A system configured to remove from a coronary sinus a medium injected into the coronary artery, the system comprising: a) a collection catheter having a distal end positionable within a coronary sinus; b) an aspiration unit in fluid communication with the collection catheter; c) an injection device; d) an injection catheter; e) an injection sensor configured to cooperate with at least one of the injection device and the injection catheter, wherein: - the injection sensor is external to a patient's body during use of the system; - the injection sensor is configured to detect an injection of a medium in the injection catheter; said system further comprising: f) an interface unit, the interface unit being electrically connected to the injection sensor and the aspiration unit, wherein the interface unit is configured to: i) establish a start time of the coronary artery injection of medium when the injection sensor detects the injection of the medium in the injection catheter; ii) determine a volume of medium in the injection which is above a predetermined threshold; iii) initiate aspiration by the aspirating unit to the collection catheter a predetermined time after a start time of the injection, the initiation of operation occurring only if, and when the volume of medium in the injection is determined to be above the predetermined threshold; and iv) cease operation of the collection catheter a predetermined time after a cessation of the medium injection in the injection catheter, above the predetermined threshold. a) a collection catheter having a distal end positionable within a coronary sinus; b) an aspiration unit in fluid communication with the collection catheter; c) an injection device; d) an injection catheter; e) an injection sensor configured to cooperate with at least one of the injection device and the injection catheter, wherein: - the injection sensor is external to a patient's body during use of the system; - the injection sensor is configured to detect an injection of a medium in the injection catheter; said system further comprising: - the injection sensor is external to a patient's body during use of the system; - the injection sensor is configured to detect an injection of a medium in the injection catheter; said system further comprising: f) an interface unit, the interface unit being electrically connected to the injection sensor and the aspiration unit, wherein the interface unit is configured to: i) establish a start time of the coronary artery injection of medium when the injection sensor detects the injection of the medium in the injection catheter; ii) determine a volume of medium in the injection which is above a predetermined threshold; iii) initiate aspiration by the aspirating unit to the collection catheter a predetermined time after a start time of the injection, the initiation of operation occurring only if, and when the volume of medium in the injection is determined to be above the predetermined threshold; and iv) cease operation of the collection catheter a predetermined time after a cessation of the medium injection in the injection catheter, above the predetermined threshold. i) establish a start time of the coronary artery injection of medium when the injection sensor detects the injection of the medium in the injection catheter; ii) determine a volume of medium in the injection which is above a predetermined threshold; iii) initiate aspiration by the aspirating unit to the collection catheter a predetermined time after a start time of the injection, the initiation of operation occurring only if, and when the volume of medium in the injection is determined to be above the predetermined threshold; and iv) cease operation of the collection catheter a predetermined time after a cessation of the medium injection in the injection catheter, above the predetermined threshold.