Background and Purpose
Severe ischemic changes are a rare but devastating complication following direct superficial temporal artery to middle cerebral artery (STA MCA) bypass in Moyamoya patients. This study was undertaken to determine whether pre-operative MR imaging and/or cerebrovascular reserve (CVR) assessment using reference standard stable xenon enhanced computed tomography (xeCT) could predict such complications.
Materials and Methods
Among all adult patients receiving direct bypass at our institution between 2005 and 2010 who received a clinically interpretable xeCT examination, we identified index cases (patients with >15 ml post-operative infarcts) and control cases (patients without post-operative infarcts and without transient or permanent ischemic symptoms). Differences between groups were evaluated using the Mann Whitney test. Univariate and multivariate generalized linear model regression were employed to test predictors of post-operative infarct.
Results
Six index cases were identified and compared with 25 controls. Infarct size in the index cases was 95±55 ml. Four of six index cases (67%), but no control patients, had pre-operative acute infarcts. Baseline CBF was similar, but CVR was significantly lower in the index cases compared with control cases. For example, in the anterior circulation, median CVR was 0.4% (range: −38.0% to 16.6%) in index vs. 26.3% (range: −8.2% to 60.5%) in control patients (p=0.003). Multivariate analysis demonstrated that the presence of a small pre-operative infarct (regardless of location) and impaired CVR were independent, significant predictors of severe post-operative ischemic injury.
Conclusion
Acute infarcts and impaired CVR on pre operative imaging are independent risk factors for severe ischemic complications following STA MCA bypass in Moyamoya disease.
Aneurysmal dilation of saphenous vein grafts is a relatively rare complication of the now common surgical procedure of coronary artery bypass graft (CABG) surgery. The true prevalence of this condition is not clear, however, literature review by Jorgensen et. al.
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