Centrifugal blood pump for temporary ventricular assist devices with low priming and ceramic bearings.

A new model of centrifugal blood pump for temporary ventricular assist devices has been developed and evaluated. The design of the device is based on centrifugal pumping principles and the usage of ceramic bearings, resulting in a pump with reduced priming (35 ± 2 mL) that can be applied for up to 30 days. Computational fluid dynamic (CFD) analysis is an efficient tool to optimize flow path geometry, maximize hydraulic performance, and minimize shear stress, consequently decreasing hemolysis. Initial studies were conducted by analyzing flow behavior with different impellers, aiming to determine the best impeller design. After CFD studies, rapid prototyping technology was used for production of pump prototypes with three different impellers. In vitro experiments were performed with those prototypes, using a mock loop system composed of Tygon tubes, oxygenator, digital flow meter, pressure monitor, electronic driver, and adjustable clamp for flow control, filled with a solution (1/3 water, 1/3 glycerin, 1/3 alcohol) simulating blood viscosity and density. Flow-versus-pressure curves were obtained for rotational speeds of 1000, 1500, 2000, 2500, and 3000 rpm. As the next step, the CFD analysis and hydrodynamic performance results will be compared with the results of flow visualization studies and hemolysis tests.

Study of a centrifugal blood pump in a mock loop system.

An implantable centrifugal blood pump (ICBP) is being developed to be used as a ventricular assist device (VAD) in patients with severe cardiovascular diseases. The ICBP system is composed of a centrifugal pump, a motor, a controller, and a power supply. The electricity source provides power to the controller and to a motor that moves the pump's rotor through magnetic coupling. The centrifugal pump is composed of four parts: external conical house, external base, impeller, and impeller base. The rotor is supported by a pivot bearing system, and its impeller base is responsible for sheltering four permanent magnets. A hybrid cardiovascular simulator (HCS) was used to evaluate the ICBP's performance. A heart failure (HF) (when the heart increases beat frequency to compensate for decrease in blood flow) was simulated in the HCS. The main objective of this work is to analyze changes in physiological parameters such as cardiac output, blood pressure, and heart rate in three situations: healthy heart, HF, and HF with left circulatory assistance by ICBP. The results showed that parameters such as aortic pressure and cardiac output affected by the HF situation returned to normal values when the ICBP was connected to the HCS. In conclusion, the test results showed satisfactory performance for the ICBP as a VAD.

In vitro assessment of the Apico Aortic Blood Pump: anatomical positioning, hydrodynamic performance, hemolysis studies, and analysis in a hybrid cardiovascular simulator.

The Apico Aortic Blood Pump (AABP) is a centrifugal continuous flow left ventricular assist device (LVAD) with ceramic bearings. The device is in the initial development phase and is being designed to be attached directly to the left ventricular apex by introducing an inlet cannula. This paper reports results from in vitro experiments. In order to evaluate implantation procedures and device dimensioning, in vitro experiments included an anatomic positioning study for the analysis of surgical implantation procedure and device dimensions and positioning that was performed using the body of a pig. The results revealed no damage caused by the device, and the surgical implantation procedure was considered feasible. Hydrodynamic performance curves were obtained to verify the applicability of the device as an LVAD, showing adequate performance. Mechanical blood trauma was analyzed through 6-h hemolysis tests, with total pressure head of 100 mm Hg and flow of 5 L/min. Mean normalized index of hemolysis was 0.009 g/100 L (±0.002 g/100 L). Studies using a hybrid cardiovascular simulator were conducted for three types of circulatory conditions: normal healthy conditions, concentric hypertrophic heart failure (CHHF), and CHHF with AABP assistance. Analysis of cardiovascular parameters under those three conditions demonstrated that when the AABP was assisting the system, parameters under CHHF conditions went back to normal healthy values, indicating the AABP's effectiveness as CHHF therapy. Our preliminary results indicate that it is feasible to use the AABP as a LVAD. The next steps include long-term in vivo experiments.

In vivo evaluation of centrifugal blood pump for cardiopulmonary bypass-Spiral Pump.

The Spiral Pump (SP), a centrifugal blood pump for cardiopulmonary bypass (CPB), has been developed at the Dante Pazzanese Institute of Cardiology/Adib Jatene Foundation laboratories, with support from Sintegra Company (Pompeia, Brazil). The SP is a disposable pump with an internal rotor-a conically shaped fuse with double entrance threads. This rotor is supported by two ball bearings, attached to a stainless steel shaft fixed to the housing base. Worm gears provide axial motion to the blood column, and the rotational motion of the conically shaped impeller generates a centrifugal pumping effect, improving pump efficiency without increasing hemolysis. In vitro tests were performed to evaluate the SP's hydrodynamic performance, and in vivo experiments were performed to evaluate hemodynamic impact during usual CPB. A commercially available centrifugal blood pump was used as reference. In vivo experiments were conducted in six male pigs weighing between 60 and 90 kg, placed on CPB for 6 h each. Blood samples were collected just before CPB (T0) and after every hour of CPB (T1-T6) for hemolysis determination and laboratory tests (hematological and biochemical). Values of blood pressure, mean flow, pump rotational speed, and corporeal temperature were recorded. Also, ergonomic conditions were recorded: presence of noise, difficulty in removing air bubbles, trouble in installing the pump in the drive module (console), and difficulties in mounting the CPB circuit. Comparing the laboratory and hemolysis results for the SP with those of the reference pump, we can conclude that there is no significant difference between the two devices. In addition, reports made by medical staff and perfusionists described a close similarity between the two devices. During in vivo experiments, the SP maintained blood flow and pressure at physiological levels, consistent with those applied in cardiac surgery with CPB, without presenting any malfunction. Also, the SP needed lower rotational speed to obtain average blood flow and pressure, compared with the reference pump.

In vitro assessment of the apico aortic blood pump: anatomical positioning, hydrodynamic performance, hemolysis studies, and analysis in a hybrid cardiovascular simulator

Abstract: The Apico Aortic Blood Pump (AABP) is acentrifugal continuous flow left ventricular assist device(LVAD) with ceramic bearings. The device is in the initialdevelopment phase and is being designed to be attacheddirectly to the left ventricular apex by introducing an inletcannula. This paper reports results from in vitro experiments.In order to evaluate implantation procedures anddevice dimensioning, in vitro experiments included an anatomicpositioning study for the analysis of surgical implantationprocedure and device dimensions and positioningthat was performed using the body of a pig. The resultsrevealed no damage caused by the device, and the surgicalimplantation procedure was considered feasible. Hydrodynamicperformance curves were obtained to verify theapplicability of the device as an LVAD, showing adequateperformance. Mechanical blood trauma was analyzedthrough 6-h hemolysis tests, with total pressure head of100 mm Hg and flow of 5 L/min. Mean normalized index ofhemolysis was 0.009 g/100 L (±0.002 g/100 L).Studies usinga hybrid cardiovascular simulator were conducted for threetypes of circulatory conditions: normal healthy conditions,concentric hypertrophic heart failure (CHHF), and CHHFwith AABP assistance. Analysis of cardiovascular parametersunder those three conditions demonstrated that whenthe AABP was assisting the system, parameters underCHHF conditions went back to normal healthy values, indicatingthe AABP’s effectiveness as CHHF therapy. Ourpreliminary results indicate that it is feasible to use theAABP as a LVAD. The next steps include long-term invivo experiments.

Centrifugal blood pump for temporary ventricular assist deviceswith low priming and ceramic bearings

A new model of centrifugal blood pump for temporaryventricular assist devices has been developed andevaluated. The design of the device is based on centrifugalpumping principles and the usage of ceramic bearings,resulting in a pump with reduced priming (35 ± 2 mL) thatcan be applied for up to 30 days. Computational fluiddynamic (CFD) analysis is an efficient tool to optimizeflow path geometry, maximize hydraulic performance, andminimize shear stress, consequently decreasing hemolysis.Initial studies were conducted by analyzing flow behaviorwith different impellers, aiming to determine the bestimpeller design.After CFD studies, rapid prototyping technologywas used for production of pump prototypes withthree different impellers. In vitro experiments were performedwith those prototypes, using a mock loop systemcomposed of Tygon tubes, oxygenator, digital flow meter,pressure monitor, electronic driver, and adjustable clampfor flow control, filled with a solution (1/3 water, 1/3 glycerin,1/3 alcohol) simulating blood viscosity and density.Flow-versus-pressure curves were obtained for rotationalspeeds of 1000, 1500, 2000, 2500, and 3000 rpm.As the nextstep, the CFD analysis and hydrodynamic performanceresults will be compared with the results of flow visualizationstudies and hemolysis tests.

Study of a centrifugal blood pump in a mock loop system

Abstract: An implantable centrifugal blood pump (ICBP)is being developed to be used as a ventricular assist device(VAD) in patients with severe cardiovascular diseases.TheICBP system is composed of a centrifugal pump, a motor, acontroller, and a power supply. The electricity source providespower to the controller and to a motor that moves thepump’s rotor through magnetic coupling. The centrifugalpump is composed of four parts: external conical house,external base, impeller, and impeller base.The rotor is supportedby a pivot bearing system, and its impeller base isresponsible for sheltering four permanent magnets. Ahybrid cardiovascular simulator (HCS) was used to evaluatethe ICBP’s performance. A heart failure (HF) (whenthe heart increases beat frequency to compensate fordecrease in blood flow) was simulated in the HCS. Themain objective of this work is to analyze changes in physiologicalparameters such as cardiac output, blood pressure,and heart rate in three situations: healthy heart, HF, andHF with left circulatory assistance by ICBP. The resultsshowed that parameters such as aortic pressure and cardiacoutput affected by the HF situation returned to normalvalues when the ICBP was connected to the HCS. Inconclusion, the test results showed satisfactory performancefor the ICBP as a VAD. Key Words: Ventricularassist device—Centrifugal blood pump—Cardiovascularsimulator.

Introductory tests to in vivo evaluation: magnetic coupling influence in motor controller.

An implantable centrifugal blood pump has been developed with original features for a ventricle assist device (VAD). This pump is part of a multicenter and international study with objective to offer simple, affordable, and reliable devices to developing countries. Previous computational fluid dynamics investigations were performed followed by prototyping and in vitro tests. Also, previous blood tests for assessment of hemolysis showed mean normalized index of hemolysis (NIH) results of 0.0054 ± 2.46 × 10⁻³ mg/100 L (at 5 L/min and 100 mm Hg). To precede in vivo evaluation, measurements of magnetic coupling interference and enhancements of actuator control were necessary. Methodology was based on the study of two different work situations (1 and 2) studied with two different types of motors (A and B). Situation 1 is when the rotor of pump is closest to the motor and situation 2 its opposite. Torque and mechanical power were collected with a dynamometer (80 g/cm) and then plotted and compared for two situations and both motors. The results showed that motor A has better mechanical behavior and less influence of coupling. Results for situation 1 showed that it is more often under magnetic coupling influence than situation 2. The studies lead to the conclusion that motor A is the best option for in vivo studies as it has less influence of magnetic coupling in both situations.

Implantable centrifugal blood pump with dual impeller and double pivot bearing system: electromechanical actuator, prototyping, and anatomical studies.

An implantable centrifugal blood pump has been developed with original features for a left ventricular assist device. This pump is part of a multicenter and international study with the objective to offer simple, affordable, and reliable devices to developing countries. Previous computational fluid dynamics investigations and wear evaluation in bearing system were performed followed by prototyping and in vitro tests. In addition, previous blood tests for assessment of normalized index of hemolysis show results of 0.0054±2.46 × 10⁻³ mg/100 L. An electromechanical actuator was tested in order to define the best motor topology and controller configuration. Three different topologies of brushless direct current motor (BLDCM) were analyzed. An electronic driver was tested in different situations, and the BLDCM had its mechanical properties tested in a dynamometer. Prior to evaluation of performance during in vivo animal studies, anatomical studies were necessary to achieve the best configuration and cannulation for left ventricular assistance. The results were considered satisfactory, and the next step is to test the performance of the device in vivo.

Implantable centrifugal blood pump with dual impellerand double pivot bearing system: electromechanical actuator, prototyping, and anatomical studies

An implantable centrifugal blood pump hasbeen developed with original features for a left ventricularassist device. This pump is part of a multicenter and internationalstudy with the objective to offer simple, affordable,and reliable devices to developing countries. Previous computationalfluid dynamics investigations and wear evaluationin bearing system were performed followed byprototyping and in vitro tests. In addition, previous bloodtests for assessment of normalized index of hemolysis showresults of 0.0054 2.46 ¥ 10-3 mg/100 L. An electromechanicalactuator was tested in order to define the bestmotor topology and controller configuration. Three differenttopologies of brushless direct current motor (BLDCM)were analyzed.An electronic driver was tested in differentsituations, and the BLDCM had its mechanical propertiestested in a dynamometer. Prior to evaluation of performanceduring in vivo animal studies, anatomical studieswere necessary to achieve the best configuration and cannulationfor left ventricular assistance. The results wereconsidered satisfactory, and the next step is to test theperformance of the device in vivo.