ECG of Atrial Flutter and Fibrillation

00:01 Another form of a supraventricular rhythm which is similar to the one we just saw but slightly different is called atrial flutter.

00:10 And again, this is a circus movement of depolarization in the atrium with every - often every third or fourth beat getting through the AV node causing a ventricular depolarization.

00:20 Let's see an example. Again, it's a circus movement, it usually goes at 300 per minute.

00:26 Often, 2:1 block so you get a ventricular rate of 150. And on the EKGs, the flutter waves have a sawtoothing appearance.

00:36 Looks like sawtoothing.

00:38 Here we see an example. Notice, this is a heart rate of 75, so that's - if you divide 300 down to 75 that's 4:1.

00:48 So, this is 4:1 flutter and you'll notice the beats occurring.

00:53 They're actually - there are some 4:1, and then sometimes it'll go to 3:1 and 2:1, it can go back and forth.

01:01 In this case it's 4:1. And look at the flutter waves there.

01:04 You see the sawtoothing in between the QRSs? If you see the first beat that's the QRS.

01:10 And then sawtooth, sawtooth, sawtooth, QRS, sawtooth, sawtooth, sawtooth, QRS, sawtooth and so forth.

01:19 You'll notice also this patient has a left bundle branch block.

01:25 They have a wide QRS, greater than three little boxes that preexisted the atrial flutter.

01:31 And again, we're in this pattern, the sawtoothing pattern means atrial flutter usually at 300 per minute.

01:39 You'll notice there's one big box between the saw teeth.

01:42 Here's another example. Here - beautiful flutter waves.

01:47 Notice, again, this is also a rate of - ventricular rate of 75, so it's 4:1 atrial flutter.

01:54 See how clear it is. Sometimes it's not quite so clear but in any case, this is another example of 4:1 AV block with atrial flutter.

02:04 And of course, the ventricular rate is 75 per minute.

02:08 Now, atrial fibrillation is not as organized. It's not a circus movement.

02:13 In fact, it's chaotic atrial activity in the atria.

02:16 I like to tell the patients with my hand.

02:19 So, this is a supraventricular tachycardia, it's going very fast and then periodically the ventricle goes.

02:25 But what happens in atrial fibrillation is this.

02:29 It's totally random and irregular; the number of beats that are getting through.

02:35 So, you have a completely irregular heart rhythm as opposed to atrial flutter which is regular or supraventricular tachycardia which is regular.

02:43 So atrial fibrillation again, the result of multiple chaotic depolarization waves in the atria.

02:50 Some of the waves get through the AV node in a random fashion leading to a tachycardia with a very irregular heart rate.

02:58 The QRS is usually narrow, again, unless we get to the same thing I mentioned before.

03:03 The heart rate is so fast that you get a so-called rate related right bundle.

03:08 And that occurs only when the QRSs are very close together.

03:12 So, here is atrial fibrillation with a reasonable heart rate, not too fast.

03:18 Notice, you - the distance between the two R - the R's of the QRS is completely random.

03:26 Some are short, some are long, some are medium.

03:30 So, this is called an irregularly irregular rhythm. It's completely irregular random.

03:37 And you can do that by - if you have a compass and you put it on the first QRS to QRS rate the next one, it's much shorter.

03:47 Oh, the next one is much longer. Oh, the next one is intermediate. Oh, it's much shorter.

03:51 So again, the next one much longer.

03:53 And you'll see little waves occurring there but they're not organized.

03:57 They're - they are fibrillation waves, not flutter waves.

04:02 So, the heart rate is more irregular than in flutter.

04:04 The waves seen between the QRS's are variable in size and shape.

04:08 They're not nicely sawtooth. There's no sawtoothing.

04:12 Here we see, again, this example of a normal ECG, normal QRSs, no hypertrophy, no myocardial infarct and a markedly irregular heartbeat.

04:23 Look at the bottom strip. You'll see how totally irregular that is.

04:27 You don't see sawtooth, you don't see abnormal P waves. This is atrial fibrillation.

04:32 You can tell it by the grossly irregular heart rate.

04:36 You can measure out the distances between the two R waves all the way through, every one of them is slightly different.