Acquired accessory left atrium.

The patient was a 61-year-old woman brought to our hospital due to dyspnea and lower extremity swelling in shock state three weeks after mitral valve replacement due to rheumatic mitral regurgitation. Cardiothoracic examination revealed bilateral diffuse rales, metallic first heart sound and a loud holo systolic murmur in apex with radiation to axilla. Transesophageal echocardiography revealed a large echo lucent area representing a separate chamber in the lateral part of left atrium which communicates with left ventricle through a relatively large orifice far from normal functioning prosthesis. In operation left atrial dissection was confirmed but the patient did not wean from cardiopulmonary bypass and died on the operating table.