Model-referenced cardiovascular circulatory simulator: construction and control.

Physiological feasibility is the most important requirement for cardiovascular circulatory simulators (CCSs). However, previous simulators have been validated by a comparison with specific human data sets, which are valid only for very limited conditions, and so it is difficult to validate the fidelity of a CCS for various body conditions. To overcome this critical limitation, we propose a model-referenced CCS that reproduces the behavior of an electrical-analog model of the cardiovascular circulatory system, for which physiological fidelity is well established over a wide range.

Safety-enhanced optimal control of turbodynamic blood pumps.

A safety-enhanced optimal (SEO) control algorithm for turbodynamic blood pump is proposed. Analysis of in vivo animal experimental data reveals that two new control indices-the gradient of pulsatility of pump pressure head with respect to pump speed and the gradient of minimum pump flow-have their peak within a proximity to the suction point but not at the exact suction point. They were also verified to satisfy the requirement of cost function for the extremum seeking control (ESC).

Experimental verification of the feasibility of the cardiovascular impedance simulator.

Mock circulatory systems (MCS) are often used for the development of cardiovascular devices and for the study of the dynamics of blood flow through the cardiovascular system. However, conventional MCS suffer from the repeatability, flexibility, and precision problems because they are typically built up with passive and linear fluidic elements such as compliance chamber, manual valve, and tube. To solve these limitations, we have developed an impedance simulator, comprised of a feedback-controlled positive displacement pump that is capable of generating analogous dynamic characteristics as the conventional fluidic elements would generate, thereby replacing the conventional passive fluidic elements that often cause problems.

Application of extremum seeking control to turbodynamic blood pumps.

Ventricular assist devices now clinically used for treatment of end-stage heart failure require responsive and reliable control to accommodate the continually changing demands of the body. However, due to the varying physiologic conditions and the limited use of the sensors to detect hemodynamic load and suction, it is difficult to control pump speed appropriately. The author introduces an adaptive pump speed controller to provide maximum cardiac perfusion while avoiding ventricular suction.

In vitro evaluation of multiobjective hemodynamic control of a heart-assist pump.

Ventricular assist devices now clinically used for treatment of end-stage heart failure require responsive and reliable hemodynamic control to accommodate the continually changing demands of the body. This is an essential ingredient to maintaining a high quality of life. To satisfy this need, a control algorithm involving a trade-off between optimal perfusion and avoidance of ventricular collapse has been developed.