EKG of the Week

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+ EKG Interpretation

Dr. Ohlbaum's Explanation

There are several interesting things on this EKG. I want to start at the very beginning. Before you even start to look at the tracing, do you notice anything “odd”?

Look to the far left at the very beginning. Do you notice the rectangular “thing” at the beginning where the line goes up and over and then down before it starts to record. Look at any other tracing you have and you notice that it goes up 10mm (ie 2 big boxes), over one big box and then back to baseline. This one goes up 20mm. What does that mean? That up and over and down is the standardization. It means that 10 mm is really 10 mm or that 10mm is a millivolt. That is what it should be and you should notice that on every EKG as you glance at it. Here it means that it is blown up double size so 20 mm is “really” only 10 mm and it takes 20 mm to be a millivolt. So, everything looks too big. That means that when the volts of an R or S is huge it is NOT LVH, it is just blown up big. And an ST that looks like it is 2 little boxes down or up is really only one little box up or down.

It is important to notice that before you look further. Why do people record like this? Well, I never do. It is usually done by someone who is trying to pick something (usually a P wave) out of artifact but remember, the artifact gets doubled too so I think it stays just as confusing. And people think the ST is more depressed which is confusing. And worst of all, if you do it on purpose on one patient the machine stays that way for all the patients who follow unless you are very careful to set it back (if you notice a machine doing this the easiest fix is to turn whole machine off and then back on- it comes back up at the preset normal)

OK. So now let’s look at the actual EKG. Is it regular? The P’s are regular though many seem to hide in the preceding T wave. But the QRS is not regular. Why is that? Is there a P before every QRS? Yes. But is there a QRS after every P? No. There are QRS complexes after the first 4 P waves but the PR is getting longer and longer, and the 5th P wave (which is hiding in a T) is not followed by a QRS and neither is the 9th. So, this is sinus rhythm, with 2nd degree AV block (some of the Ps are conducted and some are not) and it is Mobitz I because the PR gets longer and longer and then a QRS is dropped.

What else? Well the P looks big but remember it is double the size it should be. Same with some of the QRS voltage. I think the inferior Q’s raise the question of an old inferior MI but remember III alone would not count so it comes down to AVF- is that Q one box wide, one box deep (would need to be 2 on this paper) and ¼ the size of the R wave. I think it is borderline and would call it “possible” old inferior MI. The ST and Ts are ok.

Further Reading:

Follow up EKGs:

Full EKG Index