A catheter apparatus maintaining blood flow by vein bypass, made of any plastic and similar raw materials, that is open on both ends, characterized in that the catheter apparatus comprises; a first path connecting both ends • One balloon on a point close to each of both ends, • a Protective layer positioned on the balloons , • a Second path enabling deflation inflation of the balloons , having a monolithic pipe shape adhered to the first path side by side, whose one open end terminates within the balloon , • a Check valve apparatus that is monolithic with a back end of the second path and provides substances such as air and liquid with an injector for inflation and deflation of the balloon , • a Protective segment surrounding externally the first path and second path , thus preventing their blockage when compressed, the protective segment configured to have various lengths from a back end of the balloon to a backside of the catheter , and is monolithic along with the first path and the second path , • a Cover that prevents the catheter apparatus from going out of the vein or its movement, that is located on a body side of the catheter apparatus , positioned on back of the balloon , that can be moved over the catheter apparatus as it is wider than a width of the of the catheter apparatus , that has a flexible structure having both ends open and having the shape of funnel or circle or ellipsis or different shapes, • a Clamping apparatus used to fix the cover on its relevant location, • At least one third path in the shape of a pipe with both ends open, having one end positioned within the first path , another end located out of the first path and used to draw the liquid or air, • a Connection apparatus integrated with an outer back end of the third path and that enables connection with the external injector and the catheters. • One balloon on a point close to each of both ends, • a Protective layer positioned on the balloons , • a Second path enabling deflation inflation of the balloons , having a monolithic pipe shape adhered to the first path side by side, whose one open end terminates within the balloon , • a Check valve apparatus that is monolithic with a back end of the second path and provides substances such as air and liquid with an injector for inflation and deflation of the balloon , • a Protective segment surrounding externally the first path and second path , thus preventing their blockage when compressed, the protective segment configured to have various lengths from a back end of the balloon to a backside of the catheter , and is monolithic along with the first path and the second path , • a Cover that prevents the catheter apparatus from going out of the vein or its movement, that is located on a body side of the catheter apparatus , positioned on back of the balloon , that can be moved over the catheter apparatus as it is wider than a width of the of the catheter apparatus , that has a flexible structure having both ends open and having the shape of funnel or circle or ellipsis or different shapes, • a Clamping apparatus used to fix the cover on its relevant location, • At least one third path in the shape of a pipe with both ends open, having one end positioned within the first path , another end located out of the first path and used to draw the liquid or air, • a Connection apparatus integrated with an outer back end of the third path and that enables connection with the external injector and the catheters. <EOS>