Right upper lobe pulmonary edema caused by acute mitral regurgitation. Diagnosis by transesophageal echocardiography.

Unilateral pulmonary edema is a distinctly unusual clinical entity, often misdiagnosed initially as one of the more common causes of focal lung disease. Predominantly lobar pulmonary edema is rarer still. We report a case of right upper lobe pulmonary edema caused by the acute onset of severe mitral regurgitation. In addition, we briefly review the other causes of unilateral pulmonary edema, focusing on the cases that have been reported in association with heart failure and valvular heart disease. The majority of cases of right upper lobe pulmonary edema have been associated with mitral regurgitation. In addition to confirming the presence of mitral regurgitation, transesophageal echocardiography proved useful in delineating the mechanism for edema formation. It detected differential gradients between the right and left pulmonary venous systems and documented the direction of the regurgitant flow.