VT vs SVT with Aberrancy

A · Axis

Lead I QRS polarity

Choose the predominant QRS direction

Lead aVF QRS polarity

Used with lead I to determine the frontal axis quadrant

Lead aVR QRS polarity

A dominant positive QRS supports a northwest axis pattern

Select lead I, aVF, and aVR polarity.

AAxis

Northwest axis with lead I negative and aVF negative

BBroad

QRS duration greater than 200 ms

CConcordance

All QRS complexes in V1 through V6 predominantly positive or all predominantly negative

DDissociation

AV dissociation, capture beats, or fusion beats

EEarly

Slow initial QRS activation or time to peak greater than 40 ms

FFragmentation

Josephson sign with notching near the nadir of the S wave in V1