The left atrium is one of the four chambers of the heart, located on the upper left side. It receives oxygen-rich blood returning from the lungs through the pulmonary veins and passes it to the left ventricle through the mitral valve. On echocardiography, the left atrium is routinely measured because enlargement can indicate conditions such as mitral valve disease, heart failure, or chronic high blood pressure. A dilated left atrium is also associated with an increased risk of atrial fibrillation. Sonographers assess its size, shape, and any masses or thrombi within it as part of a standard cardiac exam.
Sonography Term