Design of a Continuous Flow Centrifugal Pediatric Ventricular Assist Device

Al, Throckmorton; Hg, Wood; Day, Steven W.; Song, Xinwei; Pc, Click; Pe, Allaire; Db, Olsen

doi:10.1177/039139880302601108

Cited by 16 publications

(9 citation statements)

References 28 publications

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“…In fact, these refinements appear to have resulted in improved outcomes over time despite the increasing use of VADs in smaller and more complex patients. [17][18][19] Further study is warranted to optimize criteria for patient 20 and device selection.…”

Section: Discussionmentioning

confidence: 99%

Outcomes of Children Bridged to Heart Transplantation With Ventricular Assist Devices

Blume

Naftel²,

Bastardi³

et al. 2006

Circulation

333

177

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for the Pediatric Heart Transplant Study Investigators Background-Current ventricular assist devices (VADs) in the United States are designed primarily for adult use. Data on VADs as a bridge to transplantation in children are limited. Methods and Results-A multi-institutional, prospectively maintained database of outcomes in children after listing for heart transplantation (nϭ2375) was used to analyze outcomes of VAD patients (nϭ99, 4%) listed between January 1993 and December 2003. Median age at VAD implantation was 13.3 years (range, 2 days to 17.9 years); diagnoses were cardiomyopathy (78%) and congenital heart disease (22%). Mean duration of support was 57 days (range, 1 to 465 days). Seventy-three percent were supported with a long-term device, with 39% requiring biventricular support. Seventy-seven patients (77%) survived to transplantation, 5 patients were successfully weaned from support and recovered, and 17 patients (17%) died on support. In the recent era (2000 to 2003), successful bridge to transplantation with VAD was achieved in 86% of patients. Peak hazard for death while waiting was the first 2 weeks after VAD placement. Risk factors for death while awaiting a transplant included earlier era of implantation (Pϭ0.05), female gender (Pϭ0.02), and congenital disease diagnosis (Pϭ0.05). There was no difference in 5-year survival after transplantation for patients on VAD at time of transplantation as compared with those not requiring VAD. Conclusions-VAD support in children successfully bridged 77% of patients to transplantation, with posttransplantation outcomes comparable to those not requiring VAD. These encouraging results emphasize the need to further understand patient selection and to delineate the impact of VAD technology for children.

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Section: Discussionmentioning

confidence: 99%

Outcomes of Children Bridged to Heart Transplantation With Ventricular Assist Devices

Blume

Naftel²,

Bastardi³

et al. 2006

Circulation

333

177

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“…1: (i) an inducer section with stationary blades to reduce prerotation in the inflow and to house the active magnetic bearings; (ii) a rotating impeller region with four helically curved blades mounted to the hub which impart kinetic energy to the fluid; (iii) a stationary diffuser section with curved blades specifically designed to convert the kinetic energy to potential energy or pressure; and (iv) a flow straightener region with stationary blades mounted to the outlet pump housing. The pump is designed to deliver 0.5 to 3 Lpm with pressure rises of 50–95 mm Hg to meet the cardiophysiologic demands of pediatric patients (19).…”

Section: Methodsmentioning

confidence: 99%

Fluid Force Predictions and Experimental Measurements for a Magnetically Levitated Pediatric Ventricular Assist Device

et al. 2007

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The latest generation of artificial blood pumps incorporates the use of magnetic bearings to levitate the rotating component of the pump, the impeller. A magnetic suspension prevents the rotating impeller from contacting the internal surfaces of the pump and reduces regions of stagnant and high shear flow that surround fluid or mechanical bearings. Applying this third-generation technology, the Virginia Artificial Heart Institute has developed a ventricular assist device (VAD) to support infants and children. In consideration of the suspension design, the axial and radial fluid forces exerted on the rotor of the pediatric VAD were estimated using computational fluid dynamics (CFD) such that fluid perturbations would be counterbalanced. In addition, a prototype was built for experimental measurements of the axial fluid forces and estimations of the radial fluid forces during operation using a blood analog mixture. The axial fluid forces for a centered impeller position were found to range from 0.5 +/- 0.01 to 1 +/- 0.02 N in magnitude for 0.5 +/- 0.095 to 3.5 +/- 0.164 Lpm over rotational speeds of 6110 +/- 0.39 to 8030 +/- 0.57% rpm. The CFD predictions for the axial forces deviated from the experimental data by approximately 8.5% with a maximum difference of 18% at higher flow rates. Similarly for the off-centered impeller conditions, the maximum radial fluid force along the y-axis was found to be -0.57 +/- 0.17 N. The maximum cross-coupling force in the x direction was found to be larger with a maximum value of 0.74 +/- 0.22 N. This resulted in a 25-35% overestimate of the radial fluid force as compared to the CFD predictions; this overestimation will lead to a far more robust magnetic suspension design. The axial and radial forces estimated from the computational results are well within a range over which a compact magnetic suspension can compensate for flow perturbations. This study also serves as an effective and novel design methodology for blood pump developers employing magnetic suspensions. Following a final design evaluation, a magnetically suspended pediatric VAD will be constructed for extensive hydraulic and animal testing as well as additional validation of this design methodology.

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“…A broad variety of different blood pump applications have been analysed by the research group from the Universities of Utah and Virginia, ranging from centrifugal [3,8,46,127] and axial [138] pumps for adults to centrifugal [135] and axial [134] pumps for pediatric use.…”

Section: Rheological Modellingmentioning

confidence: 99%

A review of computational fluid dynamics analysis of blood pumps

et al. 2009

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Ventricular assist devices (VADs) provide long- and short-term support to chronically ill heart disease patients; these devices are expected to match the remarkable functionality of the natural heart, which makes their design a very challenging task. Blood pumps, the principal component of the VADs, must operate over a wide range of flow rates and pressure heads and minimise the damage to blood cells in the process. They should also be small to allow easy implantation in both children and adults. Mathematical methods and computational fluid dynamics (CFD) have recently emerged as powerful design tools in this context; a review of the recent advances in the field is presented here. This review focusses on the CFD-based design strategies applied to blood flow in blood pumps and other blood-handling devices. Both simulation methods for blood flow and blood damage models are reviewed. The literature is put into context with a discussion of the chronological development in the field. The review is illustrated with specific examples drawn from our group's Galerkin/least squares (GLS) finite-element simulations of the basic Newtonian flow problem for the continuous-flow centrifugal GYRO blood pump. The GLS formulation is outlined, and modifications to include models that better represent blood rheology are shown. Haemocompatibility analysis of the pump is reviewed in the context of haemolysis estimations based on different blood damage models. Our strain-based blood damage model that accounts for the viscoleasticity associated with the red blood cells is reviewed in detail. The viability of design improvement based on trial and error and complete simulation-based design optimisation schemes are also discussed.

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Design of a Continuous Flow Centrifugal Pediatric Ventricular Assist Device

Cited by 16 publications

References 28 publications

Outcomes of Children Bridged to Heart Transplantation With Ventricular Assist Devices

Outcomes of Children Bridged to Heart Transplantation With Ventricular Assist Devices

Fluid Force Predictions and Experimental Measurements for a Magnetically Levitated Pediatric Ventricular Assist Device

A review of computational fluid dynamics analysis of blood pumps

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