Can be difficult to distinguish from<unk>  fibrillation
Regular
AV Node Independent
Sinus tachycardia<unk>  tachycardia (uni-focal or multi-focal)<unk>  fibrillation<unk> 
Idiopathic fascicular left ventricular tachycardia
AV Node Dependent
Paroxysmal supraventricular tachycardia (PSVT)
AV node re-entry tachycardia (AVNRT)
AV re-entry tachycardia (AVRT)
Lown-Ganong-Levine syndrome
Wolff–Parkinson–White syndrome
Junctional tachycardia
Irregular
Multifocal<unk>  tachycardia (MAT)
Sinus tachycardia with frequent PACs, PJCs, PVCs<unk>  fibrillation<unk>  fibrillation with RVR<unk>  with variable conduction
Digoxin Toxicity
AV Node Independent
Sinus tachycardia<unk>  tachycardia (uni-focal or multi-focal)<unk>  fibrillation<unk> 
Idiopathic fascicular left ventricular tachycardia
AV Node Dependent
Paroxysmal supraventricular tachycardia (PSVT)
AV node re-entry tachycardia (AVNRT)
AV re-entry tachycardia (AVRT)
Lown-Ganong-Levine syndrome
Wolff–Parkinson–White syndrome
Junctional tachycardia
Sinus tachycardia<unk>  tachycardia (uni-focal or multi-focal)<unk>  fibrillation<unk> 
Idiopathic fascicular left ventricular tachycardia
Paroxysmal supraventricular tachycardia (PSVT)
AV node re-entry tachycardia (AVNRT)
AV re-entry tachycardia (AVRT)
Lown-Ganong-Levine syndrome
Wolff–Parkinson–White syndrome
Junctional tachycardia
AV node re-entry tachycardia (AVNRT)
AV re-entry tachycardia (AVRT)
Lown-Ganong-Levine syndrome
Wolff–Parkinson–White syndrome
Lown-Ganong-Levine syndrome
Wolff–Parkinson–White syndrome
Multifocal<unk>  tachycardia (MAT)
Sinus tachycardia with frequent PACs, PJCs, PVCs<unk>  fibrillation<unk>  fibrillation with RVR<unk>  with variable conduction
Digoxin Toxicity<unk>  fibrillation with RVR
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<unk>  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<unk>  fibrillation/atrial<unk>  with variable AV conduction AND bundle branch block^<unk>  fibrillation/atrial<unk>  with variable AV conduction AND accessory pathway (e.g. WPW)<unk>  fibrillation + hyperkalemia
Polymorphic ventricular tachycardia
Torsades de pointes
Nonsustained ventricular tachycardia
Monomorphic ventricular tachycardia
PSVT with aberrant conduction:
PSVT with bundle branch block^
PSVT with accessory pathway<unk>  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<unk>  with bundle branch block^
Hyperkalemia
Digoxin toxicity
Severe metabolic acidosis<unk>  fibrillation/atrial<unk>  with variable AV conduction AND bundle branch block^<unk>  fibrillation/atrial<unk>  with variable AV conduction AND accessory pathway (e.g. WPW)<unk>  fibrillation + hyperkalemia
Polymorphic ventricular tachycardia
Torsades de pointes
Nonsustained ventricular tachycardia
Torsades de pointes
Nonsustained ventricular tachycardia
^Fixed or rate-related
Arrhythmias:
Narrow-complex tachycardias
Wide-complex tachycardias
AV blocks
Second Degree AV Block Type I (Wenckeback)
Second Degree AV Block Type II
Third Degree AV Block
Premature<unk>  contraction
Premature junctional contraction
Premature ventricular contraction
Sick sinus syndrome
Non-arrhythmic cardiac causes:
Acute coronary syndrome
Cardiomyopathy
Congenital heart disease
Congestive heart failure (CHF)
Mitral valve prolapse
Pacemaker complication
Pericarditis
Myocarditis
Valvular disease
Psychiatric causes:
Panic attack
Anxiety
Somatic Symptom Disorder
Drugs and Medications:
Alcohol
Caffeine
Drugs of abuse (e.g. cocaine)
Medications (e.g. digoxin, theophylline)
Tobacco
Misc
Anemia
Hyperthyroidism
Pulmonary embolism
Dehydration
Sepsis
Pheochromocytoma
Narrow-complex tachycardias
Wide-complex tachycardias
AV blocks
Second Degree AV Block Type I (Wenckeback)
Second Degree AV Block Type II
Third Degree AV Block
Premature<unk>  contraction
Premature junctional contraction
Premature ventricular contraction
Sick sinus syndrome
Second Degree AV Block Type I (Wenckeback)
Second Degree AV Block Type II
Third Degree AV Block
Acute coronary syndrome
Cardiomyopathy
Congenital heart disease
Congestive heart failure (CHF)
Mitral valve prolapse
Pacemaker complication
Pericarditis
Myocarditis
Valvular disease
Panic attack
Anxiety
Somatic Symptom Disorder
Alcohol
Caffeine
Drugs of abuse (e.g. cocaine)
Medications (e.g. digoxin, theophylline)
Tobacco
Anemia
Hyperthyroidism
Pulmonary embolism
Dehydration
Sepsis
Pheochromocytoma
Atrial flutter
Can be difficult to distinguish from atrial fibrillation
Wide-complex tachycardia
Regular
Narrow-complex tachycardia
AV Node Independent
Atrial fibrillation 
Sinus tachycardia