Atrioventricular reentrant tachycardia
|Atrioventricular reentrant tachycardia|
|Classification and external resources|
Conduction pathway in atrioventricular reentrant tachycardia, a form of supraventricular tachycardia
Atrioventricular reentrant tachycardia, atrioventricular reciprocating tachycardia or AVRT, is a supraventricular tachycardia (SVT) most commonly associated with Wolff-Parkinson-White syndrome, in which an accessory pathway allows electrical signal from the ventricles to enter the atria and cause premature contraction and repeat stimulation of the atrioventricular node.
Signs and symptoms
An episode of SVT may present with palpitations, dizziness, shortness of breath, or syncope. The electrocardiogram would appear as a narrow-complex SVT. Between episodes of tachycardia the patient is likely to be asymptomatic, however the electrocardiogram would demonstrate the classic delta wave in Wolff–Parkinson–White syndrome.
Two distinct pathways are involved: the normal atrioventricular conduction system, and an accessory pathway. During AVRT, electrical signal passes in the normal manner from the AV node into the ventricles. It then, pathologically, passes back into the atria via the accessory pathway, causing atrial contraction, and returns to the AV node to complete the reentrant circuit; see figure. Once initiated, the cycle may continue causing an episode of tachycardia.
Acute management is as for SVT in general. The aim is to interrupt the circuit. In the shocked patient, DC cardioversion may be necessary. In the absence of shock, inhibition at the AV node is attempted. This is achieved first by a trial of vagal maneuvers, then if this fails using intravenous adenosine; the latter causes complete electrical blockade at the AV node. Long-term management consists of radiofrequency ablation of the accessory pathway.
- Josephson ME. Preexcitation syndromes. In: Clinical Cardiac Electrophysiology, 4th, Lippincot Williams & Wilkins, Philadelphia 2008. p.339
- Hampton J. The ECG Made Easy. Elsevier 2008
- UpToDate: Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway
- UK Resuscitation Council. Adult tachycardia algorithm. 2010.
- AV nodal reentrant tachycardia
- Electrical conduction system of the heart
- Wolff-Parkinson-White syndrome