to be identified as normal sinus rhythm.

    00:27 Now compare it to this rhythm.

    00:30 This ECG is atrial fibrillation, see the difference? Where are the P waves? Where is the regularity between the QRS complexes? Okay, this one looks very different than normal sinus rhythm.

    00:47 Remember those patients that we were not quite sure how to tackle? Well, now we're finally ready to try to diagnose them.

    00:55 This time around, we're going to check on this fella right here.

    00:59 Since we've already analyzed and identified a normal sinus rhythm, you know, at first glance, then this ain't it.

    01:07 There's definitely something wrong with this ECG.

    01:10 But what exactly is it? Now let's take a closer look.

    01:14 Once again, let's recap.

    01:16 The electrical impulse travels from the atria to the ventricles.

    01:20 Now its pathway is being reflected on the ECG paper.

    01:24 The impulse originates at the SA or sinoatrial node, and it travels through the atria.

    01:30 And this is what causes the atrial depolarization or contraction and makes the P wave on the ECG strip.

    01:37 Now at the AV node, the impulse is still laid and it's reflected in the ECG strip as an isoelectric line called the PR segment.

    01:47 Then the impulse courses through the Purkinje fibers, it's causing depolarization or contraction of the ventricles, which is reflected on the paper as the QRS complex.

    01:58 Next, the interval of time between depolarization and repolarization of the ventricles is reflected as a flat, or isoelectric line called the ST segment.

    02:10 And finally, the ventricle repolarize or relax.

    02:15 This is what forms the T wave.

    02:17 Take a look at the graphic we have for you here.

    02:20 Start up at the top, I'd love for you to put your finger at the top there at the SA node.

    02:26 Now look at that signal shooting out across both atria.

    02:30 Then you see it hit the AV node, and it's disseminated into the ventricles.

    02:36 Now the atrium are contracting, you have a little bit of a pause, remember, that's the PR, and then the ventricles contract.

    02:43 So I would encourage you to spend some time with us.

    02:47 Look how organized it is, how systematic it is, how the heart is pumping atrium, ventricles, atrium, ventricles, atrium ventricles.

    02:56 That's what makes an efficient pump.

    03:00 Now we're gonna compare it to atrial fibrillation.

    03:03 You see we have going on there? It's like chaos, right? So the atrium are not firing as systematically as you see SA node to AV node down to the ventricles.

    03:17 So not even all of the signals are making it through.

    03:22 That's what atrial fibrillation looks like in the heart.

    03:26 So I really would encourage you if you have solid in your mind, hey, normal sinus rhythm.

    03:32 That's why we have a P wave for every QRS and everything is regular.

    03:36 Atrial fib? That's why it looks like such a mess in that slide.

    03:41 Because we have this going on, and we don't have a consistent SA node, AV node down to the ventricles.

    03:51 So let's review how to analyze any strip.

    03:54 First, we look at the heart rate and rhythm, then we look at the P waves, then the PR interval, the QRS duration, the ST segment, the T wave and the QT interval.

    04:07 So step one, take a look at this strip, like I want you to actually practice with me.

    04:13 You'll learn much more efficiently if we do this together.

    04:17 So we're going to look at the heart rate and rhythm.

    04:20 First, we identify six seconds of a strip, we count the QRS complexes and multiply by 10 to calculate the beats per minute.

    04:28 So we laid out a six second strip.

    04:31 We counted the beats and we have 10 beats.

    04:36 So 10 QRS times 10 equals 100 beats a minute.

    04:41 Now, we've seen these before, but do you remember the name? These are calipers.

    04:47 Now calipers were the original measuring tool, but now you do it most often on a monitor with digital calibers.

    04:55 But this is what we used to use old school and still would work just fine for you.

    05:01 But we've looked at the rate, we know it's about 100.

    05:03 Now we're going to look at the rhythm, is the rhythm regular? Well, you would measure between complex one and two to determine if it's the same distance between one and two and two and three.

    05:15 Wow, you can tell by eyeballing it that it is not the same, but be diligent, be systematic, measure between one and two, then two and three, then three, and four.

    05:27 So you have a really strong feeling like, Yeah, this is not regular.

    05:34 Step two, we're gonna look at the P waves.

    05:36 So we don't have one clear P wave present for each QRS.

    05:41 And they do not all look the same.

    05:44 So it would be hard to tell a regular PTP interval because we can't even measure it.

    05:49 So we would not call it regular.

    05:51 Now in sinus rhythm, a normal P wave or an atrial contraction precedes every QRS.

    05:58 You always start with normal, and then compare what you actually have.

    06:02 Atrial fib? No discernible P waves, or an absence of discrete waves, meaning waves that we could tell our P waves, sinus rhythm, P wave, every QRS, atrial fib? We got a mess.

    06:17 So there's no discernible P wave or an absence of ones that we can recognise as a P wave.

    06:24 Now measure the PR interval? What? We can't.

    06:29 If we don't have P waves, we certainly can't measure a PR interval.

    06:34 Now let's look at the QRS duration.

    06:37 Now we're going to measure that the same way to the best of our ability, right? Where the Q wave starts off the isoelectric line through the width fest, the R and the S.

    06:47 So the normal would be less than 0.12, or three small squares.

    06:54 Remember, the small squares are worth point .04 seconds each.

    06:58 So if we have three of those, we want to less than 0.12.

    07:02 So measure the QRS duration on the strip, hey, don't look at the answer that we're gonna supply for you.

    07:08 But measure the QRS duration on this strip, while you pause the video and then come back and check your answer.

    07:19 Now step five, we're going to look at the ST segment.

    07:23 Do we see any depression or elevation on this strip? So we see where the isoelectric line should be? Does it look like that ST segment is depressed or elevated? No, not really.

    07:41 Now we're going to try and look at the T waves.

    07:43 Remember, we want them to be rounded and not peaked or tall.

    07:48 Well just really kind of have a mess there.

    07:51 But you can somewhat see them but it's very difficult to see which is a common characteristic of atrial fib.

    07:58 That line in between the QRS complexes is just kind of a mess.

    08:02 Now, QT interval this would be very difficult to measure.

    08:06 So we know what normal is, but it's really not easy to do that on atrial fibrillation strip. So when we're wrapping this up, you're gonna see throughout this video series, we take a normal sinus rhythm strip, and then we compare the strip we're interpreting.

    08:22 So in sinus rhythm, you've got a normal P wave or atrial contraction for every QRS complex.

    08:28 Atrial fib, no discernible P waves or just a total absence of them from what you're seeing on the strip.

    08:36 Now as far as the rhythm goes, the rhythms regular in sinus rhythm, but it can vary slightly when someone's...

    08:44 breathing, and atrial fibrillation is irregularly irregular ventricular rate for measuring QRS to QRS.

    08:53 Now what about the rate? While the rate ranges between 60 and 100 beats a minute in sinus rhythm, and the rate can range between 101-175 beats a minute for atrial fibrillation.

    09:07 Now that's when there's a rapid ventricular response, so the rate may sometimes be lower.

    09:13 So let's review why this strip is actually atrial fibrillation.

    09:18 The heart rate is between 101-175, the rhythm is irregular, there's no discernible P waves before the QRS.

    09:27 The PR interval can't be measured and the QRS, we're going to let you know is about less than point one two.

    09:35 Thank you for watching this part of our video series.


    About the Lecture

    The lecture Atrial Dysrhythmias: Atrial Fibrillation (Nursing) by Rhonda Lawes is from the course Analysis of Abnormal ECG Strips (Nursing).


    Included Quiz Questions

    1. PR segment
    2. ST segment
    3. U wave
    4. P wave
    1. Count the number of QRS complexes in a 6-second strip and multiply by 10
    2. Count the QRS complexes in a 3-second strip and multiply by 20
    3. Count the P waves in a 3-second strip and multiply by 20
    4. Count the P waves in a 6-second strip and multiply by 10
    1. Irregular P-P intervals
    2. A PR interval that cannot be measured
    3. Distinct T waves
    4. P wave preceding each QRS complex
    5. A heart rate of 60 beats/minute
    1. 100–175 beats/min
    2. 60–100 beats/min
    3. 70–120 beats/min
    4. 150–200 beats/min
    1. P wave
    2. PR interval
    3. QT interval
    4. QRS complex
    5. ST segment

    Author of lecture Atrial Dysrhythmias: Atrial Fibrillation (Nursing)

     Rhonda Lawes

    Rhonda Lawes


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