The atrioventricular (AV) node is a key part of the heart’selectrical system, controlling the transmission of the heart’s electrical impulse from the atria to the ventricles. This tiny structure is strategically located near the center of the heart at the spot wherethe two atria and the two ventriclesare in close proximity.
Disorders of the AV node can causecardiac arrhythmias, in which the heart can beat either too slowly (bradycardia) or too rapidly (tachycardia). Both bradycardia or tachycardia can produce significant symptoms.
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What Is the AV Node?
Its job is to help coordinate the contraction of the atria and the ventricles in response to the heart’s electrical signal.
What Does the AV Node Do?
The AV node controls the passage of the heart’s electrical signal from the atria to the ventricles.
This brief delay in the transmission of the electrical signal through the AV node is critical to a normal heartbeat and the efficient functioning of the heart.
Clinical Significance
Without this brief delay in the electrical impulse, the atria would not be able to finish beating—allowing the ventricles to completely fill with blood—before the ventricles themselves begin to beat.
Some people are born with two distinct electrical pathways through the AV node, which can make them prone to an arrhythmia calledAV nodal reentrant tachycardia (AVNRT).
Disease of the AV node can cause either a delay or a partial or complete block in the transmission of electrical impulses from the atria to the ventricles, a condition known asheart block.
A delay in conduction through the AV node is seen on theECGas an increased PR interval. (The PR interval measures the time between atrial contraction and ventricular contraction.)
With second degree AV block, some impulses from the atria are blocked from reaching the ventricles. With third-degree AV block, all of the impulses are blocked.
Occasionally AV nodal block is significant enough to produce severebradycardiaand insertion of apacemakermay be required.
One common cause of AV nodal block is likely to require a permanent pacemaker, namely,myocardial infarction (heart attack). The AV node receives its blood supply from the AV nodal artery; in 90% of people this artery branches from theright coronary artery. So AV nodal block due to a heart attack is most commonly seen with right coronary artery heart attacks.
Fortunately, even in these cases the AV node usually recovers sufficiently within a few days to make a permanent pacemaker unnecessary.
A Word From Verywell
The AV node is a very important part of the heart’s electrical system. It transmits the heart’s electrical signal from the atrium to the ventricle, optimizes the coordination of each heartbeat, and, if atrial fibrillation occurs, protects the ventricles from being bombarded with a dangerous number of electrical signals. Disorders of the AV node can produce either tachycardia or bradycardia.
4 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Saremi F, Hassani C, Sánchez-quintana D.Septal atrioventricular junction region: Comprehensive imaging in adults.Radiographics. 2016;36(7):1966-1986.Holmqvist F, Daubert JP.First-degree AV block-an entirely benign finding or a potentially curable cause of cardiac disease?.Ann Noninvasive Electrocardiol.2013;18(3):215-24. doi:10.1111/anec.12062Kwon CH, Kim SH.Intraoperative management of critical arrhythmia.Korean J Anesthesiol. 2017;70(2):120-126. doi:10.4097/kjae.2017.70.2.120Lim Y, Singh D, Poh KK.High-grade atrioventricular block.Singapore Med J. 2018;59(7):346-350. doi:10.11622/smedj.2018086Additional ReadingKusumoto FM, Schoenfeld MH, Barrett C, et al.2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay.Journal of the American College of Cardiology. 2019;74(7):e51-e156. doi:10.1016/j.jacc.2018.10.044
4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Saremi F, Hassani C, Sánchez-quintana D.Septal atrioventricular junction region: Comprehensive imaging in adults.Radiographics. 2016;36(7):1966-1986.Holmqvist F, Daubert JP.First-degree AV block-an entirely benign finding or a potentially curable cause of cardiac disease?.Ann Noninvasive Electrocardiol.2013;18(3):215-24. doi:10.1111/anec.12062Kwon CH, Kim SH.Intraoperative management of critical arrhythmia.Korean J Anesthesiol. 2017;70(2):120-126. doi:10.4097/kjae.2017.70.2.120Lim Y, Singh D, Poh KK.High-grade atrioventricular block.Singapore Med J. 2018;59(7):346-350. doi:10.11622/smedj.2018086Additional ReadingKusumoto FM, Schoenfeld MH, Barrett C, et al.2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay.Journal of the American College of Cardiology. 2019;74(7):e51-e156. doi:10.1016/j.jacc.2018.10.044
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Saremi F, Hassani C, Sánchez-quintana D.Septal atrioventricular junction region: Comprehensive imaging in adults.Radiographics. 2016;36(7):1966-1986.Holmqvist F, Daubert JP.First-degree AV block-an entirely benign finding or a potentially curable cause of cardiac disease?.Ann Noninvasive Electrocardiol.2013;18(3):215-24. doi:10.1111/anec.12062Kwon CH, Kim SH.Intraoperative management of critical arrhythmia.Korean J Anesthesiol. 2017;70(2):120-126. doi:10.4097/kjae.2017.70.2.120Lim Y, Singh D, Poh KK.High-grade atrioventricular block.Singapore Med J. 2018;59(7):346-350. doi:10.11622/smedj.2018086
Saremi F, Hassani C, Sánchez-quintana D.Septal atrioventricular junction region: Comprehensive imaging in adults.Radiographics. 2016;36(7):1966-1986.
Holmqvist F, Daubert JP.First-degree AV block-an entirely benign finding or a potentially curable cause of cardiac disease?.Ann Noninvasive Electrocardiol.2013;18(3):215-24. doi:10.1111/anec.12062
Kwon CH, Kim SH.Intraoperative management of critical arrhythmia.Korean J Anesthesiol. 2017;70(2):120-126. doi:10.4097/kjae.2017.70.2.120
Lim Y, Singh D, Poh KK.High-grade atrioventricular block.Singapore Med J. 2018;59(7):346-350. doi:10.11622/smedj.2018086
Kusumoto FM, Schoenfeld MH, Barrett C, et al.2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay.Journal of the American College of Cardiology. 2019;74(7):e51-e156. doi:10.1016/j.jacc.2018.10.044
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