Evaluation of the vertebrobasilar system in thoracic aortic surgery.

BACKGROUND: We evaluated the probability of vertebrobasilar system malperfusion due to occlusion of the left subclavian artery as assessed by preoperative magnetic resonance angiography in patients scheduled to undergo thoracic aortic surgery. METHODS: (Study 1) From January 2000 through March 2009, we studied variations of vertebral arteries in 301 patients scheduled to undergo thoracic aortic surgery. We classified vertebral artery variations into 3 categories according to the findings on preoperative magnetic resonance angiography: connection type, interrupted right vertebral artery, and interrupted left vertebral artery. (Study 2) From February 2007 through January 2010, we evaluated the cerebral complication in 41 patients who had occlusion of the left subclavian artery with a stent graft. RESULTS: (Study 1) On preoperative magnetic resonance angiography, the vertebral artery was classified as connection type in 247 patients, interrupted right vertebral artery in 34, and interrupted left vertebral artery in 20. (Study 2) We performed subclavian obstruction test, left-right subclavian artery bypass, or left subclavian artery-left common carotid artery bypass to the 3 patients with interrupted right vertebral artery, respectively. Forty patients (98%) out of 41 patients had no complication after occlusion of the left subclavian artery. CONCLUSIONS: Preoperative magnetic resonance angiography is useful for detection of the patients with high risk of vertebrobasilar system malperfusion due to occlusion of the left subclavian artery.