You can try applying the Brugada criteria to the ECG. The criteria are not 100% reliable.
- Is there an absence of RS complexes in all the chest leads?
- Is the R-S nadir (interval betw. 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
- Broad complex tachycardia
- Irregularly irregular
- Very short R-R intervals
- "Pure" delta waves
- More on WPW
If there is any doubt treat as for VT but do not use agents that block the AV node (such as Adenosine )