Study on Guide System Based on the Blood Flow Force for Intravascular Catheter

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It is usually difficult to guide a catheter safely inside blood vessels. We have devised a guide system based on the fluid force of blood vessel in order to control the direction of advance of a catheter being passed through artery blood vessels with 2-6 mm inner diameter. This system consists of a cylindrical streamer with a 1 mm diameter, 1.5 mm long and 20mum wall thickness, two supporting legs and one filament of 20 mum. Movement of the streamer can be controlled by adjusting the length of the wire. We studied the behavior of the cylindrical streamer by numerical analysis of fluid force, and investigated the cahracteristics of a model system by experiment using a simulator of pulsating blood flow (range of Reynolds number : 71-930, dynamic viscosity : 1-6 mm2/s). We obtained relation between attack angle and dimensionless lift, dimensionless drag and dimensionless lift, and then designed a prototype guide system and succeeded to guide branched vessels of the simulator.A new type of actuator which consists of an eccentric thin silicon rubber tube and deforms spirally by hydraulic pressure was invented to simplify the control of a position and an angle of the streamer, and showed its usefulness in experiment.Also a safety detaching method for endovascular treatment with laser light was invented. We attached the mechanism to the end of a catheter and confirmed its usefulness by experiments on rabbits.