A case of unilateral pulmonary edema in the acute on chronic mitral regurgitation

Unilateral pulmonary edema (UPE) is a rare manifestation of mitral regurgitation (MR) and may be misdiagnosed as pneumonia. We report a 63-year-old man with a history of mitral valve repair who presented with dyspnea and right-sided pulmonary edema (PE). Despite initial antibiotic therapy, the PE did not improve. Echocardiography revealed severe MR due to pseudo-prolapse of the anterior mitral leaflet, with the regurgitant jet directed toward the right pulmonary veins. Right heart catheterization demonstrated a prominent V wave on the right pulmonary capillary wedge pressure. This case highlights the diagnostic value of echocardiography and catheterization in acute-on-chronic MR-induced UPE.

・Differential diagnosis of unilateral pulmonary edema is often necessary to distinguish it from pneumonia or heart failure due to mitral regurgitation.・Echocardiographic evaluation of flow direction and mechanism, combined with bilateral pressure waveform confirmation by right heart catheterization, is crucial for diagnosis.・Unilateral pulmonary edema can occur not only in acute but also in acute-on-chronic mitral regurgitation.