Hi, welcome to our video series on electrocardiograms.
In this one, we're going to specifically discuss an atrial dysrhythmia known as atrial flutter.
Now, here it is, the ECG that's normal sinus rhythm.
That is the most important place to start when you're talking about any dysrhythmia.
You want to know what normal is, so then you can differentiate between what is abnormal.
Now, we're back with our patients. This time, we need to check on this woman.
After our previous discussions, at first glance,
we definitely know something is wrong with this ECG.
But what exactly is it? Let's take a closer look. This ECG is atrial flutter.
So, compare atrial flutter to atrial fibrillation.
Look at that. With atrial flutter, we've got these fairly consistent waves
in between the QRS complexes. But in the atril fib strip, we've just got trash, right?
There's no real discernable waves, things that we can measure.
So, the difference between atrial fib and atrial flutter
is another way for you to help keep these in your long-term memory.
So, look at the QRS distances on atrial fib. They're very irregular.
But if we look at the ones in atrial flutter, hey, that seems to be more consistent.
So, we're going to use this example to help you understand
and visualize what's actually going on in the heart of someone experiencing atrial flutter.
For this case, I'll give you a clue.
The main characteristic of this kind of condition has to do with this sound.
Any ideas? Right. That was a saw.
It makes me think of those scary movies we watch at Halloween.
But atrial flutter has sawtooth P waves and a regular QRS rhythm.
So, take a look at that saw blade.
That is a great graphic to help you look at these waves
and see why they're called sawtooth waves.
Now, once again, let's recap.
Remember, the electrical impulse travels from the atria to the ventricles,
and its trajectory is what's going to get documented on the ECG strip.
So, at first, the electrical impulse gets created at the SA or sinoatrial node
and starts travelling toward the AV node.
This causes contraction of the musculature of the atria and the formation of the P wave.
Now, when the impulse reaches the AV node, it doesn't just pass through it.
Remember, it gets delayed. This delay is documented in the ECG strip as the PR segment.
So, the PR segment corresponds to the passage of the impulse through the AV node.
Next, we have a QRS complex.
The QRS complex represents ventricular contraction
which is caused by the migration of the impulse from the AV node to the Purkinje fibers.
Moving on, we can see the T wave.
Now, this is caused by repolarization or relaxation of the ventricle.
And as previously mentioned, the interval between ventricular depolarization and repolarization
gets documented as the ST segment.
Finally, we have the U wave, which is believed to be the product
of a delayed repolarization of the Purkinje fibers.
And remember, this wave may or may not be present on the ECG strip.
So, here we have normal sinus rhythm. All is well. Look at that. It's a beautiful thing.
The electrical impulse is moving from the atria down through the ventricles,
SA node, AV node, it's exquisite. It's like a dancer.
This is how an efficient heart is supposed to move in response to electrical activity.
Now, look at atrial flutter. If you covered the top half of your screen
and you just looked at the bottom, they look pretty similar.
And what's going on in the ventricles seems to be similar
in both normal or sinus rhythm and atrial flutter.
But look at what's going on in the atrium. That's why we call this atrial flutter.
That tells us where the problem is.
You see that electricity going around and around and around in circles?
That's what's giving us those flutter waves in between the QRS complexes.
Because you have these seven steps
and we've discussed them in each one of our parts of the video series.
So, I'm not going to read through them,
but just remind you, you have to be methodical when you're interpreting ECGs.
The more consistent you are in moving through the steps,
the more accurate your analysis of the ECG strip will be. So, let's do it together.
So, assess the heart rate and rhythm.
So, remember we look at a six-second strip, we count the QRS complexes,
and we multiply that by 10. That will tell us how many beats a minute.
Now, just a quick review. Why are we multiplying it by 10?
Well, if we have an accurate six-second strip, we know there are 60 seconds in a minute,
so that's why we multiply that number by 10.
Now, we have a number for you up on the screen. Pause the video for just a minute
and make sure that you can perform the same assessment of the heart rate.
Now, we're going to look and see if the rhythm is regular.
So, consider both the ventricular and the atrial rates.
So, you're going to want to measure P to P to P.
Whoa, okay, so we're looking at that, the atrial rates in between.
These look different than other P waves that we've seen
and very different than what you see in normal sinus rhythm.
So, look at those rates.
Can you come up with the same numbers that we're showing you on the screen?
Now, we looked at those P waves.
We know that they are sawtooth in appearance,
and they happen with a very regular rhythm.
In fact, when you had those calipers, if you went from the peaks of the P wave
and measured all the way down, you would see that those truly are consistent.
They happen with a very regular rhythm, and it is higher than the ventricular rate.
Well, how do I measure the ventricular rate?
Remember, you're looking at those QRSs, and we have more P waves, those sawtooths,
that we have QRS complexes. So, we're looking at those P waves.
Atrial flutter is going to have this variable AV conduction. How do I know that?
Well, sometimes, I'm going to see three waves in between and then four.
I'm going to see a difference in the distance between the QRS complexes.
So, in sinus rhythm, the P wave is that atrial contraction.
It happens, one, before every QRS complex.
An atrial flutter with the sawtooth waves, the P waves are sawtooth shaped,
they happen at regular intervals,
and they represent a much higher rate than the ventricular rate.
So, in this one, they're about 300. Okay, why is that significant?
I promise you, after practice and effort, when you look up at the monitor
and see those sawtooth waves, you're going to know what your patient is in,
what rhythm they're experiencing. Patients don't tend to stay in this very long.
They either convert back to sinus rhythm or they could devolve into atrial fibrillation.
So, keep that in mind, but this has a very distinctive look.
Step three, measure the PR interval. Yeah, you can't, right?
We don't have the normal P wave to do that, so the PR interval cannot be measured in atrial flutter.
So, sawtooth waves, impossible to measure the PR interval.
If we're looking at the QRS duration, we're expecting it to be less than 0.12 or three small squares.
Remember those tiny squares? How many seconds are they worth?
If you said 0.4 for each tiny square, you are right. So, 3 times 0.4 is 0.12.
So, the QRS, in order to be normal, has to be less than 0.12.
When you look at the QRS complexes on our atrial flutter strip, yeah, they look normal,
they appear the same, and when we measure them, they're going to be less than 0.12.
So, now is your turn to practice.
I want you to measure the QRS duration on this strip
and compare your answers with what you see on the screen.
Step five, look at the ST segment. Well, can we? No.
It's indiscernible again because we can't see the T wave.
Those sawtooth waves are like divas.
They're the only ones that want to be visible that's why can't see the PR
and we can't see the ST or even the T wave that we would normally look at in step six.
So, measuring the QT interval is one more thing that we cannot measure.
So, pause and recall. I want you to develop a list in your notes of the seven steps,
which parts can be measures in atrial flutter, and which parts cannot.
So, let's compare all in one table sinus rhythm to atrial flutter.
When you're studying, here's what I'd like you to do. I like to use post-it notes.
You can just use your hand, but I think office products are a lot more fun.
I want you to cover different sections and see if you can remember what's underneath them.
So, for example, on this one, I would use six post-it notes.
I would put them over each one of the blocks.
Now, what I would do is try and recall what was underneath the post-it note
just by thinking through what I know, then I would pull the post-it note off,
check my answer, put it back, pick another one.
So, that's an excellent way to do pause and recall
because here's what happens when you take a test.
You look at a chart like and you're like, you read it, I got it. Let me tell you, we don't got it. Okay?
You have to practice questioning yourself.
When you look at a chart and you think, oh, I have this, I know it,
that means it's living in your working memory.
Things don't survive very long in your working memory.
You've gotta nudge them into your long-term memory
and the best way to do that is to ask yourself questions.
But a lot of times, students don't know how to ask themselves questions.
Here's one very simple strategy.
But let's walk through the chart together just so you have an explanation,
but I hope you'll try my study strategy.
That really is effective in helping you make sure you're getting this information
into a part of your brain, in your neocortex, so you can retrieve it when you need it.
So, P waves. Normal sinus rhythm, you have a normal P wave.
It's an atrial contraction before every QRS complex.
One P wave, one QRS. One P wave, one QRS.
Atrial flutter, hey, that's that weird sawtooth thing.
Actually, I think it's beautiful, but you have that sawtooth shape.
They happen at regular intervals but they're happening at a much higher rate
than you see the QRSs. So, we don't have one P wave for every QRS.
We will have multiple P waves for every one QRS.
Let's look at the rhythm. Now, in normal sinus rhythm, the rhythm is regular.
They can vary slightly with what? Right, respirations.
But with atrial flutter, there's a regular ventricular rate.
Now, when we say that, we mean the R-R interval.
So, the very top spikey part of the QRS, if you measure that,
it's going to be regular in atrial flutter.
There's also going to be a regular ratio of flutter waves to the QRS complexes.
So, you may see something like four flutter waves to one QRS.
We would call that four to one atrial flutter. Now, looking at the rate.
Normal sinus rhythm ranges between 60 and 100.
But in atrial flutter, the rate can really range.
Usually, it's greater than 100 a minute,
and it might look like these really narrow complex tachycardia,
so you want to watch really closely to differentiate atrial flutter as the actual rhythm.
So, the heart rate is likely going to be over 100.
The R-R is going to be regular with flutter waves in between and in consistent ratio.
The P waves are going to look sawtooth in appearance.
The PR interval is not able to be measured. And the QRS will be normally less than 0.12.
Thank you for watching this part of our video series.