Sunday, September 15, 2013

Right Bundle Branch Block with ST elevation in V2, V3. Why?

This young male patient had a very atypical presentation for STEMI (near syncope and abdominal pain after smoking an unknown drug), but we can pretend that it was not atypical and think about how we would interpret the ECG:

There is right bundle branch block with an rSR' in V1 and wide S-wave in lateral leads.  The ST segment is elevated in V2-V4.  Usually, in RBBB, the only secondary repolarization abnormalities are some minimal ST depression in V2 and V3 and there should not be ST elevation (see image of normal RBBB at bottom, and image of RBBB with anterior STEMI still further down).       In the right context, might this be STEMI?  Interpretation below.

My Interpretation:

Normally, in RBBB, the transition from rSR' to RS or to qRS is between leads V3 and V4.  On this ECG, the transition is between V1 and V2.  There is no R' wave in V2 or V3, thus there is no discordant ST depression and discordant negative T-wave, as one would normally see in these leads in RBBB.   Instead, there is a wide S-wave, which in RBBB is usually followed by an upright T-wave, but not by ST elevation (in uncomplicated RBBB).   

But this case is probably an exception: in a young male, when the S-wave is in leads V2 and V3 (which is very uncommon in RBBB), it may be normal to have some ST elevation, as young males usually have ST elevation in V2 and V3 (early repolarization) and in this case of RBBB, that ST elevation would not be hidden by the repolarization abnormalities (ST depression and T-wave inversion) which normally come with RBBB.

My admittedly invented diagnosis: RBBB with early transition, and with ST elevation due to early repolarization that is not obscured by RBBB because of the early transition.

In any case, when I was showed this ECG by a worried resident, I was quite sure it was not STEMI even before hearing the clinical history, and much moreso after.  And he ruled out for MI.

Normal RBBB:
                          There are secondary repolarization abnormalities: ST depression and T-wave                   inversion in leads with an R' (V1-V3)

RBBB with anterior STEMI (LAD occlusion):
There is STE in V2 and V3 concordant with the R' wave.  This was an acute LAD occlusion.


  1. Dear Sir
    1. Why the 1st 2 ST segments are different?
    2. The R' wave in v2 is adherent to the R wave. Isn't it?
    3. Is there a Q wave in aVL?
    4. Does it differ if R' is shorter or taller than R ?

    1. 1. All I can say is they are different leads.
      2. That second "adherent" R-wave is simultaneous with the S-wave of the rSR' in V1, just confirming that the voltages are opposite in these two leads because of the earlier transition.
      3. There is, but that is common in RBBB (without MI)
      4. In RBBB, R' is almost always taller than the r-wave, and always wider.

  2. Is it just me but does it look like we have some type of abarent p wave activity? There are a couple of p waves that look strange and early conduction simular to a PAC.

    1. There is sinus "arrhythmia" with varying rate. The second complex is distorted by artifact. But I think the p-waves across the bottom (lead II) are all alike. No?

      Steve Smith

  3. I think the morphology doesn't quite match that of Brugada type 2 or 3, but the snycope, RBBB, and ST elevation immediately made Brugada jump into my differential. Also, the fact the patient had smoked something made me even more concerned that a drug may have unmasked his underlying disease. Could you provide a little discussion on why you didn't consider Brugada? (I have a hard time with Brugada type 2/3).


    1. Brugada always has a downsloping ST segment and inverted T-wave in V1. Types 2 and 3 always have a saddle configuration in lead V2. See these posts:

  4. Does RBBB on an ECG imply that there is early transition or should both RBBB and early transition be listed on the ECG report?

    1. RBBB will always have a large R wave in V1 and thus one could say "early transition", except that the term is meant only for normal conduction. So I would not use it in RBBB.


DEAR READER: I have loved receiving your comments, but I am no longer able to moderate them. Since the vast majority are SPAM, I need to moderate them all. Therefore, comments will rarely be published any more. So Sorry.

Recommended Resources