A catheter design and method is provided for the aspiration of thrombus, clot, atherosclerotic emboli in the vascular bed. The aspiration catheter includes an aspiration lumen, a guidewire lumen having an exchange port, and a recess in the aspiration unit. The aspiration catheter lumen is divided into two sections: (i) proximal, and (ii) distal. The distal section has a distal opening.