Hemodynamic effects on the treatment of cerebral aneurysms evaluated using hydraulic vascular model

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1, Parent occlusion therapy for basilar head aneurysm.Using a hydraulic model, half-life of the dye in the model aneurysm was measured as an index of the intraaneurysmal stagnation. The ratio of diameters of the two posterior communicating arteries (PCom) is defined as diameter ratio (DR). Occlusion therapy was simulated in 4 different sites.Occlusion therapy significantly increased the half-life depending on the occlusion site and DR values with the maximum values of infinite in Type A and 25 sec in Type D. placement of the bypass decreased the tangential flow volume to the aneurysmal neck, and increased the time markedly in Types A and B, considerably in Type C and slightly in Type D.Parent artery occlusion therapy has been considered less beneficial for the patients with the diameter ratio less than 0.70. Additional bypass placement to the occlusion therapy is very useful in enhancing the aneurysmal stagnation.2, Characteristics of curvature aneurysms at paraclinoid area.Hemodynamics of paraclinoid aneurysms were investigated focusing on the effects of their locations and shape of the carotid siphon. Transparent silicon model of the carotid siphon was constructed. When the siphon angle was 0゜, the half-life value was the lowest in the C2-C3 junction aneurysm, highest in the C3 segment aneurysm and intermediate in the C2 segment aneurysm. While the C2-C3 junction aneurysm maintained low values regardless of the angle, the C3 segment aneurysm values decreased and C2 segment aneurysm values increased with increases in the angle. These changes of half-life occur because the point at which the faster moving fluid component strikes the curved wall changes according to the siphon angle.These results are considered useful to determine the surgical indications, treatment modalities and postsurgical management of the aneurysms.