PIV Measurements of Flow in a Centrifugal Blood Pump: Time-Varying Flow

Measurements of the time-varying flow in a centrifugal blood pump operating as a left ventricular assist device (LVAD) are presented. This includes changes in both the pump flow rate as a function of the left ventricle contraction and the interaction of the rotating impeller and fixed exit volute. When operating with a pulsing ventricle, the flow rate through the LVAD varies from 0-11L∕min during each cycle of the heartbeat. Phase-averaged measurements of mean velocity and some turbulence statistics within several regions of the pump, including the inlet, blade passage, exit volute, and diffuser, are reported at 20 phases of the cardiac cycle. The transient flow fields are compared to the constant flow rate condition that was reported previously in order to investigate the transient effects within the pump. It is shown that the quasi-steady assumption is a fair treatment of the time varying flow field in all regions of this representative pump, which greatly simplifies the comprehension and modeling of this flow field. The measurements are further interpreted to identify the effects that the transient nature of the flow field will have on blood damage. Although regions of recirculation and stagnant flow exist at some phases of the cardiac cycle, there is no location where flow is stagnant during the entire heartbeat.

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Synchronous Control with Heartbeat in a Magnetically Levitated Centrifugal Blood Pump by Estimating a Pump Flow Rate with a Radial Disturbance Observer–Validation in a Simple Mock Circulation Loop–

Journal of the Japan Society of Applied Electromagnetics and Mechanics ◽

10.14243/jsaem.29.72 ◽

2021 ◽

Vol 29 (1) ◽

pp. 72-77

Author(s):

Yui TANAKA ◽

Tomotaka MURASHIGE ◽

Wataru HIJIKATA

Keyword(s):

Flow Rate ◽

Disturbance Observer ◽

Circulation Loop ◽

Blood Pump ◽

Centrifugal Blood Pump ◽

Synchronous Control ◽

Pump Flow ◽

Mock Circulation ◽

Pump Flow Rate ◽

Mock Circulation Loop

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Experimental and Computational Studies of the Relative Flow Field in a Centrifugal Blood Pump

Critical Reviews in Biomedical Engineering ◽

10.1615/critrevbiomedeng.v28.i12.200 ◽

2000 ◽

Vol 28 (1-2) ◽

pp. 119-125 ◽

Cited By ~ 4

Author(s):

B. T. H. Ng ◽

Weng Kong Chan ◽

S. C. M. Yu ◽

HaiDong Li

Keyword(s):

Flow Field ◽

Blood Pump ◽

Computational Studies ◽

Centrifugal Blood Pump ◽

Relative Flow

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Impact of ejection on magnitude and time course of ventricular pressure-generating capacity

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.265.3.h899 ◽

1993 ◽

Vol 265 (3) ◽

pp. H899-H909 ◽

Cited By ~ 24

Author(s):

D. Burkhoff ◽

P. P. De Tombe ◽

W. C. Hunter

Keyword(s):

Time Course ◽

Cardiac Cycle ◽

Left Ventricular Pressure ◽

Left Ventricular ◽

Ventricular Pressure ◽

Time Varying ◽

Generating Capacity ◽

Ejection Phase ◽

Time Point ◽

Ventricular Dynamics

This study focuses on elucidating how ventricular afterloading conditions affect the time course of change of left ventricular pressure (LVP) throughout the cardiac cycle, with particular emphasis on revealing specific limitations in the time-varying elastance model of ventricular dynamics. Studies were performed in eight isolated canine hearts ejecting into a simulated windkessel afterload. LVP waves measured (LVPm) during ejection were compared with those predicted (LVPpred) according to the elastance theory. LVPm exceeded LVPpred from a time point shortly after the onset of ejection to the end of the beat. The instantaneous difference between LVPm and LVPpred increased steadily as ejection proceeded and reached between 45 and 65 mmHg near end ejection. This was in large part due to an average 35-ms prolongation of the time to end systole (tes) in ejecting compared with isovolumic beats. The time constant of relaxation was decreased on ejecting beats so that, despite the marked prolongation of tes, the overall duration of ejecting contractions was not greater than that of isovolumic beats. The results demonstrate a marked ejection-mediated enhancement and prolongation of ventricular pressure-generating capacity during the ejection phase of the cardiac cycle with concomitant acceleration of relaxation. None of these factors are accounted for by the time-varying elastance theory.

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Does the Blood Pump Flow Rate have an Impact on the Dialysis Dose During Low Dialysate Flow Rate Hemodialysis?

Blood Purification ◽

10.1159/000486843 ◽

2018 ◽

Vol 46 (4) ◽

pp. 279-285 ◽

Cited By ~ 2

Author(s):

Maxime Leclerc ◽

Clémence Bechade ◽

Patrick Henri ◽

Elie Zagdoun ◽

Erick Cardineau ◽

...

Keyword(s):

Flow Rate ◽

Blood Pump ◽

Bivariate Analysis ◽

Dialysis Dose ◽

Dialysate Flow ◽

Pump Flow ◽

Dialysate Flow Rate ◽

Pump Flow Rate ◽

A Prospective Study ◽

The Impact

We conducted a prospective study to assess the impact of the blood pump flow rate (BFR) on the dialysis dose with a low dialysate flow rate. Seventeen patients were observed for 3 short hemodialysis sessions in which only the BFR was altered (300,350 and 450 mL/min). Kt/V urea increased from 0.54 ± 0.10 to 0.58 ± 0.08 and 0.61 ± 0.09 for BFR of 300, 400 and 450 mL/min. For the same BFR variations, the reduction ratio (RR) of β2microglobulin increased from 0.40 ± 0.07 to 0.45 ± 0.06 and 0.48 ± 0.06 and the RR phosphorus increased from 0.46 ± 0.1 to 0.48 ± 0.08 and 0.49 ± 0.07. In bivariate analysis accounting for repeated observations, an increasing BFR resulted in an increase in spKt/V (0.048 per 100 mL/min increment in BPR [p < 0.05, 95% CI (0.03–0.06)]) and an increase in the RR β2m (5% per 100 mL/min increment in BPR [p < 0.05, 95% CI (0.03–0.07)]). An increasing BFR with low dialysate improves the removal of urea and β2m but with a potentially limited clinical impact.

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An experimental performance comparison of Newtonian and non-Newtonian fluids on a centrifugal blood pump

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/09544119211057626 ◽

2022 ◽

pp. 095441192110576

Author(s):

Ahmet Onder ◽

Rafet Yapici ◽

Omer Incebay

Keyword(s):

Flow Rate ◽

Rotational Speed ◽

Performance Test ◽

Newtonian Fluids ◽

Friction Reduction ◽

Blood Pump ◽

Actual Performance ◽

Centrifugal Blood Pump ◽

Working Fluids ◽

Pump Performance

The use of substitute fluid with similar rheological properties instead of blood is important due to ethical concerns and high blood volume consumption in pump performance test before clinical applications. The performance of a centrifugal blood pump with hydrodynamic journal bearing is experimentally tested using Newtonian 40% aqueous glycerin solution (GS) and non-Newtonian aqueous xanthan gum solution of 600 ppm (XGS) as working fluids. Experiments are performed at four different rotational speeds which are 2700, 3000, 3300, and 3600 rpm; experiments using GS reach between 8.5% and 37.2% higher head curve than experiments using the XGS for every rotational speed. It was observed that as the rotational speed and flow rate increase, the head curve difference between GS and XGS decreases. This result can be attributed to the friction reduction effect when using XGS in experiments at high rotation speed and high flow rate. Moreover, due to different fluid viscosities, differences in hydraulic efficiency were observed for both fluids. This study reveals that the use of Newtonian fluids as working fluids is not sufficient to determine the actual performance of a blood pump, and the performance effects of non-Newtonian fluids are remarkably important in pump performance optimizations.

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A Portable Pneumatic Driving Unit for a Left Ventricular Assist Device

The International Journal of Artificial Organs ◽

10.1177/039139888801100311 ◽

1988 ◽

Vol 11 (3) ◽

pp. 186-190 ◽

Cited By ~ 2

Author(s):

N. Kabei ◽

E. Shimemura ◽

Y. Sakurai ◽

K. Tsuchiya

Keyword(s):

Flow Rate ◽

Pressure Sensors ◽

Left Ventricular ◽

Pressure Level ◽

Blood Pump ◽

Ventricular Assist ◽

Output Pressure ◽

Output Flow ◽

New Type ◽

Output Characteristics

The authors developed a portable air driving unit for an artificial heart. As the portable energy source of the driver, a commercially available Ni-Cd battery was used. A linear compressor was selected as a portable size compressor. To reduce the number of parts to be assembled, a new type of pneumatic system was employed. In this system, the pressure level was regulated by varying the output flow rate of the compressor instead of using a pressure regulator and large air reservoirs. A one-board microcomputer and pressure sensors were used to control the pressure level. The total weight of the unit is 9.5 Kg. After assembling the components into the portable unit, a blood pump was connected to examine the output characteristics of the system. It was confirmed that the unit could drive the blood pump continuously for more than 2 hours under the following conditions: output flow rate of the blood pump = 5 L/min and output pressure — 100 mmHg.

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