You can try applying the Brugada criteria to the ECG. The criteria are not 100% reliable.
- Is there an absent\ce of RS complexes in all the chest leads?
- Is the R-S nadir ( interval between the start of the QRS complex and the lowest part of the S wave) > 100mS in any V lead?
- Are there capture beats, fusion beats, or evidence of AV dissociation?
- Is there an absence of typical classical BBB?
Yes to any = VT, No to all= SVT
If there is any doubt, or you are not sure how to apply these criteria, assume the rhythm is VT
Differentiating Polymorphic VT from AF with pre-excitation
Features of the ECG in WPW-with Atrial Fibrillation
- Broad complex tachycardia
- Irregularly irregular
- Very short R-R intervals
- "Pure" delta waves
If there is any doubt treat as for VT but do not use agents that block the AV node ( such as Adenosine )