Third Degree AV Block (Nursing)

by Rhonda Lawes, PhD, RN

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    00:01 Third degree AV block is called complete heart block.

    00:05 Okay, this is a big deal.

    00:08 This is like the atria and the ventricles are no longer communicating.

    00:12 I will never forget the patient that we got to call, there's going to be a direct admit, from the doctor's office building that was connected to the hospital.

    00:21 We expected the patient to be over in like less than 10 minutes.

    00:24 We waited, we waited, we waited.

    00:28 It took her hours to get there.

    00:30 When she finally rolled into the unit, we thought, "Well, maybe she isn't in third degree heart block." We hooked up to the monitor.

    00:36 For sure, she was in third degree heart block.

    00:40 We said, "Ma'am, where have you been?" And she's like, "Well, I wanted to do some laundry and clean the house before I came into the hospital." We were like, it was crazy.

    00:50 But you know, some people are we want to be in control and keep our lives in order.

    00:55 But she legit was in 3rd-degree AV block.

    00:59 Now let me explain to you what we knew as nurses and she didn't really see as a problem as the patient, otherwise she wouldn't have gone home and done laundry and housework before she came to us.

    01:11 Now look at these P waves.

    01:15 Okay, if you plot them across.

    01:19 Boy, they will plot out equally that P is just happening with equal distances between P to P.

    01:26 If you look at the QRS complexes go R to R to R to R.

    01:32 Yeah, they're going fine, aren't they? But yet, there's not a P wave for every QRS.

    01:40 They're completely not communicating.

    01:45 So you may hear people say, the Ps march out meaning same distance, same distance, same distance, same distance.

    01:51 Ours do the same thing.

    01:53 Same distance, same distance, same distance, same distance, but they are not working together, they are like disconnected.

    02:03 Because in 3rd-degree AV block, it's a complete failure of the AV node to conduct any impulses from the atria to the ventricles.

    02:13 That's what makes this one different, and obviously, much more serious for your patient.

    02:19 So we call it complete block.

    02:22 3rd-degree is complete block because there is a total failure.

    02:26 The AV node doesn't conduct any impulses from the atria to the ventricles, and this is what makes 3rd-degree block so serious.

    02:36 Now, sometimes you may hear someone call it AV disassociation, meaning they are disconnected, not talking to each other.

    02:43 This patient is at the highest risk for ventricular standstill, It can end up in sudden cardiac death.

    02:50 So while she went home and got her house in order, she could have gone into sudden cardiac death at home, which would have been horrible.

    03:00 Now I tell you that story, because she ended up being fine.

    03:03 She went through treatment, and she went back home to clean her house again and to do her laundry.

    03:08 But this is what could have happened.

    03:11 But she's really good at talking her husband into taking her home first, and then bringing her back.

    03:18 Now when we're looking at the blocks, sometimes they can look a little different.

    03:21 So we wanted to show you this.

    03:23 Key point: No association between the atria and ventricle.

    03:27 But look, it can be on either side of the AV node.

    03:31 So if it's on the distal side, then we can get a wide QRS complex.

    03:36 But if it's on the proximal side, the QRS complex is more narrow, like you see in our illustration.

    03:43 So we want to make sure you understand that there can be kind of two locations.

    03:47 It can be on which two sides.

    03:51 Right, we refer to that is distal side and proximal side.

    03:57 Now look at the difference in the QRS complexes.

    04:01 Which one tends to have a wider QRS? Beautiful, all right, you're really doing good tracking with us.

    04:13 Wow, this is overwhelming.

    04:15 All the possible causes of 3rd-degree AV block.

    04:19 But in addition to teaching you the causes, we're going to teach you a strategy on the most effective way to study when you have 12 points to remember.

    04:28 We're going to show you visually how to chunk information.

    04:32 So we know causes of 3rd-degree AV block when we look at these, let's see if we can chunk them together.

    04:38 First, pause the video and I want you to read through all 12 bullet points, then come back and restart the video.

    04:52 Okay, now here's an example of how you could chunk information.

    04:56 You see that first bullet point? Well, that's something that happened problem in the conduction system probably caused by coronary artery disease.

    05:05 That's kind of a big segment, then down on the bottom to a congenital disorder and underlying structural heart disease.

    05:14 we can chunk those together as direct issues with the heart muscle itself.

    05:20 So we've shown you how to chunk these first ones together, what I want you to do is to look at the second side and look at how you would group those together.

    05:32 Now, this is really tough for students.

    05:34 But this is what helps you be successful in nursing school.

    05:38 First of all, your expectation that you're going to remember, all 12 points won't happen.

    05:44 You want to remember the most important points.

    05:47 So see how we've got the first category, the first bullet point or we're saying a direct damage to the conduction system.

    05:55 Is there anything on that right side that would also be direct damage to the to the conduction system? No, not really, in my mind.

    06:04 But what about the structural damage from heart disease? Well, I could kind of group together things like post-cardiac surgery, and cardiomyopathies.

    06:14 That would be one chunk.

    06:16 Now see, is that visualized on the screen.

    06:19 Cool. All right, we're starting to eliminate some of our points.

    06:23 Now, a congenital disorder means I'm just born with something, I could also throw that into an underlying structural heart disease, meaning anything that kind of changes the actual heart itself.

    06:37 So now, we've reduced our 12 points down to much fewer.

    06:42 Now we've got a lot of other things in there like Lyme disease, rheumatologic disease, autoimmune disease, amyloidosis, sarcoidosis, muscular dystrophy.

    06:51 I wouldn't be able to remember all those diseases, I would chunk those together as some diseases.

    06:57 If you can remember those, that's great.

    07:00 But know that this is how you're successful in nursing school, you don't just try to memorize everything, you chunk information together with understanding.

    07:11 So now, you know, when you see a test question or you see a patient, hey, if they've had anything that could damage their conduction system, if they've had anything that could damage their structure of their heart, muscle, and then some various and assorted diseases, then I know that this patient is an increased risk for 3rd-degree AV block.

    07:32 So there you go.

    07:33 You can't memorize everything.

    07:35 But if you chunk intentionally with understanding, when you see it in a test question, you'll know if there is damage to the heart, possible damage to the heart, be worried about 3rd-degree AV block.

    07:48 Now when we treat AV block its pacing, because the patient has the significantly increased risk of ventricular standstill and sudden cardiac death.

    07:59 So back to our chart.

    08:01 Third degree is the complete failure of the impulse from the atrioventricular node to the ventricles.

    08:08 So there's this AV disassociation and these weird escape rhythms.

    08:12 They could be junctional or ventricular, but it's pretty bizarre looking.

    08:17 How do we treat it? It's an internal pacemaker.

    08:21 Now we've talked about our strategy and covering up the slides and then asking yourself questions.

    08:25 Here's some examples.

    08:27 So let's pretend you had all of these covered, you can just look away for that.

    08:31 Which one is technically not a true block? Right.

    08:37 1st-degree.

    08:40 Which type of block is usually benign? Good.

    08:46 2nd-degree type I.

    08:50 What is another name for Wenckebach.

    08:55 Good.

    08:56 2nd-degree type I.

    09:00 Thank you for watching this part of our video series.

    About the Lecture

    The lecture Third Degree AV Block (Nursing) by Rhonda Lawes, PhD, RN is from the course Analysis of Abnormal ECG Strips (Nursing).

    Included Quiz Questions

    1. It is a complete heart block
    2. There is no electrical communication between the atria and ventricles
    3. There is not one QRS for each P wave
    4. It is an incomplete heart block
    5. The only electrical communication is in the atria
    1. Lyme disease
    2. Autoimmune disease
    3. AV nodal disease
    4. Myocardial infarction
    5. Liver disease
    1. There is an AV dissociation and escape rhythms that may be junctional or ventricular
    2. The PR interval is more than 0.20 seconds
    3. The PR interval is constant except for dropped QRS
    4. It progressively lengthens, then the QRS complex is missing
    1. Internal pacemaker
    2. Defibrillation
    3. Cardioversion
    4. Heart valve surgery

    Author of lecture Third Degree AV Block (Nursing)

     Rhonda Lawes, PhD, RN

    Rhonda Lawes, PhD, RN

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