Washout Hole Flow Measurement for the Development of a Centrifugal Blood Pump

Nishida, Masahiro; Yamada, Takashi; Asztalos, Balázs

doi:10.1046/j.1525-1594.1998.06140.x

Cited by 14 publications

(8 citation statements)

References 5 publications

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“…[30-33] Furthermore, centrifugal pumps are afterload sensitive, making precise control of blood flow rate challenging in the pediatric population. [34] Conventional roller pumps can produce pulsatile flow but are rarely able to generate a physiologic waveform. [35] Significant variation in hemodynamic energy created by various pulsatile roller pumps has been demonstrated.…”

Section: Discussionmentioning

confidence: 99%

A Novel Rotary Pulsatile Flow Pump for Cardiopulmonary Bypass

et al. 2014

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It has been suggested that pulsatile blood flow is superior to continuous flow in cardiopulmonary bypass (CPB). However, adoption of pulsatile flow (PF) technology has been limited due to practically and complexity of creating a consistent physiologic pulse. A pediatric pulsatile rotary ventricular pump (PRVP) was designed to address this problem. We evaluated the PRVP in an animal model, and determined its ability to generate PF during CPB. The PRVP (modified peristaltic pump, with tapering of the outlet of the pump chamber) was tested in 4 piglets (10-12kg). Cannulation was performed with right atrial and aortic cannulae, and pressure sensors were inserted into the femoral arteries. Pressure curves were obtained at different levels of flow and compared with both the animal's baseline physiologic function and a continuous flow (CF) roller pump. Pressure and flow waveforms demonstrated significant pulsatility in the PRVP setup compared to CF at all tested conditions. Measurement of hemodynamic energy data, including the percent pulsatile energy and the surplus hydraulic energy, also revealed a significant increase in pulsatility with the PRVP (p <0.001). PRVP creates physiologically significant PF, similar to the pulsatility of a native heart, and has the potential to be easily implemented in pediatric CPB.

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Section: Discussionmentioning

confidence: 99%

A Novel Rotary Pulsatile Flow Pump for Cardiopulmonary Bypass

et al. 2014

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“…Another alternative is to place washout holes in strategic positions in the rotor. These holes lower the resistance to the flow in the gap allowing more flow for the same pressure head . The flow through the holes, however, is difficult to keep smooth, and additional shear and flow separation may occur .…”

mentioning

confidence: 99%

The Spiral Groove Bearing as a Mechanism for Enhancing the Secondary Flow in a Centrifugal Rotary Blood Pump

Amaral¹,

Groß-Hardt²,

Timms³

et al. 2013

Artificial Organs

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The rapid evolution of rotary blood pump (RBP) technology in the last few decades was shaped by devices with increased durability, frequently employing magnetic or hydrodynamic suspension techniques. However, the potential for low flow in small gaps between the rotor and pump casing is still a problem for hemocompatibility. In this study, a spiral groove hydrodynamic bearing (SGB) is applied with two distinct objectives: first, as a mechanism to enhance the washout in the secondary flow path of a centrifugal RBP, lowering the exposure to high shear stresses and avoiding thrombus formation; and second, as a way to allow smaller gaps without compromising the washout, enhancing the overall pump efficiency. Computational fluid dynamics was applied and verified via bench-top experiments. An optimization of selected geometric parameters (groove angle, width and depth) focusing on the washout in the gap rather than generating suspension force was conducted. An optimized SGB geometry reduced the residence time of the cells in the gap from 31 to 27 ms, an improvement of 14% compared with the baseline geometry of 200 μm without grooves. When optimizing for pump performance, a 15% smaller gap yielded a slightly better rate of fluid exchange compared with the baseline, followed by a 22% reduction in the volumetric loss from the primary pathway. Finally, an improved washout can be achieved in a pulsatile environment due to the SGB ability to pump inwardly, even in the absence of a pressure head.

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“…As the devices become smaller in size, mechanical trauma to blood cell elements as well as thrombus formation secondary to flow stagnation inside the narrow clearance between the pump housing and impeller is expected to increase. To compensate for the problem of flow stagnation, wash‐out holes have been incorporated in the impeller to create a secondary flow inside the pump (14–17). Although adverse effects of the secondary flow have been reported, we believe that a proper amount of secondary flow will be effective in minimizing flow stagnation behind the impeller as well as mechanical trauma to red blood cells.…”

mentioning

confidence: 99%

Quantification of the Secondary Flow in a Radial Coupled Centrifugal Blood Pump Based on Particle Tracking Velocimetry

et al. 2005

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Secondary flow in the centrifugal blood pump helps to enhance the washout effect and to minimize thrombus formation. On the other hand, it has an adverse effect on pump efficiency. Excessive secondary flow may induce hemolytic effects. Understanding the secondary flow is thus important to the design of a compact, efficient, biocompatible blood pump. This study examined the secondary flow in a radial coupled centrifugal blood pump based on a simple particle tracking velocimetry (PTV) technique. A radial magnetically coupled centrifugal blood pump has a bell-shaped narrow clearance between the impeller inner radius and the pump casing. In order to vary the flow levels through the clearance area, clearance widths of 0.25 mm and 0.50 mm and impeller washout holes with diameters of 0 mm, 2.5 mm, and 4 mm were prepared. A high-speed video camera (2000 frames per second) was used to capture the particle images from which radial flow components were derived. The flow in the space behind the impeller was assumed to be laminar and Couette type. The larger the inner clearance or diameter of washout hole, the greater was the secondary flow rate. Without washout holes, the flow behind the impeller resulted in convection. The radial flow through the washout holes of the impeller was conserved in the radial as well as in the axial direction behind the impeller. The increase in the secondary flow reduced the net pump efficiency. Simple PTV was successful in quantifying the flow in the space behind the impeller. The results verified the hypothesis that the flow behind the impeller was theoretically Couette along the circumferential direction. The convection flow observed behind the impeller agreed with the reports of other researchers. Simple PTV was effective in understanding the fluid dynamics to help improve the compact, efficient, and biocompatible centrifugal blood pump for safe clinical applications.

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Washout Hole Flow Measurement for the Development of a Centrifugal Blood Pump

Cited by 14 publications

References 5 publications

A Novel Rotary Pulsatile Flow Pump for Cardiopulmonary Bypass

A Novel Rotary Pulsatile Flow Pump for Cardiopulmonary Bypass

The Spiral Groove Bearing as a Mechanism for Enhancing the Secondary Flow in a Centrifugal Rotary Blood Pump

Quantification of the Secondary Flow in a Radial Coupled Centrifugal Blood Pump Based on Particle Tracking Velocimetry

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