The AV node is the gateway between the atria and ventricles. It is responsible for holding the impulses from the SA node until the ventricles are ready to receive them. In the diseased heart, the atria may fire rapidly and erratically. Without the AV node, the ventricles would be unable to keep up with these impulses. It is the responsibility of the AV node to filter these impulses out so that the ventricles can keep up.