scholarly journals The Effect of Blood Viscosity on Shear-Induced Hemolysis using a Magnetically Levitated Shearing Device

2021 ◽  
Author(s):  
James A Krisher ◽  
Richard A Malinauskas ◽  
Steven W Day
Keyword(s):  
Shear Rate ◽  
Blood Viscosity ◽  
Plasma Viscosity ◽  
Ventricular Assist Devices ◽  
Complex Flow ◽  
Ventricular Assist ◽  
Blood Damage ◽  
Blood Pumps ◽  
Magnetically Levitated ◽  
Rotary Blood Pumps

Introduction: Blood contacting medical devices, including rotary blood pumps, can cause shear-induced blood damage that may lead to adverse effects in patients. Due in part to an inadequate understanding of how cell-scale fluid mechanics impact red blood cell membrane deformation and damage, there is currently not a uniformly accepted engineering model for predicting blood damage caused by complex flow fields within ventricular assist devices (VADs). Methods: We empirically investigated hemolysis in an axial Couette flow device typical of a rotary VAD to expand our current understanding of shear-induced blood damage in two ways. First, we used a magnetically levitated device to accurately control the shear rate and exposure time experienced by blood and to minimize the effects of other uncharacterized stresses. Second, we explored the effects of both hematocrit and plasma viscosity on shear-induced hemolysis to characterize blood damage based on the viscosity-independent shear rate, rather than on shear stress. Results: Over a shear rate range of 20,000-80,000 1/s, the Index of Hemolysis was found to be largely independent of hematocrit, bulk viscosity, or the suspension media viscosity. Conclusion: It is recommended that future investigations of shear-induced blood damage report findings with respect to the viscosity-neutral term of shear rate, in addition to the bulk whole blood viscosity measured at an appropriate shear rate relevant to the flow conditions of the device.

Cardiac transplantation and mechanical circulatory support

2020 ◽  
pp. 3428-3435
Author(s):  
Jayan Parameshwar ◽  
Steven Tsui
Keyword(s):  
Side Effects ◽  
Cardiac Transplantation ◽  
First Generation ◽  
Immunosuppressive Agents ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Blood Pumps ◽  
Rotary Blood Pumps

Cardiac transplantation is the treatment of choice for selected patients with advanced heart failure: median survival approaches 12 years and recipients enjoy an excellent quality of life, but availability is severely limited by shortage of donor organs. The need for lifelong immunosuppression is associated with side effects, including an increased incidence of malignancy. Newer immunosuppressive agents reduce nephrotoxicity and delay the onset of cardiac allograft vasculopathy, but may produce other side effects. Ventricular assist devices are mechanical blood pumps that work in parallel or series with the native ventricles. First-generation volume-displacement pulsatile ventricular assist devices have been superseded by rotary blood pumps that generate continuous flow. Significant complications include bleeding, thromboembolism, device failure due to pump thrombosis, and infection.

Measuring real-time blood viscosity with a ventricular assist device

2019 ◽  
Vol 233 (5) ◽  
pp. 562-569 ◽  
Author(s):  
Wataru Hijikata ◽  
Takuro Maruyama ◽  
Yuki Suzumori ◽  
Tadahiko Shinshi
Keyword(s):  
Shear Rate ◽  
Ventricular Assist Device ◽  
Blood Viscosity ◽  
Vibrational Excitation ◽  
High Shear Rate ◽  
Ventricular Assist Devices ◽  
High Shear ◽  
Assist Device ◽  
Ventricular Assist ◽  
Artificial Hearts

Ventricular assist devices assist in blood circulation and form a crucial component of artificial hearts. While it is important to measure parameters such as the flow rate, pressure head and viscosity of the blood, implanting additional devices to do such measurements is inadvisable. To this end, we demonstrate the adaptation of a ventricular assist device for the purpose of measuring blood viscosity. Such an approach eliminates the need for additional dedicated viscometers in artificial hearts. In the proposed method, the blood viscosity is measured by applying radial vibrational excitation to the impeller in a ventricular assist device using its magnetic levitation system. During the measurement, blood is exposed to a combination of a low shear rate (≈100/s) generated by the radial vibration of the impeller and a high shear rate (>10,000/s) generated by the impeller’s rotation. The apparent viscosity of blood depends on the shear rate, so we determined which shear rate was the dominant one in the proposed method. The measurement results showed that the viscosity measured by the proposed method was in good agreement with the reference viscosity measured with a high shear rate. The mean absolute deviation in the measurements using the proposed method and those obtained using a concentric cylindrical viscometer at a high shear rate was 0.12 mPa s for four samples of porcine blood, with viscosities ranging from 2.32 to 2.75 mPa s.

Blood and plasma viscosity of winter flounder: influence of temperature, red cell concentration, and shear rate

1983 ◽  
Vol 61 (10) ◽  
pp. 2344-2350 ◽  
Author(s):  
Mark S. Graham ◽  
Garth L. Fletcher
Keyword(s):  
Shear Rate ◽  
Blood Viscosity ◽  
Cell Concentration ◽  
Plasma Viscosity ◽  
Winter Flounder ◽  
Red Cell ◽  
Pseudopleuronectes Americanus ◽  
Total Blood ◽  
Influence Of Temperature ◽  
Rate Dependent

The effects of temperature, red cell concentration, and shear rate on the viscosity of blood from the winter flounder (Pseudopleuronectes americanus) were evaluated using a cone-plate viscometer. The viscosity of blood and plasma was shear rate dependent at all temperatures studied (−1 to 20 °C) with the highest values occurring at the lowest temperature and shear rate. At normal hematocrits (20%), plasma appeared to account for at least 50% of the total blood viscosity. The effects of hematocrit on viscosity were dependent on temperature. At higher temperatures (10–20 °C), increases in hematocrit resulted in a near-exponential increase in viscosity. At lower temperatures (5 °C) and shear rates (4.5 s−1) no significant increase in viscosity occurred between hematocrits of 11 and 43%. The influence of temperature and shear rate on blood viscosity suggest that winter flounder may have to contend with a fivefold increase in blood viscosity when acclimating from summer to winter water temperatures.

Robust physiological control of rotary blood pumps for heart failure therapy

2018 ◽  
Vol 66 (9) ◽  
pp. 767-779 ◽  
Author(s):  
Daniel Rüschen ◽  
Sebastian Opitz ◽  
Philip von Platen ◽  
Leonie Korn ◽  
Steffen Leonhardt ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiovascular System ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Heart Failure Therapy ◽  
Physiological Control ◽  
Detailed Model ◽  
Blood Pumps ◽  
Rotary Blood Pumps ◽  
Varying Demand

Abstract Left ventricular assist devices (LVADs) have become a viable alternative to heart transplantation in heart failure therapy. In clinical practice, rotary blood pumps used as LVADs are operated at a constant rotational speed and thus do not adapt to the varying demand of the patient. This paper presents a robust control approach for automatic adaptation of the blood pump speed to the blood flow demand of the patient’s body, which enables a defined load sharing between an LVAD and the native ventricle. Robust stability was checked using a detailed model of the human cardiovascular system with uncertainties that describe the most important native physiological control loops as well as a range of pathologies. The robust assistance controller was tested in an in vivo setup and was able to stabilize the cardiovascular system after myocardial infarction.

scholarly journals Haemolysis induced by mechanical circulatory support devices: unsolved problems

Perfusion ◽  
2020 ◽  
Vol 35 (6) ◽  
pp. 474-483
Author(s):  
Inge Köhne
Keyword(s):  
Shear Stress ◽  
Continuous Flow ◽  
Mechanical Circulatory Support ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Ventricular Assist ◽  
Theoretical Approaches ◽  
Blood Pumps ◽  
Mechanical Circulatory Support Devices ◽  
Support Devices

Since the use of continuous flow blood pumps as ventricular assist devices is standard, the problems with haemolysis have increased. It is mainly induced by shear stress affecting the erythrocyte membrane. There are many investigations about haemolysis in laminar and turbulent blood flow. The results defined as threshold levels for the damage of erythrocytes depend on the exposure time of the shear stress, but they are very different, depending on the used experimental methods or the calculation strategy. Here, the results are resumed and shown in curves. Different models for the calculation of the strengths of erythrocytes are discussed. There are few results reported about tests of haemolysis in blood pumps, but some theoretical approaches for the design of continuous flow blood pumps according to low haemolysis have been investigated within the last years.

Computational Fluid Dynamics Analyses of a Micro Pediatric Ventricular Assist Blood Pump

2011 ◽  
Author(s):  
Xiao-chen Yang ◽  
Yan Zhang ◽  
Xing-min Gui ◽  
Sheng-shou Hu
Keyword(s):  
Fluid Dynamics ◽  
Heart Failure ◽  
Computational Fluid Dynamics ◽  
Blood Pump ◽  
Ventricular Assist ◽  
Blood Pumps ◽  
Blade Tip ◽  
Hemolytic Property ◽  
Rotary Blood Pumps ◽  
Dynamics Analyses

The heart failure patients supported by the mechanical rotary blood pumps have been validated and investigated in recent decades. A series of adult blood pumps have been investigated in our research group in the last several years and one of them is currently under clinical trials. This present paper aimed at analyzing a micro pediatric blood pump (MPBP) with Computational fluid dynamics (CFD) tool. MPBP is developed to assist the ventricular according to the practice of pediatric heart failure in Fuwai Hospital of Chinese Academy of Medical Sciences. The blade tip diameter of the MPBP is 10 mm. Some advanced structures proposed in our adult blood pumps were further improved in the MPBP and a cantilevered stator applied in the blood pump is a novel try. The results of the numerical simulation show that the MPBP can generate the flow rates of 0.74–3.21 lpm at the rotational speeds of 9,000–11,000 rpm, producing the pressure rises of 36.9–89.7 mmHg. The structural advantage, hydraulic performance and hemolytic property of the MPBP were analyzed in detail. Overall, the attempt of the cantilevered stator blade improved the performance of the blood pump effectively and the MPBP deserves a promising prospect.

Design Optimization of Rotary Blood Pumps: Alternatives to Anticoagulation Therapy

2011 ◽  
Author(s):  
Gaurav Girdhar ◽  
Michalis Xenos ◽  
Wei-Che Chiu ◽  
Yared Alemu ◽  
Bryan Lynch ◽  
...  
Keyword(s):  
Heart Valves ◽  
Anticoagulation Therapy ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Shear Stresses ◽  
Ventricular Assist ◽  
Bridge To Transplant ◽  
Life Saving ◽  
Optimization Methodology ◽  
Rotary Blood Pumps

Mechanical circulatory support (MCS) devices such as the ventricular assist devices (VADs) provide life saving short-term bridge-to-transplant solutions (1) to a large proportion of patients who suffer from chronic heart failure. Although hemodynamically efficient, such devices are burdened with high incidence of thromboembolic events due to non-physiological flow past constricted geometries where platelets (the principal cellular clotting elements in blood) are exposed to elevated shear stresses and exposure times (2) — requiring mandatory anticoagulation. We recently developed an optimization methodology — Device Thrombogenicity Emulator (DTE)(3) — that integrates device specific hemodynamic stresses (from numerical simulations) with experimental measurements of platelet activation. The DTE was successfully applied by our group to measure / optimize the thromboresistance of mechanical heart valves (MHV) (3, 4).

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