Control issues in rotary heart assist devices

Heart assist devices are mechanical pumps used in patients with cardiovascular diseases who are awaiting heart transplantation. With increasing clinical success, these devices are being used for longer periods of time, and automatic control has become an important requirement. The principal control requirement is to mimic the normal response of the heart to changes in demand for cardiac output, and control therefore provides many challenging problems for control engineers involved in this important multidisciplinary area of research. A team of engineers and physicians at the University of Pittsburgh is developing a hierarchical structure for a control system to support a rotary-type heart assist device. In this paper, we review various types of devices, the control algorithms used, and the problems that must be solved.