A 45-year-old man presented with fatigue for the previous two days. Because of severe hypoxemia and chest radiograph showing severe consolidation only in the right lung field, he was admitted to a near-by district hospital under the diagnosis of acute pneumonia. Since his respiratory condition rapidly deteriorated, he was transferred to our hospital. The diagnosis of unilateral cardiogenic pulmonary edema was made based upon the echocardiographic examination which showed severe mitral regurgitation secondary to chordal rupture of the posterior mitral valve leaflet (P2). After successful intensive medical treatment with diuretics and extracorporeal membrane oxygenation, mitral valve repair was performed with quadrangular resection of the posterior mitral leaflet (P2) and insertion of 28 mm Cosgrove ring. It is important to recognize acute and severe mitral regurgitation as a main cause of unilateral cardiogenic pulmonary edema. Prompt differentiation from acute pneumonia is critical to save lives of the patients. <Learning objective: Unilateral cardiogenic pulmonary edema is an unusual condition and may often be misdiagnosed as acute pneumonia, resulting in an increased risk of mortality. A correct differentiation from pneumonia is critical to save lives of the patients. It is important to recognize acute and severe mitral regurgitation as a main cause of this unusual condition.>.
Keywords: Acute mitral regurgitation; Differentiation from pneumonia; Unilateral cardiogenic pulmonary edema.