A system for controlling reperfusion in a blood vessel of a patient including a flexible elongated member configured and dimensioned for insertion in the vessel of the patient, the elongated member having a proximal portion and a distal portion, the elongated member configured for insertion so the distal portion extends distal of a clot in the blood vessel. A sensor is positioned at the distal portion of the elongated member for positioning distal of the blood clot, the sensor measuring a parameter of blood downstream of the clot. An indicator communicates with the sensor, the indicator indicating a measured parameter for insertion of an instrument for controlling blood flow.
