An extracorpeal blood circuit for removal of contrast from human blood using a filter and withdrawal filter pump and a by-pass pump. The withdrawal filter blood pump operates when a contrast bolus has been detected. Otherwise the bypass blood pump maintains physiological blood flow from the coronary sinus preventing the need for deflation and re-inflation of the balloon catheter. When contrast is detected blood the bypass blood pump is stopped to prevent contrast from leaking back into the patients circulatory system via the bypass pump and CS blood flow is maintained at its physiological blood flow resulting in the heart being oblivious to the transition by the prefilter blood pump.