Friday, March 16, 2018

Are these Wellens' waves?

This ECG was sent to me by one of my residents, who was puzzled by it:

This ECG is from a 21 yo M with PMH of poly-substance abuse.  He presented with nausea and vomiting after drinking the night before.  He denied any chest pain or shortness of breath.  He has no other significant medical history he does not take any medications.

This one was read by the computer as "Acute STEMI" (!!)
What do you think?
My resident thought this looked like Wellens' pattern in lead V2

Some hours later, this was recorded:
Now there is resolution of the inverted T-wave in V2

Electrolytes were normal.

My response:

I looked at the ECGs before reading anything.

The one read as acute STEMI was clearly early repol to me.  

What particularly confuses one would be the T-wave inversion in V2.  However, also notice that there is an rSr' in both V1 and V2.  Notice that in the second ECG, these are gone and the T-wave inversion is not present.  Both of these findings (rSr' and T-wave inversion in lead V2) are seen if V1 and V2 are recorded too high on the chest, which is a very common recording error, but not well known among physicians.  The second ECG is normalized.  I strongly suspect that they were not recorded with the leads in the same position.  Or the patient was lying down for the first one and sitting up for the second, which changes the position of the heart in the chest.

I showed this to Brooks Walsh, see below.  He added this important aspect:

There is one complication: normally, the P-wave in V1 is biphasic.  When the leads are placed too high, the P-wave in V1 is all negative, because all atrial depolarization is moving down, away from the highly placed leads.

In this case, there are all upright P-waves in V1 in both ECGs.  But look also at limb leads: the P-wave is inverted!  Thus, in this case, there is an ectopic atrial rhythm, not sinus rhythm.  This ectopic atrial rhythm accounts for the upright P-waves in V1 and V2, even though the leads were placed too high.

In other words, if you depend on P-wave morphology in lead V1 to tell you if the leads are placed too high, you would be misled!

Learning Points:

1. rSr' in lead V1 is often a result of leads placed too high

2. this also results in T-wave inversion in lead V2.

3. this should also result in an all negative P-wave in V1, unless there is a co-existing ectopic atrial rhythm, as in this case.

My friend, co-author and frequent blog poster, Brooks Walsh, just wrote a great article on this topic.

Here it is:

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