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Anterior Wall M.I. With Bifascicular Block

Fri, 10/19/2012 - 20:46 -- Dawn

This is a good example of acute anterior wall M.I., with ST elevation in V1 through V6, as well as in Leads I and aVL.  The extensive distribution of ST segment elevations across the anterior and high lateral walls indicates a proximal LAD artery occlusion.  In addition, this ECG shows right bundle branch block, with a QRS width of 144 ms (.14 sec.) and an rsR' pattern in V1. There is also a wide s wave in Lead I which is partly obscurred in V6 by the ST elevation.  The right axis deviation (98 degrees) suggests a left posterior fascicular block which, when coupled with the RBBB, is a bi-fascicular block.  P waves are difficult to see.  Do you think they are found at the end of the QRS complexes, representing a long first-degree AVB?  Look at leads V3 through V6 for clues.

Please feel free to add your comments below.  The more "gurus" the better.

A good ECG to teach your students that a patient facing a life-threatening emergency may have a "normal" rate and regular rhythm.  There is something in this ECG for beginners through advanced students.

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Comments's picture

Nice illustrative example by Dawn - with a number of teaching points:

  • Figuring out the axis in a tracing with RBBB is challenging. One focuses on the FIRST part of the QRS deflection (ie, the straight part) - which as Dawn indicates in lead I is clearly negative. Thus, there is LPHB as well as RBBB here.
  • Signs of a very large MI (likely due to very proximal LAD occlusion) are many - diffuse precordial ST elevation AND also in leads I, aVL - and the RBBB/LPHB. Hard to know if the conduction defects are new or old (without a prior tracing) - but assuming they are new - the patient is at high risk of developing either complete AV block and/or cardiogenic shock.
  • I do not see sinus P waves .... I hesitate to diagnose 1st degree based on what I see - but rather am entertaining possible 2:1 AV block vs accelerated junctional rhythm. Additional strips are needed to clarify what the rhythm is (with this being another sign of poor large infarct and poor prognosis).

For anyone interested - I've made a site to assist in localization of the MI and identification of the culprit vessel. GO TO:

Ken Grauer, MD   [email protected] 

Submitted by Dawn on

Thanks, Dr Ken, for your great teaching points. We wish we had a long rhythm strip. It's frustrating to be unsure of the rhythm, but the danger is clear for this patient, as you pointed out. I encourage all instructors and students to follow Dr Ken Grauer's link to his information on localizing MIs   

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