A new control system for left ventricular assist devices based on patient-specific physiological demand

Faragallah, George; Wan, Yan‐Jun; Divo, Eduardo; Simaan, Marwan A.

doi:10.1080/17415977.2012.667092

Cited by 21 publications

(13 citation statements)

References 15 publications

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“…RBF-based Meshless solvers have been able to provide reliable simulations for several applications [11,12,15]. As a preliminary test to the multi-scale algorithms, a simplified model of [18,21]. The values associated with each of the resistances, compliances, or inductances, are well documented in the literature [21][22][23].…”

Section: Preliminary Resultsmentioning

confidence: 99%

“…A time-varying capacitance, C t ( ), represents the contractile behavior of the ventricle. A diode acts as the corresponding cardiac valve and insures unidirectional flow over the relaxation and contraction phases of the cardiac cycle [18,21].…”

Section: Lumped-parameter Modelmentioning

confidence: 99%

“…The heart is also represented in this system though a combination of diodes that model heart valves, resitances and inductances, as well as a time-varying elastance function (inverse of the compliance) that drives the circuit. The latter serves as the analogue of the elastance of the myocardium [18].…”

Section: Introductionmentioning

confidence: 99%

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Multi-scale cardiovascular flow analysis by an integrated meshless-lumped parameter model

Bueno¹,

Divo²,

Kassab³

2018

Int. J. CMEM

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A computational tool that integrates a Radial basis function (RBF)-based Meshless solver with a Lumped Parameter model (LPM) is developed to analyze the multi-scale and multi-physics interaction between the cardiovascular flow hemodynamics, the cardiac function, and the peripheral circulation. The Meshless solver is based on localized RBF collocations at scattered data points which allows for automation of the model generation via CAD integration. The time-accurate incompressible flow hemodynamics are addressed via a pressure-velocity correction scheme where the ensuing Poisson equations are accurately and efficiently solved at each time step by a Dual-Reciprocity Boundary Element method (DRBEM) formulation that takes advantage of the integrated surface discretization and automated point distribution used for the Meshless collocation. The local hemodynamics are integrated with the peripheral circulation via compartments that account for branch viscous resistance (R), flow inertia (L), and vessel compliance (C), namely RLC electric circuit analogies. The cardiac function is modeled via time-varying capacitors simulating the ventricles and constant capacitors simulating the atria, connected by diodes and resistors simulating the atrioventricular and ventricular-arterial valves. This multi-scale integration in an in-house developed computational tool opens the possibility for model automation of patient-specific anatomies from medical imaging, elastodynamics analysis of vessel wall deformation for fluid-structure interaction, automated model refinement, and inverse analysis for parameter estimation.

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Section: Preliminary Resultsmentioning

confidence: 99%

Section: Lumped-parameter Modelmentioning

confidence: 99%

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Multi-scale cardiovascular flow analysis by an integrated meshless-lumped parameter model

Bueno¹,

Divo²,

Kassab³

2018

Int. J. CMEM

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“…Such analysis requires an appropriate model for the peripheral vasculature in order to set the pulsatile boundary conditions at inlets and outlets, and this is accomplished using a OD lumped parameter (electric circuit compartment) model of the vasculature and of the VAD itself [40] coupled to the 3D CFD patient-specific model. We expect to report these results in a forthcoming publication.…”

Section: Journal Of Biomechanical Engineeringmentioning

confidence: 99%

Mathematical Modeling of Patient-Specific Ventricular Assist Device Implantation to Reduce Particulate Embolization Rate to Cerebral Vessels

Argueta-Morales

Tran

Ceballos

et al. 2014

Journal of Biomechanical Engineering

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Stroke is the most devastating complication after ventricular assist device (VAD) implantation, with an incidence of 14%-47% despite improvements in device design and anticoagulation. This complication continues to limit the widespread implementation of VAD therapy. Patient-specific computational fluid dynamics (CFD) analysis may elucidate ways to reduce this risk. A patient-specific three-dimensional model of the aortic arch was generated from computed tomography. A 12 mm VAD outflow-graft (VAD-OG) "anastomosed" to the aorta was rendered. CFD was applied to study blood flow patterns. Particle tracks, originating from the VAD, were computed with a Lagrangian phase model and percentage of particles entering the cerebral vessels was calculated. Twelve implantation configurations of the VAD-OG and three particle sizes (2, 4, and 5 mm) were considered. Percentage of particles entering the cerebral vessels ranged from 6% for the descending aorta VAD-OG anastomosis, to 14% for the ascending aorta at 90 deg VAD-OG anastomosis. Values were significantly different among all configurations (X(2) = 3925, p < 0.0001). Shallower and more cephalad anastomoses prevented formation of zones of recirculation in the ascending aorta. In this computational model and within the range of anatomic parameters considered, the percentage of particles entering the cerebral vessels from a VAD-OG is reduced by nearly 60% by optimizing outflow-graft configuration. Ascending aorta recirculation zones, which may be thrombogenic, can also be eliminated. CFD methods coupled with patient-specific anatomy may aid in identifying the optimal location and angle for VAD-OG anastomosis to minimize stroke risk.

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“…Faragallah and colleagues (2012) [103] developed a control system that set the target flow rate based on the systemic vascular resistance. The SVR was estimated in real time using a 6th order NM, using …”

Section: Flow Control Based On Systemic Vascular Resistancementioning

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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A new control system for left ventricular assist devices based on patient-specific physiological demand

Cited by 21 publications

References 15 publications

Multi-scale cardiovascular flow analysis by an integrated meshless-lumped parameter model

Multi-scale cardiovascular flow analysis by an integrated meshless-lumped parameter model

Mathematical Modeling of Patient-Specific Ventricular Assist Device Implantation to Reduce Particulate Embolization Rate to Cerebral Vessels

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

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