Atrioventricular reentrant tachycardia occurs when a reentrant circuit is present outside of the AV node through an abnormal conduction pathway that connects the atrium to the ventricles. This pathway is termed an “accessory pathway” or a “bypass tract.” The presence of this congenitally abnormal accessory pathway is seen in Wolff-Parkinson-White (WPW) syndrome.
If an action potential is able to traverse the accessory pathway and then return retrograde through the AV node ― or vice versa ― a reentrant circuit can be created, resulting in AVRT.
Findings on ECG include the following:
A narrow complex tachycardia
Variable findings, depending on the direction of the circuit and location of the accessory conduction pathway
1. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric, Sixth Edition, Saunders, Philadelphia, 2008.
2. Surawicz B, et al. AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram. Circulation. 2009; doi:10.1161/CIRCULATIONAHA.108.191095.