[A case of atelectasis of the middle lobe associated with congestive heart failure].

A 74-year-old man was admitted to our hospital for work up of a shadow in the right middle lobe on chest X-ray film. He had hypertension, aortic regurgitation, and atrial fibrillation on admission. Bronchoscopy demonstrated total obstruction of the right B4 orifice, but the etiology of obstruction was unknown. He was discharged and followed up. The shadow in the middle lobe disappeared spontaneously and the cardiac silhouette was slightly smaller than that on the first admission. The shadow in the middle lobe reappeared again with the progression of cardiomegaly. Because hypertension became uncontrolled and pretibial edema developed, he was readmitted. Bronchoscopy showed the same findings as on the first admission. After treatment of heart failure for one month, bronchoscopy demonstrated partial patency of the right B4 orifice. As cardiomegaly improved, the shadow in the middle lobe diminished and then disappeared, and chest CT scan showed patency of the right B4. These findings suggest that congestive heart failure caused the atelectasis of the right middle lobe, so-called middle lobe syndrome. A possible mechanism of the right B4 obstruction is that the right B4 was compressed between the middle lobe artery and the dilated middle lobe vein due to heart failure.