Atrioventricular node

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The atrioventricular node (abbreviated AV node) is an area of specialized tissue between the atria and the ventricles of the heart, which conducts the normal electrical impulse from the atria to the ventricles. The AV node is also known as the Aschoff-Tawara node.

The AV node receives two inputs from the atria: posteriorly via the crista terminalis, and anteriorly via the interatrial septum.^[1]

An important property that is unique to the AV node is decremental conduction. 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 ~0.1 second before spreading to the ventricle walls. The reason it is so important to delay the cardiac impulse is to ensure that the atria are empty completely before the ventricles contract (Campbell et al, 2002).

The blood supply of the AV node is from a branch of the right coronary artery in 85% to 90% of individuals, and from a branch of the left circumflex artery in 10% to 15% of individuals.

In certain types of supraventricular tachycardia, a person could have two AV Nodes; this will cause a loop in electrical current and uncontrollably-rapid heart beat. When this electricity catches up with itself, it will dissipate and return to normal heart-beat speed.

[edit] See also

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

[edit] References

1. ^ ACC/AHA/ESC Guidelines for the Management of Patients with Atrial Fibrillation - Executive Summary (Full text)

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."

v • d • e Anatomy of torso, cardiovascular system: heart

atria (interatrial septum, musculi pectinati) • ventricles (interventricular septum, trabeculae carneae, chordae tendinae, papillary muscle) • valves base • apex • grooves (coronary/atrioventricular, interatrial, anterior interventricula, posterior interventricular) • surfaces (sternocostal, diaphragmatic) • borders (right, left) right heart (vena cavae, coronary sinus) → right atrium (auricle, fossa ovalis, limbus of fossa ovalis, crista terminalis, valve of the inferior vena cava, valve of the coronary sinus) → tricuspid valve → right ventricle (conus arteriosus, moderator band/septomarginal trabecula)  → pulmonic valve → (pulmonary artery and pulmonary circulation) left heart (pulmonary veins) → left atrium (auricle) → mitral valve → left ventricle → aortic valve (aortic sinus) → (aorta and systemic circulation) pericardium  (sinus) • epicardium • myocardium • endocardium • cardiac skeleton (fibrous trigone, fibrous rings) conduction system cardiac pacemaker • SA node • AV node• bundle of His • Purkinje fibers