page_title: AV nodal reentrant tachycardia
section_title: Mechanisms
hierarchical_section_title: AV nodal reentrant tachycardia / Mechanisms
context_page_description: AV-nodal reentrant tachycardia is a type of abnormal fast heart rhythm. It is a type of supraventricular tachycardia, meaning that it originates from a location within the heart above the bundle of His. AV nodal reentrant tachycardia is the most common regular supraventricular tachycardia. It is more common in women than men. The main symptom is palpitations. Treatment may be with specific physical maneuvers, medications, or, rarely, synchronized cardioversion. Frequent attacks may require radiofrequency ablation, in which the abnormally conducting tissue in the heart is destroyed.
  AVNRT occurs when a reentrant circuit forms within or just next to the atrioventricular node. The circuit usually involves two anatomical pathways: the fast pathway and the slow pathway, which are both in the right atrium. The slow pathway is located inferior and slightly posterior to the AV node, often following the anterior margin of the coronary sinus. The fast pathway is usually located just superior and posterior to the AV node. These pathways are formed from tissue that behaves very much like the AV node, and some authors regard them as part of the AV node.
context_section_description: The fundamental mechanism of AVNRT is a re-entrant circuit within the atrioventricular node. This can take several forms. "Typical", "common", or "slow-fast" AVNRT uses the slow AV nodal pathway to conduct towards the ventricle (the anterograde limb of the circuit) and the fast AV nodal pathway to conduct to the atria (the retrograde limb).  The re-entrant circuit can be reversed such that the fast AV nodal pathway is the anterograde limb and the slow AV nodal pathway is the retrograde limb, referred to as "atypical", "uncommon", or "fast-slow" AVNRT.  Atypical AVNRT may also use the slow AV nodal pathway as the anterograde limb and left atrial fibres that approach the AV node from the left side of the inter-atrial septum as the retrograde limb, and is sometimes referred to as "slow-slow" AVNRT.
caption: During typical AVNRT, electrical impulses travel down the slow pathway of the AV node and back up the fast pathway.
exif: {}