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.