[Experimental simulation study on cerebral hemodynamics--Part 2: Bilateral severe internal carotid arterial stenosis and theoretical study].

Although cerebrovascular surgery, typically bypass procedure for example, is considered to change hemodynamics not only near the region but in remote sites, their quantitative speculation and evaluation are usually difficult because of mutually related multiple factors in a living body. One of the effective means is to stimulate expected operative procedures and resulting changes by use of a hydraulic vascular model. We have already reported the hemodynamics in bilateral moderate ICA stenosis and their changes after EC-IC bypass. In this research, vascular model of bilateral severe ICA stenosis has been manufactured with silicon and glass tubes. Peripheral vascular resistance (Rp) is so adjusted as to obtain an arterial flow of 180 ml/min at an intraluminal pressure of 60 mmHg. Four kinds of stenosis segments, Ra (2.59 mm in diameter), Rb (1.94 mm), Rc (1.12 mm) and Rd (0.84 mm) are prepared and used in the models. In addition, theoretical study was performed in an unilateral ICA stenosis to evaluate quantitatively and extensively the effects of stenosis and cut bypass flow on the ICA flow and bypass flow. The results obtained are as follows: 1. Under marked low flow conditions from 55% to 30% of normal value simulated in this study, collateral flow from the opposite ICA has reached the maximum and therefore its increase is no more expected against the advance of the stenosis. 2. Both increase of the hemispheric flow and decrease of the carotid flow were still observed after EC-IC bypass procedures.(ABSTRACT TRUNCATED AT 250 WORDS)