RBBB Abnormalities Missed

The original presentation of this case appeared as  "What's Wrong with Mr. Wilson?"… You can read the original post here.

Much has been written lately about RBBB abnormalities that were missed. 

Dr. Smith has recently posted two cases here, and here discussing this.

First, let's review the 12 lead of a typical RBBB. When learning to recognize abnormalities, we must first be intimately familiar with what "normal" looks like. 

Editors note: Some astute readers may notice some subtle abnormalities of the ST segments here (so technically, not a normal ECG). I use this example to illustrate typical morphologies of the QRS complex:

                                                                                                                                            *image credit LITFL


Typical features of an uncomplicated RBBB:

  • Widened QRS of at least 120 ms
  • rSR' in V1-V3
  • Widened S wave in the lateral leads, most notably in leads I and aVL
  • Should follow the rule of "appropriate discordance" (if you are unfamiliar with this rule, refer to this previous post: Right Bundle Branch Block–Part II

Instead of the typical rSR' pattern in V1, you may in fact see any of the following morphologies:

It is not abnormal to have a small amount of discordant ST depression in the right precordial leads. However, ST elevation in the right precordial leads is never normal. In fact, the ST segments should not be distorted enough in RBBB to cause ST elevation at all. This is precisely why RBBB does not confound STEMI interpretation in the way that LBBB does, where ST elevation may be a normal finding.

Now let's take a look at the 12 lead of our 57 year old male patient who complained of feeling "really sick":


ECG findings:

  • There is sinus rhythm at a rate of about 80 bpm, with RBBB
  • Left axis deviation (bi-fasicular block)
  • Abnormally upright T waves in V1-V3
  • Questionable T wave in lead I
  • Slight elevation of the ST segment in V1-V2
  • Significant abnormal Q waves in V1-V4 with loss of initial R wave 

Overall, this is an ugly ECG. There should never be any ST elevation, and certainly the Q waves in V1-V3 are very abnormal and significant.

If we look at a normal RBBB and our patient's ECG side by side, the abnormalities become obvious:

From the previously mentioned RBBB posts by Dr. Stephen Smith (links above):

  • RBBB should not have ST elevation at baseline.
  • In RBBB, there should be some ST depression in V2 and V3. An isoelectric ST segment may represent relative ST elevation.
  • The presence of such well developed anterior Q waves suggest completed transmural STEMI.

Dr. Smith elaborates further on the Q waves:

"The wide Q waves suggest "transmural" MI (completed MI with infarction of the entire thickness of the ventricle). This was common before the days of reperfusion of STEMI, but still happens in patients who present late and therefore do not get timely reperfusion therapy"

The story of our patient:

The ECG recorded above was taken at admission to the cath lab. He was found to have a 99% lesion of his LAD. His ejection fraction was in the 30s.

He received a stent and a balloon pump, and was admitted to the ICU. His prognosis questionable.

Two weeks prior, he had started to feel very short of breath, along with a cough. On exertion, he felt "much more tired than normal".

After a few days he went to his PCP. His hx was significant for hypertension and smoking. It is unknown whether or not an ECG was acquired at that time.. He was, however, diagnosed with an URI and sent home with antibiotics.

He started to feel slightly better after a day or two, then began to decline again. He found himself without the energy to walk across the room. He had his wife drive him to the ED.

At the ED, they found him to be hypotensive (86/58) and not improving after the antibiotics. An ECG very similar to the one recorded above was acquired. Although it was not found to be diagnostic, there was concern that his issues could be cardiac. He was scheduled for a non-emergent cath a few days later.

At that time, the above ECG was acquired and the lesion was found.


  • ECG abnormalities can be missed at many levels of care.
  • Become the "expert"– you can save lives!
  • You can not discover an abnormality until you are crystal clear on what "normal" looks like
  • Missed abnormalities can lead to delays in much needed patient care and possibly worsened outcomes

For more information, be sure to read our series on RBBB:

Right Bundle Branch Block–Part I

Right Bundle Branch Block–Part II

Right Bundle Branch Block–Part III


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Cardiac Rhythm Analysis, 12-Lead ECG Interpretation, Resuscitation

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