Wednesday, November 19, 2014

Chest Pain and Right Bundle Branch Block

A male in late middle age with a history of RCA stent 8 years prior complained of chest pain.  EMS recorded the following ECG:
What do you see?  The computer read "Right Bundle Branch Block"















There is RBBB and LAFB, which can make it difficult to see the end of the QRS.  I have annotated it here:
The lines mark the end of the QRS and beginning of the ST segment.  In RBBB, there should be no ST elevation, or minimal.  In fact, V1-V3 should have some ST depression and T-wave inversion.  In other words, the ST segment and T-wave should be discordant to (in the opposite direction of) the positive R' wave [see the 2nd ECG of this post].  Here you can see abnormal (diagnostic) ST elevation and an upright T-wave in V2-V3, with diagnostic ST elevation in V4-V6 and in I and aVL, and with reciprocal ST depression in III and aVF.  So this is diagnostic of proximal LAD occlusion.


New RBBB + LAFB is a very bad sign.  It is highly associated with proximal LAD occlusion and bad outcomes.

See this paper by Widimsky et al, which shows the high association of RBBB, especially with LAFB, with LAD occlusion.  Furthermore, among 35 patients with acute left main coronary artery occlusion, 9 presented with RBBB (mostly with LAH) on the admission ECG.

Here are three more dramatic cases that illustrate RBBB + LAFB

Case 1 of cardiac arrest with unrecognized STEMI, died.

Case 2 with 68 minutes of CPR and good outcome

Case 3 with LAD occlusion, cardiac arrest, could not be resuscitated


Case Progression

In order to keep patient confidentiality, I will only give the barest of follow up:

As the emergency physician was immediately assessing the patient, he had a v fib arrest.  He could not be resuscitated in the ED but was taken to the cath lab while on LUCAS (mechanical) CPR, underwent successful PCI of a proximal LAD occlusion during chest compression, and after opening the artery, achieved ROSC (return of spontaneous circulation).   

13 comments:

  1. Hi Steve,
    Great EKG & case. Certainly appreciate the ischemic changes & finding you mentioned. Don't appreciate the LAFB, as lead I doesn't have the accompanying q wave and has absent QR pattern we see in AVL. Also- axis is extreme right. Are you convinced sinus rhythm? AIVR?

    Sam

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    Replies
    1. Sam,
      Yes, very confusing because lead I would lead you to believe that there is right axis deviation, but aVL has a qR (with rS in inferior leads) which suggest left axis deviation! I can't explain the contradiction, so I'm going with II, III, aVF and aVL as it makes more sense physiologically.
      Better explanation? 100 degree axis? Possibly.
      Steve

      Delete
    2. As this gentleman had a prior IWMI (RCA occlusion), it is conceivable that he would have baseline q-waves inferiorly. If you add LAFB to a prior IWMI the initial vector will actually point inferiorly as the left posterior fasicle is the dominant factor during the first 80-100 ms. This will necessarily erase the inferior q-waves, replacing them with r-waves, and direct the axis leftward. (Dr. Bill Nelson mentions this in a chapter from his book he has up on his website.)

      We've also got RBBB, which results in strong terminal rightward forces which will move the *mean* frontal axis rightward. The LV and septum have already depolarized, and the late RV is electrically unopposed. If you imagine the initial forces (septal left-to-right then LV right-to-left) which occupy the first 80ms or so you can determine the "pre-blocked" axis. The preblocked axis in this case is actually leftward (+I, +aVL, -II, -III).

      Delete
    3. Thank you Christopher. Nice analysis!
      Steve

      Delete
  2. Would you proceed to a temp pacemaker implantation in case of RBBB, LAH and AW STEMI to avoid a possible complete heart block's consequences?

    ReplyDelete
    Replies
    1. Only if the PR interval started to lengthen.

      Delete
  3. Hi Dr Smith! I love your blog! Should I be worried about a patient with chest pain who has a new RBBB and LPFB? Or is that not so bad compared to RBBB and LAFB? Thanks!

    ReplyDelete
    Replies
    1. Thanks! That is much much less common and so there is little data. But my guess is that it is nearly as worrisome.
      Steve Smith

      Delete
  4. HI Dr. Smith, Do you think he has de Winter T waves in v4,v5?

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    Replies
    1. tsbqb11,
      No, de Winter's T-waves require a depressed ST takeoff. OK?
      Steve Smith

      Delete

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