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Encyclopedia > Atrioventricular node

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. Image File history File links Gray501. ... Image File history File links Gray501. ... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ... In anatomy, the atrium (plural: atria) refers to a chamber or space. ... In the heart, a ventricle is a heart chamber which collects blood from an atrium (another heart chamber that is smaller than ventricle) and pumps it out of the heart. ... The heart and lungs, from an older edition of Grays Anatomy. ...


The AV node receives two inputs from the atria: posteriorly via the crista terminalis, and anteriorly via the interatrial septum.[1] The right horn and transverse portion of the sinus venosus ultimately become incorporated with and form a part of the adult right atrium, the line of union between it and the auricula being indicated in the interior of the atrium by a vertical crest, the crista terminalis of His. ... Look up septum in Wiktionary, the free dictionary. ...


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. Atrial fibrillation (AF or afib) is an abnormal heart rhythm (cardiac arrhythmia) which involves the two small, upper heart chambers (the atria). ... Atrial flutter is a rhythmic, fast rhythm that occurs in the atria of the heart. ...


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. The coronary circulation consists of the blood vessels that supply blood to, and remove blood from, the heart. ... The LCX, or left circumflex artery (or circumflex artery, or circumflex branch of the left coronary artery) follows the left part of the coronary sulcus, running first to the left and then to the right, reaching nearly as far as the posterior longitudinal sulcus. ...


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. A supraventricular tachycardia (SVT) is a rapid rhythm of the heart in which the origin of the electrical signal is either the atria or the AV node. ...


See also

The EKG complex. ... The sinoatrial node (abbreviated SA node, also called the sinus node) is the impulse generating (pacemaker) tissue located in the right atrium of the heart. ...

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.


External links



 

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