Atrioventricular

Atrioventricular refers to structures and relationships between the atria and ventricles of the heart. The term is used in anatomy, physiology, and clinical cardiology to describe the atrioventricular region, including the atrioventricular valves and the atrioventricular conduction system, as well as embryologic areas such as the atrioventricular canal.

Atrioventricular valves are the mitral valve on the left side and the tricuspid valve on the right. They regulate blood flow from the atria to the ventricles and prevent backflow during ventricular contraction. These valves are supported by chordae tendineae and papillary muscles and are anchored to the fibrous rings of the heart (the AV annulus).

The atrioventricular conduction system includes the atrioventricular node and the bundle of His (AV bundle) with its right and left bundle branches. The AV node slows electrical impulses from the atria, providing a necessary delay that allows ventricular filling, before impulses propagate to the ventricles via the His-Purkinje system.

Embryologically, the atrioventricular region includes the atrioventricular canal and the membranous portion of the interventricular septum. Defects in this region can lead to atrioventricular canal defects, particularly in certain congenital conditions.

Clinical relevance: conduction disorders involving the AV node or AV bundle are collectively known as atrioventricular blocks. These range from first-degree blocks with prolonged PR interval to second-degree and complete (third-degree) blocks, potentially requiring surveillance or intervention.