Blood Pump System Research Articles

ECG R-Wave Detection and Its Application in Left Ventricular Assist Device

Heart failure is one of the major diseases endangering human life. As a transitional support treatment before heart transplantation, the left ventricular assist device (LVAD) has significantly improved the quality of life and survival rate of patients with end-stage heart failure. In the automatic detection of electrocardiogram (ECG), the detection of QRS wave groups is the most critical aspect, which affects the correctness and accuracy of subsequent data analysis and processing. The paper used the data from the MIT-BIH database and the data collected from human ECG as the original number of samples for further processing. It processed the data through a high-order finite impulse response (FIR) low-pass filter and Shannon energy algorithm, and added the use of a high-order adaptive median filter algorithm on a field programmable gate array (FPGA) to minimize the noise of the processed real-time data. Finally, the tested ECG R-wave was used to drive the LVAD. After successful simulation by MATLAB and Modelsim software, the scheme of the real-time ECG signal controlling blood pump system was realized on the FPGA platform. The experiment showed that the method proposed could accurately extract the R-wave and control the LVAD to pump blood simultaneously.

Development of Inspired Therapeutics Pediatric VAD: Benchtop Evaluation of Impeller Performance and Torques for MagLev Motor Design.

Despite the availability of first-generation extracorporeal mechanical circulatory support (MCS) systems that are widely used throughout the world, there is a need for the next generation of smaller, more portable devices (designed without cables and a minimal number of connectors) that can be used in all in-hospital and transport settings to support patients in heart failure. Moreover, a system that can be universally used for all indications for use including cardiopulmonary bypass (CPB), uni- or biventricular support (VAD), extracorporeal membrane oxygenation (ECMO) and respiratory assist that is suitable for use for adult, neonate, and pediatric patients is desirable. Providing a single, well designed, universal technology could reduce the incidence of human errors by limiting the need for training of hospital staff on a single system for a variety of indications throughout the hospital rather than having to train on multiple complex systems. The objective of this manuscript is to describe preliminary research to develop the first prototype pump for use as a ventricular assist device for pediatric patients with the Inspired Universal MCS technology. The Inspired VAD Universal System is an innovative extracorporeal blood pumping system utilizing novel MagLev technology in a single portable integrated motor/controller unit which can power a variety of different disposable pump modules intended for neonate, pediatric, and adult ventricular and respiratory assistance. A prototype of the Inspired Pediatric VAD was constructed to determine the hemodynamic requirements for pediatric applications. The magnitude/range of hydraulic torque of the internal impeller was quantified. The hydrodynamic performance of the prototype pump was benchmarked using a static mock flow loop model containing a heated blood analogue solution to test the pump over a range of rotational speeds (500-6000 RPM), flow rates (0-3.5L/min), and pressures (0 to ~420 mmHg). The device was initially powered by a shaft-driven DC motor in lieu of a full MagLev design, which was also used to calculate the fluid torque acting on the impeller. The pediatric VAD produced flows as high as 4.27L/min against a pressure of 127 mmHg at 6000 RPM and the generated pressure and flow values fell within the desired design specifications. The empirically determined performance and torque values establish the requirements for the magnetically levitated motor design to be used in the Inspired Universal MagLev System. This next step in our research and development is to fabricate a fully integrated and functional magnetically levitated pump, motor and controller system that meets the product requirement specifications and achieves a state of readiness for acute ovine animal studies to verify safety and performance of the system.

Extended finite element method for fluid‐structure interaction in wave membrane blood pump

Numerical simulations of cardiac blood pump systems are integral to the optimization of device design, hydraulic performance and hemocompatibility. In wave membrane blood pumps, blood propulsion arises from the wave propagation along an oscillating immersed membrane, which generates small pockets of fluid that are pushed towards the outlet against an adverse pressure gradient. We studied the Fluid-Structure Interaction between the oscillating membrane and the blood flow via three-dimensional simulations using the Extended Finite Element Method (XFEM), an unfitted numerical technique that avoids remeshing by using a fluid fixed mesh. Our three-dimensional numerical simulations in a realistic pump geometry highlighted, for the first time in this field of application, that XFEM is a reliable strategy to handle complex industrial problems. Moreover, they showed the role of the membrane deformation in promoting a blood flow towards the outlet despite an adverse pressure gradient. We also simulated the pump system at different pressure conditions and we validated the numerical results against in-vitro experimental data.

A Short-Term In Vivo Evaluation of the Istanbul Heart Left Ventricular Assist Device in a Pig Model.

A continuous-flow centrifugal blood pump system has been recently developed as an implantable left ventricular assist device for patients with endstage heart failure. The objective of this study was to evaluate the initial in vivo performance of a newly developed left ventricular assist device (iHeart or Istanbul heart; Manufacturing and Automation Research Center, Koc University, Istanbul, Turkey) in an acute setting using a pig model. Three pigs (77, 83, 92 kg) received implants via a median sternotomy, with animals supported for up to 6 hours. An outflow cannula was anastomosed to the ascending aorta. Anticoagulation was applied by intravenous heparin administration. During the support period, pump performance was evaluated under several flow and operating conditions. All pigs were humanely sacrificied after the experiments, and organs were examined macroscopically and histopathologically. Flow rate ranged between 1.5 and 3.6 L/min with pump speeds of 1500 to 2800 revolutions/min and motor current of 0.6 to 1.3 A. Initial findings confirmed thatthe iHeart ventricular assist device had sufficient hydraulic performance to support the circulation. During the experimental period, plasma free hemoglobin levels were found to be within normalranges.Thrombus formation was not observed inside the pump in all experiments. The iHeart ventricular assist device demonstrated encouraging hemodynamic performance and good biocompatibility in the pig model for use as an implantable left ventricular assist device. Further acute in vivo studies will evaluate the short-term pump performance prior to chronic studies for long-term evaluation.

Clinical Reasoning and Collaboration for Functional Mobility and Ambulation Under Multiple Conditions of Concurrent CentriMag Ventricular Assistive Devices: A Case Report

Background: The CentriMag Extracorporeal Blood Pumping System is an effective means of temporary ventricular support for patients acutely decompensating from cardiac shock. Out-of-bed activities are not currently recommended by the manufacturer, leaving patients functionally limited and restricted to the intensive care unit (ICU). Purpose: This report aims to describe progression of functional mobility and ambulation with CentriMag ventricular assist device (VAD) equipment using appropriate clinical reasoning and multidisciplinary collaboration. Methods: Functional mobility activities were initiated on the first physical therapy (PT) session and progressed throughout the length of stay and included sit–stand transfers, bed–chair transfers, standing activities, and ambulation. Outcomes: The patient remained in the cardiovascular surgical ICU for 30 days and received PT for 13 total treatment sessions with 4 different physical therapists without adverse events. Out-of-bed activities were performed during all 13 PT sessions and the average session duration was 49.8 minutes. Ambulation was documented on 9/13 sessions and on the days the patient ambulated, and the average distance was approximately 183 feet. The patient was seen on 7 occasions with biventricular assist device CentriMag devices and 6 occasions with the concurrent CentriMag right VAD–HeartMate II left VAD. Discussion: As the technology and scope of application for VADs continues to progress, it is imperative that the acute care PT understands the complexities, risks, and benefits of functional mobility in critically ill patients. Conclusion: This report suggests that mobilization with CentriMag devices is feasible, without adverse events, using appropriate clinical decision-making, and suggests that patients who ambulate under multiple conditions of CentriMag VADs may demonstrate functional improvements.

Anticoagulation Therapy during Extracorporeal Membrane Oxygenator Support in Pediatric Patients.

Extracorporeal membrane oxygenation (ECMO) is a salvage therapy for critically ill patients. Although ECMO is becoming more common, hemorrhagic and thromboembolic complications remain the major causes of death in patients undergoing ECMO treatments. These complications commence upon blood contact with artificial surfaces of the circuit, blood pump, and oxygenator system. Therefore, anticoagulation therapy is required in most cases to prevent these problems. Anticoagulation is more complicated in pediatric patients than in adults, and the foreign surface of ECMO only increases the complexity of systemic anticoagulation. In this review, we discuss the pathophysiology of coagulation, anticoagulants, and monitoring tools in pediatric patients receiving ECMO.

Diffusion in Tube Dialyzer.

Nowadays, kidney failure is a problem of many peoples in the world. We know that the main function of kidney is maintaining the chemical quality of blood particularly removing urea through urine. But when they malfunction, the pathologic state known as uremia results in a condition in which the urea is retained in the body. Failure of the kidney results in building up of harmful wastes and excess fluids in the body. Kidney diseases (failures) can be due to infections, high blood pressure (hypertension), diabetes, and/or extensive use of medication. The best form of treatment is the implantation of a healthy kidney from a donor. However, this is often not possible due to the limited availability of human organs. Chronic kidney failure requires the treatment using a tube dialyzer called dialysis. Blood is taken out of the body and passes through a special membrane that removes waste and extra fluids. The clean blood is then returned to the body. The process is controlled by a dialysis machine (tube dialyzer) which is equipped with a blood pump and monitoring systems to ensure safety. So this article investigates the real application of mathematics (diffusion) in medical science, and it also contains the mathematical formulation and interpretation of tube dialyzer in relation to diffusion.

Compact Electro-Mechanical-Fluidic Model for Actuated Fluid Flow System

This paper presents a compact electro-mechanical-fluidic system-modeling method for multidomain system simulation based on multidomain physics that considers the total energy conservation condition, in terms of respective potential and flow quantities. Models for electrical, mechanical, and fluidic domains are developed to design the example of a blood pumping system, where the blood flow is driven by electrically controlled organic actuators. The electrical domain includes an organic mosfet -based control circuit, the mechanical domain includes organic actuators, and the fluidic domain includes a flexible fluid-flow channel. Control circuit, actuators, and fluid models are coupled through equivalent circuits, where interconnection relationships between two neighboring domains are expressed using the energy conservation concept. The model accuracy is verified with finite element method (FEM) based numerical simulation. Significantly faster simulation speed than with FEM and good accuracy were achieved.

In Vitro Study of a Medical Device to Enhance Arteriovenous Fistula Eligibility and Maturation.

The arteriovenous fistula eligibility (AFE) system (Flow Forward Medical, Olathe, KS) is a small, temporary, wearable rotary blood pump system designed to rapidly dilate peripheral veins in hemodialysis patients and improve outcomes after arteriovenous fistula (AVF) creation. A benchtop pulsatile mock circulatory loop was developed to model forearm circulation and to compare the hemodynamics of the AFE system with those of a conventional radiocephalic AVF. The AFE system maintained a mean wall shear stress (mWSS) within the 2.5-7.5 Pa target range for cephalic outflow veins of 2-6 mm diameter, which when applied clinically will provide better control of mWSS during the outflow vein maturation process when compared with a conventional AVF. These results support further study to determine whether or not vein preconditioning with the AFE system under controlled levels of mWSS will promote improved AVF outcomes.

Mechanical heart support at the Deutsches Herzzentrum Berlin: Recent developments (2011)

Since the inception of the mechanical circulatory support (MCS) program at the Deutsches Herzzentrum Berlin (DHZB) in 1987, more than 1600 patients have received support with 18 different designs of technical blood pump systems, in accordance with the respective state of the art. At the beginning, pulsatile pneumatic extracorporeal ventricular assist devices (VAD) and implantable pneumatic total artificial hearts (TAH) were available, followed by pulsatile electromechanical implantable devices. At this time the assist program was based on three objectives: bridging to recovery, bridging to heart transplantation (HTx) and for permanent support. Very soon (in 1995) patients of advanced age – over 65 years – were included in the program. In 1998 rotary blood pumps with continuous flow entered the program, from 2006 edging out step by step the pulsatile systems. Today the implantable pulsatile systems have disappeared from the DHZB program, with the exception of the extracorporeal uni- or biventricular pneumatic EXCOR systems (Berlin Heart GmbH), which are the only systems available for newborns and children. The only approved total artificial heart is the CardioWest device, implanted in rare cases after explantation of the natural heart. Miniaturized rotary blood pumps, axial flow turbines or centrifugal radial flow pumps are leading today's market. The size and configuration of one of these pumps, the hydrodynamically and magnetically levitated HeartWare HVAD, allowed its application as a biventricular implantable assist device. The worldwide first clinical implantation of this system was performed at the DHZB in 2009. With the increasing number of patients needing immediate circulatory support and the stagnating or even decreasing number of donor hearts available for HTx, the extreme discrepancy means that other therapies are gaining increasing importance. The objectives of the MCS program therefore had to focus on permanent VADs, thus creating a growing population of long-term outpatients with implanted systems, living with their families a near-normal life. Within a quarter century VAD implantation has grown from an experimental procedure into an established and generally accepted therapy. Facing the rapidly increasing population of patients with end-stage heart failure and the stagnating number of heart transplants, the use of VAD technology may represent the most advanced progress in cardiac care in the coming years. Further minaturization of the devices will allow the treatment of patients with a wide age spectrum, from newborn children to the elderly, even with biventricular support. The ultimate goal will be the development of a durable total artificial heart, based on the rotary blood pump technology, with transcutaneous energy transfer through the intact skin, guaranteeing the patients optimal quality of life for many years of support.

Development of Magnetic Bearing System for a New Third-Generation Blood Pump

A magnetic bearing system is a crucial component in a third-generation blood pump, particularly when we consider aspects such as system durability and blood compatibility. Many factors such as efficiency, occupying volume, hemodynamic stability in the flow path, mechanical stability, and stiffness need to be considered for the use of a magnetic bearing system in a third-generation blood pump, and a number of studies have been conducted to develop novel magnetic bearing design for better handling of these factors. In this study, we developed and evaluated a new magnetic bearing system having a motor for a new third-generation blood pump. This magnetic bearing system consists of a magnetic levitation compartment and a brushless direct current (BLDC) motor compartment. The active-control degree of freedom is one; this control is used for controlling the levitation in the axial direction. The levitation in the radial direction has a passive magnetic levitation structure. In order to improve the system efficiency, we separated the magnetic circuit for axial levitation by using a magnetic circuit for motor drive. Each magnetic circuit in the bearing system was designed to have a minimum gap by placing mechanical parts, such as the impeller blades, outside the circuit. A custom-designed noncontact gap sensor was used for minimizing the system volume. We fabricated an experimental prototype of the proposed magnetic bearing system and evaluated its performance by a control system using the Matlab xPC Target system. The noncontact gap sensor was an eddy current gap sensor with an outer diameter of 2.38 mm, thickness of 0.88 mm, and resolution of 5 µm. The BLDC motor compartment was designed to have an outer diameter of 20 mm, length of 28.75 mm, and power of 4.5 W. It exhibited a torque of 8.6 mNm at 5000 rpm. The entire bearing system, including the motor and the sensor, had an outer diameter of 22 mm and a length of 97 mm. The prototype exhibited sufficient levitation performance in the stop state and the rotation state with a gap of 0.2 mm between the rotor and the stator. The system had a steady position error of 0.01 µm in the stop state and a position error of 0.02 µm at a rotational speed of 5000 rpm; the current consumption rates were 0.15 A and 0.17 A in the stop state and the rotation state, respectively. In summary, we developed and evaluated a unique magnetic bearing system with an integrated motor. We believe that our design will be an important basis for the further development of the design of an entire third-generation blood pump system.

Study on Acceleration Control Algorithm of Blood Pump Driven by Large Gap Magnetic Force

Based on the startup dynamics model axial flow blood pump system driven by large gap magnetic force, a method that realized optimal control in the blood pump acceleration by using VB programming was brought forward. In this method, Runge-Kutta algorithm was used to solve and analysis the model and the result that speed, flow and net head etc. time-domain curves were obtained; further more, suitable stable points in the speed curve could be found by setting threshold, and finally Hermite interpolation was used to discrete speed curve in conditions to get time constant and steps etc. speed control parameter. Relative to the old method for the speed control of blood pump, it is more accurate and controllability condition.

Design of a Centrifugal Blood Pump: Heart Turcica Centrifugal

A prototype of a new implantable centrifugal blood pump system named Heart Turcica Centrifugal (HTC) was developed as a left ventricular assist device (LVAD) for the treatment of end-stage cardiac failure. In the development of HTC, effects of blade height and volute tongue profiles on the hydraulic and hemolytic performances of the pump were investigated. As a result, the prototype was manufactured using the best blade height and volute tongue profiles. Performance of the prototype model was experimentally evaluated in a closed-loop flow system using water as the medium. The hydraulic performance requirement of an LVAD (5 L/min flow rate against a pressure difference of 100 mm Hg) was attained at 2800 rpm rotational speed.

Why nephrologists should perform therapeutic plasma exchange

Why nephrologists should perform therapeutic plasma exchange

M4-4 回転磁場を用いたマイクロロータリーポンプの開発(M4 ポンプ,液滴・気泡駆動)

A micro pump has not been developed for a micro TAS to transport blood because of size effects. We have developed a micro rotary pump worked by a rotary magnetic field. The rotor was designed by morphology based on mimetics of a shape of mosquito's sucking blood pump system with high performance. This pump consists of a rotor implanted magnets, a square-shaped casing and four input-output ports. We measured pressure and flow rate of the scale-up model of the micro rotary pump and compared them with numerically estimated values.

Investigation of the Washout Effect in a Magnetically Driven Axial Blood Pump

For a long-term implementation of the magnetically driven CircuLite blood pump system, it is extremely important to be able to ensure a minimum washout flow in order to avoid dangerous stagnation regions in the gap between the impeller and the motor casing as well as near the pivot-axle area at the holes in the impeller's hub. In general, stagnation zones are prone to thrombus formation. Here, the optimal impeller/motor gap width will be determined and the washout flow for different working conditions will be quantitatively calculated. The driving force for this secondary flow is mainly the strong pressure difference between both ends of the gap. Computational fluid dynamics (CFD) and digital particle image velocimetry (DPIV) will be used for this analysis.

Numerical and experimental analysis of non-circular gears and cam-follower systems as function generators

The paper shows an analysis of two mechanisms that are typically used as function generators. The former consists of a pair of non-circular gears, which drives a slider-crank mechanism, the latter is a cam-follower system. Both mechanisms are designed to obtain a specific motion law. In this paper the proposed application is to generate a pulsating blood flow during cardiopulmonary by-pass for cardiac surgery. The prescribed motion law can be obtained by a volumetric pump, which can be used to modulate the blood flow in external circulation machines. The reciprocating motion consists of a quick forward stroke, corresponding to the Systolic phase, and a slow return stroke, corresponding to the Diastolic phase. The study has been focused on specific transmission characteristics that are related to a mechanical blood pumping design. In particular, experimental tests have been analyzed to understand benefits and drawbacks for using non-circular gears and polynomial cams in pure mechanical transmissions with limited motion regulation but with specific prescribed motion law. The contribution of the paper can be recognized in comparing numerically and experimentally a traditional cam transmission with a non-circular gear solution to show proper operation feasibility for both solutions without using complex control equipment, even for a robust/reliable demanding application like a blood pumping system.

1616 水撃作用が血液ポンプ系に及ぼす影響(S33-2 血液ポンプ・特殊ポンプ,S33 流体機械の諸問題)

1616 水撃作用が血液ポンプ系に及ぼす影響(S33-2 血液ポンプ・特殊ポンプ,S33 流体機械の諸問題)

Hemolytic Performance of a MagLev Disposable Rotary Blood Pump (MedTech Dispo): Effects of MagLev Gap Clearance and Surface Roughness

Mechanical shaft seal bearing incorporated in the centrifugal blood pumps contributes to hemolysis and thrombus formation. In addition, the problem of durability and corrosion of mechanical shaft seal bearing has been recently reported from the safety point of view. To amend the shortcomings of the blood-immersed mechanical bearings, a magnetic levitated centrifugal rotary blood pump (MedTech Dispo Model 1; Tokyo Medical and Dental University, Tokyo, Japan) has been developed for extracorporeal disposable application. In this study, the hemolytic performance of the MedTech Dispo Model 1 centrifugal blood pump system was evaluated, with special focus on the narrow blood path clearance at the magnetic bearing between rotor and stator, and on the pump housing surface roughness. A pump flow of 5 L/min against the head pressure of 100 mm Hg for 4 h was included in the hemolytic test conditions. Anticoagulated fresh porcine blood was used as a working fluid. The clearance of blood path at the magnetic bearing was in the range of 100-250 micro m. Pump housing surface roughness was controlled to be around Ra = 0.1-1.5 micro m. The lowest hemolytic results were obtained at the clearance of 250 micro m and with the polished surface (Ra = 0.1 micro m) yielding the normalized index of hemolysis (NIH) of less than 0.001 g/100 L, which was 1/5 of the Biopump BP-80 (Medtronic Inc., Minneapolis, MN, USA, and 1/4 of the BPX-80. In spite of rough surface and narrow blood path, NIH levels were less than clinically acceptable level of 0.005 g/100 L. The noncontact, levitated impeller system is useful to improve pump performance in blood environment.

원심형 혈액펌프의 최적화 수력설계 및 성능해석

This paper presents the hydrodynamic design and performance analysis method for a miniaturized centrifugal blood pump using three-dimensional computational fluid dynamics (CFD) code. In order to obtain the hydraulically high efficient configuration of a miniaturized centrifugal blood pump for cardiopulmonary circulation, a well-established commercial CFD code was incorporated considering detailed flow dynamic phenomena in the blood pump system. A prototype of centrifugal blood pump developed by the present design and analysis method has been tested in the mock circulatory system. Predicted results by the CFD code agree very well with in vitro hydraulic performance data for a centrifugal blood pump over the entire operating conditions. Preliminary in vivo animal testing has also been conducted to demonstrate the hemodynamic feasibility for use of centrifugal blood pump as a mechanical circulatory support. A miniaturized centrifugal blood pump developed by the hydraulic design optimization and performance prediction method presented herein shows the possibility of a good candidate for intra and extracorporeal cardiopulmonary circulation pump in the near future.