A method of determining a mean arterial pressure index of a patient having an implantable blood pump including determining a pump speed and a pump flow value; analyzing the pump speed and the pump flow value to a pump loss constant value; determining a graft hydraulic resistance value during a systolic phase of a cardiac cycle based on the analysis of the pump speed and the pump flow value to the pump loss constant value; determining a mean arterial pressure index during a diastolic phase of the cardiac cycle based on the determined graft hydraulic resistance value; comparing the mean arterial pressure index of the patient to a mean arterial pressure index range; and generating an alert when the mean arterial pressure index varies with respect to a mean arterial pressure index range.