A system for assisting a patient's heart has a pump, an oxygenator, a holder having a pump receiving portion for removably receiving the pump and an oxygenator receiving portion for removably receiving the oxygenator, and a harness configured to surround at least a portion of a patient's torso. The holder is connected to the harness. The system further has a brace connected to at least a portion of the harness. The brace is configured to extend behind a back portion of a user's head and to support tubing connected to at least one of the pump and the oxygenator. A priming tray and wet-to-wet connector connecting the cardiac assist system to the cannula so are also disclosed.