Atrioventricular node (AV node)

The atrioventricular node (AV Node) is a bundle of conduction cells that regulate the communication of atrial electrical activity with ventricular electrical activity. The AV node has a long refractory period allowing it to “block” conduction to the His-purkinje system of the ventricles if there are excessive atrial depolarizations as in atrial fibrillation or atrial flutter.

Pathologic fibrosis of the AV node can occur especially with aging resulting in first degree AV block, second degree AV block (Type I or Type II) or complete heart block known as third degree heart block.