Atrioventricular node
AV node visible near bend of red line.
Heart; conduction system
Latin	nodus atrioventricularis
Artery	atrioventricular nodal branch

The atrioventricular node (abbreviated AV node) is an area of specialized tissue between the atria and the ventricles of the heart, specifically in the posteroinferior region of the interatrial septum near the opening of the coronary sinus, which conducts the normal electrical impulse from the atria to the ventricles. It is located at the center of Koch's Triangle--a triangle enclosed by the septal leaflet of the tricuspid valve, the coronary sinus, and the membraneous part of the interatrial septum^[1].

The AV node may also be (rarely) referred to as the Aschoff-Tawara node.^[2]

[edit] Function

The AV node receives two inputs from the atria: posteriorly via the crista terminalis, and anteriorly via the interatrial septum.^[3]

An important property that is unique to the AV node is decremental conduction, in which the more frequently the node is stimulated, the slower it conducts. This is the property of the AV node that prevents rapid conduction to the ventricle in cases of rapid atrial rhythms, such as atrial fibrillation or atrial flutter.

The atrioventricular node delays impulses for a while (aprox. 0.12s) before allowing impulses through to the His-Purkinje conduction system, which spreads impulses to the ventricular walls. The reason it is important to delay the cardiac impulse is to ensure that the atria have ejected their blood into the ventricles before the ventricles contract.^[4]

The AV node is located between the right atrium and right ventricle. It slows the signals and allows the ventricles to fill before it moves on.

[edit] Blood supply

The blood supply of the AV node is from the posterior interventricular artery. When the RCA supplies the posterior descending artery and thus the AV node, the coronary system is said to be "right dominant," and when the posterior descending artery is supplied by the LCX, the system is "left dominant."

[edit] See also

• Electrical conduction system of the heart
• Sinoatrial node (SA node)

[edit] References

1. ^ http://medical-dictionary.thefreedictionary.com/_/viewer.aspx?path=dorland&name=triangle_of-Koch.jpg
2. ^ synd/454 at Who Named It
3. ^ ACC/AHA/ESC Guidelines for the Management of Patients with Atrial Fibrillation - Executive Summary (Full text)
4. ^ Campbell, N., & Reece, J. (2002). Biology. 6th ed. San Francisco: Benjamin Cummings.

[edit] External links

• SUNY Figs 20:06-02 - "The conduction system of the heart."
• Norman/Georgetown thoraxlesson4 (thoraxheartinternalner)
• http://www.healthyheart.nhs.uk/heart_works/heart03.shtml

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