Bundle Branch Block : Mnemonic

If the QRS complex is wide (>0.12 s/>3 small squares), the ventricular activity may be arising from the ventricle conducting system. caused by a ‘bundle branch block’.

WiLLiaM MaRRoW (classic mnemonic)

Wi – V1
LL – LBBB
M – V6

M – V1
RR – RBBB
W – V6

ViLLheiM MaRRooN (more accurate)

V – V1
LL – LBBB
M – V6

M – V1
RR – RBBB
N – V6

With a Left bundle branch block (LBBB), you get W or more accurately V shaped complex (rS) in V1 and M shaped complex (R) in V6.

With a Right bundle branch block (RBBB), you get M shaped complex (rSR’) in V1 and W or more accurately N shaped complex (qRs) in V6.

lbbb rbbb ecg

If LBBB is present, no comment can be made on the rest of the ST segment, and thus it may be a sign of acute MI.

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