Step 2: Analyzing the P Waves (Nursing)

by Rhonda Lawes, PhD, RN

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    00:01 So, we've done step one.

    00:02 We've looked at the heart rate and the rhythm.

    00:05 I reviewed what's going on in the heart with all the different parts of the ECG? Now, we're going to look at, how to analyze the P wave? What's that? Okay, so what does it mean the P wave? That's right, atrial depolarization.

    00:20 See, you can do this. It takes some effort.

    00:23 But the more you keep answering questions, you're going to make those connections between the neurons in your brain, make those super strong, and that's what you want.

    00:32 So let's analyze the P wave.

    00:34 We know the P wave is the depolarization of the atrium.

    00:38 Keep in mind, it's both the left and the right.

    00:41 Now, sometimes I was just talking about on the right side of the heart, but it's happening at the same time.

    00:46 So, look at our picture.

    00:47 You can see that we have that reaching way over to the left side, and right there on the right side.

    00:54 Okay, so they both are going at the same time.

    00:58 Both of those atrium and ventricles.

    01:00 So in the cardiac cycle, the P wave represents the depolarization of the atria.

    01:06 That means they undergo contraction.

    01:08 So have you thought about, why if the heart has two atria, there's only one single waveform for the P wave? Well, both the left and right atria depolarize, at about the same time, and so they're kind of just on top of each other.

    01:22 That's why you only see one P wave or a single wave on the strip.

    01:28 So step two is analyzing the P waves.

    01:32 But I want to explain what I mean when I say that.

    01:34 There are four important questions that you should ask when you're analyzing the P waves.

    01:39 Number one, first of all, are they there? So are the P waves present? And so looking at this strip, we put a blue box over each one of the P wave.

    01:50 So yeah, we've got P waves. They are present.

    01:54 Number two, is there one P wave for each QRS? I look at each one of the beats on a six second strip.

    02:02 P wave QRS, P wave QRS, P wave QRS, P wave QRS, P wave QRS, P wave QRS, P wave Q...

    02:09 Yeah, there is a P wave for each QRS.

    02:13 Now, are the P wave smooth, rounded, and upright? Yep.

    02:18 Yep.

    02:20 Yep.

    02:21 Yep.

    02:22 Yep.

    02:23 Yep.

    02:24 Yeah, we're good. So far, they're present.

    02:27 I have one P wave for each QRS, the waves are smooth, rounded, and upright, and do all the P waves look the same? Yeah, they do.

    02:40 This tells me, things are going well, right.

    02:44 This is what I'm looking for.

    02:46 Now, I'll talk to you in a little bit about what it means when that P wave doesn't meet all four of these criteria.

    02:53 So when you're analyzing the P wave, if the answer is no to one of these four questions, you'll tell us more about what could be going on in the heart.

    03:03 Because look at this.

    03:05 Now, in normal sinus rhythm, you see how that P wave is rounded peak, just like we thought it would be. But got some challenges going on.

    03:16 See how weird these other P waves look.

    03:18 Now, at this point, I don't want you to memorize this.

    03:22 I just want you to know, this is why we analyze a P wave and we ask those four questions.

    03:28 Because look at that second P wave that might show us right atrial enlargement.

    03:34 Look at the next P wave, the third one, right there on the bottom.

    03:37 See it.

    03:38 That could be it's got that little notch in it.

    03:41 That could be left atrial enlargement.

    03:43 So, I don't want to go into detail on this.

    03:46 I want to just to explain to you why is it so important that we answer those four questions about P waves? Because if they don't look like that, we're going to need to answer some more questions in more advanced ECG monitoring.

    03:59 But for now, if you can answer those four questions, right now we have a pretty normal rhythm.

    04:04 We're good.

    04:06 Now, here's a really unusual example of when the P waves don't look normal.

    04:11 We call it a junctional rhythm.

    04:13 Now, if you look at that strip, where do you see the P waves? Well, they're not there.

    04:19 Because a junctional rhythm the impulse originates at the AV node Know it has some retro grade and antegrade direction.

    04:26 But that's why you don't see the normal P wave.

    04:29 Sometimes the P wave will be inverted.

    04:31 And it may be under or after the QRS complex because the heart rate is so slow.

    04:36 So it's there.

    04:38 It's just not in the typical place that we expect it to be, and it likely doesn't look normal.

    04:44 So this patient needs further assessment.

    04:47 When you have these abnormal P waves they happen with enlarged atria or when they come from outside the SA node, this needs to be evaluated by the healthcare provider to determine the extent of follow up care that might be necessary.

    About the Lecture

    The lecture Step 2: Analyzing the P Waves (Nursing) by Rhonda Lawes, PhD, RN is from the course The Basics of ECG Strips (Nursing).

    Included Quiz Questions

    1. Depolarization of the left atrium
    2. Depolarization of the right atrium
    3. Repolarization of the left atrium
    4. Repolarization of the right atrium
    5. Repolarization of the left ventricle
    1. P waves are present on the ECG strip
    2. All the P waves look similar
    3. There are 2 P waves for each QRS complex
    4. The P waves are notched and inverted
    5. The P waves are taller than the R waves

    Author of lecture Step 2: Analyzing the P Waves (Nursing)

     Rhonda Lawes, PhD, RN

    Rhonda Lawes, PhD, RN

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