Giant coronary artery aneurysm presenting as a mediastinal mass

A fit and well 72-year-old white man with an abnormal chest radiograph was referred to the cardiology clinic for assessment of probable right heart enlargement. There was no preceding history of pulmonary hypertension or coronary artery disease. Blood pressure was 115/70 mm Hg. Precordial auscultation disclosed no abnormalities. There were no signs of pulmonary hypertension. There were no electrocardiographic features of myocardial ischemia or infarction. Chest radiography (Figure 1, panel A) showed an abnormal prominence of the right heart border. Transthoracic echocardiography revealed a cystic cavity adjacent to the right atrium. Computerized tomography of the thorax revealed a spherical mass (dimensions 6.5 x 8.5 cm), lying anterior and lateral to the right atrium (Figure 1, panel B). Dynamic intravenous contrast injection resulted in enhancement of the mass with similar timing and density to the heart chambers. Magnetic resonance imaging showed the proximal right coronary artery adjacent to the mass (Figure 1, panel C). Using a cine gradient echo technique, blood flow was clearly demonstrated within the mass (Figure 1, panel D), suggesting the diagnosis of a very large right coronary aneurysm. Cardiac catheterization was performed from the right fem oral artery. There was diffuse atheromatous change with severe ectasia throughout the left coronary artery. The proximal right coronary artery opened into a large, spherical cavity which filled with contrast medium in a swirling fashion, with slow opacification of the distal right coronary artery (Figure 1, panel E), confirming the diagnosis of a giant right coronary artery aneurysm. At surgery, a large, spherical mass was present anterior to the right atrium. Cardiopulmonary bypass was established and the aneurysm was incised. The wall was thin, and atheromatous plaque was present. The right coronary artery lumen was identified, the proximal and distal ends were mobilized, and an end-to-end anastomosis was performed. Postoperative recovery was uneventful and repeat right coronary arteriography before discharge showed a widely patent anastomosis and good flow into a large distal territory.