Supraventricular tachycardia DDx


  • SVTs are supraventricular tachycardias, that can be either atrial tachydysrhythmias (such as atrial fibrillation) or atrioventricular tachydysrhythmias. This document concerns the latter.
  • Atrioventricular tachydysrhythmias arise from an abnormal impulse produced by, or dependent on, the AV node.

Types of atrioventricular tachydysrhythmia

  • AV nodal reentrant tachycardia (AVNRT) (most common form, >50%); involves a reentrant circuit in the AV node itself
  • AV reentrant tachycardia (AVRT); involves a reentrant circuit formed by aberrant myocardial accessory pathways between the atria and ventricles. Conduction may be orthodromic or antedromic down the normal His-Purkinje pathway, the latter tends to produce a wide QRS complex.
  • Junctional ectopic tachycardia (rare)
  • Nonparoxysmal junctional tachycardia (rare)


AVNRT; associated with:

  • Myocardial ischemia
  • Rheumatoid heart disease
  • Pericarditis
  • Mitral valve prolapse
  • Medications, poisoning and toxic exposures (e.g. caffeine, theophylline)

AVRT; associated with:

  • Presence of an accessory tract, often with evidence of a preexcitation syndrome on the baseline ECG (e.g. Lown-Ganong-Levine syndrome)
  • Ebstein’s anomaly

Junctional ectopic tachycardia and nonparoxysmal junctional tachycardia

  • Cardiac ischemia
  • Digoxin toxicity
  • Cardiac surgery

Consider secondary causes of tachycardia

Critical Care


Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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