Vacuum-Assisted Venous Drainage during Fetal Cardiopulmonary Bypass

Lubbers, Walter C.; Baker, Richard S.; Sedgwick, Joseph A.; Lam, Christopher T.; Schenbeck, Jennifer L.; McNamara, Jerri L; Ferguson, Robert; Lombardi, John; Gardner, Aimee; Clark, Kenneth E.; Eghtesady, Pirooz

doi:10.1097/01.mat.0000178966.79876.3d

Cited by 42 publications

(34 citation statements)

References 17 publications

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“…The nominal tip clearance was specified as 200 mm and was adjustable between 200 and 0 mm with approximately 5 mm precision. The 46 mm impeller consisting of six blades was designed by the threedimensional inverse design method described previously [21] and the volute was designed by a parameterized geometrical model based on the velocity coefficients method [21]. To facilitate Fig.…”

Section: Pump Designmentioning

confidence: 99%

Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump

Antaki

et al. 2008

Proc Inst Mech Eng H

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A persistent challenge facing the quantitative design of turbodynamic blood pumps is the great disparity of spatial scales between the primary and auxiliary flow paths. Fluid passages within journals and adjacent to the blade tips are often on the scale of several blood cells, confounding the application of macroscopic continuum models. Yet, precisely in these regions there exists the highest shear stress, which is most likely to cause cellular trauma. This disparity has motivated these microscopic studies to visualize the kinematics of the blood cells within the small clearances of a miniature turbodynamic blood pump. A transparent model of a miniature centrifugal pump having an adjustable tip clearance (50-200 microm) was prepared for direct optical visualization of the region between the impeller blade tip and the stationary housing. Synchronized images of the blood cells were obtained by a microscopic visualization system, consisting of an inverted microscope fitted with long-working-distance objective lens (40x), mercury lamp, and high-resolution charge-coupled device camera electronically triggered by the rotation of the impeller. Experiments with 7 microm fluorescent particles revealed the influence of the gap dimension on the trajectory across the blade thickness. The lateral component of velocity (perpendicular to the blade) was dramatically enhanced in the 50 microm gap compared with the 200 microm gap, thereby reducing the exposure time. Studies with diluted bovine blood (Ht = 0.5 per cent) showed that the concentration of cells traversing the gap is also reduced dramatically (30 per cent) as the blade tip clearance is reduced from 200 microm to 50 microm. These results motivate further investigation into the microfluidic phenomena responsible for cellular trauma within turbodynamic blood pumps.

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Section: Pump Designmentioning

confidence: 99%

Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump

Antaki

et al. 2008

Proc Inst Mech Eng H

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“…We also acknowledge that a more convincing argument for the technique introduced herein would be made by repeating this study with multiple blood pump types. However, we are encouraged by the prior study of Wu et al 26 which illustrated the use of flow and head coefficient are applicable to both axial and centrifugal pumps. Nevertheless, further experimentation with other rotodynamic blood pumps is highly encouraged.…”

Section: Discussionmentioning

confidence: 91%

“…Engineering tools for evaluating and optimizing rotodynamic blood pumps are computer simulations [5][6][7]26 and flow visualization. 10,11,25,27 Computational Fluid Dynamics (CFD) is a relatively quick method for predicting a steady flow field; however it is much more challenging to simulate unsteady conditions, 22 and in some cases prohibitive.…”

Section: Introductionmentioning

confidence: 99%

Classification of Unsteady Flow Patterns in a Rotodynamic Blood Pump: Introduction of Non-Dimensional Regime Map

Shu

Vandenberghe

Brackett

et al. 2015

Cardiovasc Eng Tech

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Rotodynamic blood pumps (also known as rotary or continuous flow blood pumps) are commonly evaluated in vitro under steady flow conditions. However, when these devices are used clinically as ventricular assist devices (VADs), the flow is pulsatile due to the contribution of the native heart. This study investigated the influence of this unsteady flow upon the internal hemodynamics of a centrifugal blood pump. The flow field within the median axial plane of the flow path was visualized with particle image velocimetry (PIV) using a transparent replica of the Levacor VAD. The replica was inserted in a dynamic cardiovascular simulator that synchronized the image acquisition to the cardiac cycle. As compared to steady flow, pulsatile conditions produced periodic, transient recirculation regions within the impeller and separation in the outlet diffuser. Dimensional analysis revealed that the flow characteristics could be uniquely described by the non-dimensional flow coefficient (Φ) and its time derivative ([Formula: see text]), thereby eliminating impeller speed from the experimental matrix. Four regimes within the Φ-[Formula: see text] plane were found to classify the flow patterns, well-attached or disturbed. These results and methods can be generalized to provide insights for both design and operation of rotodynamic blood pumps for safety and efficacy.

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“…Therefore computational fluid dynamics was used to both calibrate the mean line formulae, and to optimize the unspecified features of the blood flow path. The procedure, described previously18,19,74-76 utilized a commercial CFD program (CFX 11, ANSYS, Inc., Canonsburg, PA, USA) employing both k – ε and SST turbulent models, that is coupled to an external optimization algorithm (see Fig. 8).…”

Section: Methodsmentioning

confidence: 99%

PediaFlow™ Maglev Ventricular Assist Device: A Prescriptive Design Approach

Antaki

Ricci

Verkaik

et al. 2010

Cardiovasc Eng Tech

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This report describes a multi-disciplinary program to develop a pediatric blood pump, motivated by the critical need to treat infants and young children with congenital and acquired heart diseases. The unique challenges of this patient population require a device with exceptional biocompatibility, miniaturized for implantation up to 6 months. This program implemented a collaborative, prescriptive design process, whereby mathematical models of the governing physics were coupled with numerical optimization to achieve a favorable compromise among several competing design objectives. Computational simulations of fluid dynamics, electromagnetics, and rotordynamics were performed in two stages: first using reduced-order formulations to permit rapid optimization of the key design parameters; followed by rigorous CFD and FEA simulations for calibration, validation, and detailed optimization. Over 20 design configurations were initially considered, leading to three pump topologies, judged on the basis of a multi-component analysis including criteria for anatomic fit, performance, biocompatibility, reliability, and manufacturability. This led to fabrication of a mixedflow magnetically levitated pump, the PF3, having a displaced volume of 16.6 cc, approximating the size of a AA battery and producing a flow capacity of 0.3-1.5 L/min. Initial in vivo evaluation demonstrated excellent hemocompatibility after 72 days of implantation in an ovine. In summary, combination of prescriptive and heuristic design principles have proven effective in developing a miniature magnetically levitated blood pump with excellent performance and biocompatibility, suitable for integration into chronic circulatory support system for infants and young children; aiming for a clinical trial within 3 years.

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Vacuum-Assisted Venous Drainage during Fetal Cardiopulmonary Bypass

Cited by 42 publications

References 17 publications

Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump

Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump

Classification of Unsteady Flow Patterns in a Rotodynamic Blood Pump: Introduction of Non-Dimensional Regime Map

PediaFlow™ Maglev Ventricular Assist Device: A Prescriptive Design Approach

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