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Objective:To evaluate the clinical value of intraoperative transesophageal echocardiography (TEE) in monitoring left ventricular assist device (LVAD) implantation.Methods:Between March 2019 and November 2021, 23 consecutive patients from TEDA International Cardiovascular Hospital, including 21 cases with dilated cardiomyopathy, 1 case with myocardial noncompaction and 1 case with ischemic cardiomyopathy, underwent HeartCon blood pump, a type of third generation LVAD implantation for severe heart failure. TEE was preformed in all cases before and after cardiopulmonary bypass. The dimensions of left-sided and right-sided cardiac chamber, ventricular function, de-airing, interventricular septal position, inlet cannulae position and the function of device were observed and recorded during LVAD implantation. Paired t test was used for statistical analysis of left-sided and right-sided heart parameters in pre- and post-operative measurements. Results:The left heart was dilated significantly and coexistent with right heart enlargement in some degree before LVAD implantation in total 23 cases. More than moderate mitral regurgitation (MR) in 16 cases and less than moderate MR in 7 cases were present. Mild or trace aortic regurgitation (AR) existed in 13 cases. More than moderate tricuspid regurgitation (TR) in 4 cases and less than moderate TR in 16 cases were observed. Left atrial appendage thrombosis was detected in 2 cases. After LVAD implantation, TEE revealed that the left ventricular end-diastolic diameter reduced significantly (42 mm/m 2 vs 32.8 mm/m 2, P<0.05) and left ventricular ejection fraction increased accordingly (22.2% vs 34.0%, P<0.05). There were no significant differences in right ventricular diameter and fractional area change between pre- and post-operative findings(all P>0.05). The ratio of left ventricular inner diameter to right ventricular inner diameter (2.09 vs 1.69, P<0.05) decreased in total 23 cases after LVAD implantation.Interventricular septal position became neutral position instead of pre-oprative rightward position. The severity of MR decreased in varying degrees in total 23 cases after LVAD implantation. All patients underwent tricuspid valvuloplasty with residual mild regurgitation in 8 cases. Conclusions:HeartCon blood pump can effectively unload the left ventricle with sufficient cardiac output in patients with severe congestive heart failure. TEE plays a major role in the clinical decision making during LVAD implantation, which can evaluate pre-operative cardiac abnormalities, intra-operative air embolism, inlet cannulae position, cannulas patency and cardiac function, especially blood volume status and the balance between double ventricles, which is critical for optimal functioning of the device.
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Objective The flow field of electromagnetically driven pulsating perfusion blood pump was simulated by computational fluid dynamics (CFD) method, and the flow state of blood in blood pump was improved by modifying the structure of pump head, so as to improve its anti-hemolytic performance. Methods The influences of changes in pump head structure on flow field in the pump were analyzed by using Fluent 17.0. Four simulation experiments were carried out to analyze streamline distributions of the internal liquid, the turbulent flow energy distribution on axis of the model, pressure loss of blood flowing through the pump head and shear stress on surface of the model. Results In the four experiments, when the angle between the inlet and outlet of the pump head was symmetrical and the angle between the pump head and the symmetrical axis (α) was 30°, there was no obvious disturbance in the flow line and the turbulence degree was low. In Experiment 1, the pressure loss was 376.8 Pa, with the minimum value. The maximum shear stress in Experiment 2 and 3 was 258.6 Pa and 302.8 Pa, respectively, which met the biomechanical requirements of blood pump such as pressure loss and hemolysis. The model with α=30° was selected as pump head structure of the pulsating blood pump driven by electromagnetic force, and was fabricated by 3D printing technology. Conclusions By optimization of the pump head, the hemolysis performance of the blood pump was improved. The research results can be applied to the design and experiment of a new electromagnetic drive pulse perfusion blood pump.
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The high rotational speed of the axial flow blood pump and flow separation of the centrifugal blood pump are the main causes for blood damage in blood pump. The mixed flow blood pump can effectively alleviate the high rotational speed and the flow separation. Based on this, the purpose of this study is to explore the performance of the mixed blood pump with a closed impeller. A mixed flow blood pump with closed impeller was studied by numerical simulation in this paper. The flow field characteristics and the pressure distribution of this type of blood pump were analyzed. The hydraulic performance of the blood pump and the possible damages to red blood cells were also discussed. At last, pump performance was compared with the mixed flow blood pump with semi-open impeller. The results show that the mixed flow blood pump with close impeller studied in this paper can operate safely and efficiently with a good performance. The pump can reach the pressure head of 100 mmHg at 5 L/min mass flow rate. Flow in the blood pump is uniform and no obvious separation or vortex occurs. Pressure distribution in and on the impeller is uniform and reasonable, which can effectively avoid the thrombosis of blood. The average mean value of hemolysis index is 4.99 × 10 . The pump has a good biocompatibility. Compared with the mixed flow blood pump with semi-open impeller, the mixed flow blood pump with closed impeller has higher head and efficiency, a smaller mean value of hemolysis index prediction, a better hydraulic performance and the ability to avoid blood damage. The results of this study may provide a basis for the performance evaluation of the closed impeller mixed flow blood pump.
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Humans , Computer Simulation , Equipment Design , Heart-Assist Devices , Hemolysis , ThrombosisABSTRACT
@#Blood pump is the core component of artificial ventricular assist device, and thrombosis is a severe complication of blood pump in clinical application. Methods of controlling and reducing thrombosis include materials surface modification, structure and parameters optimization of blood pump, and others. The typical symptoms of thrombosis and the hazard of various types of blood pump, the formation mechanism and primary factors for thrombosis, and the simulation prediction models for thrombosis were reviewed in this paper.
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The main obstacle of artificial heart in extending its applications in clinic has been its overhigh price rather than technical property. The new generation of artificial heart must enable the patients to be able to afford it. The author's permanent maglev pumps, both VAD(ventricular assist device) and TAH(total artificial heart), reduce their price to lower than 10 USDs, ca.1/10 of the third generation of artificial heart electric maglev pump. Moreover, thepermanent maglev pump not only retains all the advantages of the electric maglev pump, but also has many innovations: its impeller vane was designed according to the streamlines in the pump, so that the blood damage was reduced as low as possible; It can produce either nonpulsatile or pulsatile flow; It can be made in LVAD or TAH, as wish. Besides, it needs no rotor position detector, no electric magnetic push and pull device for rotor suspension, and no feed-back controller for levitation. This is why itscosts can remarkably reduced. Animal experiments for up to two months and clinical trial lasted 43 hours of permanent maglev LVAD demonstrated that the performances were excellent and perfect
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An implantable axial blood pump was designed according to the circulation assist requirement of severe heart failure patients of China. The design point was chosen at 3 L/min flow rate with 100 mm Hg pressure rise when the blood pump can provide flow rates of 2-7 L/min. The blood pump with good hemolytic and anti-thrombogenic property at widely operating range was designed by developing a structure that including the spindly rotor impeller structure and the diffuser with splitter blades and cantilevered main blades. Numerical simulation and particle image velocimetry (PIV) experiment were conducted to analyze the hydraulic, flow fields and hemolytic performance of the blood pump. The results showed that the blood pump could provide flow rates of 2-7 L/min with pressure rise of 60.0-151.3 mm Hg when the blood pump rotating from 7 000 to 11 000 r/min. After adding the splitter blades, the separation flow at the suction surface of the diffuser has been reduced efficiently. The cantilever structure changed the blade gap from shroud to hub that reduced the tangential velocity from 6.2 m/s to 4.3-1.1 m/s in blade gap. Moreover, the maximum scalar shear stress of the blood pump was 897.3 Pa, and the averaged scalar shear stress was 37.7 Pa. The hemolysis index of the blood pump was 0.168% calculated with Heuser's hemolysis model. The PIV and simulated results showed the overall agreement of flow field distribution in diffuser region. The blood damage caused by higher shear stress would be reduced by adopting the spindle rotor impeller and diffuser with splitter blades and cantilevered main blades. The blood could flow smoothly through the axial blood pump with satisfactory hydraulics performance and without separation flow.
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Humans , China , Computer Simulation , Equipment Design , Heart Failure , Therapeutics , Heart-Assist Devices , Hemolysis , Models, CardiovascularABSTRACT
The rotary left ventricular assist device (LVAD) has been an effective option for end-stage heart failure. However, while clinically using the LVAD, patients are often at significant risk for ventricular collapse, called suction, mainly due to higher LVAD speeds required for adequate cardiac output. Some proposed suction detection algorithms required the external implantation of sensors, which were not reliable in long-term use due to baseline drift and short lifespan. Therefore, this study presents a new suction detection system only using the LVAD intrinsic blood pump parameter (pump speed) without using any external sensor. Three feature indices are derived from the pump speed and considered as the inputs to four different classifiers to classify the pumping states as no suction or suction. The results using a combined human circulatory system and LVAD model show that the proposed method can detect ventricular suction effectively, demonstrating that it has high classification accuracy, stability, and robustness. The proposed suction detection system could be an important part in the LVAD for detecting and avoiding suction, while at the same time making the LVAD meet the cardiac output demand for the patients. It could also provide theoretical basis and technology support for designing and optimizing the control system of the LVAD.
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Humans , Computer Simulation , Heart Failure , General Surgery , Heart Ventricles , Heart-Assist Devices , Models, Cardiovascular , SuctionABSTRACT
Objective To investigate the effects of rounding on the prediction of flow field and hemolysis for FDA benchmark blood pumps by using the method of computational fluid dynamics（CFD）. Methods Key properties such as hydraulic characteristics, mean velocity distributions and hemolysis index of FDA benchmark blood pump under three operating conditions were simulated, and the influence of the above simulation result was further compared when the impeller was equipped with or without rounding. Results The rounding of blood pump impeller had impacts on pump head (the maximum percentage difference between the impeller with rounding and without rounding was 57.38%), velocity distributions, which led to a considerable impact on predicted hemolysis levels (the maximum error between the impeller with rounding and without rounding was more than one order of magnitude). Conclusions Impeller with rounding was beneficial for optimization of blood pump performance. The research findings are of great importance for better use of CFD to aid the hemocompatibility design of blood pump.
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Abstract Introduction A ventricular assist device (VAD) is an electromechanical pump used to treat heart failures. For designing the physiological control system for a VAD, one needs a mathematical model and its related parameters. This paper presents a characterization procedure for determining the model parameter values of the electrical, mechanical, and hydraulic subsystems of a pediatric Rotary Blood Pump (pRBP). Methods An in vitro test setup consisting of a pRBP prototype, a motor driver module, an acrylic reservoir, mechanical resistance and tubings, pressure and fluid flow sensors, and data acquisition, processing, and visualization system. The proposed procedure requires a set of experimental tests, and a parameter estimation algorithm for determining the model parameters values. Results The operating limits of the pRBP were identified from the steady-state data. The relationship between the pressure head, flow rate, and the rotational speed of the pRBP was found from the static tests. For the electrical and mechanical subsystems, the dc motor model has a viscous friction coefficient that varies nonlinearly with the flow. For the hydraulic subsystem, the pressure head is assumed to be a sum of terms related to the resistance, the inertance, the friction coefficient, and the pump speed. Conclusion The proposed methodology was successfully applied to the characterization of the pRBP. The combined use of static and dynamic tests provided a precise lumped parameter model for representing the pRBP dynamics. The agreement, regarding mean squared deviation, between experimental and simulated results demonstrates the correctness and feasibility of the characterization procedure.
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Objective To propose the design of a pulsate blood pump driven by magnetic coupling and verify its feasibility. Methods The blood pump was designed based on the magnetic transmission reciprocating force model and the push-and-pull structure, and the coupling force was calculated by building the magnetic force-driven model. The prototype of the blood pump was then manufactured, on which the extracorporeal circulation simulation test was conducted to obtain the pressure and flow rate. Results Physiological saline was used as the circulation medium. When the afterload was fixed and increase the preload, the output of the blood pump would decrease, but showing no obvious linear trend. While the preload was fixed and increase the afterload, the output of the blood pump was reduced, showing a linear trend. With the driving frequency set as 75 per minute, and the preload and afterload adjusted in the range of 0.665-3.990 kPa (5-30 mmHg) and 5.320-11.970 kPa (40-90 mmHg), respectively, the output of the blood pump could reach 2.0-3.1 L/min while guaranteeing the linear relationship. Conclusions The proposed magnetic coupling-driven pulsate blood pump can basically meet the need of extracorporeal membrane pulmonary circulation, while it still needs further improvement. The research results have a valuable application prospect, especially with great significance in replacement of blood pump currently used in the extra-corporeal membrane oxygenation (ECMO) equipment in clinic.
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Objective To design a percutaneous left heart assist device (blood pump) which can be used in critical cardiovascular diseases. Methods According to the aerofoil theory, a percutaneous left ventricular assist device was designed. The flow produced by blood pumps with 3 different design parameters (rotation angle of the blade, distance of the outlet from the blade, length of the outlet ) was measured so as to choose the optimal design of the blood pump. Results The flow was measured with a simple flow measurement device. When the blood pump was designed to adopt a single blade with the rotation angle of 720°, or the distance between the outlet and the blade was 0 mm, or the length of the outlet was 4 mm, the flow of the blood pump was the maximum. Conclusions To choose the design parameters that produce the maximum flow can contribute to manufacture a percutaneous left ventricular assist device with the function of pumping in vitro, which will provide a theoretical and data support for the eventual development of the percutaneous left ventricular assist device in clinic.
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Objective To evaluate the safety and efficacy of FW-Ⅱ axial blood pump short term assistance for treating acute heart failure.Methods We selected 5 patients who were difficult to remove cardiopulmonary bypass,and implanted FW-Ⅱ axial blood pump by left atrium-pump-femoral artery.Perioperative hemodynamics,circulating markers of myocardial injury,vW factor levels in plasma and white blood cell-platelet aggregates in different rotational speed were observed and analyzed.Results All patients were assisted for(24.0 ± 2.6) h by FW-Ⅱ axial blood pump with speed of 7 000-9 000 r/min,flow of 1.9-3.0 L/min,and no mechanical dysfunction.Compared with mean artery pressure(MAP),cardiac index(CI) and systemic vascular resistance index (SVRI) before implantation of FW-Ⅱ axial pump was (50.29 ± 6.98) mmHg (1 mmHg=0.133kPa),(1.70±0.23)L· min-1 · m-2 and (2 009.86 ±129.46) dyn· s · cm-5,MAP and CI significantly increased,while SVRI significantly reduced at 8 000 r/min after pump assistance [(65.43 ± 6.90) mmHg,(2.53 ± 0.27) L · min-1 · m-2,(1 578.14 ± 356.70) dyn · s · cm-5,P ＜ 0.01).CK-MB and cTnI levels reached significant decrease after 12 hours of pump assistance and maintained low level [(66 ± 11) IU/L and (8.4 ± 3.8) μg/L,P ＜ 0.01].Compared with 7 000 r/min,vW factor levels significantly increased at 8 500 r/min [(2.59 ± 0.57) U/L vs (1.26 ± 0.43) U/L,P ＜0.01].Platelet activation and white blood cell-platelet aggregation was the lowest at 8 000 r/min,and reached the most high level at 7 000 and 9 000 r/min [(15 ± 3) ％,(33 ± 3) ％ and (31 ± 5) ％)].Conclusion FW-Ⅱ axial flow pump can be effectively used for short-term treatment of acute ischemic left ventricular failure,8 000 r/min is optimum speed to balance hemodynamics and biocompatility.
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This paper mainly introduces the development of blood pump.Firstly,the latest research on blood pump is explained and the advantages and disadvantages of different kinds of blood pumps are compared.Then,the flow visualization,design and calculation of blood pump are introduced.At last,the questions during the blood pump development such as hemolysis and thrombus,are analyzed.It is suggested that a good blood pump should be miniature,implantable,portable and long-lasting.
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Objective To evaluate the effect of combination transfer pump and single blood pump to 32 cases of renal failure patient who need blood purification therapy.Methods The combination transfer pump and single blood pump were used.According to the clinical requirement,the parameters of transfer pump were set such as therapy time,replacement liquid flow rate,dialysate flow rate,temperature of warmer and filtrate flow rate,etc.Results 32 patients with varying degrees of illness have been alleviated.Patients' acute left heart failure,water and electrolyte turbulences,acid intoxication and azotemia caused by liquid retention were corrected,which ensured a role for further treatment.Conclusion It is the functions of adjustable time and transfusion volume that are used in the combination transfer pump,the task of which is accomplished by several transfer pumps together.This method is easy to implement and can meet the clinical requirement largely without special CBP instrument.