Right bundle branch block – Part II

Once you’ve identified a RBBB on the 12 lead ECG, the next thing you want to do is determine whether or not you’re dealing with a normal RBBB or an abnormal RBBB (or new RBBB).

You may remember this graph from my previous post: Who benefits the most from reperfusion therapy?


It shows that patients with “new BBB” receive the most benefit in terms of lives saved per 1000 treated with fibrinolytics (based on the FTT Collaborate Group). We often here it claimed that patients with “new LBBB” receive the highest benefit from prompt reperfusion therapy, but it’s worth pointing out that the FTT Collaborative Group did not distinguish between LBBB and RBBB.

Generally speaking, RBBB does not mimic or obscure the ECG diagnosis of acute STEMI the way LBBB does. However, sometimes it can (remember the update to Funky Trouble-Looking RBBB with AMI).

So how do we know what’s “normal” for right bundle branch block? We use the concept of “appropriate T wave discordance”. This concept usually comes up in the context of discussing LBBB, but it’s also useful for RBBB (and paced rhythms, ventricular rhythms, non-specific IVCD, and so on).

For RBBB, the concept is that when the terminal deflection of the QRS complex is positive, the T wave should be negative. Likewise, when the terminal deflection is negative, the T wave should be positive.

You may recall this graph from my previous post: Identifying AMI in the presence of LBBB – Sgarbossa’s Criteria – Part II.


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

Remember, the terminal deflection is the last deflection in the QRS complex.

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 combo-pads are applied, revealing the following heart rhythm.


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

A 12 lead ECG is captured.


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

See also:

Right bundle branch block Part I

Right bundle branch block Part II

Right bundle branch block Part III

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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EMS 12-Lead

Cardiac Rhythm Analysis, 12-Lead ECG Interpretation, Resuscitation

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Comments
Jared
59 Year Old Male: Unwell
Field Dx: Uncompensated cardiogenic shock. Tachycardia caused by compensation mechanism. Probable cause: Complete heart block due to the global nature of the changes. Tx: O2 @ 15 lpm NRB and possibly CPAP if pressure rises enough, 324 ASA, amio drip, possible norepi, and diesel. Put pads on in case he tanks. Definitive Tx: Needs cathed.
2015-07-02 17:46:57
Jonas
59 Year Old Male: Unwell
CPAP. IV. Nitro if BP can be controlled. Kidneys may be in acute failure causing extra fluid, or CHF, or both. Big ole triangular looking t-waves would have me thinking calcium. Monitor to see if conditions improve with CPAP. Place pads on patient, and have help with you in the ambulance.
2015-07-02 17:17:30
Brian Brubaker
59 Year Old Male: Unwell
At a quick glance it looks like tombstones (R on T). At closer look without calipers, it appears to be accelerated ideoventricular rhythm due to complete heart block. Not enough information to go off of, so cardioverting or pacing might just kill the patient quicker than anything. Transport immediately since his sick heart could stop…
2015-07-02 05:49:02
Holden
59 Year Old Male: Unwell
I've only studied cardiology for a few months and have read Dubin's book 1.5 times so I'm not an expert by any means. However, can a possible interpretation be a junctional tachycardia with aberrant ventricular conduction and a STEMI? No P waves and aberrancy causing a slightly wide QRS (but not wide enough for V-Tach).
2015-07-02 00:50:22
James
59 Year Old Male: Unwell
This is a ugly EKG. Wide complex irregular tachycardia around 150's. A-fib and a-flutter are possibilities. He's severely symptomatic. At this point, all treatment is same, electricity. If A fib, it may not want to "shock out" easily. This may be a case where initial cardioversion at max joules would be prudent. Pulmonary edema likely…
2015-07-01 22:00:13

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