Atrioventricular node (AV node)


Consists of atrial muscle cells, stellate P cells, and transitional cells in a collagen mix.

Lies at the apex of Koch’s triangle in the right heart near the septum of the tricuspid valve anteriorly, the ligament of Todara posteriorly and the subeustachian isthmus from the inferior septal aspect of the tricuspid valve to the coronary sinus.

On the left side of the ventricular septum it lies under the noncoronary sinus of the aortic valve.

Specialized tissue that conducts cardiac impulse from the atria to the ventricles.

Acts as the pacemaker for the entire heart.

Acts as a second pacemaker receiving impulses to contract from the

Sinoatrial node and transmits it through the atrioventricular bundle to the ventricles.

Its firing conducts cardiac action potentials that cause the ventricles to contract and force blood into the aorta.

Approximately 1 x 3 x 5 mm in size.

Conducts cardiac rhythm via two pathways: first pathway is associated with a slow conduction velocity and shorter refractory period and the second pathway has a faster conduction velocity with a linger refractory period.

Proximal portion of the AV node receives impulses from the internodal tracts connecting from the Sinoatrial node and these impulses utilize the sodium fast channel.

In the AV node the conduction is slowed with a calcium channel mediated conduction.

The more frequently the AV node is stimulated the slower it conducts a property known as decremental conduction.

Decremental conduction prevents rapid conduction of atrial rhythms such as atrial fibrillation or atrial flutter to the ventricles.

Normal intrinsic firing rate without stimulation from the SA node is 40-60 times per minute.

The blood supply to the AV node is from the posterior interventricular artery, a branch of the right coronary artery in individuals with a dominant right coronary artery.

In individuals that do not have a dominant right coronary artery, the blood vessel that supplies the AV node is the posterior interventricular artery branching from the left circumflex artery in which the left coronary circulation is dominant.

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