[Vertebral artery occlusion therapy for a VA-PICA giant aneurysm: hemodynamic analysis by hydraulic vascular model]

Although therapeutic occlusion of the vertebral artery has been an accepted treatment for an inaccessible VA giant aneurysm, several problems have been reported such as incomplete thrombosis, growth or rupture of the aneurysms, and cerebral embolism originating from the aneurysmal cavity. Hemodynamic changes after occlusion therapy are suspected to be responsible for these phenomena. It is usually difficult to solve these problems or to predict them before operation because multiple factors are related in a complex fashion in a living body. One of the effective means is to simulate these hemodynamic conditions by a hydraulic vascular model. To evaluate hemodynamics after gradual therapeutic occlusion of the vertebral artery, a glass sphere of 2.5 cm in diameter was placed in a hydraulic model and regarded as a VA-PICA aneurysm. 40% glycerol solution at 25 degrees C, having similar viscosity and specific gravity to human whole blood at 37 degrees C, was used as a perfusate in this study. The dye was injected into the aneurysm and intensity change of the transmitted light was measured. Half-life of the dye was calculated from the thus-obtained clearance curve and was regarded as an index of intra-aneurysm stagnation. The flow volumes of each arterial site have been estimated in our previous study: 60 ml/min to the territory of one posterior cerebral artery, and 80 ml/min to the cerebellum and the brain stem. Clearance curves were recorded in the following various conditions. The flow value of the PICA was set to be 5, 10, 15, 20, 25, and 30 ml/min.(ABSTRACT TRUNCATED AT 250 WORDS)