Modeling, Estimation, and Control of Human Circulatory System With a Left Ventricular Assist Device

Wu, Yi; Allaire, Paul E.; Tao, Gang; Olsen, D. B.

doi:10.1109/tcst.2006.890288

Cited by 69 publications

(56 citation statements)

References 24 publications

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“…Feedback control strategies to physiologically adapt the operation of turbo dynamic VADs (tVADs) to the oxygen demand and to optimize left-ventricular unloading have been subject to continuous research [5][6][7][8][9][10]. A number of approaches for realizing a speed modulation of tVADs has been analyzed earlier.…”

Section: Introductionmentioning

confidence: 99%

Numerical Optimal Control of Turbo Dynamic Ventricular Assist Devices

et al. 2013

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Abstract:The current paper presents a methodology for the derivation of optimal operating strategies for turbo dynamic ventricular assist devices (tVADs). In current clinical practice, tVADs are typically operated at a constant rotational speed, resulting in a blood flow with a low pulsatility. Recent research in the field has aimed at optimizing the interaction between the tVAD and the cardiovascular system by using predefined periodic speed profiles. In the current paper, we avoid the limitation of using predefined profiles by formulating an optimal-control problem based on a mathematical model of the cardiovascular system and the tVAD. The optimal-control problem is solved numerically, leading to cycle-synchronized speed profiles, which are optimal with respect to an arbitrary objective. Here, an adjustable trade-off between the maximization of the flow through the aortic valve and the minimization of the left-ventricular stroke work is chosen. The optimal solutions perform better than constant-speed or sinusoidal-speed profiles for all cases studied. The analysis of optimized solutions provides insight into the optimized Bioengineering 2014, 1 23 interaction between the tVAD and the cardiovascular system. The numerical approach to the optimization of this interaction represents a powerful tool with applications in research related to tVAD control. Furthermore, patient-specific, optimized VAD actuation strategies can potentially be derived from this approach.

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Section: Introductionmentioning

confidence: 99%

Numerical Optimal Control of Turbo Dynamic Ventricular Assist Devices

et al. 2013

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“…These equations are usually derived for each type of pump from experimental results, and show either static relation or dynamic relation. Static equation (Wu et al 2007) means that the flow rate of the pump is an algebraic function of the pump parameters at the same time instance. Dynamic equation (Choi et al 1997) (differential equation) implies that the pump flow is determined by the pump parameters at the present instance and before.…”

Section: Modeling Of Rbpsmentioning

confidence: 99%

“…The long-term use of rotary blood pumps is expected to benefit end-stage CHF patients to a greater level, as a destination therapy or bridge-to-recovery device. Scientists and researchers have been actively studying issues to extend the lives of RBPs, such as optimizing pump design using computational fluid dynamics to increase efficiency and reduce hemolysis (Untaroiu et al 2005), suspension of pump impeller with magnetic or hydrodynamic forces (Hoshi et al 2005;Goldowsky 2004), effect of blood pumps on natural heart function and remodeling (Wohlschlaeger et al 2005), and the physiological control system that automatically regulates the pump speed (Giridharan and Skliar 2006;Schima et al 2006;Chen et al 2005;Wu et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Effects of Muscle Pump on Rotary Blood Pumps in Dynamic Exercise: A Computer Simulation Study

Lim

2008

Cardiovasc Eng

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Computer simulation is an important tool to study the interaction between rotary blood pumps (RBPs) and human circulatory system. This interaction is critical for the development of reliable physiological control systems of long-term RBPs. This paper presents a numerical model of the human circulatory system, which innovatively takes the muscle pump into account in dynamic exercise. Simulation results demonstrate that the inclusion of muscle pump will change the response of hemodynamic variables and RBP parameters. These findings also show the necessity to verify the performance of RBPs and their physiological control systems in dynamic exercise with the muscle pump taken into account. By using Matlab Simulink software to simulate real-time circulatory properties, this study provides the bench-top test environment for long-term RBPs and their physiological controller.

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“…Wu et al (2007), achieved this in-silico by initialising the pump speed at maximum level, causing suction, before switching the control system on [116]. For evaluation of RVAD component of a dual LVAD control system, Olegario et al (2003) induced LV suction in-vitro and in-vivo by increasing the LVAD speed by 700 RPM [117].…”

Section: Induced Suctionmentioning

confidence: 99%

“…Adjusting pump speed to maintain AoP would be able to compensate for a reduced baroreflex mechanism. This approach was proposed by Wu and colleagues as a primary control objective [93], [113], [116]. The authors identified that solely maintaining AoP constant without knowledge of the venous return may result in suction events, so they included constant ΔP control as a secondary objective.…”

Section: Aortic Pressurementioning

confidence: 99%

Automatic control of dual left ventricular assist devices as a biventricular assist device

Stevens¹

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In this thesis, we investigate automated methods for the control of rotary blood pumps in the treatment of heart failure. Heart failure is a common end-point for many forms of cardiovascular disease resulting in significant morbidity and mortality. Ventricular assist devices (VADs) are blood pumps designed to assist a failing heart and are used both to support patients whilst they are awaiting a heart transplant, or as an alternative to transplantation. Small rotary VADs can provide long-term support of the left ventricle (LVAD), right ventricle (RVAD) or both ventricles of the heart simultaneously.Unfortunately, the lack of a commercially available rotary RVAD has led to the implantation of two rotary LVADs as an ad hoc biventricular assist device (BiVAD). Clinicians currently operate such dual LVADs at a constant speed, which ensures balanced left and right pump flows for inactive patients.However, changes in levels of patient activity will lead to altered cardiac output requirements, which may disturb this balance. In turn, this can lead to undesirable events such as pulmonary venous congestion or ventricular suction. A control system that automatically adjusts pump speed with changes in the required cardiac output could alleviate such events and so offer significant benefits. However, while such physiological control systems have been investigated for single LVADs, limited work has been completed on dual LVAD control. In addition, there is no generally accepted framework for the evaluation of these systems that encompasses a broad range of patient scenarios, activity levels and heart conditions. Therefore, the primary aim of this thesis was to develop and evaluate a number of physiological control systems suitable for dual rotary LVADs.The first objective was to characterise the methods that are currently used to operate dual LVADs in the clinic. Using both in-vitro and in-vivo methods, it was shown that balanced left and right flow rates could be obtained by operating the RVAD slower than the LVAD, albeit at speeds below the manufacturer's recommendations (1400 -1800 RPM), which, according to other investigators, may adversely affect impeller washout. Operating both at the same design speed is only possible in patients with high pulmonary vascular resistance (PVR), high left ventricular contractility or high RVAD outflow cannula resistance. This thesis demonstrates that if the RVAD outflow cannula is restricted to a diameter between 6.5 and 8.1 mm, suitable steady-state haemodynamics (systemic flow rate 5 L.min -1 , MAP 90mmHg and LAP less than 25mmHg) can be achieved while maintaining impeller stability and optimal device washout. It was also established that changes in pump speed or outflow graft diameter were required to overcome elevations in pulmonary vascular resistance, thereby justifying the necessity of a physiological control system for dual LVADs.The second objective was to develop an in vitro evaluation protocol for control system testing utilising a mock circulation loop (MCL). The test...

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Modeling, Estimation, and Control of Human Circulatory System With a Left Ventricular Assist Device

Cited by 69 publications

References 24 publications

Numerical Optimal Control of Turbo Dynamic Ventricular Assist Devices

Numerical Optimal Control of Turbo Dynamic Ventricular Assist Devices

Effects of Muscle Pump on Rotary Blood Pumps in Dynamic Exercise: A Computer Simulation Study

Automatic control of dual left ventricular assist devices as a biventricular assist device

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