Definition: 3 or more episodes of sustained ventricular tachycardia, ventricular fibrilation, or ICD shocks within 24 hours
Most have underlying structural heart disease, but also seen in those with structurally normal hearts (i.e. Brugada syndrome, Long QT syndrome)
Type 2 Diabetes is protective
CAD
HFrEF
QT prolongation
Ischemia
Electrolyte derangement
Iatrogenic (i.e. QT prolonging medications)
Hyperthyroidism
Infection/Fever
Brugada syndrome
Short QT syndrome, long QT syndrome
Early repolarization syndrome, especially in inferior leads
Electrical storm
Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise 
Heat stroke
Regular
Undifferentiated shock
Monomorphic ventricular tachycardia
Undifferentiated shock 
PSVT with aberrant conduction: