A suction catheter system is described with a suction extension interfaced with a guide catheter to form a continuous suction lumen extending through a portion of the guide catheter and through the suction extension. The suction extension can be positioned by tracking the suction nozzle through a vessel while moving a proximal portion of the suction extension within the lumen of the guide catheter. The suction extension can comprise a connecting section with a non-circular cross section for interfacing with the inner lumen of an engagement section of the guide catheter. The tubular body of the guide catheter can have a reduced diameter distal section the can be useful to restrain the movement of the suction extension.
