Re-entry supraventricular tachycardia

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Definition

An arrhythmia caused by a second connection between atria and ventricles, in addition to the normal conduction system. There are two types:

  • AVRNT (Atrio-Ventricular Node Re-entry Tachycardia) - the second connection is closely related to the AV node.
  • AVRT (Atrio-Ventricular Re-entry Tachycardia) - the second connection is not related to the AV node.

Clinical Features

Symptoms can be associated with exertion

ECG findings

Rate of 130-250. Narrow QRS complex (except in bundle branch block), P waves are: inverted, masked by QRS complex (AVNRT) or occur halfway between complexes (AVRT), one P wave per QRS complex.

Management

  • Drugs - adenosine or verapamil. (Flecanide, sotalol, dispyramide are other options).
  • Electrical - pacing and cardioversion as above.
  • Vagal - carotid sinus massage, pressure on closed eyes, application of ice to face.
  • Ablation - burning away the dodgy bit of conduction pathway.