A method and apparatus for performing coronary perfusion and cardiac reoxygenation that enables accurate control of oxygen levels in blood used for the coronary circulation. Deoxygenated blood and oxygenated blood are collected and oxygen levels are measured by sensors. The deoxygenated and oxygenated blood is then mixed and the mixed blood is measured by another sensor. The sensors provide data used to provide real-time oxygen level measurement and adjustment for blood supplied for coronary circulation.