Unsuspected idiopathic mediastinal fibrosis complicating coronary bypass operation.

A 66-year-old woman was referred for coronary bypass operation to the left anterior descending and the circumflex arteries. She had a systemic inflammatory process of unknown origin. On opening the pericardium, fibrotic plaques encircling the entire ascending aorta were found. Aortic cannulation and proximal anastomosis of the planned vein graft were impossible. The right internal mammary was anastomosed to the left anterior descending artery, the left to the obtuse marginal after femoral arterial cannulation. Pathologic examination revealed idiopathic mediastinal fibrosis.