Right bundle branch block – Part 2

Generally speaking, right bundle branch block does not mimic or obscure the ECG diagnosis of acute STEMI the way left bundle branch block does.

But how do we know what’s “normal” for right bundle branch block? One of the things we consider is the rule of appropriate T-wave discordance.

This concept usually comes up in the context of discussing left bundle branch block, but it’s also useful for right bundle branch block — with a caveat!

With right bundle branch block the T-wave should be deflected opposite the terminal deflection of the QRS complex.

In other words, when the terminal deflection of the QRS complex is positive, the T wave should be negative, and when the terminal deflection is negative, the T wave should be positive.

That’s a little bit different from left bundle branch block where we use the majority of the QRS complex as opposed to the terminal deflection.

RBBB_discordant_T_waves_wm

The blue and red arrows show the expected relationship between the terminal deflection and the T wave with RBBB.

Consider the following case.

EMS is contacted for a 77 year old male complaining of chest pain. On arrival, you find the patient lying supine on the couch. He is ashen in color and diaphoretic with absent radial pulses. He responds sluggishly but appropriately and states that he is having severe sub-sternal chest pain.

His shirt is cut off and the combipads are applied, revealing the following heart rhythm.

RBBB_STEMI_Paddles_wm

It appears to be sinus rhythm with wide QRS complexes and occasional PVCs.

A 12-lead ECG is acquired.

RBBB_STEMI_01_wm

Using the concept of “appropriate T wave discordance” is there anything about this ECG that bothers you?

See also:

Right bundle branch block: Part 1

Right bundle branch block: Part 2

Right bundle branch block: Part 3

7 Comments

  • Scott T says:

    great blog, i am learning so much,keep up the good work

  • Tom B says:

    Thanks, Scott T! I'm glad you're enjoying it.Tom

  • Christopher says:

    Would I be seeing T concordance in the inferior leads? Inferior ischemia?

  • Tom B says:

    C. Watford – You're definitely seeing inappropriately concordant T wave inversion in leads III and aVF.It could be ischemia. Or, it could be reciprocal changes! Look at the precordial leads and see if anything stands out….Tom

  • Anonymous says:

    It is rather interesting for me to read this article. Thanx for it. I like such themes and anything that is connected to this matter. I would like to read a bit more on that blog soon.

  • Anonymous says:

    It is certainly interesting for me to read the article. Thanks for it. I like such themes and everything connected to them. I definitely want to read a bit more on that blog soon.

  • Igor PT says:

    indeed, precordial leads make the diagnosis, V1 it's normal, V2 and V3 have the rsR' pattern ( or qR?), and with a final S', and a positive quick positive T wave, not normal in the presence of RBBB, in the leads with rsR' pattern, that should strongly suspects of STEMI. The reciprocal changes in inferior leads also state the ods, and undoubtly, V4 makes the diagnosis of STEMI!

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