EKG of the Week

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This patient is a 59 yr old man with history of CAD, paroxysmal afib who presented with feeling of rapid HR and chest pain. The computer read this EKG as sinus tach. Is it??

+ EKG Interpretation

Dr. Ohlbaum's Explanation

I think we all agree it is fast, and regular and narrow. What can do that? Sinus tach would give you a regular narrow complex rhythm but would it be this fast? This is not a young person on a treadmill. What is the maximal sinus rate? The max sinus rate is 220-age, so for this man his maximum (with exercise) is right about 160. And he is just lying on a bed, so this is probably too fast.

What else? This is clearly not the afib he has had in the past since this is regular. SVT can give you a regular narrow QRS tachycardia but that is usually just a bit faster than this. He does not have a retrograde P.

When I see a regular, narrow complex rhythm right around 150, my first thought is atrial flutter with 2:1 block. Once you think of that, it is easy to follow flutter waves-I look at different leads since in some leads one of those flutters will often be hiding in the QRS. If you cover up the QRS in the inferior leads you can see the flutter in the basline and if you use calipers in V2 and V3 you can march a little flutter wave “straddling” the T wave.

This is atrial flutter with 2:1 block.

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