The use of left ventricular assist devices (LVADs) has been a viable therapeutic option for end-stage heart failure patients. These devices are commonly used as bridge-to-transplant or destination therapy, and as the risk of adverse events has been reduced with improved device design, LVAD support is being considered as an option for class III heart failure patients as well. Recently, the use of continuous flow LVADs has become common due to their small size and improved reliability. However, control of these devices can be challenging as opposed to the previous generation of pulsatile devices. Current control systems operate the pump at a fixed speed set by the clinician. The speed is set high enough to provide adequate circulatory support but not too high as to cause suction and ventricular collapse. These control systems cannot increase flow in response to physiologic demand and therefore, patients with these devices have limited exercise capacity. As patients are now leaving the hospital and returning to their daily activities, a control system that respond to patient demand is necessary. The primary objective of the proposed research is to develop a control system for continuous flow blood pumps that can reduce the risk of suction and adapt pump flow in response to circulatory demand. We have developed a pressure sensor that can be integrated to the inlet of a continuous flow LVAD and maintain a seamless blood interface. Using this pressure sensor, the following specific aims of the control system will be developed. (1) The onset of ventricular suction can be detected as a negative transient in the inlet pressure signal, and pump speed can be immediately reduced to resolve the suction event. (2) The peak-to-peak inlet pressure signal can be used in a feedback control loop to mimic the Frank-Starling mechanism and maintain adequate circulatory support in response to changes in ventricular preload. (3) The control system set point can be automatically adjusted based on the frequency of detected suction events in order to adapt to physiologic changes. The control system has been developed in vitro using the FDA approved HeartMate II axial flow pump, and tested in an initial acute sheep study. We propose to further develop and evaluate the control system in a series of acute and chronic sheep studies. The Penn State Division of Artificial Organs has extensive experience and expertise in LVAD development and large animal testing that we will utilize for the proposed research.
Heart disease is the number one cause of death in the United States with over 500,000 deaths per year. Due to insufficient donor heart availability, the use of left ventricular assist devices (LVADs) has been a viable therapeutic option for end-stage heart failure patients. The proposed research is to develop a control system for LVADs that will adapt pump flow to the patient's circulatory needs and minimize the risk of adverse events.