An unusual case of right bundle branch block – Discussion

Here is the conclusion to an unusual case of right bundle branch block.

Let's take another look at the 12-lead ECG.

This 12-lead ECG shows acute anterior STEMI in the presence of right bundle branch block, but you really need a trained eye to see it.

We talk a lot about the "rule of appropriate T-wave discordance" with bundle branch blocks. What makes this case difficult is the fact that the T-waves are appropriately discordant.

However, the J-points are concordant in leads V1-V4!

If you look carefully you will see that the point at which the QRS complex turns into the ST-segment (the J-point or "junction" point) is elevated above the isoelectric line.

That's abnormal for right bundle branch block. In fact, if the J-point isn't isoelectric in the right precordial leads it should be slightly depressed (in the same direction as the T-waves).

Lead V4 looks the most abnormal.

If you're still having doubts, consider that Q-waves are present in leads V1-V4.

That's what Tomas Garcia, M.D. means when he says to "consider the company" that any ECG abnormality keeps.

Finally, let's look at leads III and aVF.

We are forced to assume that these are reciprocal changes even though the terminal QRS is isoelectric. You'd need an old ECG for comparison to know for certain.

This patient was in fact suffering LAD occlusion.

See also:

An unusual case of left bundle branch block

An unusual case of left bundle branch block – Discussion


  • Brandon O says:

    I like Dr. Smith’s trick of finding the J-point in the clearest lead and drawing a vertical line to pinpoint it on the rest of them.

  • Tom B says:

    That is a great trick, Brandon!

  • G. Denton says:

    Not to sure I agree with you on this one Tom. I’d have to see a cath lab report linking an LAD lesion to this EKG. Here’s why I doubt it. If you locate the start of the QRS in leads V1 – V4 and measure out 150 m/sec (the width of the QRS) and add the required 40 m/sec past the J-point (AHA STEMI Provider Manual page 43 et al.)the point is less than 1 mm from the baseline. Discordance with RBBB is not as compelling as with LBBB so that is interesting but lacks weight. The V4 example pointed out as the “most abnormal” is the most misleading, at 190 m/secs out it is within a mm of the baseline. The same applies for the recipricol changes. Find the obvious start of the QRS and measure out the appropriate distance (QRS 150 m/sec plus 40 m/sec) and you will see that the “recipricol change” is actually part of the QRS. This example shows a sick heart in an old patient. The a-fib, RBBB, and indicated age prove that. I’d like to see an EKG on this patient after they normalized his ventricular rae, or better yet, a few weeks after he was cathed and stented. An interesting case for sure, but i wouldn’t want to start fibrinolytics with this EKG. I love your work Tom and this argument is purely acedemic. Thanks.

  • Brady says:

    Why doesn’t anyone actually just look at the actual axis’ numbers on the top of the 12lead? that’s the most accurate way to see axis deviation and therfore, the actual BBB

  • Tom B says:

    Hello, G. Denton!

    Is that you, Gary? If so, it’s been way too long! Thanks for the comment and I hope all is well.

    As many a disappointed contributor could tell you, I rarely run a case study when the outcome is unknown. I like to deal in reality.

    I don’t have the cath report for this case but the contributor verified that it was a STEMI, the culprit artery was the LAD, and the patient received a stent.

    Since I probably won’t be able to get my hands on the cath report, I’ll simply reply to the points you made.

    First, (as you know) the ECG abnormality we call “STEMI” is an imperfect surrogate for an acute thrombosis in an epicardial coronary artery, and an expert electrocardiographer can often pick out patients that need reperfusion therapy whether they meet the conventional criteria or not.

    This can be based on reciprocal changes, the rule of proportionality, changes in R-wave progression, the presence of absence of Q-waves, hyperacute T-waves, contour of the ST-segments, pseudo-normalization, changes on serially obtained ECGs, and so on.

    In other words, it is the conventional criteria that lacks weight. If I had a nickel for every STEMI case I’ve seen that didn’t meet the criteria I could get that Red Ryder BB gun with the compass in the stock.

    As for where to measure the ST-segment, there is not broad agreement on that point (accidental pun). However, the 2010 AHA ECC Guidelines use the J-point and so did the Universal Definition of Myocardial Infarction published in 2007.

    The issue here is whether or not the J-point should ever be elevated in leads V1-V3 in the presence of RBBB, and I submit to you that they should not be. If anything they should be depressed (or isoelectric). Amal Mattu, M.D. makes a similar point here Add the Q-waves and this finding is all the more alarming (even if inconclusive).

    I stand by my previous observation that ST-elevation is present in lead V4. The J-point is clearly elevated about 2.5 mm even though it drops rapidly into the T-wave.

    As for the reciprocal changes in leads III and aVF, you are correct in that we must be careful not to confuse the QRS complex with the ST-segment (and the artifact isn’t helping us here) but even taking into account the QRS duration I believe a very subtle amount of ST-depression (J-point depression) is present here.

    Having said all that, I wouldn’t start thrombolytics based on this 12-lead ECG either! At least not in the field. I would, however, consider sending the patient to the cardiac cath lab after correlating with an old ECG, wall motion abnormalities on a bedside echo, positive point-of-care biomarkers, changes on serially obtained ECGs, or a consult with cardiology.

    Like you said, this is mostly academic. When it comes to ECG findings this subtle the discussion can take on a patina of the esoteric (to paraphrase the 2003 ACLS Reference Textbook chapter on Wide Complex Tachycardias). Then again, to ECG aficionados like us, these are the fun ones to debate! 🙂

    Do you not agree?


  • G Denton says:


    I do agree, these are the fun ones to debate, and thanks for taking the time to exchange ideas.

    I’m glad we agree that this EKG would not be enough to justify Fibrinolytics, and we both agree a trip to the cath lab, if symptomatic, would be the best bet. On treatment we agree, and that is most important. I also agree that the J point should not be elevated in the early V leads.

    My calculations using the J-point or the J-point plus 40/msecs leave me with the same conclusion, I don’t think this EKG meets electrocardiographic criteria for a STEMI. The difference of opinions is what makes medicine fun. I challenge your contributor to find us a post cath EKG with normalized ST segments (and hopefully a better ventricular rate!!) All for fun of course.

    Since you mentioned the 2010 guidelines and the Universal Definition of MI 2007, you must have noticed the addition of a 2mm requirement for STEMI in V2 and V3 for males over 40, 2.5mm for males under 40, and 1.5mm for females. All other leads remain at 1mm. That is a nice addition to the criteria and, in my humble opinion, makes using the J-point more reliable.

    Thanks for letting me play and keep up the good work.

  • Tom B says:

    Gary –

    My pleasure!

    I contacted “Captain Jack” to see if he can follow up and get a copy of the cath report, but I’ll see if he can get his hands on a post-cath 12-lead ECG as well.

    I did notice the 2 mm requirement in the guidelines for leads V2 and V3 (and I agree with it) but keep in mind that was due to the fact that most patients have deep S-waves in leads V2 and V3 so we would expect some ST-elevation in the opposite direction.

    This patient has abnormal depolarization with a terminal R-wave in leads V2 and V3 so if anything we would expect the opposite finding.


  • G Denton says:


    Thanks for all your help, I hope Capt Jack can find the cath report and post cath EKG’s. Even an old EKG of this patient prior to this event would be helpful. I love this case, it is one of those rare ones that really stimulates the mind.

    I think we all assumed (correctly I hope) that this 69 year old patient had pre-existing a-fib and RBBB.

    You seem keen on considering the effect of some expected ST discordance from the terminal R waves in V2, V3. I see where you are going, but personally,I wouldn’t put so much weight on that. The right ventricle is a dwarf compared to the left, and when depolarized unopposed (and viewed in the early V leads) often causes the flip of the T wave but less often, and to less a degree, creates j point depression. The 2010 AHA guidelines use the “AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram Part IV” that state clearly “The ST segment criteria for the diagnosis of acute ischemia/infarction are not affected by the presence of fascicular blocks or by Right Bundle Branch Block. They are affected by the presence of Left Bundle Branch block because of the more pronounced secondary ST and T wave changes that occur in this setting.”

    Great stuff. Thanks again for letting me play, it stimulates me to crack open the books and stay current on all that is changing. Every encounter with you has left me with a new fact and/or a fresh perspective.

  • Tom B says:

    Gary –

    I agree with you that majority of the time the J-point will be isoelectric with RBBB. What I meant to imply is that if it’s going to be shifted it’s going to be discordant to the terminal deflection.

    In other words, concordant J-points in the setting of RBBB are abnormal even in leads V2 and V3 (where we would normally allow 1 to 1.5 mm of ST-elevation for male patients).

    It’s the absence of deep S-waves in these leads that (to me) is significant and obviates the need for 2 mm.

    Great discussion and let’s hope “Captain Jack” comes through!


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