Giant right atrium after mitral valve replacement: plain film findings in 15 patients.

We reviewed the radiographs of 166 patients who had undergone mitral valve replacement and found 15 (9%) with giant right atrium. It was confirmed in 13 cases by angiography and/or echocardiography. It was proved at autopsy in one case and confirmed by a Swan-Ganz catheter delineating the lateral right atrial wall in another case. Tricuspid insufficiency of varying severity was present in all patients. Progressive bulging of the right heart border on frontal radiographs and an anterior masslike density on lateral radiographs were the important findings. The bulging right heart border was seen in all 15 patients. The anterior masslike density was noted in seven of nine patients with lateral radiographs; its upper border was sharp in four and indistinct in three. Giant right atrium may be misdiagnosed as pleural effusion, pericardial effusion, and mediastinal neoplasm. Correct diagnosis is important so that unnecessary procedures are not performed.