A pumping system for assisting a patient's heart includes a blood pump disposed outside the patient's body and having an inlet and an outlet. An inlet cannula is configured for insertion percutaneously into the vascular system of the patient, and in fluid communication with the blood pump inlet to provide blood to the blood pump. An outlet perfusion cannula is configured for insertion percutaneously into the vascular system of the patient, and in fluid communication with the blood pump outlet to provide blood to the patient's vascular system. A control system is provided to control the blood pump and includes at least two control units for redundant control of the blood pump. Each control unit includes a watchdog for monitoring the control unit. A variation of the pumping system includes a bidirectional cannula for insertion percutaneously into the vascular system of the patient and to extend into the patient's heart.