Junctional Rhythm

Background

  • In junctional rhythm the electrical impulse starts in the AV node instead of the SA node.
    • NB the AV node does possess autorhythmicity but is usually much slower than the SA node and so is overridden.
  • In the context of severe bradycardia, this is an escape mechanism.  In the context of normal/tachycardia, this is abnormal
  • Results in electrical impulses travelling simultaneously to the atria and ventricles
    • results in an inverted P wave seen just after or within the QRS complex.  The QRS is usually narrow unless there is co-existent LBBB/RBBB

Aetiology

  • Inappropriate slowing of sinus rhythm to 40-60bpm either due to changes in autonomic tone or disease of the sinus node
  • Enhanced AV-node automaticity- usually caused by digoxin toxicity, post-op cardiac surgery, during MI or severe calcium dysregulation in the cardiac sarcoplasmic reticulum.

Presentation

  • The patient may present with dyspnoea and presyncope

Management

  • Depends on the underlying cause
    • If digoxin toxicity- atropine and/or digitoxin immune FAb (digibind) may be given

junctional rhythm

 

 

 

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