EKG: What is this? LBBB?

Stephen W. Smith

10/28/2010 7:05:44 AM #

Wow.  This is a tough one.  Rhythms are not my specialty, but there is inferior STEMI underlying this rhythm:

I see sinus rhythm with two different QRS morphologies, both with IVCD, one wide and one very wide, and 2  (multiform) PVC’s (2nd and 5th complex).  Only the very wide morphology is visible in V1-V3, and it has an RBBB look to it.  There is what appears to be pre-excitation in the very wide complex (with a very short PR interval).

II, III, aVF, aVL and V2 have excessively discordant (opposite the QRS) ST elevation or depression.   II, III, and aVF, no matter what the complex morphology, have ST elevation that is discordant to a negative QRS (normal for BBB or IVCD), but the ratio of STE to S-wave is high (far greater than my cutoff of 0.20).   This is true also for the PVCs.   There is excessively discordant reciprocal depression in aVL.  Again, this is true also for the PVCs.  

V2 has excessively discordant ST depression, discordant to a tall (RBBB) complex.  However, if there is pre-excitation here, that can account for the ST abnormalities.  And all complexes in V1-V3 have this doubly abnormal QRS, so I cannot confirm concomitant posterior MI.

Diagnosis: sinus with multiform PVCs.  Intermittent pre-excitation with atypical BBB or IVCD.  Inferior STEMI, with possible posterior extension.

Steve Smith (Dr. Smith's ECG blog)

Nick Adams

11/7/2010 4:32:30 PM #

Ok.....Let me have a stab at it.  It's unfortunate that patient's hearts don't read the cariology books to better display a more textbook type dysrhythmia.  Anyway, this is what I see.  First of all, I would do another 12 lead EKG to capture an intrinsic beat in V-1.  I do see the inferior MI with the patient's intrisic rhythm in (beats 1, 3, and 6) II, II, and aVF with reciprocal changes seen in the high lateral leads of I and aVL.  The patient's ventricular axis on thier normal beats is approximately -30 degrees.  The other beats that present wide in a RBBB pattern are sinus in nature with a PRI of approximately 180 ms, whereas the intrinsic beats have a PRI of 220 ms.  The ventricular axis of these wider QRS morphology's is of a more pathological LAD @ -60 degrees.  This, and the fact that V1 is positive and V6 is negative, leads me to beleive that this is ventricular in origin.  I cannot see pacer spikes, but it screams pacemaker.  If they do not have a pacemaker, I would put the pacer pads on because the pt is diplaying multiple blocks in the presence of ST segment elevation (RBBB with a LAFB, and a 1 degree AVB with intrinsic beats).  Yes?  No?.......I don't know