Discussion
Pseudoaneurysms of the thoracic aorta have been reported as a rare but life-threatening complication of aortic surgery, infection, or trauma. In the case of post-operative cardiac patients, the literature suggests that hypertension, infection, previous aortic operation, and graft wrapping are risk factors for their occurrence(1,2). Even in high-risk aortic dissection patients, there is a low incidence of pseudoaneurysms arising(1).
The first report of chronic sternal wire erosion into the ascending aorta was in 1994, 9 years following coronary artery bypass(3). To our knowledge, the only other case of chronic sternal wire erosion of the ascending thoracic aorta following repair of aortic dissection was published in 2003(4). Other reports of sternal wire migration to the pulmonary artery(5) and right ventricle(6) have also been described.
There have been descriptions of sternal re-entry to address aortic pseudoaneurysms without the use of CPB or circulatory arrest(7). However, data from large series indicate that, for optimum long-term results, extramediastinal cannulation offer a safer and more versatile approach, particularly for large pseudoaneurysms(1). Other series have reported bilateral cannulation of both carotid arteries through limited cervicotomies for brain protection, as well as femoral cannulation for the institution of CPB(8). Our case has described the use of a two-stage procedure, including extra-anatomical carotid-to-subclavian bypass to enhance brain protection and augment CPB strategies.