Cardiology question

[mobey]

I have been doing rhythm interpretation for a long time, but this question stumped me when asked by a fellow student.

If you cannot "see" the atria repolarize because the QRS buries it, why can't you see it in something like a 3rd Degree block?

If this question is not clear let me know.

(basically... why can't you see the "T" wave of the atria when the qrs is absent?)

[scott33]

Look at the difference in size of the QRS (depolarization of the ventricles) compared to the T-wave (repolarization of the ventricles) in the normal EKG. Now apply that same priciple to the atria. The depolarization of the atria show a small insignificant looking P-wave, so following the same logic, the waveform from the repolarization of the atria, would be something you may not even see on the EKG.

I take the "buried behind the QRS" just to mean the event of repolarization.

I have absolutely nothing to back my argument up. :-({|=

[mobey]

I kind of assumed it would just be too small to see... but I am not too sure

[mrmeaner]

If you cannot "see" the atria repolarize because the QRS buries it

I would say that this assumption is the problem. I've heard the same statement, but as scott said, it doesn't seem realistic to be able to see atrial repolarization.

[AZCEP]

The biggest problem is the axis of the lead that you are looking at. Only aVR will give a good look at repolarization of the atria, but very few, if any, providers will routinely use this lead to monitor in. Ventricular activity tends to obscure atrial repolarization, but even when you completely eliminate it, the activity you are looking for is difficult to see.