Wolff-Parkinson-White Syndrome (Nursing)

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

00:04 On this portion we're going to talk about Wolff-Parkinson-White syndrome.

00:10 Now we always start with a normal sinus rhythm.

00:13 So see if you can pause and recall as to why this particular rhythm we consider to be normal sinus rhythm.

00:23 Alright, no matter what you got there remember, stopping and trying to recall information from your own brain is the most effective study strategy.

00:34 Now let's quickly recap what an ECG strip looks like when a heart is beating in a normal sinus rhythm.

00:41 There's a P wave with a normal shape and duration preceding every QRS complex.

00:46 The rhythm is regular, but remember that it can vary slightly during respirations.

00:51 Also, the rate is within the normal range, which is between 60 and 100 beats a minute.

00:58 And lastly, these P waves are positive in leads I, II, and biphasic mean they have kind of like a little notch in them, in lead V1.

01:08 With these basic characteristics, you know that this is a healthy heart in a normal sinus rhythm.

01:15 You're really getting good at this.

01:17 Now in with all of our practicing, when a patient comes in with this ECG, you already know that this isn't a normal sinus rhythm.

01:26 This patient has Wolff-Parkinson-White syndrome.

01:30 Let's take another look at our beating heart here and do a brief recap on the waves and intervals of an ECG strip.

01:38 Remember, the electrical impulse travels from the atria to the ventricles and its pathway an influence on the heart muscle is what's reflected on the ECG strip.

01:48 Now the impulse originates in the sinus or the sinoatrial or here's a third name, the SA node, they all mean the same.

01:57 It travels from the SA node through the left and right atria, causing their contraction which is reflected in the ECG as the P wave.

02:08 The impulse then heads through to the AV node, but it doesn't just pass through, it gets delayed or slowed down.

02:16 This delay is documented in the ECG strip as the PR segment.

02:22 Next, we have the QRS complex, which represents ventricular contraction.

02:28 This contraction is caused by the impulse entering the ventricles and dispersing through the Purkinje fibers.

02:35 The next wave is the T wave, which is caused by the repolarization or relaxation of the ventricles.

02:42 This period of time or interval between ventricular depolarization and repolarization is represented as the ST segment in an ECG.

02:52 Finally, we have the U wave, which actually may or may not be present on the ECG strip.

02:59 Although we don't exactly know what causes it, it's believed to be the result of a delayed repolarization of the Purkinje fibers.

03:06 Well, WPW is a congenital condition in which the impulse originates in the SA node, or somewhere else inside the atria, but it doesn't pass through the AV node.

03:18 So if it doesn't pass through the AV node to get to the ventricles instead, it travels down an abnormal accessory conduction pathway that bypasses the AV node.

03:29 This accessory pathway is called the bundle of Kent.

03:33 In Wolff-Parkinson-White or WP W, the ventricles are depolarized faster than usual.

03:40 So because the normal delay that happens in the AV node doesn't take place, This is called the preexcitation syndrome or PES.

03:50 So this is a heart condition in which part of the cardiac ventricles are activated too early.

03:55 See, without the AV node delay, the period of time between the atrial depolarization and ventricular depolarization shortens meaning the PR interval shortens.

04:07 Again this is how the impulse should travel.

04:13 And here it is how it travels in a heart with Wolff-Parkinson-White.

04:44 Let's talk about the symptoms of WPW.

04:48 Symptoms most often appear between the ages of 11 and 50.

04:52 However, it is one of the most common causes of a fast heart rate in infants and children.

04:59 Now caution you, you know that infants and pediatric patients have faster heart rate patients than adults.

05:06 But we're talking about fast heart rates that are problematic.

05:10 So WPW is one of the most common causes of fast heart rate problems in our pediatric population.

05:18 Now how it will feel when that heart is going too fast? It will feel like they have this rapid pounding heartbeat.

05:24 They're going to feel dizzy, because they're not being perfused very well, and they're going to feel light headed.

05:32 Anytime you're looking at a list of symptoms, ask yourself why.

05:36 So why would the patient say they feel like they have a rapid pounding heartbeat? Well, that one's easy, because they have a rapid pounding heartbeat, right? It's going through that accessory pathway.

05:46 It's going faster than normal.

05:49 And that is why it feels like that to them.

05:52 Do you remember what we talked about why they would feel dizzy and lightheaded? Good, I hope you said, Well, they're not perfusing their brain very well, because that rapid heartbeat doesn't pump as efficiently as normal sinus rhythm.

06:09 So the more you can picture what that looks like, into your mind, what it would feel like as a patient, you're going to ask better H and P questions, better assessment questions, and you're really going to be able to recognize the signs and symptoms when you see a patient who's struggling with WPW.

06:28 So let's start looking at the ECG criteria for WPW.

06:33 Now it's all about the delta wave.

06:37 Now look, we did the P the Q, the R, the S, the T, the V, the U.

06:42 what's a delta wave? Well, a big hint is if you look at the changes, the difference in the QRS complex you see in this strip, in what you saw in normal sinus rhythm.

06:54 Well, if you start moving through those seven steps, what do you identify is different? Well, hopefully you picked up the presence of the PR interval is much shorter than normal, right? It's pretty close, right up to what we see is the QRS, but that QRS looks kind of weird.

07:14 Look, it's it's wider than normal, and it's actually wider than the normal range of 0.12.

07:21 Now they call this kind of a slurred onset of the QRS waveform.

07:27 That's actually the delta wave.

07:29 So instead of looking like a typical QRS where we have Q, straight up R, straight back down S.

07:38 This one has a kind of a slurred onset.

07:42 It looks like a lazier curve moving up there.

07:46 In that part of the waveform, that's the delta wave.

07:50 Now you'll always see it in the early part of the QRS.

07:52 So that is something to look for in WPW.

07:56 Two things: short PR and that slurred start up to the QRS, and that's the delta wave.

08:05 Okay, now we've brought this in the black line is if this was just a normal sinus rhythm beat.

08:13 That's why we have a normal PR interval, we've got QRS, the T wave that all looks normal.

08:20 But why I wanted to show you this is I wanted them to draw in in a green line and shaded area, that's the area that's different in a delta wave.

08:31 So if I'm looking at a normal sinus rhythm, I would see that black line that's how it would look.

08:36 But a delta wave, the part of the QRS complex that changes will be shaded in green