<aside> 💡 Confusingly, SVT and AVNRT (which is a type of SVT) are often used synonymously

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Overview

• SVT is an umbrella term that encompasses any arrhythmia which has an origin superior to the ventricles - specifically the bundle of His
  • Includes atrial fibrillation, atrial flutter, AVNRT, sinus tachycardia
    • Confusingly, SVT and AVNRT (which is a type of SVT) are often used synonymously

Types of SVT

AVNRT

Wolff-Parkinson White

Atrial flutter

Atrial Fibrillation (1)

Classification of SVTs

• The most useful classifications are regularity and origin
  • Regularity
    • Irregular - atrial fibrillation and flutter
    • Regular - AVNRT, sinus tachycardia
  • Can also be classified by origin
    • Atrioventricular
      • AVNRT and AVRT (most commonly Wolff Parkinson White)
    • Atrial
      • Most others: AF, flutter, sinus tachycardia, atrial tachycardia

Narrow complex tachycardia differentials

1. Sinus Tachy

   1. Fast
   2. QRS, P and T waves present

2. AV node re-entry tachycardia

   1. QRS complex < 3 small squares
   2. Regular
   3. Absent p-waves

3. AF

   1. Irregularly irregular

4. Atrial flutter

   1. Atrial rate 300 bpm
   2. Sawtooth pattern
   3. QRS regular contractions

   

Atrial Tachycardia

• “Atrial tachycardia” is where the electrical signal originates in the atria somewhere other than the sinoatrial node.
  • This is not caused by a signal re-entering from the ventricles but instead from abnormally generated electrical activity in the atria. This ectopic electrical activity causes an atrial rate of >100bpm.