Physiology of Continuous-Flow Pumps

2012 ◽  
Vol 23 (1) ◽  
pp. 46-54 ◽  
Author(s):  
Dawn M. Christensen
Keyword(s):  
Continuous Flow ◽  
Blood Pump ◽  
Circulatory Support ◽  
Cardiovascular Physiology ◽  
Rotary Blood Pump ◽  
Monitoring Methods ◽  
Failing Heart ◽  
Blood Pumps ◽  
Rotary Blood Pumps

The use of mechanical pumps for circulatory support started in the mid-1950s. The evolution of these devices has led to the present-day use of continuous-flow pumps to take over the function of a patient’s failing heart. The physiology associated with rotary blood pump use is quite different from normal cardiovascular physiology. Clinicians caring for patients who are supported by rotary blood pumps must have an understanding of the differences in physiology, monitoring methods, and unique complications associated with the use of these pumps.

The Heart-Pump Interaction: Effects of a Microaxial Blood Pump

2002 ◽  
Vol 25 (11) ◽  
pp. 1082-1088 ◽  
Author(s):  
J. Stoliński ◽  
C. Rosenbaum ◽  
W. Flameng ◽  
B. Meyns
Keyword(s):  
Cardiac Cycle ◽  
Differential Pressure ◽  
Blood Pump ◽  
Pump Performance ◽  
Failing Heart ◽  
Pump Flow ◽  
Heart Pump ◽  
Blood Pumps ◽  
Clinical Conditions ◽  
Rotary Blood Pumps

Background: When we use rotary blood pumps as an assist device, an interaction takes place between the pump performance and the native heart function (native heart influences pump performance and vice versa). The interaction between native heart and rotary blood pump can be useful to predict recovery of the failing heart. Methods: The rotary blood pumps used were microaxial catheter-mounted pumps with an external diameter of 6.4mm (Impella, Aachen, Germany). The pump-heart interaction was studied in five juvenile sheep with a mean body weight of 68.5 ± 8.7 kg. The pumps were introduced via the left carotid artery and placed in transvalvular aortic position. Recorded parameters were pump speed (rpm), generated flow (L/min) and differential pressure (mm Hg) obtained at high frequency rate of data recordings (25 sets of data per second). This allowed continuous analysis of the pump performance during cardiac cycle. Under clinical conditions the interaction was studied in a 60-year-old male, in whom the device was applied due to postcardiotomy heart failure after myocardial infarction. Results: Heart-pump interaction was analyzed based on pump flow differential pressure. This relationship, analyzed continuously during cardiac cycle, presents as a loop. The dynamic contribution of the heart to the flow generated by the pump leads to continuous fluctuation in the pressure head and the creation of hysteresis. The improved function of the failing heart under clinical conditions after seven days of mechanical support was expressed by: increased hysteresis of the loop caused by increased gradient of flow generated during cardiac cycle, a more pronounced ventricular ejection phase that indicates more dynamic heart contribution to the generated flow, and finally increased gradient of the differential pressure during cardiac cycle, caused predominantly by increased aortic pressure and decreased left ventricle pressure during diastolic phase. Conclusions: The heart-pump interaction based on the pump flow-differential pressure relationship can be useful in predicting the possibility to wean the patient from the device.

Preliminary evaluation of a predictive controller for a rotary blood pump based on pulmonary oxygen gas exchange

2019 ◽  
Vol 233 (2) ◽  
pp. 267-278 ◽  
Author(s):  
Feng Huang ◽  
Zhe Gou ◽  
Yang Fu
Keyword(s):  
Gas Exchange ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Left Ventricular ◽  
Blood Pump ◽  
Rotary Blood Pump ◽  
Blood Pumps ◽  
Control Objective ◽  
Predictive Controller ◽  
Rotary Blood Pumps

Physiological control of rotary blood pumps is becoming increasingly necessary for clinical use. In this study, the mean oxygen partial pressure in the upper airway was first quantitatively evaluated as a control objective for a rotary blood pump. A model-free predictive controller was designed based on this control objective. Then, the quantitative evaluation of the controller was implemented with a rotary blood pump model on a complete cardiovascular model incorporated with airway mechanics and gas exchange models. The results show that the controller maintained a mean oxygen partial pressure at a normal and constant level of 138 mmHg in the left heart failure condition and restored basic haemodynamics of blood circulation. A left ventricular contractility recovery condition was also replicated to assess the response of the controller, and a stable result was obtained. This study indicates the potential use of the oxygen partial pressure index during pulmonary gas exchange when developing a multi-objective physiological controller for rotary blood pumps.

Turbulence Measurements in an Axial Rotary Blood Pump with Laser Doppler Velocimetry

2017 ◽  
Vol 40 (3) ◽  
pp. 109-117 ◽  
Author(s):  
Chan Y. Schüle ◽  
Klaus Affeld ◽  
Max Kossatz ◽  
Christian O. Paschereit ◽  
Ulrich Kertzscher
Keyword(s):  
Laser Doppler Velocimetry ◽  
Laser Doppler ◽  
Ventricular Assist Devices ◽  
Blood Pump ◽  
Doppler Velocimetry ◽  
Rotary Blood Pump ◽  
Measured Velocity ◽  
Blood Pumps ◽  
Velocity Spectra ◽  
Rotary Blood Pumps

Background The implantation of rotary blood pumps as ventricular assist devices (VADs) has become a viable therapy for quite a number of patients with end-stage heart failure. However, these rotary blood pumps cause adverse events that are related to blood trauma. It is currently believed that turbulence in the pump flow plays a significant role. But turbulence has not been measured to date because there is no optical access to the flow space in rotary blood pumps because of their opaque casings. Methods This difficulty is overcome with a scaled-up model of the HeartMate II (HM II) rotary blood pump with a transparent acrylic housing. A 2-component laser Doppler velocimetry (LDV) system was used for the measurement of time resolved velocity profiles and velocity spectra upstream and downstream of the rotor blades. Observing similarity laws, the speed and pump head were adjusted to correspond closely to the design point of the original pump – 10,600 rpm speed and 80 mmHg pressure head. A model fluid consisting of a water-glycerol mixture was used. Results The measured velocity spectra were scalable by the Kolmogorov length and the Kolmogorov length was estimated to be between 14 and 24 μm at original scale, thus being about 1.5 to 3 times the size of a red blood cell. Conclusions It can be concluded that turbulence is indeed present in the investigated blood pump and that it can be described by Kolmogorov's theory of turbulence. The size of the smallest vortices compares well to the turbulence length scales as found in prosthetic heart valves, for example.

scholarly journals Methodology for measuring the gap size using a fiber-optic displacement sensor exemplified by a centrifugal blood pump

2020 ◽  
Vol 12 (2) ◽  
pp. 46
Author(s):  
Maciej Gawlikowski ◽  
Przemysław Kurtyka ◽  
Jerzy Zalewski ◽  
Magda Zarwańska-Doffek ◽  
Artur Kapis
Keyword(s):  
Heart Failure ◽  
Ventricular Assist Device ◽  
Fiber Optic ◽  
Displacement Sensor ◽  
Blood Pump ◽  
Rotary Blood Pump ◽  
Assist Device ◽  
Ventricular Assist ◽  
Blood Pumps ◽  
Rotary Blood Pumps

In order to avoid blood clotting, in the second generation of rotary blood pumps the impeller is suspended without mechanical bearing, using balance of magnetic and hydrodynamic forces. Reaching single tens of microns gap between pump housing and impeller is crucial for level of blood traumatization by the pump. In this paper we would like to present the method of physical measurement of this gap on a running pump with the use of commercial fiber-optic proximity sensor on the example of Polish rotary blood pump ReligaHeart ROT. We also discussed technical requirements of the construction of laboratory stand. Full Text: PDF ReferencesS. Westaby, "Rotary blood pumps as definitive treatment for severe heart failure", Future Cardiol. 9, 2 (2013). CrossRef R. Delgado, M. Bergheim, "HeartMate® II left ventricular assist device: a new device for advanced heart failure", Epert Rev. Med. Devices, 2, 5 (2005). CrossRef M. Ozban, T. Yagdi, C. Engin et al, Transplant proc., 44, 6 (2012). CrossRef A.T. Lanfear, M. Hamandi, J. Fan et al., "Trends in HeartMate 3: What we know so far", J. Card. Surg., 35, 1 (2020). CrossRef Ch. Zengsheng, S. Anqiang, W. Hongyu, "Non-physiological shear stress-induced blood damage in ventricular assist device", Medicine in Novel Technology and Devices, 3 (2019). CrossRef A. M. Robertson, A. Sequeira, R. G. Owens, Rheological models of blood In: L. Formaggia, A. Quarteroni, A Veneziani (eds) Cardiovascular Mathematics (Milano, Springer-Verlag 2009) CrossRef M. Gawlikowski et al., "Necessity of telemonitoring in patients treated by means of cardiac assist systems on the example of Polish rotary blood pump ReligaHeart ROT", Advances in Intelligent Systems and Computing, 925 (2019). CrossRef R. Kustosz, et al., "The tin coating utilisation as blood contact surface modification in implantable rotary left ventricle assist device religaheart ROT", Arch. Matall. Mater., 60, 3 (2015). CrossRef S. S. Patil, A. D. Shaligram, "Analytical study of performance variations of fiber optic micro-displacement sensor configurations using mathematical modeling and an experimental test jig", IJSER, 4, 11 (2013). DirectLink Philtec Application Note, 6, 25 (2017) CrossRef

Speed Modulation of the HeartWare HVAD to Assess In Vitro Hemocompatibility of Pulsatile and Continuous Flow Regimes in a Rotary Blood Pump

2018 ◽  
Vol 42 (9) ◽  
pp. 879-890 ◽  
Author(s):  
Jarod T. Horobin ◽  
Michael J. Simmonds ◽  
Deepika Nandakumar ◽  
Shaun D. Gregory ◽  
Geoff Tansley ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Flow Regimes ◽  
Blood Pump ◽  
Rotary Blood Pump ◽  
Speed Modulation

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.

scholarly journals An accelerated thrombosis model for computational fluid dynamics simulations in rotary blood pumps

2021 ◽  
Author(s):  
Christopher Blum ◽  
Sascha Groß-Hardt ◽  
Ulrich Steinseifer ◽  
Michael Neidlin
Keyword(s):  
Platelet Activation ◽  
Clinical Data ◽  
Thrombus Formation ◽  
Fluid Dynamic ◽  
Surrogate Marker ◽  
Blood Pump ◽  
Funding Agency ◽  
Heartmate Ii ◽  
Blood Pumps ◽  
Rotary Blood Pumps

AbstractPurposeThrombosis is one of the major complications in blood-carrying medical devices and a better understanding to influence design of such devices is desirable. Over the past years many computational models of thrombosis have been developed. However, open questions remain about the applicability and implementation within a pump development process. The aim of the study was to develop and test a computationally efficient model for thrombus risk prediction in rotary blood pumps.MethodsWe used a two-stage approach to calculate thrombus risk. At the first stage, the velocity and pressure fields were computed by computational fluid dynamic (CFD) simulations. At the second stage, platelet activation by mechanical and chemical stimuli was determined through species transport with an Eulerian approach. The model was implemented in ANSYS CFX and compared with existing clinical data on thrombus deposition within the HeartMate II.ResultsOur model shows good correlation (R2>0.94) with clinical data and identifies the bearing and outlet stator region of the HeartMate II as the location most prone to thrombus formation. The calculation of platelet activation requires an additional 10-20 core hours of computation time.DiscussionThe concentration of activated platelets can be used as a surrogate marker to determine risk regions of thrombus deposition in a blood pump. Model expansion, e.g. by including more chemical species can easily be performed. We make our model openly available by implementing it for the FDA benchmark blood pump.DeclarationsFundingThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Open access funding enabled and organized by Projekt DEAL.Conflict of interestAll of the authors have nothing to disclose.Availability of data and materialThe raw data can be retrieved by request from the authors.Code availabilityThe implementation of the thrombus model in the FDA benchmark blood pump geometry is available on https://doi.org/10.5281/zenodo.5116063.Authors’ contributionsAll authors contributed to the study conception and design. CB developed the numerical model, performed the simulations, gathered, analysed and discussed the results. SGH, MN and US were involved in the analysis and discussion of the results. MN supervised the project. MN and CB wrote the manuscript based on the input of all co-authors. All co-authors read and approved the final version of the manuscript.

DESIGN AND DEVELOPMENT OF MINIATURE SLOTTED IMPELLER FOR SAI SPANDAN TOTAL ARTIFICIAL HEART FOR DESTINATION THERAPY

2021 ◽  
pp. 37-39
Author(s):  
Pradeep Kumar Radhakrishnan ◽  
Sujatha Mohanty ◽  
Pulivarthi Nageshwar Rao ◽  
Sivakrishna Rao G V ◽  
Nagesh Kumar ◽  
...  
Keyword(s):  
Total Artificial Heart ◽  
Circulatory Support ◽  
Blood Component ◽  
Centrifugal Pumps ◽  
Ventricular Assist ◽  
Circulatory Assist Devices ◽  
Blood Pumps ◽  
Pump Housing ◽  
Evaluation Metric ◽  
Rotary Blood Pumps

In recent years, the use of rotary blood pumps (RBPs) as continuous ow VADs has surged ahead, and virtually eliminated the use of pulsatile-ow or volume-displacement pumps for implantable, chronic mechanical circulatory support (MCS). Circuit Design modications like that in Saispandan has imparted pulsatility into RBP.Impeller designs are a signicant factor when designing centrifugal pumps as mechanical circulatory assist devices as smaller diameter impellers with higher rotational speeds to achieve target outputs would cause more blood component trauma compared to larger diameter impellers.Hydraulic performance and hemolysis tests in the same pump housing with different prototypes is needed. Ventricular assist parameters for efcient circulatory support would include an output of 5 L/min against 100 mmHg at speeds of 2500-3500 rpm. Vein height does not contribute signicantly to evaluation metric in most studies.

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