17Atrioventricular Node

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Atrioventricular node

The atrioventricular node (abbreviatedAV node) is a

part of the electrical control system of the heart that coor-

dinates the top of the heart. It electrically connects atrial

and ventricular chambers.[1] The AV node is an area of

specializedtissuebetween theatriaand theventriclesof

theheart, specifically in the posteroinferior region of the

interatrial septum near the opening of the coronary si-

nus, which conducts the normal electrical impulse from

the atria to the ventricles. The AV node is quite compact

(~1 x 3 x 5 mm).[2] It is located at the center of Kochs

Trianglea triangle enclosed by the septal leaflet of thetricuspid valve, the coronary sinus, and the membraneous

part of the interatrial septum.[3]

1 Structure

The AV node receives two inputs from the atria: posteri-

orly, via thecrista terminalis, and anteriorly, via the in-

teratrialseptum.[4]

1.1 Blood supply

The blood supply of the AV node is via the AV nodal

artery. The origin of this artery is most commonly (about

90% of hearts) a branch of the right coronary artery,

with the remainder originating from the left circumflex

artery.[5][6][7] This is associated with the dominanceof

the coronary artery circulation. Inright-dominant indi-

viduals the blood supply is from theright coronary artery

while in left dominant individuals it originates from the

left circumflex artery.

1.2 Development

BMP (Bone morphogenetic protein)cell signalingplays

a key role in diverse aspects of cardiac differentiation

and morphogenesis. (BMPs) are multifunctional signal-

ing molecules critical for the development of AV node.

BMP influences AV node development through Alk3 re-

ceptor (Activin receptor-like kinase 3). Abnormalities

seen in BMP and Alk3 are associated with some cardio-vascular diseases like Ebsteins anomaly and AV conduc-

tion disease.[8]

2 Function

Contraction of myocytes (heart muscle cells) requires

depolarization and repolarization of their cell mem-

branes. Movement of ions across cell membranes causes

these events. The cardiac conduction system (and AV

node part of it) coordinates myocyte mechanical activ-

ity. A wave of excitation spreads out from the sinoatrial

node through the atria along specialized conduction chan-

nels. This activates the AV node.[1] The atrioventricular

node delays impulses by approximately 0.12s. This de-lay in the cardiac pulse is extremely important: It ensures

that the atria have ejected their blood into the ventricles

first before the ventricles contract.[9]

This also protects the ventricles from excessively fast rate

response to atrialarrhythmias(see below).[10]

AV conduction during normal cardiac rhythm occurs

through two different pathways:

the first pathway has a slow conduction velocity

but shorterrefractory period

the second pathway has a faster conduction veloc-

ity but longer refractory period.[11]

An important property that is unique to the AV node is

decremental conduction,[12] 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 fibrillationoratrial flutter.

The AV nodes normal intrinsic firing rate without

stimulation (such as that from the SA node) is 40-60

times/minute.

[13]

3 Clinical relevance

Atrioventricular conduction disease (AV block) de-

scribes impairment of the electrical continuity be-

tween the atria and ventricles. It occurs when the

atrial depolarization fail to reach the ventricles or is

conducted with a delay. It can result from an injury

or be a genetically inherited disorder.[14]

Atrioventricular nodal re-entrytachycardia.[11]

Cystic tumour of atrioventricular nodal region

(CTAVN) CTAVN is ofendodermalorigin and oc-

1
https://en.wikipedia.org/wiki/Endodermalhttps://en.wikipedia.org/wiki/Cystic_tumour_of_atrioventricular_nodal_regionhttps://en.wikipedia.org/wiki/Tachycardia,_atrioventricular_nodal_reentryhttps://en.wikipedia.org/wiki/Atrioventricular_blockhttps://en.wikipedia.org/wiki/Atrial_flutterhttps://en.wikipedia.org/wiki/Atrial_fibrillationhttps://en.wikipedia.org/wiki/Refractory_period_(physiology)https://en.wikipedia.org/wiki/Arrhythmiashttps://en.wikipedia.org/wiki/Sinoatrial_nodehttps://en.wikipedia.org/wiki/Sinoatrial_nodehttps://en.wikipedia.org/wiki/Repolarizationhttps://en.wikipedia.org/wiki/Depolarizationhttps://en.wikipedia.org/wiki/Myocyteshttps://en.wikipedia.org/wiki/Cell_signalinghttps://en.wikipedia.org/wiki/Left_circumflex_arteryhttps://en.wikipedia.org/wiki/Right_coronary_arteryhttps://en.wikipedia.org/wiki/Coronary_artery_dominancehttps://en.wikipedia.org/wiki/Left_circumflex_arteryhttps://en.wikipedia.org/wiki/Left_circumflex_arteryhttps://en.wikipedia.org/wiki/Right_coronary_arteryhttps://en.wikipedia.org/wiki/Septumhttps://en.wikipedia.org/wiki/Crista_terminalishttps://en.wikipedia.org/wiki/Coronary_sinushttps://en.wikipedia.org/wiki/Coronary_sinushttps://en.wikipedia.org/wiki/Interatrial_septumhttps://en.wikipedia.org/wiki/Hearthttps://en.wikipedia.org/wiki/Ventricle_(heart)https://en.wikipedia.org/wiki/Atrium_(heart)https://en.wikipedia.org/wiki/Biological_tissue


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2 6 EXTERNAL LINKS

curs exclusively in the area of the AV node,tricuspid

valve, andinteratrial septum.[15]

4 See also

This article uses anatomical terminology; for an

overview, seeanatomical terminology.

Electrical conduction system of the heart

Sinoatrial node(SA node)

5 References

[1] Gray, Huon H.; Keith D. Dawkins, Iain A. Simpson and

John M. Morgan (2002). Lecture Notes on Cardiology.

Boston: Blackwell Science. p. 135. ISBN 978-0-86542-864-5.

[2] Full Size Picture triangle of-Koch.jpg. Retrieved on

2008-12-22

[3] Harrisons Principles of Internal Medicine, 17e Section

3: Disorders of Rhythm

[4] Fuster V, Rydn LE, Asinger RW, et al. (Octo-

ber 2001). ACC/AHA/ESC guidelines for the man-

agement of patients with atrial fibrillation. Jour-

nal of the American College of Cardiology 38 (4):

123166. doi:10.1016/S0735-1097(01)01587-X.PMID

11583910.

[5] Van der Hauwaert LG, Stroobandt R, Verhaeghe L (Octo-

ber 1972). Arterial blood supply of the atrioventricular

node and main bundle. British Heart Journal 34 (10):

104551. doi:10.1136/hrt.34.10.1045. PMC 458545.

PMID 5086972.

[6] Pejkovi, B.; Krajnc, I.; Anderhuber, F.; Kosuti, D.

(2008). Anatomical aspects of the arterial blood sup-

ply to the sinoatrial and atrioventricular nodes of the hu-

man heart. The Journal of international medical research

36 (4): 691698. doi:10.1177/147323000803600410.

PMID 18652764.

[7] Saremi, F.; Abolhoda, A.; Ashikyan, O.; Milliken,

J. C.; Narula, J.; Gurudevan, S. V.; Kaushal, K.;

Raney, A. (2007). Arterial Supply to Sinuatrial and

Atrioventricular Nodes: Imaging with Multidetector

CT. Radiology 246 (1): 99107; discussion 1089.

doi:10.1148/radiol.2461070030.PMID 18024438.

[8] Stroud DM, Gaussin V, Burch JB, et al. (Novem-

ber 2007). Abnormal Conduction and Mor-

phology in the Atrioventricular Node of Mice

With Atrioventricular CanalTargeted Deletion of

Alk3/Bmpr1a Receptor. Circulation 116 (22): 2535

43. doi:10.1161/CIRCULATIONAHA.107.696583.

PMC 2947829.PMID 17998461.

[9] Campbell, N., & Reece, J. (2002). Biology. 6th ed. San

Francisco: Benjamin Cummings



Boston: Blackwell Science. p. 136. ISBN 978-0-86542-

864-5.



Boston: Blackwell Science. p. 157. ISBN 978-0-86542-

864-5.

[12] Patterson E, Scherlag BJ (October 2002). Decremen-

tal conduction in the posterior and anterior AV nodal in-

puts. Journal of Interventional Cardiac Electrophysiology

7 (2): 13748. doi:10.1023/A:1020833604423. PMID

12397223.

[13] Guyton, ArthurC.; John E. Hall (2006). Textbook of Med-

ical Physiology(11 ed.). Philadelphia: Elsevier Saunders.

p. 120.ISBN 0-7216-0240-1.

[14] Benson DW (October 2004). Genetics of atrioven-

tricular conduction disease in humans. The Anatom-ical Record. Part A: Discoveries in Molecular, Cel-

lular, and Evolutionary Biology 280 (2): 9349.

doi:10.1002/ar.a.20099.PMID 15372490.

[15] Sharma G, Linden MD, Schultz DS, Inamdar KV (Jan-

uary 2009). Cystic tumor of the atrioventricular node:

an unexpected finding in an explanted heart. Car-

diovascular Pathology : the Official Journal of the

Society for Cardiovascular Pathology 19 (3): e758.

doi:10.1016/j.carpath.2008.10.011. PMID 19144541.

6 External links Anatomy figure: 20:06-02at Human Anatomy On-

line, SUNY Downstate Medical Center - The con-

duction system of the heart.

thoraxlesson4 at The Anatomy Lesson by

Wesley Norman (Georgetown University)

(thoraxheartinternalner)

http://www.healthyheart.nhs.uk/heart_works/

heart03.shtml
http://www.healthyheart.nhs.uk/heart_works/heart03.shtmlhttp://www.healthyheart.nhs.uk/heart_works/heart03.shtmlhttp://mywebpages.comcast.net/wnor/thoraxheartinternalner.jpghttp://www.wesnorman.com/thoraxlesson4.htmhttp://ect.downstate.edu/courseware/haonline/figs/l20/200602.htmhttps://www.ncbi.nlm.nih.gov/pubmed/19144541https://en.wikipedia.org/wiki/PubMed_Identifierhttps://dx.doi.org/10.1016%252Fj.carpath.2008.10.011https://en.wikipedia.org/wiki/Digital_object_identifierhttps://www.ncbi.nlm.nih.gov/pubmed/15372490https://en.wikipedia.org/wiki/PubMed_Identifierhttps://dx.doi.org/10.1002%252Far.a.20099https://en.wikipedia.org/wiki/Digital_object_identifierhttps://en.wikipedia.org/wiki/Special:BookSources/0-7216-0240-1https://en.wikipedia.org/wiki/International_Standard_Book_Numberhttps://www.ncbi.nlm.nih.gov/pubmed/12397223https://en.wikipedia.org/wiki/PubMed_Identifierhttps://dx.doi.org/10.1023%252FA%253A1020833604423https://en.wikipedia.org/wiki/Digital_object_identifierhttps://en.wikipedia.org/wiki/Special:BookSources/978-0-86542-864-5https://en.wikipedia.org/wiki/Special:BookSources/978-0-86542-864-5https://en.wikipedia.org/wiki/International_Standard_Book_Numberhttps://en.wikipedia.org/wiki/Blackwell_Sciencehttps://en.wikipedia.org/wiki/Bostonhttps://en.wikipedia.org/wiki/Special:BookSources/978-0-86542-864-5https://en.wikipedia.org/wiki/Special:BookSources/978-0-86542-864-5https://en.wikipedia.org/wiki/International_Standard_Book_Numberhttps://en.wikipedia.org/wiki/Blackwell_Sciencehttps://en.wikipedia.org/wiki/Bostonhttps://www.ncbi.nlm.nih.gov/pubmed/17998461https://en.wikipedia.org/wiki/PubMed_Identifierhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947829https://en.wikipedia.org/wiki/PubMed_Centralhttps://dx.doi.org/10.1161%252FCIRCULATIONAHA.107.696583https://en.wikipedia.org/wiki/Digital_object_identifierhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947829https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947829https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947829https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947829https://www.ncbi.nlm.nih.gov/pubmed/18024438https://en.wikipedia.org/wiki/PubMed_Identifierhttps://dx.doi.org/10.1148%252Fradiol.2461070030https://en.wikipedia.org/wiki/Digital_object_identifierhttps://www.ncbi.nlm.nih.gov/pubmed/18652764https://en.wikipedia.org/wiki/PubMed_Identifierhttps://dx.doi.org/10.1177%252F147323000803600410https://en.wikipedia.org/wiki/Digital_object_identifierhttps://www.ncbi.nlm.nih.gov/pubmed/5086972https://en.wikipedia.org/wiki/PubMed_Identifierhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC458545https://en.wikipedia.org/wiki/PubMed_Centralhttps://dx.doi.org/10.1136%252Fhrt.34.10.1045https://en.wikipedia.org/wiki/Digital_object_identifierhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC458545https://www.ncbi.nlm.nih.gov/pmc/articles/PMC458545https://www.ncbi.nlm.nih.gov/pubmed/11583910https://en.wikipedia.org/wiki/PubMed_Identifierhttps://dx.doi.org/10.1016%252FS0735-1097%252801%252901587-Xhttps://en.wikipedia.org/wiki/Digital_object_identifierhttp://www.americanheart.org/downloadable/heart/222_ja20017993p_1.pdfhttp://www.americanheart.org/downloadable/heart/222_ja20017993p_1.pdfhttp://www.accessmedicine.com/content.aspx?aID=2874462http://www.accessmedicine.com/content.aspx?aID=2874462http://medical-dictionary.thefreedictionary.com/_/viewer.aspx?path=dorland&name=triangle_of-Koch.jpghttps://en.wikipedia.org/wiki/Special:BookSources/978-0-86542-864-5https://en.wikipedia.org/wiki/Special:BookSources/978-0-86542-864-5https://en.wikipedia.org/wiki/International_Standard_Book_Numberhttps://en.wikipedia.org/wiki/Blackwell_Sciencehttps://en.wikipedia.org/wiki/Bostonhttps://en.wikipedia.org/wiki/Sinoatrial_nodehttps://en.wikipedia.org/wiki/Electrical_conduction_system_of_the_hearthttps://en.wikipedia.org/wiki/Anatomical_terminologyhttps://en.wikipedia.org/wiki/Interatrial_septumhttps://en.wikipedia.org/wiki/Tricuspid_valvehttps://en.wikipedia.org/wiki/Tricuspid_valve


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