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" (!!)
Some hours later, this was recorded:
Electrolytes were normal.
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:
This one was read by the computer as "Acute STEMI" (!!)
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| What do you think? My resident thought this looked like Wellens' pattern in lead V2 |
Some hours later, this was recorded:
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| Now there is resolution of the inverted T-wave in V2 |
Electrolytes were normal.
My response:
I looked at the ECGs before reading anything.
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: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!
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:
Thank you..
ReplyDeleteAny significance of upright P wave in lead aVL?
It just means that the bulk of atrial depolarization is towards aVL
DeleteSorry; little correction..... I ment T wave...
DeleteNo. If Wellens' is due to a proximal LAD occlusion (but not mid-LAD) that reperfused, there will be T-inversion in aVL as well as precordial leads, if that is what you mean.
DeleteGREAT case that illustrates a number of important points about lead placement. As per Drs. Smith & Walsh, the most probable reason for the change in ST-T wave appearance in lead V2 is a change in electrode lead placement for the reasons stated in this post. I’d add that even if electrode lead position was accurate in the 1st ECG — that the biphasic (pos-neg) ST-T wave in V2 would still most likely be part of the early repolarization pattern, in which lead V2 here simply reflects TRANSITION between the prominent negative T wave from V1 — to the prominent positive T wave in V3 in this patient with marked repolarization changes. Upward sloping ST segment concavity (ie, “smiley”-configuration) plus prominent J-point notching in numerous leads all strongly support this being a repolarization variant. The rhythm is interesting. Lack of a clear upright P wave in lead II in the 1st ECG (no upright P is seen in any of the 6 beats of the long lead II) — tells us that the mechanism of the rhythm in the 1st ECG is not sinus. The presence then of an upright P wave in leads I and aVL + a neg P in lead III confirms this to be a low atrial or coronary sinus rhythm. Then in the 2nd ECG — IF you focus on the long lead II rhythm strip — you will see a CHANGE in P wave morphology (ie, there is a tiny positive deflection in front of the 2nd QRS in ECG #2, and then a somewhat larger P in front of the 3rd QRS complex — but P waves are absent in front of all other beats!). Given the gradual change in R-R intervals over the course of this long lead II rhythm strip — this most likely reflects a wandering atrial pacemaker (which is a common normal variant rhythm in a young adult without underlying heart disease). So as per Drs. Smith/Walsh — the reason P waves in leads V1, V2 in the 1st ECG do not have a negative component despite almost certain placement 1 or 2 interspaces too high — is that the P wave is not arising from the SA node. Final Point — In addition to the presence of an r’ and P wave negativity in V1, V2 — the appearance of a QRS complex in V1, V2 that looks very similar to the QRS in lead aVR is another clue that the V1, V2 electrodes were probably placed too high when ECG #1 was recorded (Note the QRS in leads V1, V2 looks very different compared to that for the QRS in lead aVR in ECG #2, in which presumably electrode lead placement is more accurate). So, I’d add a 4th LEARNING POINT: Always begin the interpretation of ANY 12-lead ECG by spending the 2-3 seconds it takes to perform an “educated look” at a simultaneously-obtained long lead II rhythm strip. Do this BEFORE you look at the rest of the 12-lead. You’ll be AMAZED by how doing so will pick up otherwise too-easy-to-overlook changes in the rhythm. And if you do not see an upright P wave in the long lead II — then you KNOW that the mechanism of the rhythm is not sinus. THANKS to Drs. Smith and Walsh for presenting!
ReplyDeleteThe link to Dr. Walsh's article seems to be broken. Try: http://www.ajemjournal.com/article/S0735-6757(18)30126-8/fulltext
ReplyDeleteWow... Prof Ken Grauer.... I think I have just become so much smarter by reading your comments.
ReplyDelete