BiVACOR Pty Ltd.

Brisbane, Australia

BiVACOR Pty Ltd.

Brisbane, Australia
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Nestler F.,Queensland University of Technology | Nestler F.,The Prince Charles Hospital | Bradley A.P.,Queensland University of Technology | Wilson S.J.,Queensland University of Technology | Timms D.L.,BiVACOR Pty Ltd.
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.


Gregory S.D.,Queensland University of Technology | Gregory S.D.,Prince Charles Hospital | Timms D.,Prince Charles Hospital | Timms D.,BiVACOR Pty Ltd. | And 6 more authors.
Annals of Biomedical Engineering | Year: 2011

The optimal treatment option for end stage heart failure is transplantation; however, the shortage of donor organs necessitates alternative treatment strategies such as mechanical circulatory assistance. Ventricular assist devices (VADs) are employed to support these cases while awaiting cardiac recovery or transplantation, or in some cases as destination therapy. While left ventricular assist device (LVAD) therapy alone is effective in many instances, up to 50% of LVAD recipients demonstrate clinically significant postoperative right ventricular failure and potentially need a biventricular assist device (BiVAD). In these cases, the BiVAD can effectively support both sides of the failing heart. This article presents a technical review of BiVADs, both clinically applied and under development. The BiVADs which have been used clinically are predominantly first generation, pulsatile, and paracorporeal systems that are bulky and prone to device failure, thrombus formation, and infection. While they have saved many lives, they generally necessitate a large external pneumatic driver which inhibits normal movement and quality of life for many patients. In an attempt to alleviate these issues, several smaller, implantable second and third generation devices that use either immersed mechanical blood bearings or hydrodynamic/magnetic levitation systems to support a rotating impeller are under development or in the early stages of clinical use. Although these rotary devices may offer a longer term, completely implantable option for patients with biventricular failure, their control strategies need to be refined to compete with the inherent volume balancing ability of the first generation devices. The BiVAD systems potentially offer an improved quality of life to patients with total heart failure, and thus a viable alternative to heart transplantation is anticipated with continued development. © 2011 Biomedical Engineering Society.


Gregory S.D.,Queensland University of Technology | Gregory S.D.,The Prince Charles Hospital | Pearcy M.J.,Queensland University of Technology | Pearcy M.J.,The Prince Charles Hospital | And 3 more authors.
Artificial Organs | Year: 2013

Right heart dysfunction is one of the most serious complications following implantation of a left ventricular assist device, often leading to the requirement for short- or long-term right ventricular assist device (RVAD) support. The inflow cannulation site induces major hemodynamic changes and so there is a need to optimize the site used depending on the patient's condition. Therefore, this study evaluated and compared the hemodynamic influence of right atrial cannulation (RAC) and right ventricular cannulation (RVC) inflow sites. An in vitro variable heart failure mock circulation loop was used to compare RAC and RVC in mild and severe biventricular heart failure (BHF) conditions. In the severe BHF condition, higher ventricular ejection fraction (RAC: 13.6%, RVC: 32.7%) and thus improved heart chamber and RVAD washout were observed with RVC, which suggested this strategy might be preferable for long-term support (i.e., bridge-to-transplant or destination therapy) to reduce the risk of thrombus formation. In the mild BHF condition, higher pulmonary valve flow (RAC: 3.33L/min, RVC: 1.97L/min) and lower right ventricular stroke work (RAC: 0.10W, RVC: 0.13W) and volumes were recorded with RAC. These results indicate an improved potential for myocardial recovery, thus RAC should be chosen in this condition. This in vitro study suggests that RVAD inflow cannulation site should be chosen on a patient-specific basis with a view to the support strategy to promote myocardial recovery or reduce the risk of long-term complications. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.


Gregory S.D.,Queensland University of Technology | Gregory S.D.,The Prince Charles Hospital | Loechel N.,Queensland University of Technology | Loechel N.,The Prince Charles Hospital | And 7 more authors.
Artificial Organs | Year: 2013

Successful anatomic fitting of a total artificial heart (TAH) is vital to achieve optimal pump hemodynamics after device implantation. Although many anatomic fitting studies have been completed in humans prior to clinical trials, few reports exist that detail the experience in animals for in vivo device evaluation. Optimal hemodynamics are crucial throughout the in vivo phase to direct design iterations and ultimately validate device performance prior to pivotal human trials. In vivo evaluation in a sheep model allows a realistically sized representation of a smaller patient, for which smaller third-generation TAHs have the potential to treat. Our study aimed to assess the anatomic fit of a single device rotary TAH in sheep prior to animal trials and to use the data to develop a three-dimensional, computer-aided design (CAD)-operated anatomic fitting tool for future TAH development. Following excision of the native ventricles above the atrio-ventricular groove, a prototype TAH was inserted within the chest cavity of six sheep (28-40kg). Adjustable rods representing inlet and outlet conduits were oriented toward the center of each atrial chamber and the great vessels, with conduit lengths and angles recorded for future analysis. A three-dimensional, CAD-operated anatomic fitting tool was then developed, based on the results of this study, and used to determine the inflow and outflow conduit orientation of the TAH. The mean diameters of the sheep left atrium, right atrium, aorta, and pulmonary artery were 39, 33, 12, and 11mm, respectively. The center-to-center distance and outer-edge-to-outer-edge distance between the atria, found to be 39±9mm and 72±17mm in this study, were identified as the most critical geometries for successful TAH connection. This geometric constraint restricts the maximum separation allowable between left and right inlet ports of a TAH to ensure successful alignment within the available atrial circumference. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.


Alomari A.-H.H.,University of Dammam | Savkin A.V.,University of New South Wales | Stevens M.,Prince Charles Hospital | Stevens M.,Queensland University of Technology | And 14 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.


Timms D.L.,BiVACOR Pty Ltd | Gregory S.D.,Prince Charles Hospital | Stevens M.C.,University of Queensland | Fraser J.F.,Prince Charles Hospital
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.


Patent
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.


Patent
Bivacor Pty Ltd and Queensland University of Technology | Date: 2015-01-13

A cannula including a hollow cannula body having first and second tubular end portions, a collapsible section interconnecting the end portions, the collapsible section including a plurality of circumferentially spaced arms extending between the end portions, wherein in an extended configuration the arms are substantially aligned with the first and second end portions and in a collapsed configuration the arms deform to extend radially outwardly and a flange extending radially outwardly from the first end portion, so that the arms and flange are spaced apart when the cannula body is in the collapsed configuration, thereby allowing tissue to be sandwiched therebetween to thereby effect a seal between the cannula and the tissue so that the cannula provides an opening through the tissue.


Patent
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.

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