Single atrium is a rare congenital heart disease, is defect condition that the paragraph 1 and paragraph 2 of interatrial septum are not growth at embryonic development phase. Atrial septal traces do not exist, and intact ventricular septum, it is also known as two-three-or single-chamber atrial heart chamber heart three. Single atrium can stand alone, but often left superior vena cava and the merger dextrocardia, left-bit heart or transposition of abdominal visceral malformation, especially common cleft mitral leaf missing before, and even the existence of atrioventricular canal malformation.
Single atrial pathogenesis: from the vena cava and pulmonary vein of the animals and blood in a single mixed atrium, right ventricular filling because of the small resistance, the majority of the blood into the left ventricle, pulmonary venous blood flow back to the atrium only by the second part of mitral valve re-entry into the left ventricular circulation, the clinical cyanosis can occur. On both sides of the atrium, ventricle, aorta and pulmonary artery oxygen saturation with nearly the same. Combined single-chamber atrial venous drainage is more common, The first, left superior vena cava cited inflow or co-coronary sinus of the left atrium. The second, the inferior vena cava or azygos vein azygos vein half and hepatic venous drainage directly into the joint of the right atrium side, forming a mixture of atrial blood.