Atrioventricular

Atrioventricular Node

The atrioventricular node (AV node) is a critical component of the cardiac conduction system, which is responsible for coordinating the heart's rhythm. It is located at the center of the heart, between the atria and the ventricles, and plays a vital role in the electrical conduction pathway of the heart.

Anatomy and Location

The AV node is situated in the right atrium, near the lower part of the interatrial septum, close to the opening of the coronary sinus. It is positioned at the junction between the atria and the ventricles, which allows it to effectively regulate the transmission of electrical impulses from the atria to the ventricles.

Function

The primary function of the AV node is to act as a gatekeeper for electrical impulses traveling from the atria to the ventricles. It slows down the electrical signal before it passes into the ventricles, ensuring that the atria have enough time to contract and pump blood into the ventricles before they contract. This delay is crucial for maintaining an efficient and coordinated heartbeat.

The AV node also serves as a backup pacemaker for the heart. In the event that the sinoatrial node (SA node), the primary pacemaker, fails to function properly, the AV node can generate electrical impulses at a slower rate to maintain a basic level of cardiac function.

Clinical Significance

Disorders of the AV node can lead to various types of heart block, which are characterized by impaired conduction of electrical impulses from the atria to the ventricles. These can range from first-degree heart block, where conduction is merely delayed, to complete heart block, where no impulses are conducted.

Treatment for AV node dysfunction may involve the use of medications, such as beta-blockers or calcium channel blockers, to manage symptoms. In more severe cases, implantation of a pacemaker may be necessary to ensure proper heart rhythm.

Related Structures

• Sinoatrial node
• Bundle of His
• Purkinje fibers

See Also

• Cardiac conduction system
• Electrocardiogram

References

• Guyton, A. C., & Hall, J. E. (2016). Textbook of Medical Physiology. Elsevier.
• Lilly, L. S. (2016). Pathophysiology of Heart Disease: A Collaborative Project of Medical Students and Faculty. Lippincott Williams & Wilkins.