Conduits for Cerebrovascular Bypass
Conduits for Cerebrovascular Bypass
Direct cerebral revascularization is an important procedure in the treatment of certain complex aneurysms and skull base tumors when acute sacrifice of the internal carotid artery is required. It likely remains an appropriate treatment in a small subgroup of patients with cerebral ischemia refractory to maximal medical management. Similar to cardiovascular surgery, the choice of a graft conduit is critical for a successful outcome. The standard conduits are interposition vein grafts (usually the greater saphenous vein), free arterial grafts (radial artery), and pedicled arterial grafts (superficial temporal artery). The goal of this review is to summarize the conduits commonly used in cerebral revascularization with emphasis on their patency rates and flow characteristics. Comparisons are made with similar data available in the cardiovascular literature.
The theoretical basis of an extracranial-intracranial bypass to increase CBF for cerebroocclusive disease was first established by Fisher in 1951. The first successful STA-MCA bypass operations were reported by Yassargil and colleagues in 1970. Since that pioneering work, cerebrovascular bypass has been undertaken in the management of complex skull base tumors, giant and fusiform aneurysms, and a select group of patients with medically refractory cerebral ischemia. The choice of the appropriate bypass graft depends on the size of the recipient vessel, availability of the donor vessel, availability of graft material, and the extent of blood flow augmentation required.
Low-flow grafts (15-25 ml/minute), such as an STA, are used if some collateral vessels are present and the need for blood flow augmentation is minimal or if only distal branches are available for anastomosis. High-flow grafts (70-140 ml/minute), such as an SVG, are used in cases in which acute ICA occlusion and replacement are required. The RA allows for flow at a moderate volume of 40 to 70 ml/minute.
Direct cerebral revascularization is an important procedure in the treatment of certain complex aneurysms and skull base tumors when acute sacrifice of the internal carotid artery is required. It likely remains an appropriate treatment in a small subgroup of patients with cerebral ischemia refractory to maximal medical management. Similar to cardiovascular surgery, the choice of a graft conduit is critical for a successful outcome. The standard conduits are interposition vein grafts (usually the greater saphenous vein), free arterial grafts (radial artery), and pedicled arterial grafts (superficial temporal artery). The goal of this review is to summarize the conduits commonly used in cerebral revascularization with emphasis on their patency rates and flow characteristics. Comparisons are made with similar data available in the cardiovascular literature.
The theoretical basis of an extracranial-intracranial bypass to increase CBF for cerebroocclusive disease was first established by Fisher in 1951. The first successful STA-MCA bypass operations were reported by Yassargil and colleagues in 1970. Since that pioneering work, cerebrovascular bypass has been undertaken in the management of complex skull base tumors, giant and fusiform aneurysms, and a select group of patients with medically refractory cerebral ischemia. The choice of the appropriate bypass graft depends on the size of the recipient vessel, availability of the donor vessel, availability of graft material, and the extent of blood flow augmentation required.
Low-flow grafts (15-25 ml/minute), such as an STA, are used if some collateral vessels are present and the need for blood flow augmentation is minimal or if only distal branches are available for anastomosis. High-flow grafts (70-140 ml/minute), such as an SVG, are used in cases in which acute ICA occlusion and replacement are required. The RA allows for flow at a moderate volume of 40 to 70 ml/minute.
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