Unilateral pulmonary edema in two patients with mitral regurgitation

History: Two patients were admitted with dyspnoea, the first after an infection, the second in association with an ischemic cardiomyopathy. Investigations: Chest radiography displayed an interstitial infiltrate in the right upper lobe in the first patient and in the right lower lobe in the second one. In both patients the transthoracic echocardiogram (TEE) showed significant mitral regurgitation with systolic reversal of flow as far as the right superior and inferior pulmonary veins, respectively. Diagnosis, treatment and course: Both patients had unilateral pulmonary edema associated with mitral regurgitation. Mitral valvuloplasty was performed in the first patient while the second one was treated medically. Conclusion: Unilateral pulmonary edema associated with mitral regurgitation is a distinct but unusual clinical entity, often mis-diagnosed initially as being caused by one of the more common focal lung diseases. The TEE indicated the cause and provided the reason for the mechanism of the edema formation.