Therapeutic occlusion of the basilar artery has been one of the alternative treatments for surgically or intravascularly inaccessible basilar bifurcation giant aneurysms. However, several problems have been reported, such as incomplete thrombosis of the aneurysms, their growth or rupture, and cerebral embolism originating from their cavities. Since hemodynamic changes after occlusion therapy are suspected to be responsible for these phenomena, they were investigated by a hydraulic vascular model. A hydraulic vascular model of the vertebrobasilar artery was constructed with silicone and glass tubes. A glass-made sphere of 2.5 cm in diameter was attached to the model and was regarded as a basilar head aneurysm. A 40% glycerol solution at 25 degrees C was found to be of similar viscosity and specific gravity to those of human whole blood at 37 degrees C and was perfused in the model. A device to measure intra-aneurysmal clearance was made from a stable luminous source and a Cds photocell. Good correlation was found between the output and an intra-aneurysmal dye concentration. The dye was injected into the aneurysm and its half-life was calculated from clearance curves. It was then regarded as an index of stagnation in an aneurysmal cavity. The flow volumes were estimated as: 60ml/min to the territory of one posterior cerebral artery (PCA) and 80ml/min to the cerebellum and the brain stem. Half-life was recorded in the following conditions: 120ml/min of flow in the basilar artery (BA) into bilateral PCAs stimulating the condition before BA occlusion, and various flow values (60ml/min to 10ml/min) of P1 segment simulating the conditions after BA occlusion distal to the superior cerebellar artery.(ABSTRACT TRUNCATED AT 250 WORDS)
Basilar Artery Cerebrovascular Circulation