Blood Pump Research Articles

Optimization of Hemolytic Performance for Blood Pump Based on Temperature Field Analysis and Three Control Strategies

Optimization of Hemolytic Performance for Blood Pump Based on Temperature Field Analysis and Three Control Strategies

Effect of Blade Thickness on Hemodynamics and Hemolysis: A Case Study of Pediatric Centrifugal Blood Pumps.

Blood pumps have become popular whether for use as an implantable ventricular assist device or as extracorporeal membrane oxygenation. The quality of these pumps is assessed according to their ability to reduce the risk of blood damage thanks to an optimal choice of their geometric and operating properties. Lack of the research focused on the geometrical optimization of impellers has prompted this study. This study evaluated a computational and experimental analysis comparing the hemolytic performance of three centrifugal pumps. For this purpose, methods of Eulerian and Lagrangian are respectively used for hemodynamic and hemocompatibility investigations. Referring to the pediatric demands, these pumps function under clinically applicable pressure-flow conditions: 1 l/min of blood flow and a pressure differential of 60 mm Hg. These three pumps all use the same volute, but their impellers differ in terms of blade thickness. The objective is to examine how surface area affects the generation of hemolysis. In silico simulations were employed for both of the following tasks: first, identifying the distributions of velocities, pressures, and shear stresses; second, applying the Lagrangian approach to estimate the hemolysis index. Results showed the importance of the flow passage and the surface of the clearance on the hemocompatibility of the pumps. However, it was observed that there is not a linear effect of the blade thickness on the shear stress or index of hemolysis. Additionally, this work can provide information to develop an optimal design of a more hemocompatible blood pump.

Dynamic modeling of variable speed left ventricular assist devices coupled to the cardiovascular system.

Most of the modeling of the Left Ventricular Assist Devices (LVADs) coupled with the cardiovascular system is based on the assumption of constant rotational speed. Compared with the traditional inertial model, the validated hysteresis model can take into account the unsteady characteristics of LVADs, but it fails to work under the condition of variable speed modulation. This study takes into consideration the impact of speed variations on the unsteady hysteresis effects. The time constant in the hysteresis model is treated as a time-varying parameter, thereby developing a new model applicable to variable speed modulation. Under sinusoidal speed modulation at various phases, a comparative analysis was undertaken among the steady-state model, inertial model, and the new model. Transient Computational Fluid Dynamics (CFD) simulations and existing experimental results are used for validation. The new model provides a more accurate method for the predicting the characteristics of LVAD in the coupled model under varying pump speeds, and exhibits higher linearity in the work done by the left ventricle and the blood pump, and , which is aligning closely with the experimental results. This enhancement renders it applicable for proactive control predictions and passive control validations.

One-shot manufacturable soft-robotic pump inspired by embryonic tubular heart.

Soft peristaltic pumps, which use soft ring actuators instead of mechanical pistons or rollers, offer advantages in transporting liquids with non-uniform solids, such as slurry, food, and sewage. Recent advances in 3D printing with flexible thermoplastic polyurethane (TPU) present the potential for single-step fabrication of these pumps, distinguished from handcrafted, multistep traditional silicone casting methods. However, because of the relatively high hardness of TPU, TPU-based soft peristaltic pumps contract insufficiently and thus cannot perform as well as silicone-based ones. Improving the performance is crucial for fully automated, one-step manufactured soft pumps to lead to industrial use. This study aims to enhance TPU-based soft pumps through bioinspired design. Specifically, it proposed a design inspired by embryonic tubular hearts, in contrast to previous studies that mimicked digestive tracts. The new design facilitated long-axis stretching of an elliptical lumen during non-concentric contractile motion, akin to embryonic tubular hearts. The design was optimized for ring actuators and pumps 3D-printed with shore hardness 85 A TPU filament. The ring actuator achieved over 99% lumen closure with the best designs. The soft pumps transported water at flow rates of up to 218 ml min-1and generated a maximum discharge pressure of 355 mm Hg, comparable to the performance of blood pumps used in continuous renal replacement therapy.

Dynamic Stability Analysis of Magnetically Levitated Rotor in a Nutation Blood Pump

Dynamic Stability Analysis of Magnetically Levitated Rotor in a Nutation Blood Pump

Hemolysis analysis of centrifugal blood pump based on numerical simulation

Abstract The operation of blood pump will cause mechanical damage to red blood cells and lead to hemolysis. Based on this, CFD technology is used to simulate the three-dimensional flow field of centrifugal blood pump. According to the analysis of velocity field, pressure field and stress field; Based on the hemolysis power function model, the hemolysis performance of blood pump is predicted by Lagrange particle tracking method, and the impeller structure is adjusted to improve its flow performance and reduce the hemolysis index. The research results can provide a basis for the structural improvement and performance improvement of centrifugal heart pump.

Turbulent flow field in maglev centrifugal blood pumps of CH-VAD and HeartMate III: secondary flow and its effects on pump performance.

Secondary flow path is one of the crucial aspects during the design of centrifugal blood pumps. Small clearance size increases stress level and blood damage, while large clearance size can improve blood washout and reduce stress level. Nonetheless, large clearance also leads to strong secondary flows, causing further blood damage. Maglev blood pumps rely on magnetic force to achieve rotor suspension and allow more design freedom of clearance size. This study aims to characterize turbulent flow field and secondary flow as well as its effects on the primary flow and pump performance, in two representative commercial maglev blood pumps of CH-VAD and HeartMate III, which feature distinct designs of secondary flow path. The narrow and long secondary flow path of CH-VAD resulted in low secondary flow rates and low disturbance to the primary flow. The flow loss and blood damage potential of the CH-VAD mainly occurred at the secondary flow path, as well as the blade clearances. By contrast, the wide clearances in HeartMate III induced significant disturbance to the primary flow, resulting in large incidence angle, strong secondary flows and high flow loss. At higher flow rates, the incidence angle was even larger, causing larger separation, leading to a significant decrease of efficiency and steeper performance curve compared with CH-VAD. This study shows that maglev bearings do not guarantee good blood compatibility, and more attention should be paid to the influence of secondary flows on pump performance when designing centrifugal blood pumps.

Design Improvement for Interventional Blood Pumps Based on Flow Analysis

Abstract Interventional blood pumps serve as a crucial component for temporary mechanical circulatory support in the treatment of heart failure, specifically designed to improve blood circulation recovery and survival rate in patients undergoing treatment for acute cardiovascular diseases. This study aims to design a novel interventional blood pump with a focus on achieving exceptional hydraulic performance and superior blood compatibility based on numerical simulation, which considers the interactions between the blood pump and the upstream (drainage cannula) and downstream (aorta) flow fields, establishing a full-scale flow field analysis. For the numerical method, the Reynolds-Averaged Navier-Stokes (RANS) equations coupling with the k-ɛ turbulence model are solved. The result indicates that high shear stress exists around the leading and trailing edges of impeller blades and there is a jet at the outlet of impeller, and the blade leading and trailing edge, and the outlet of the impeller are the dominant regions for higher hemolysis occurrence. It is also noted that the presence of an interventional blood pump generates significant vortex structures within the aorta. To effectively reduce the hemolysis index, back-sweep concept is applied to this study also optimize the impeller’s leading edge. The analysis result confirms that the back swept leading edge of impeller blade helps improve the blood compatibility for interventional blood pumps.

Development Of Smart Band For Vital Signs Monitoring System Based On Internet Of Things

Abstract Vital signs are important health parameters because they indicate the physiological functions of the human body. Heart rate (HR), blood pressure, body temperature, oxygen saturation (SpO2), and respiration rate are vital signs used to determine whether a person is healthy or not. HR is the rate at which the heart pumps blood and is measured by the number of heart beat per minute (beats per minute / BPM). Oxygen saturation (SpO2) indicates the level of hemoglobin in the blood that can bind to oxygen. This study aims to develop a smart band prototype for monitoring heart rate (HR) and oxygen saturation using optical spectroscopy methods and the implementation of the Internet of Things (IoT). This smart band prototype uses the MAX30102 sensor, ESP32, push button, Blynk, and Arduino IDE AVR software. The research results show that the prototype’s accuracy for HR measurement is ±98.5%, and the accuracy for SpO2 is ±99.3%. The measurement results can be sent and displayed in the Blynk application as well as to email. It can be concluded that this smart band can detect HR and SpO2 in real-time and has the potential to improve the quality of healthcare services.

Mechanical circulatory support for cardiogenic shock during the peripartum period.

Cardiomyopathies account for more than half of the cardiovascular disease during the peripartum period. In the extreme, patients may present with cardiogenic shock (CS) requiring mechanical circulatory support (MCS). The aim of this study was to report our experience with CS requiring MCS in the peripartum period. We present a single-center retrospective analysis of all CS cases involving MCS during the peripartum period that occurred between 2012 and 2023. Eleven cases were included. Median age was 33, median BMI was 30.4, and 73% underwent a caesarian-section for delivery. CS presentation occurred in 36.4% during pregnancy and in 63.6% after delivery. Most patients were in Society for Cardiovascular Angiography & Interventions (SCAI) Stage C shock and in 37% the suspected etiology was peripartum cardiomyopathy. MCS usage included intra-aortic balloon pump (4), Impella microaxial blood pump (2), veno-arterial extracorporeal membrane oxygenation (6), and temporary right ventricle assist devices (2), with some patients having multiple MCS devices. The rate of major complications was 36.4%. During a median follow-up of 4.5 years, 7 patients had sustained cardiac recovery (63.6%), 1 patient (9.1%) underwent cardiac transplantation, 2 patients (18.2%) received a durable LVAD, and 2 (18.2%) have died. MCS in severe CS cases during the peripartum period is rare and associated with favorable outcomes. High recovery rates suggest favoring first MCS/LVAD over transplant.

Impact of extracorporeal blood pump gap sizes on the performance and hemocompatibility under off-design operation.

Hemocompatibility remains the dominant challenge in rotary blood pumps, and more information on the relationship between individual pump design features, hemodynamics, and blood trauma in various operation conditions is necessary. The study evaluated the variation of gap sizes in extracorporeal blood pumps concerning their influence on blood compatibility, particularly during off-design conditions. We developed a parametric generic blood pump framework for in-silico and in-vitro design feature analysis. Thirty-six designs with varying axial and radial gap sizes between 0.5 mm and 3 mm were generated. CFD was applied to calculate and compare device hemodynamics and evaluate the performance and hemocompatibility during off-design and target operation conditions. The following quantities were analyzed: pressure difference, hemolysis potential, residence times, hydraulic efficiency, and recirculation ratio. The in-vitro prototype showed excellent agreement with in-silico predictions regarding hydraulic performance (R2 = 0.996 with a RMSE = 2.07). Our results show a modest impact of gap size variations ±10% on key metrics. Domain-resolved analyses revealed a significant contribution of the gap regions to the device's overall hemolytic performance, with an increasing contribution for off-design flow rates. Overall elevated hemolysis levels were identified if at least one gap size was held minimal. We introduced and showed the feasibility of a parametric rotary blood pump framework to systematically investigate design feature impact. Results suggest, larger and uniformly sized gaps being overall beneficial regarding hemocompatibility.

Exploring integrated heat and mass transfer in von-Kármán dynamics involving Reiner-Rivlin fluid with regression models

The rotating disk system is widely used in several important applications, including turbomachinery design, mixing and stirring processes, centrifugal blood pumps development, optimizing electronic component, cooling efficiency, and various others. Moreover, regression models offer comprehensive and reliable prediction for important parameters in flows developed by revolving disks. This article presents similarity solutions for coupled heat and mass transfer with viscous dissipation in an inelastic non-Newtonian fluid flow across a permeable revolving disk. The inclusion of diffusion terms due to Dufour and Soret effects establishes coupling between energy and concentration equations. Temperature and concentrations at disk surface are supposed to vary quadratically along the radial direction. The impacts of MHD, heat source/sink dynamics and Joule heating effects on thermal boundary layer are also scrutinized. MATLAB's bvp5c tool, based on collocation scheme, generates numerical results. Homotopy analysis method, a widely accepted analytical solution procedure, is then applied to produce the series solution. Selection of the optimal auxiliary parameter values featured in the series solution is also included. The impact of Reiner-Rivlin fluid assumption on the torque required by the disk is assessed. Furthermore, linear and quadratic regression models are developed for the skin friction factors, Nusselt number and Sherwood number.

Assessment of haemolysis models for a positive-displacement total artificial heart.

The assessment and reduction of haemolysis within mechanical circulatory support (MCS) remains a concern with regard to device safety and regulatory approval. Numerical methods for predicting haemolysis have typically been applied to rotary MCS devices and the extent to which these methods apply to positive-displacement MCS is unclear. The aim of this study was to evaluate the suitability of these methods for assessing haemolysis in positive-displacement blood pumps. Eulerian scalar-transport and Lagrangian particle-tracking approaches derived from the shear-based power-law relationship were used to calculate haemolysis in a computational fluid dynamics model of the Realheart total artificial heart. A range of power-law constants and their effect on simulated haemolysis were also investigated. Both Eulerian and Lagrangian methods identified the same key mechanism of haemolysis: leakage flow through the bileaflet valves. Whilst the magnitude of haemolysis varied with different power-law constants, the method of haemolysis generation remained consistent. The Eulerian method was more robust and reliable at identifying sites of haemolysis generation, as it was able to capture the persistent leakage flow throughout the entire pumping cycle. This study paves the way for different positive-displacement MCS devices to be compared across different operating conditions, enabling the optimisation of these pumps for improved patient outcomes.

Optimization of a centrifugal blood pump in terms of hemolysis index and hydraulic efficiency

Optimization of a centrifugal blood pump in terms of hemolysis index and hydraulic efficiency

A race against time – an evaluation of lifesaving treatment pathways for patients following cardiac arrest in a non-hospital setting.

BackgroundCardiac arrest occurs when the heart ceases pumping blood around the body. Most take place outside hospital. A sequence of effective interventions (a “chain of survival”) is essential for patient survival and recovery of organ function. Out of Hospital Cardiac Arrest (OHCA) requires prompt recognition and call for help, proficient CPR, early defibrillation and conveyance by the emergency services to an appropriate hospital. If initial resuscitation is successful, effective post-resuscitation care is required, delivered usually in the intensive care unit (ICU). New patient pathways were introduced following an update to national guidelines, which recommend conveyance of patients to centres with percutaneous coronary intervention (PCI) services where possible. ObjectiveWe have evaluated outcomes for patients, comparing those conveyed to PCI settings and those conveyed elsewhere to quantify the effect of the new patient pathway on mortality, survival and length of hospital stay. ApproachWe have linked electronic health records from emergency departments, acute hospital settings, ICUs and the national deaths register for OHCA patients living in Wales, UK. We have undertaken temporal analysis and time to event analysis to compare patient subgroups. ResultsVariation in patient pathways will be described using characteristics of conveyance method, the type of treating hospital and transfers between PCI and non-PCI settings adjusted for individual patient level confounders such as age, sex and comorbidities. ConclusionThis work is important to evaluate efficacy of operational procedures and inform national policies which aim to improve survival following OHCA and save lives.

A cavalpulmonary assist device utilising impedance pumping enhanced by peristaltic effect.

Fontan procedure, the standard surgical palliation to treat children with single ventricular defects, causes systemic complications over years due to lack of pumping at cavopulmonary junction. A device developed specifically for cavopulmonary support is thus considered, while current commercial ventricular assist devices (VAD) induce high shear rates to blood, and have issues with paediatric suitability. To demonstrate the feasibility of a small, valveless, non-invasive to blood and pulsatile rotary pump, which integrates impedance and peristaltic effects. A prototype pump was designed and fabricated in-house without any effort to optimise its specification. It was then tested in vitro, in terms of effect of pumping frequency, background pressure differences and pump size on output performance. Net flow rate (NFR) and maximum pressure head delivery are both reasonably linearly dependent on pumping frequency within normal physiological range. Positive linearity is also observed between NFR and the extent of asymmetric pumping. The device regulates NFR in favourable pressure head difference and overcomes significant adverse pressure head difference. Additionally, performance is shown to be insensitive to device size. The feasibility of the novel rotary pump integrating impedance and peristaltic effects is demonstrated to perform in normal physiological conditions without any optimisation effort. It provides promising results for possible future paediatric cavopulmonary support and warrants further investigation of miniaturisation and possible haemolysis.

Synchronous PIV measurements of a self-powered blood turbine and pump couple for right ventricle support

A blood turbine-pump system (iATVA), resembling a turbocharger was proposed as a mechanical right-heart assist device without external drive power. In this study, the iATVA system is investigated with particular emphasis on the blood turbine flow dynamics. A time-resolved 2D particle image velocimetry (PIV) set-up equipped with a beam splitter and two high speed cameras, allowed simultaneous recordings from both the turbine and pump impellers at 7 different phased-locked instances. The iATVA prototype is 3D printed using an optically clear resin following our earlier PIV protocols. Results showed that magnetically coupled impellers operated synchronously. As the turbine flow rate increased from 1.6 to 2.4 LPM, the rotational speed and relative inlet flow angle increase from 630 to 900 rpm, and 38 to 55% respectively. At the trailing edges, backflow region spanned 3/5 of the total passage outlet flow, and an extra leakage flow was observed at the leading edge. For this early turbine design, approximately, 75% of the turbine blade passage was not contributing to the impulse operation mode. The maximum non-wall shear rate was ~ 2288 s−1 near to the inlet exit, which is significantly lower than the commercial blood pumps, encouraging further research and blood experiments of this novel concept. Experimental results will improve the hydrodynamic design of the turbine impeller and volute regions and will be useful in computational fluid dynamics validation studies of similar passive devices.

Computational fluid dynamics simulating of the FDA benchmark blood pump with different coefficient sets and scaler shear stress models used in the power-law hemolysis model.

Hemolysis is the most important issue to consider in the design and optimization of blood-contacting devices. Although the use of Computational Fluid Dynamics (CFD) in hemolysis prediction studies provides convenience and has promising potential, it is an extremely challenging process. Hemolysis predictions with CFD depend on the mesh, implementation method, coefficient set, and scalar-shear-stress model. To this end, an attempt was made to find the combination that would provide the most accurate result in hemolysis prediction with the commonly cited power-law based hemolysis model. In the hemolysis predictions conducted using CFD on the Food and Drug Administration (FDA) benchmark blood pump, 3 different scalar-shear-stress models, and 5 different coefficient sets with the power-law based hemolysis model were used. Also, a mesh independence test based on hemolysis and pressure head was performed. The pressure head results of CFD simulations were compared with published pressure head of the FDA benchmark blood pump and a good agreement was observed. In addition, results of CFD-hemolysis predictions which are conducted with scalar-shear-stress model and coefficient set combinations were compared with experimental hemolysis data at three operating conditions such as 6-7L/min flow rates at 3500rpm rotational speeds and 6L/min at 2500rpm. One of the combinations of the scalar-shear-stress model and the coefficient set was found to be within the error limits of the experimental measurements, while all other combinations overestimated hemolysis.

Associated between hypertension and body mass index, cholesterol, and blood sugar levels in elderly women

Hypertension remains a significant public health problem, including in Indonesia. The highest number of sufferers is known to be the group of elderly women. Hypertension can occur because the heart pumps blood throughout the body strongly due to thickening and stiffness of the artery walls. The thickening increases with age.This study assesses the relationship between BMI, cholesterol, and blood glucose levels and women's systolic and diastolic blood pressure. This observational study was conducted using a cross-sectional design, where 330 women aged 60 years or older in West Aceh Regency were involved as samples.The correlations were conducted by simple linear regression (bivariate) and multiple linear regression tests to determine the relationship between independent variables (systolic and diastolic blood pressure) and dependent variables (BMI, cholesterol, and blood sugar level). The results of bivariate test show the correlation of BMI, cholesterol, and blood sugar levels, with systolic blood pressure are weak, as indicated by the r values below 0.25. Meanwhile, BMI with diastolic blood pressure is moderate (r=0.272). In contrast, the correlation cholesterol and blood sugar levels with diastolic blood pressure are weak, with r values below 0.25. Multivariate analysis through linear regression showed that BMI (p<0.001), cholesterol (p<0.001), and blood glucose levels (p=<0.013) were significantly associated with systolic blood pressure. Furthermore, diastolic blood pressure was only significantly associated with BMI (p<0.001). BMI plays an essential role in both systolic and diastolic blood pressure, while cholesterol and blood glucose levels only contribute to systolic blood pressure, not to diastolic blood pressure.

A less-invasive left atrial assist device concept for diastolic heart failure: First in vitro and in vivo assessment

ObjectiveA less-invasive left atrial assist device (LAADx) is a novel and implantable, extracardiac blood pump concept, intended for the treatment of diastolic heart failure, represented by heart failure with preserved ejection fraction. MethodsA mixed-flow pump was used as the working LAADx model. Its performance was evaluated at 3 speeds, using an in vitro pulsatile mock circulatory loop, with a pneumatic pump that can simulate diastolic heart failure conditions by adjusting the diastolic drive pressure. The LAADx model was implanted in 4 healthy calves. The pump's inflow and outflow cannulas were inserted into the left atrium (LA) and left ventricle (LV), respectively, without cardiopulmonary bypass. The LAADx was operated at 3 speeds, and diastolic heart failure-like conditions were induced by inflating a balloon, inserted into the LV. ResultsWith the in vitro study, diastolic heart failure-like conditions were successfully induced, exhibiting decreased cardiac output and aortic pressure as well as increased mean LA pressure both mitigated with the LAADx support. With regard to the in vivo study, simulated diastolic heart failure conditions showed a decrease in aortic pressure and an increase in LA pressure and LV end-diastolic pressure, which were again mitigated by the LAADx. Echocardiography showed good positioning of the outflow cannula and neither cardiac dysfunction nor mitral interference was observed. ConclusionsInitial in vitro and in vivo results confirmed that the LAADx model, a device concept driven by creating an extracardiac route from the LA to LV, has the potential to mitigate high LA pressure and improve LV filling of heart failure with preserved ejection fraction pathology.