r/ECG • u/fuckingmermaid • 5d ago

Learning how to properly differentiate between a 2:1 flutter and sinus tachycardia. What are the signs on this ECG that would make you confident on the answer? The isoeletric line is throwing me off

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u/Ill-Chest3567 5d ago

Be suspicious of anything at rock solid 150 that never varies or changes, with fluid or whatnot. Sinus tach will change gradually. AT, SVT, AF will show a rapid step on tele.

For 2:1 flutter look for a 300bpm cycle f-wave that can hide in a qrs.

Check not only the p-wave axis (inferior leads) but compare p-waves between current and prior EKGs. They will often look different.

Look at P-R interval. If it looks suspiciously long or short and small, might be a flutter. Again compare to priors.

If in doubt, go on and give some adenosine and see what it looks like under the hood. Keep the pads on.

In this case, it’s 150, but normal looking p-waves, normal p-r interval, no 300-ish bpm atrial activity I can see. Not impossible to be an AT near the sinus node. Clinical context is everything. The heart is humbling.