Introduction: High-flow cerebral revascularizations using arterial and venous grafts are used in the treatment of complex aneurysms, skull base tumors and in some cases of ischemia. A small number of these bypasses develop graft stenosis and may lead to occlusion over time. The pathology of graft stenosis over long-term in high-flow cerebral bypass grafts is not known.
Methods: A retrospective review of prospectively maintained cerebrovascular repository was performed to study all cerebral high flow bypasses performed between 2005 and 2010. All bypass grafts that developed stenosis and those that underwent surgical correction were identified and the preserved graft specimens were obtained from pathology repository. Histopathological analysis of the stenotic grafts was performed to study the vessel wall pathology.
Results: A total of 69 high-flow bypasses were performed between January 2005 and June 2010, which included 51 arterial grafts and 18 venous grafts for aneurysms, tumor and ischemia, with mean follow up 9 months (range 3-29 months). Eight bypass grafts had developed stenosis, of which four were repaired surgically. Intimal hyperplasia was noted in all four stenotic segments. None of the stenosis consisted of smooth muscle cell proliferation or findings of atherosclerosis.
Conclusions: Hyperplasia of the intimal layer seems to be the most common mechanism of cerebral bypass graft stenosis, which correlates with findings in peripheral vascular bypass stenoses. Further studies to evaluate the factors mediating the intimal proliferation may help to improve bypass techniques or preventive interventions.
Patient Care: Improve the techniques for cerebral bypasses, prevent bypass graft occlusions, improve outcomes in cerebral revascularization.
Learning Objectives: Describe long-term outcomes and patencies of high flow bypasses, causes of stenosis, mechanisms of stenosis in bypasses