Modeling and Control of a Brushless DC Axial Flow Ventricular Assist Device

Giridharan, Guruprasad A.; Skliar, Mikhail; Olsen, D. B.; Pantalos, George M.

doi:10.1097/00002480-200205000-00013

Cited by 76 publications

(52 citation statements)

References 9 publications

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“…Dynamic computer models of a CPD and IABP were developed and incorporated into a computer model 10 of the cardiovascular system ( Figure 2). Ventricular failure was simulated with a native heart rate of 92 bpm.…”

Section: Experimental Designmentioning

confidence: 99%

“…A detailed description of the computer simulation model of the human cardiovascular system used in this study has been previously provided 10 and used to develop and test physiologic control algorithms for VADs. [9][10][11][12][13] Briefly, the human circulatory model subdivides the human circulatory system into an arbitrary number of lumped parameter blocks, each characterized by its own resistance, compliance, pressure, and volume of blood.…”

Section: Computer Simulation Modelmentioning

confidence: 99%

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Predicted Hemodynamic Benefits of Counterpulsation Therapy Using a Superficial Surgical Approach

et al. 2006

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A volume-displacement counterpulsation device (CPD) intended for chronic implantation via a superficial surgical approach is proposed. The CPD is a pneumatically driven sac that fills during native heart systole and empties during diastole through a single, valveless cannula anastomosed to the subclavian artery. Computer simulation was performed to predict and compare the physiological responses of the CPD to the intraaortic balloon pump (IABP) in a clinically relevant model of early stage heart failure. The effect of device stroke volume (0-50 ml) and control modes (timing, duration, morphology) on landmark hemodynamic parameters and the LV pressure-volume relationship were investigated. Simulation results predicted that the CPD would provide hemodynamic benefits comparable to an IABP as evidenced by up to 25% augmentation of peak diastolic aortic pressure, which increases diastolic coronary perfusion by up to 34%. The CPD may also provide up to 34% reduction in LV end-diastolic pressure and 12% reduction in peak systolic aortic pressure, lowering LV workload by up to 26% and increasing cardiac output by up to 10%. This study demonstrated that the superficial CPD technique may be used acutely to achieve similar improvements in hemodynamic function as the IABP in early stage heart failure patients.Over the past four decades, counterpulsation with an intraaortic balloon pump (IABP) has been widely and successfully used for the short-term treatment of cardiac dysfunction. 1,2 Approximately 160,000 patients receive this treatment annually worldwide with 43% to 65% successful clinical outcomes. 3 Counterpulsation has many important clinical benefits for the heart (lower ventricular workload and increased myocardial perfusion) and the peripheral circulation (increased end-organ perfusion), which may make chronic counterpulsation a very effective treatment for patients with moderate myocardial dysfunction. 3 However, the location of an IABP catheter (descending thoracic aorta) and biocompatibility issues limit the application of IABP to short durations (typically <14 days). When IABP support was attempted for a prolonged period (>20 days), the frequency of vascular complications, infections, and bleeding were significantly higher. 4,5 Furthermore, in its current form, a balloon device mounted on a catheter is advanced from a groin artery into the descending aorta, requiring a patient to remain supine for the duration of therapy, which virtually immobilizes the patient. Consequently, the number of patients who could benefit from the IABP as an extended therapy for myocardial support and possible myocardial recovery is limited. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript surgery for implantation. To overcome these limitations, we are currently developing a volume displacement counterpulsation device (CPD) for long-term application to treat early stage heart failure patients that can be implanted using a superficial surgical approach. In this article, we present the predicted hemody...

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Section: Experimental Designmentioning

confidence: 99%

Section: Computer Simulation Modelmentioning

confidence: 99%

Predicted Hemodynamic Benefits of Counterpulsation Therapy Using a Superficial Surgical Approach

et al. 2006

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“…Giridharan et al (2002) attempted to characterise this response by switching on the pump and control system at the same time, however the dynamic behaviour of the pump somewhat masked the effect of the control system [123]. A better approach was used by Choi et al (2001), who switched on their control system after operating at a constant speed during in-vivo evaluation [80].…”

Section: Switching On Controllermentioning

confidence: 99%

“…The most significant investigations into ΔP control were performed by Giridharan and colleagues [106], [112], [123], [153]- [155]. These authors extended on the previous work by evaluating ΔP control of both axial and centrifugal pumps.…”

Section: Differential Pressurementioning

confidence: 99%

“…These authors extended on the previous work by evaluating ΔP control of both axial and centrifugal pumps. Initially the authors used fixed gain PI control, with gains determined using an exhaustive numerical search in order to minimise the controller error and pump speed oscillations [123]. These gains resulted in a settling time of 30 seconds.…”

Section: Differential Pressurementioning

confidence: 99%

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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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Control of Left Ventricular Assist Devices

Simaan¹

2020

Encyclopedia of Systems and Control

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Modeling and Control of a Brushless DC Axial Flow Ventricular Assist Device

Cited by 76 publications

References 9 publications

Predicted Hemodynamic Benefits of Counterpulsation Therapy Using a Superficial Surgical Approach

Predicted Hemodynamic Benefits of Counterpulsation Therapy Using a Superficial Surgical Approach

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

Control of Left Ventricular Assist Devices

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