[Experimental hemodynamic study on carotid ligation combined with EC-IC bypass for giant aneurysm].

Although carotid ligation or balloon occlusion has been an accepted method for the inaccessible ICA aneurysm, there have been several reports of growth or rupture of the aneurysm, and cerebral embolism originating from the site of arterial occlusion or from the aneurysm. The hemodynamic changes after operation are suspected to play some role in these events. It is, therefore, very important to predict what will happen after operation in individual patients. However, it is usually difficult 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. We have already reported the hemodynamic changes resulting from EC-IC bypass for MCA stenosis. In this research, a glass-model aneurysm of 2.5 cm in diameter is placed at the ICA bifurcation of the model to evaluate hemodynamics after therapeutic carotid occlusion with or without EC-IC bypass. Dye was injected into the aneurysm and intensity change of the light transmitted there was measured by a photocell. Half-life of the dye was calculated from thus obtained clearance curve and was regarded as an index of intraaneurysmal stagnation, while embolus formation in an aneurysm is considered to be due to the stagnation there. The results obtained are: 1. Half-life of the dye increases significantly after carotid ligation even if collateral flow through the anterior communicating artery (A-com) or EC-IC bypass equals the ICA flow before ligation. 2. The higher collateral flow through A-com results in the more normograde flow in M1 portion, which shortens the half-life.(ABSTRACT TRUNCATED AT 250 WORDS)