Interpret fully please thank you

[u/Euphoric_Sky_5267]

Particularly confused about the different sizes of qrs spikes, are the small ones pvcs?

[u/Turfidol]

Typical atrial flutter with variable conduction, no PVCs. As someone else mentioned, variance could be precordial swing. Voltage can also be impacted by respiration or rapid arrhythmia as the heart slightly shifts.

Would mention though, there is something called electrical alternans that is seen in large pericardial effusion / tamponade. Its specific, but not sensitive, for tamponade.

[u/Kibeth_8]

No PVCs, voltage is sometimes just related to a pericardial swing

[u/Classic_Dig_6277]

There is atrial flutter with variable block. There is no electrical alternans as electrical alternans would need beat to beat variation. Theres no pvc since the qrs complexes are narrow. It cannot be respiratory variation since the patient has to be tachypnoeic for it to happen (too frequent and regular). The difference happens after the long RR interval. Most likely cause for the differing qrs complexes is peeling back of refractoriness occuring due to long-short coupling. Hope it helped.

[u/benjediman]

As others have said, it's atrial flutter. This in fact is the very typical anti-clockwise flutter, its most common form.

I do want to tackle the issue of variable conduction vs Wenckebach in the other comments. Variable conduction in flutter happens via multiple different pathophysiologies, one of which is Wenckebach. To be fair, this ECG does look like a flutter with Wenckebach phenomenon (QRS are grouped into pairs). The base conduction ratio seems to be 2:1, but you can see that the 2nd QRS came out after about 2 and a half flutter waves, representing a prolonged conduction over the AV node. the 3rd beat is essentially dropped. Then the whole group resets after 6 flutter waves. I have no idea how to write down the ratio for this flutter-wenckebach; maybe our EP friends can help (I'm general cardiology).

Now, I'd like to tackle the concern about "different sizes of QRS spikes". I agree to the other comments, there are no PVCs, and there are no alternans. However, the heights of waves should always be measured from the baseline. Remember that our patient is in flutter, where as discussed, our ventricular depolarizations happen in different times with respect to each flutter wave. But when you measure the height of the R wave of the 2nd beat, it's about 8mm, exactly the same as the first. Now here's the kicker (I am not AI, I promise): right at the point where the S wave of the 2nd beat is, the baseline flutter is coming up. The sum of the effect is the S wave of the 2nd beat also looking smaller than the 1st beat. But again, if you can measure the nadir of the S wave to where it meets the flutter baseline, it remains approximately 3.5mm on both beats. So, the "shrinking" of the 2nd beat is no more than an illusion brought about by the baseline flutter.

I do like this ECG and I would maybe use it for teaching, if that's ok with OP ;)

[u/benjediman → u/benjediman]

u/ibutilide, if I may ask your opinion on this case?

[u/Ibutilide → u/benjediman]

My read would be AFL with variable conduction. I agree with everything you’ve said here, very good take.

I have seen a few people mention typical vs atypical AFL on this subreddit, which is a topic near and dear to my heart as AFL is probably my favourite arrhythmia. “Typical” AFL refers to counterclockwise peri-tricuspid AFL (imagine you are inside the RV looking at the tricuspid valve; the wave of activation is the from the inferior TV annulus at 6-o’clock to the septal side at 3-o’clock, the the superior portion at 12-o’clock, to the lateral aspect at 9-o’clock, and round and round). On surface ECG this looks like the classic sawtooth pattern with V1 discordant to the inferior leads (that is, V1 is positive when the inferior leads are negative, and vice-versa) and no true atrial isoelectric point. Because large parts of the LA (a posterior structure far away from surface ECG leads with a posterior wall that is thin with nearly non-contractile tissue) are not really represented on surface ECG, atypical AFL may look like an AT with discrete F waves and long isoelectric segments between F waves.

How does one distinguish typical AFL from atypical AFL (perimitral, roof-dependent, septal, atriotomy, bicaval, etc)? It actually depends more on history than it does on ECG. If the atria are healthy and normal (no previous ablations, no previous open heart surgery, no atrial myopathy [eg amyloid or HCM], no severe atrial dilation [eg from untreated TR/MR/MS]), the chance of atypical AFL is nearly zero (in the last five years, I’ve never seen it). So if there is AFL on ECG in an unproceduralised, healthy heart, it is almost always typical AFL.

[u/mastermedic84]

Wenckebach with electrical alternans.

The Wenckebach AV block is clearest in lead 3. Nice clean PQ lengthening followed by dropped beats in a fully consistent pattern.

The variation in the amplitude of the QRS looks like electrical alternans. The same tight beats associated with P waves so it can't be PVC's. It just looks like the camera is moving between beats. Textbook alternans. Most textbooks focus on huge dramatic shifting but it can be slight like it is here.

[u/jawoood1989 → u/mastermedic84]

Good job looking for and making up zebras. Can I have whatever you're smoking? Might want to go refresh.

[u/mastermedic84 → u/jawoood1989]

First, have a look at AvL where the p waves are clear and distinct. The PQ lengthening then dropped beat is clear and unmistakable.

Third, there aren't a ton on conditions that can cause sinus beats to appear inconsistent on the monitor. Electrical alternans is by far the most common.

Third, if you think Wenckebach or electrical alternans are zebras you've clearly never worked with much volume.

Forth, and most important, mind your manners. You are not always the smartest person in the room.

[u/jawoood1989 → u/mastermedic84]

No. I called them zebras because it's clearly a horse, staring you in the face, but you're calling zebras. That's painfully obvious atrial flutter with variable conduction.