Sunday, December 10, 2017
Sinus Rhythm With a Run of VT or SVT Aberrancy?
Edward Burns, in Life in the Fast Lane, uses these criteria to distinguish between VT and SVT with aberrancy:
These criteria favor VT:
Absence of typical RBBB or LBBB morphology
Extreme axis deviation (“northwest axis”) — QRS is positive in aVR and negative in I + aVF.
Very broad complexes (>160ms)
Positive or negative concordance throughout the chest leads,
RSR’ complexes with a taller left rabbit ear. This is the most specific finding in favour of VT. This is in contrast to RBBB, where the right rabbit ear is taller.
In this strip we have a rSR' complex in V1. The rabbit ear is taller on the right.
The QRS complexes are positive in aVR and aVF and negative in lead I. These do not meet the criteria for VT and suggest aberrancy.