Abstract: The invention is directed to a multi-function control valve assembly for use in aspirating the left ventricle of the heart during open heart bypass surgery. The control valve assembly includes a housing assembly which defines an inlet adapted for connection to a suction tube inserted into the left ventricle and an outlet adapted for connection to a pump. The control valve assembly further includes a valving arrangement that is operable to provide three distinct functions. First, the control valve assembly includes a unidirectional flow valve which is operable to only permit fluid to flow from the inlet to the outlet, thereby preventing a reverse flow situation. Second, the control valve assembly includes a positive pressure relief valve which is operable to vent the outlet when the pressure therein exceeds a predetermined positive pressure value.