Pseudohyperkalemia: hemolyzed specimen, prolonged tourniquet use prior to blood draw, thrombocytosis or leukocytosis
Redistribution (shift from intracellular to extracellular space)
Acidemia (see DKA)
Cellular breakdown: see Rhabdomyolysis/Crush syndrome, electrical/thermal burn, hemolysis, see Tumor lysis syndrome
Increased total body potassium
Inadequate excretion: Acute/chronic renal failure, Addison's disease, type 4 RTA
Drug-induced: potassium-sparing diuretic (spironolactone), angiotensin converting enzyme inhibitors (ACE-I), nonsteroidal anti-inflammatory drugs (NSAIDs)
Excessive intake: diet, blood transfusion
Other causes: succinylcholine, digitalis, beta-blockers
Acidemia (see DKA)
Cellular breakdown: see Rhabdomyolysis/Crush syndrome, electrical/thermal burn, hemolysis, see Tumor lysis syndrome
Inadequate excretion: Acute/chronic renal failure, Addison's disease, type 4 RTA
Drug-induced: potassium-sparing diuretic (spironolactone), angiotensin converting enzyme inhibitors (ACE-I), nonsteroidal anti-inflammatory drugs (NSAIDs)
Excessive intake: diet, blood transfusion
MI (hyperacute T waves)<unk> 
Benign Early Repolarization
De Winter's T waves (acute LAD occlusion)
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<unk> 
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 +<unk> 
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
Atrial flutter with bundle branch block^
Sinus tachycardia with bundle branch block^
Accelerated idioventricular rhythm (consider if less than or ~120 bpm)
Metabolic<unk> 
Digoxin toxicity
Severe metabolic acidosis
PSVT with bundle branch block^
PSVT with accessory pathway
Atrial flutter with bundle branch block^<unk> 
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 +<unk> 
Polymorphic ventricular tachycardia
Torsades de pointes
Nonsustained ventricular tachycardia
Torsades de pointes
Nonsustained ventricular tachycardia
^Fixed or rate-related
Hyperkalemia
Pseudohyperkalemia: hemolyzed specimen, prolonged tourniquet use prior to blood draw, thrombocytosis or leukocytosis
Hyponatremia
Redistribution 
Hypernatremia
Acidemia 
Hypokalemia
Cellular breakdown: see Rhabdomyolysis/Crush syndrome, electrical/thermal burn, hemolysis, see Tumor lysis syndrome