The AV node, like the sinus node, is located in the right atrium. However, it lies further down, more precisely at the transition to the right ventricle and thus in Koch’s triangle. Just like the sinus node, the AV node does not consist of nerve cells, but of specialized heart muscle cells that have the ability to depolarize and thus generate an electrical signal that leads to heart contraction.
The AV node generates an electrical potential with the help of special ion channels and also receives electrical signals from the sinus node, which it transmits to the chamber. If the sinus node fails once, the AV node can step in and the heart contraction can continue. Thus the AV node serves as a filter and in an emergency as a generator of electrical potentials.
However, it alone can only generate a heart rate of about 40 beats, while the sinus node generates a heart rate of about 60 beats. The transmission works through special wires that run from the AV node into the chamber. These lines also consist of specialized heart muscle cells, they pull right and left into the ventricle and end at the tip of the heart.
The line from the AV node is called His bundle, which in turn splits into the tawara legs and ends in the Purkinje fibers. When the electrical potential arrives in all heart cells, the heart can contract and expel blood. Since the sinus node is located upstream of the AV node, the atrium contracts just before the ventricle and thus helps to fill the ventricle with blood. 90% of the blood filling, however, occurs via a suction that emanates from the ventricle.
If there is a disturbance in the transmission of electrical signals from AV nodes to the chamber, this is called an AV block. There are different degrees of AV block. These are presented under AV block.