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Brisbane, Australia

Alomari A.-H.H.,University of Dammam | Savkin A.V.,University of New South Wales | Stevens M.,Innovative Cardiovascular Engineering and Technology ICET Laboratory | Stevens M.,Queensland University of Technology | And 13 more authors.
Physiological Measurement | Year: 2013

From the moment of creation to the moment of death, the heart works tirelessly to circulate blood, being a critical organ to sustain life. As a non-stopping pumping machine, it operates continuously to pump blood through our bodies to supply all cells with oxygen and necessary nutrients. When the heart fails, the supplement of blood to the body's organs to meet metabolic demands will deteriorate. The treatment of the participating causes is the ideal approach to treat heart failure (HF). As this often cannot be done effectively, the medical management of HF is a difficult challenge. Implantable rotary blood pumps (IRBPs) have the potential to become a viable long-term treatment option for bridging to heart transplantation or destination therapy. This increases the potential for the patients to leave the hospital and resume normal lives. Control of IRBPs is one of the most important design goals in providing long-term alternative treatment for HF patients. Over the years, many control algorithms including invasive and non-invasive techniques have been developed in the hope of physiologically and adaptively controlling left ventricular assist devices and thus avoiding such undesired pumping states as left ventricular collapse caused by suction. In this paper, we aim to provide a comprehensive review of the developments of control systems and techniques that have been applied to control IRBPs. © 2013 Institute of Physics and Engineering in Medicine. Source

Bivacor Pty Ltd. | Date: 2010-04-16

A heart pump including first and second cavities, each cavity including a respective inlet and outlet, a connecting tube extending between the first and second cavities, an impeller including: a first set of vanes mounted on a first rotor in the first cavity portion; a second set of vanes mounted on a second rotor in the second cavity portion; and, a shaft connecting the first and second rotors, the shaft extending through the connecting tube, a drive for rotating the impeller and a magnetic bearing including at least one bearing coil for controlling an axial position of the impeller, at least one of the drive and magnetic bearing being mounted outwardly of the connecting tube, at least partially between the first and second cavity portions.

Bivacor Pty Ltd. | Date: 2010-04-16

A controller for a heart pump, the controller including a processing system for determining movement of an impeller within a cavity in a first axial direction, the cavity including at least one inlet and at least one outlet, and the impeller including vanes for urging fluid from the inlet to the outlet, causing a magnetic bearing to move the impeller in a second axial direction opposite the first axial direction, the magnetic bearing including at least one coil for controlling an axial position of the impeller within the cavity, determining an indicator indicative of the power used by the magnetic bearing and causing the magnetic bearing to control the axial position of the impeller in accordance with the indicator to thereby control a fluid flow between the inlet and the outlet.

Nestler F.,Queensland University of Technology | Nestler F.,Innovative Cardiovascular Engineering and Technology Laboratory | Nestler F.,Critical Care Research Group | Bradley A.P.,Queensland University of Technology | And 2 more authors.
Artificial Organs | Year: 2014

The accurate representation of rotary blood pumps in a numerical environment is important for meaningful investigation of pump-cardiovascular system interactions. Although numerous models for ventricular assist devices (VADs) have been developed, modeling methods for rotary total artificial hearts (rTAHs) are still required. Therefore, an rTAH prototype was characterized in a steady flow, hydraulic test bench over a wide operational range for pump and hydraulic parameters. In order to develop a generic modeling method, a data-driven modeling approach was chosen. k-Nearest-neighbors, artificial neural networks, and support vector machines (SVMs) were the machine learning approaches evaluated. The best performing parameters for each algorithm were determined via optimization. The resulting multiple-input-multiple-output models were subsequently assessed under identical conditions, and a SVM with a radial basis function kernel was identified as the best performing. The achieved root mean squared errors were 0.03L/min, 0.06L/min, and 0.18W for left and right flow and motor power consumption, respectively. In comparison with existing models for VADs, the flow errors are more than 70% lower. Further advantages of the SVM model are the robustness to measurement noise and the capability to operate outside of the trained parameter range. This proposed modeling method will accelerate further device refinements by providing a more appropriate numerical environment in which to evaluate the pump-cardiovascular system interaction. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation. Source

Timms D.L.,BiVACOR Pty Ltd. | Gregory S.D.,Institute of Health and Biomedical Innovation | Stevens M.C.,University of Queensland | Fraser J.F.,Critical Care Research Group
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS | Year: 2011

Comprehensive testing and evaluation of cardiovascular device function and performance is required prior to clinical implementation. Initial proof of concept investigations are conducted within in-vitro mock circulation loops, before proof of principle is demonstrated via in-vivo animal testing. To facilitate the rapid transition of cardiovascular devices through this development period, a testing apparatus was developed that closely models the natural human cardiovascular system haemodynamics. This mock circulation system accurately replicates cardiac function, coupled to systemic and pulmonary circulations. The physiological response produced by a number of clinical cardiovascular conditions can be actively controlled by variable parameters such as vascular resistance, arterial/venous compliance, ventricle contractility, heart rate, and heart /vascular volumes, while anatomical variations such as valve regurgitation and septal defects can be included. Auto-regulation of these parameters was attempted to reproduce the Frank-Starling mechanism, baroreceptor reflex, skeletal muscle pump, and postural changes. Steady state validation of loop performance was achieved by replicating the progression of a patient's clinical haemodynamics from heart failure, through VAD support, to heart transplantation. The system has been used to evaluate pulsatile and non-pulsatile ventricular assist devices, counter pulsation devices, non-invasive cardiac output monitors and cardiovascular stents. The interaction of these devices with the cardiovascular system was also investigated with regards to physiological control strategies and cannula placement. The system is a valuable tool for the accelerated progression of cardiovascular device development. © 2011 IEEE. Source

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