Atrial

Atrial is an adjective used in anatomy and medicine to describe structures associated with the atria, the two upper chambers of the heart. The heart contains right atrium and left atrium, which receive blood returning to the heart.

The right atrium receives deoxygenated blood from the systemic veins via the superior and inferior vena cavae and the coronary sinus; the left atrium receives oxygenated blood from the pulmonary veins. The atria have thin walls compared with ventricles; the interior of the right atrium includes the smooth posterior wall and the muscular anterior portion with pectinate muscles. The interatrial septum separates the two atria; a fetal remnant called the fossa ovalis marks where the foramen ovale existed. The SA node is located near the right atrium.

Functionally, the atria act as receiving chambers and contribute to ventricular filling by contracting to propel blood into the ventricles during diastole (atrial contraction or atrial kick). They also participate in cardiac rhythm and conduction. Common pathologies affecting the atria include atrial fibrillation, atrial flutter, atrial septal defects, atrial myxomas, and atrial enlargement; thrombi can form in the atrial appendage in atrial fibrillation.

Clinical relevance centers on imaging and treatment. Diagnosis often involves echocardiography, electrocardiography, and magnetic resonance imaging. Management may include rate control, rhythm control, anticoagulation, and procedures such as catheter ablation of atrial arrhythmias or surgical maze procedures. Etymology traces to Latin atrium, meaning entrance or reception chamber; the term is used across vertebrates to refer to analogous heart structures.