Drug induced
Congenital long QT
Hypocalcemia
Hypomagnesemia
Hypokalemia
Hypothermia<unk>  as above
Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise (it is safer to incorrectly assume a ventricular dysrhythmia than supraventricular tachycardia with abberancy)
Regular
Monomorphic ventricular tachycardia
PSVT with aberrant conduction:
PSVT with bundle branch block^
PSVT with accessory pathway
Atrial flutter with bundle branch block^
Sinus tachycardia with bundle branch block^
Accelerated idioventricular rhythm (consider if less than or ~120 bpm)
Metabolic
Hyperkalemia
Digoxin toxicity
Severe metabolic acidosis
Irregular
Atrial fibrillation/atrial flutter with variable AV conduction AND bundle branch block^
Atrial fibrillation/atrial flutter with variable AV conduction AND accessory pathway (e.g. WPW)
Atrial fibrillation + hyperkalemia
Polymorphic ventricular tachycardia<unk> 
Nonsustained ventricular tachycardia
Monomorphic ventricular tachycardia
PSVT with aberrant conduction:
PSVT with bundle branch block^
PSVT with accessory pathway
Atrial flutter with bundle branch block^
Sinus tachycardia with bundle branch block^
Accelerated idioventricular rhythm (consider if less than or ~120 bpm)
Metabolic
Hyperkalemia
Digoxin toxicity
Severe metabolic acidosis
PSVT with bundle branch block^
PSVT with accessory pathway
Atrial flutter with bundle branch block^
Hyperkalemia
Digoxin toxicity
Severe metabolic acidosis
Atrial fibrillation/atrial flutter with variable AV conduction AND bundle branch block^
Atrial fibrillation/atrial flutter with variable AV conduction AND accessory pathway (e.g. WPW)
Atrial fibrillation + hyperkalemia
Polymorphic ventricular tachycardia<unk> 
Nonsustained ventricular tachycardia<unk> 
Nonsustained ventricular tachycardia
^Fixed or rate-related
Torsades de pointes
Drug induced
Brugada syndrome
Congenital long QT
Takotsubo cardiomyopathy
Hypocalcemia
Unstable angina
Hypomagnesemia