AN ANTISUCTION PHYSIOLOGICAL CONTROLLER FOR A LONG TERM LVAD

Abstract

Purpose: In the past, for patients with severe congestive heart failure (CHF), which is usually caused by the failure of the left ventricle, heart transplant was their only choice. Nowadays, a devices called long term left ventricular assist devices (LVADs) aiming at meeting the needs of these patients have been under active research. This device is composed of a rotary pump and a physiological controller to ensure that the pump functions properly. Methods: An automatical controller was designed for a long term rotary LVAD with the pressure head as the single feedback signal. The whole process of patients with CHF going from rest to exercise and then back to rest is simulated in computer program-Matlab/Simulink and a mock circulatory flow loop, and the performance of the controller was tested on them. The mock circulatory loop has a ball valve, two air-tight chambers of water with air sealed at top, a cardiac simulator produced by Symbion Inc. to simulate the total peripheral resistance, the compliance of the artery and veins, and the left heart respectively. Results and Conclusion: The left ventricular end diastolic pressure ranged from 10 mmHg to 15 mmHg in rest condition, and around 8 mmHg in the exercise condition. The aortic pressure ranged from 87 mmHg to 117 mmHg in rest condition, and 77 mmHg to 105 mmHg in exercise. The cardiac output increased from 5 L/min in rest to around 13 L/min in exercise. The controller thus is proven to be able to control LVAD properly without introducing suction in left ventricle in different physiological conditions.