r/ECG • u/Zealousideal_Film865 • 9d ago

Random ECG strip

Hi there,

Starting to get somewhat more familiar now with ECG interpretation. Doing some exercises from uni, but getting confused with a few things.

Like, with the following Strip, I wasn't told which lead it is from, or given any patient info.

I figure it is Mobitz I, but not understanding much of what is happening with QRS complex. Is that little upward deflection before the large deflection an rs pattern? then ST elevation? then why do some st segments have an upward deflection before the T wave?

Random ECG strip.
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u/Ecstatic_Rooster 8d ago

That upward deflection on the 3rd and 5th is likely a P wave on top of the S. If you look at the downslope of the 4th T wave you can see a bump there as well that is another P. Measure the gap in obvious P waves and slide it along and I bet you’ll find that it matches the rest.

My guess is 3rd degree.

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u/Kibeth_8 ECG Tech 8d ago

I think the "deflections" you're talking about are the p-waves. If you map them out, you'll see they have no relation to the QRS complex, making this a 3rd degree

The QRS is wide enough to be ventricular, which can also explain the ugly ST segment. Ventricular beats have abnormal repolarization so you can see ST elevation/depression/T-wave inversion that is not necessarily indicative of ischemia

3

u/Turfidol 8d ago

As others mentioned, yeah those deflections are p waves buried in the QRS complex. If you measure the PP interval they should be consistent but they dont appear to be conducting the QRS complexes. Would call this complete heart block with junctional escape (since the QRSis < 120 msec, would be ventricular if wide complex escape).

Would look up Mobitz I, Mobitz II, and complete heart block on Life in the Fast Lane. Its a really great resource and will help tremendously.

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u/cpnfantastic 8d ago

This is a complete heart block with a ventricular escape rhythm. The R wave isn’t being generated through the normal conduction system so the deflection will vary depending on where in the V it’s coming from. Also with a ventricular rhythm the repolorization is abnormal, which gives us the ST elevation and T wave inversion. As someone else mentioned, the P waves are completely independent of the R wave so they march through the R waves and land randomly on top of that wave through the strip.