Mycotic Pseudoaneurysm Formation at the Cannulation Site in the Ascending Aorta.

The formation of mycotic pseudoaneurysms in the ascending aorta is a rare but sometimes fatal complication after open-heart surgery, requiring cardiopulmonary bypass (CPB). There has been little cited about this rare complication. We present a case of a 51-year-old man who developed a mycotic pseudoaneurysm in the ascending aorta at a previous aortic cannulation site nine years after coronary artery bypass surgery. The patient presented to the emergency department with two weeks of worsening substernal chest pain and was found to have pseudoaneurysm in the anterior wall of the ascending aorta on chest computed tomography angiography (CTA) during his chest pain workup. The patient's blood cultures grew methicillin-susceptible Staphylococcus aureus (MSSA). During the hospital course, the patient's respiratory status worsened, and repeat CTA revealed enlargement of the pseudoaneurysm arising from the anterior proximal arch of the aorta. Chest X-ray obtained because of hypoxia demonstrated widening of the upper mediastinum, which appeared increased compared with the previous exam. Because of concern for rupture of an aneurysm, the patient was taken to the operating room for redo sternotomy and repair of the pseudoaneurysm with femoral artery cannulation for cardiopulmonary bypass. The patient completed eight weeks of IV nafcillin, and rifampin was added to decrease biofilm formation.