Mixed blood in the atrium

A single atrium is formed in the atrium. Single atrial is a rare congenital heart disease, caused by the development of the first and second septum of the atrial septum during embryonic development. The traces of the atrial septum do not exist, and the ventricular septum is intact. The single atrium can exist alone, but often combined with left superior vena cava and right heart, left heart or abdominal visceral translocation malformations, anterior mitral valve fissures, and even atrioventricular tube deformities are particularly common.