Biofunctionalization of surfaces to minimize undesirable effects in cardiovascular assistance devices

BACKGROUND: The reactivity of blood with non-endothelial surface is a challenge for long-term Ventricular Assist Devices development, usually made with pure titanium, which despite of being inert, low density and high mechanical resistance it does not avoid the thrombogenic responses. Here we tested a modification on the titanium surface with Laser Induced Periodic Surface Structures followed by Diamond Like Carbon (DLC) coating in different thicknesses to customize the wettability profile by changing the surface energy of the titanium. METHODS: Four different surfaces were proposed: (1) Pure Titanium as Reference Material (RM), (2) Textured as Test Sample (TS), (3) Textured with DLC 0.3µm as (TSA) and (4) Textured with 2.4µm DLC as (TSB). A single implant was positioned in the abdominal aorta of Wistar rats and the effects of hemodynamic interaction were evaluated without anticoagulant drugs. RESULTS: After twelve weeks, the implants were extracted and subjected to qualitative analysis by Scanning Electron Microscopy under low vacuum and X-ray Energy Dispersion. The regions that remained in contact with the wall of the aorta showed encapsulation of the endothelial tissue. TSB implants, although superhydrophilic, have proven that the DLC coating inhibits the adhesion of biological material, prevents abrasive wear and delamination, as observed in the TS and TSA implants. Pseudo- neointimal layers were heterogeneously identified in higher concentration on Test Surfaces.

Biofunctionalization of surfaces to minimize undesirable effects in cardiovascular assistance devices.

BACKGROUND: The reactivity of blood with non-endothelial surface is a challenge for long-term Ventricular Assist Devices development, usually made with pure titanium, which despite of being inert, low density and high mechanical resistance it does not avoid the thrombogenic responses. Here we tested a modification on the titanium surface with Laser Induced Periodic Surface Structures followed by Diamond Like Carbon (DLC) coating in different thicknesses to customize the wettability profile by changing the surface energy of the titanium. METHODS: Four different surfaces were proposed: (1) Pure Titanium as Reference Material (RM), (2) Textured as Test Sample (TS), (3) Textured with DLC 0.3µm as (TSA) and (4) Textured with 2.4µm DLC as (TSB). A single implant was positioned in the abdominal aorta of Wistar rats and the effects of hemodynamic interaction were evaluated without anticoagulant drugs. RESULTS: After twelve weeks, the implants were extracted and subjected to qualitative analysis by Scanning Electron Microscopy under low vacuum and X-ray Energy Dispersion. The regions that remained in contact with the wall of the aorta showed encapsulation of the endothelial tissue. TSB implants, although superhydrophilic, have proven that the DLC coating inhibits the adhesion of biological material, prevents abrasive wear and delamination, as observed in the TS and TSA implants. Pseudo- neointimal layers were heterogeneously identified in higher concentration on Test Surfaces.

Research and development of ventricular assist devices from a single center in Latin America

OBJECTIVES: Ventricular assist devices have been widely accepted as an alternative treatment for advanced heart failure, while heart transplantation is a limited procedure because of the shortage of donors. In face of a scarce availability of these devices, many centers around the world have developed their own technologies. The Institute Dante Pazzanese of Cardiology holds a dedicated engineering center for mechanical circulatory support, being responsible for creating several prototypes and notable devices, like the first Brazilian artificial heart. The objectives of this study were to provide both a historical overview and a detailed characterization of each original device developed by the center. METHODS: We describe historical and technical features of the main ventricular assist devices developed at the Institute Dante Pazzanese of Cardiology through a focused review on the institute's scientific and technical production on ventricular assist devices or blood pumps, from 1990 to 2022, indexed in the electronic databases Latin American and Caribbean Health Sciences Literature (LILACS), PubMed, and the Scientific Electronic Library Online (SciELO). RESULTS: The following devices were selected from the review: (1) The Spiral Pump is a disposable centrifugal pump with an internal conically shaped rotor, a spiral impeller, which carries threads on its surface. The device was designed for cardiopulmonary bypass in 1992, passed through consecutive design modifications and preclinical tests until approval for clinical application in 2007. (2) The Auxiliary Total Artificial Heart is an electromechanical pulsatile blood pump with left and right chambers, originally designed in 1995 to work as a heterotopic artificial heart. Preclinical studies evaluated hydrodynamic performance in mock circulatory loops and in vivo implants were performed in calves from 1999 to 2009. In 2012, it became the first nationally conceived artificial heart approved for clinical trials in Brazil. (3) The Implantable Centrifugal Blood Pump was conceived in 2006 for long-term circulatory assistance with a unique impeller design concept producing a mixed flow. Preclinical studies included hydrodynamic and hemolysis tests, analysis in a hybrid cardiovascular simulator and anatomical positioning in calves. (4) The Apico-Aortic Blood Pump consists of a miniaturized centrifugal pump originally conceived in 2012 for bridge to transplantation strategy. Preclinical studies included hydrodynamic and hemolysis tests, analysis in a hybrid cardiovascular simulator and anatomical positioning in pigs. (5) The Temporary Circulatory Support Device is a new centrifugal blood pump for temporary ventricular assistance developed with the purpose of bridge to decision or bridge to recovery strategies. Originally conceived in 2013, preclinical studies on the device consisted only of hydrodynamic and hemolysis tests. CONCLUSION: From the academic point of view, Brazil count on a few groups with a considerable output in ventricular assist device research and development. Notable devices produced at Institute Dante Pazzanese of Cardiology, from a total artificial heart to varied and innovative centrifugal pumps, have demonstrated excellent results for future clinical applications. More financial and institutional support are needed for the continuation of these promising research projects.

Apical aortic blood pump preclinical assessment for long­term use: durability test and stator topology to reduce wear in the bearing system

This study presents an assessment for long­term use of the apical aortic blood pump (AABP), focusing on wear reduction in the bearing system. AABP is a centrifugal left ventricle assist device initially developed for bridge to transplant application. To analyze AABP performance in long­term applications, a durability test was performed. This test indicated that wear in the lower bearing pivot causes device failure in long­term. A wear test in the bearing system was conducted to demonstrate the correlation of the load in the bearing system with wear. Results from the wear test showed a direct correlation between load and wear at the lower bearing pivot. In order to reduce load, thus reducing wear, a new stator topology has been proposed. In this topology, a radial stator would replace the axial stator previously used. Another durability test with the new stator has accounted twice the time without failure when compared with the original model.

A strategy for designing of customized electromechanical actuators of blood pumps

Congestive heart failure is a pathology of global incidence that affects millions of people worldwide. When the heart weakens and fails to pump blood at physiological rates commensurate with the requirements of tissues, two main alternatives are cardiac transplant and ventricular assist devices (VADs). This article presents the design strategy for development of a customized VAD electromagnetic actuator. Electromagnetic actuator is a brushless direct current motor customized to drive the pump impeller by permanent magnets located in rotor­stator coupling. In this case, ceramic pivot bearings support the VAD impeller. Electronic circuitry controls rotation switching current in stator coils. The proposed methodology consisted of analytical numerical design, tridimensional computational modeling, numerical simulations using Maxwell software, actuator prototyping, and validation in the dynamometer. The axial flow actuator was chosen by its size and high power density compared to the radial flow type. First step consisted of estimating the required torque to drive the pump. Torque was estimated at 2100 rpm and mean current of 0.5 A. Numerical analysis using finite element method mapped vectors and fields to build stator coils and actuator assemblage. After tests in the dynamometer, experimental results were compared with numerical simulation and validated the proposed model. In conclusion, the proposed methodology for designing of VAD electromechanical actuator was considered satisfactory in terms of data consistency, feasibility, and reliability.

Development of a prototype anti-pollution filter for volatile anesthetics

Introduction: The use of volatile agents during cardiopulmonary bypass allows a "single drug anesthesia" and is associated with reduced peak postoperative troponin levels. Connecting the exhaust systems to the oxygenator's gas outlet port is mandatory and allows to prevent operating room (but not atmospheric) pollution by volatile agents. The aim of this study was to create a prototype filter for volatile agents and to test its adsorption efficacy during an ex-vivo simulated conventional cardiopulmonary bypass test. Methods: We carried out bench tests to conceive a prototype filter that could prevent room and environment pollution without damaging membrane oxygenators. We performed the tests at the Engineering Center for Circulatory Assistance Laboratory, Dante Pazzanese Institute of Cardiology, São Paulo, Brazil. Bench tests included simulation of integral adsorption tests, filter dimensions and design, flow versus pressure curve, sizing, and tightness. Results: Calgon AT 410 was the best kind of activated charcoal granules for adsorption of sevoflurane, isoflurane, and desflurane. Filter dimension tests showed that a chamber of 30-cm width over 10-cm diameter filled with 200g of the Calgon AT410 granules was the minimum required to fully adsorb sevoflurane for 90min. Adsorption tests showed that the prototype filter fully adsorbed isoflurane in 100±2.3min, sevoflurane in 95±3.4min, and desflurane in 95±4.3min. Conclusion: The new version of our prototype filter adsorbed most of the volatile anesthetics agents during an ex-vivo simulated conventional cardiopulmonary bypass test.

Development of a prototype anti-pollution filter for volatile anesthetics.

INTRODUCTION: The use of volatile agents during cardiopulmonary bypass allows a "single drug anesthesia" and is associated with reduced peak postoperative troponin levels. Connecting the exhaust systems to the oxygenator's gas outlet port is mandatory and allows to prevent operating room (but not atmospheric) pollution by volatile agents. The aim of this study was to create a prototype filter for volatile agents and to test its adsorption efficacy during an ex-vivo simulated conventional cardiopulmonary bypass test. METHODS: We carried out bench tests to conceive a prototype filter that could prevent room and environment pollution without damaging membrane oxygenators. We performed the tests at the Engineering Center for Circulatory Assistance Laboratory, Dante Pazzanese Institute of Cardiology, São Paulo, Brazil. Bench tests included simulation of integral adsorption tests, filter dimensions and design, flow versus pressure curve, sizing, and tightness. RESULTS: Calgon AT 410 was the best kind of activated charcoal granules for adsorption of sevoflurane, isoflurane, and desflurane. Filter dimension tests showed that a chamber of 30-cm width over 10-cm diameter filled with 200 g of the Calgon AT410 granules was the minimum required to fully adsorb sevoflurane for 90 min. Adsorption tests showed that the prototype filter fully adsorbed isoflurane in 100 ± 2.3 min, sevoflurane in 95 ± 3.4 min, and desflurane in 95 ± 4.3 min. CONCLUSION: The new version of our prototype filter adsorbed most of the volatile anesthetics agents during an ex-vivo simulated conventional cardiopulmonary bypass test.

A strategy for designing of customized electromechanical actuators of blood pumps.

Congestive heart failure is a pathology of global incidence that affects millions of people worldwide. When the heart weakens and fails to pump blood at physiological rates commensurate with the requirements of tissues, two main alternatives are cardiac transplant and ventricular assist devices (VADs). This article presents the design strategy for development of a customized VAD electromagnetic actuator. Electromagnetic actuator is a brushless direct current motor customized to drive the pump impeller by permanent magnets located in rotor-stator coupling. In this case, ceramic pivot bearings support the VAD impeller. Electronic circuitry controls rotation switching current in stator coils. The proposed methodology consisted of analytical numerical design, tridimensional computational modeling, numerical simulations using Maxwell software, actuator prototyping, and validation in the dynamometer. The axial flow actuator was chosen by its size and high power density compared to the radial flow type. First step consisted of estimating the required torque to drive the pump. Torque was estimated at 2100 rpm and mean current of 0.5 A. Numerical analysis using finite element method mapped vectors and fields to build stator coils and actuator assemblage. After tests in the dynamometer, experimental results were compared with numerical simulation and validated the proposed model. In conclusion, the proposed methodology for designing of VAD electromechanical actuator was considered satisfactory in terms of data consistency, feasibility, and reliability.

Apical aortic blood pump preclinical assessment for long-term use: Durability test and stator topology to reduce wear in the bearing system.

This study presents an assessment for long-term use of the apical aortic blood pump (AABP), focusing on wear reduction in the bearing system. AABP is a centrifugal left ventricle assist device initially developed for bridge to transplant application. To analyze AABP performance in long-term applications, a durability test was performed. This test indicated that wear in the lower bearing pivot causes device failure in long-term. A wear test in the bearing system was conducted to demonstrate the correlation of the load in the bearing system with wear. Results from the wear test showed a direct correlation between load and wear at the lower bearing pivot. In order to reduce load, thus reducing wear, a new stator topology has been proposed. In this topology, a radial stator would replace the axial stator previously used. Another durability test with the new stator has accounted twice the time without failure when compared with the original model.

Avaliação de novo protótipo “babypump” para circulação extracorpórea (cec): teste de resposta a hemostasia in vitro / Evaluation of a new babypump prototype for extracorporeal circulation (cec): in vitro hemostasis response test

As doenças cardiovasculares são as principais causas de morte no mundo e um dos tratamentos indicados para os casos mais graves é a cirurgia, que nesta condição, necessita de circulação extracorpórea. Estas bombas propulsoras podem ser responsáveis por traumas nas células sanguíneas, levando à hemólise. Este fato motivou este estudo, cujo objetivo é a avaliação do Índice Normalizado de Hemólise, durante um ensaio “in vitro” numa circulação extracorpórea e avaliar o desempenho hidrodinâmico do dispositivo. A metodologia seguiu o procedimento “Teste de Hemólise –HarboeMethod”. Neste ensaio, o dispositivo não suportou chegar até sua rotação máxima, gerando trepidação e ruído. O INH resultou em 2,23 g/100L, esse valor encontra-se acima do valor normal máximo descrito por Nosé(1998) (0,06g/100L.), o qual reprova odispositivo para o uso, sugerindo assim o seu redelineamento, a fim de promover maior resistência ao fluxo imposto.

Clinical evaluation of the Spiral Pump® after improvements to the original project in patients submitted to cardiac surgeries with cardiopulmonary bypass.

OBJECTIVE: The objective of this paper is to present the results from Spiral Pump clinical trial after design modifications performed at its previous project. This pump applies axial end centrifugal hydraulic effects for blood pumping during cardiopulmonary bypass for patients under cardiac surgery. METHODS: This study was performed in 52 patients (51% males), between 20 to 80 (67±14.4) years old weighing 53 to 102 (71.7±12.6) kg, mostly under myocardial revascularization surgery (34.6%) and valvular surgery (32.8%). Besides the routine evaluation of the data observed in these cases, we monitored pump rotational speed, blood flow, cardiopulmonary bypass duration, urine free hemoglobin for blood cell trauma analysis (+ to 4+), lactate desidrogenase (UI/L), fibrinogen level (mg/dL) and platelet count (nº/mm3). RESULTS: Besides maintaining appropriate blood pressure and metabolic parameters it was also observed that the Free Hemoglobin levels remained normal, with a slight increase after 90 minutes of cardiopulmonary bypass. The Lactate Dehydrogenase showed an increase, with medians varying between 550-770 IU/L, whereas the decrease in Fibrinogen showed medians of 130-100 mg/dl. The number of platelets showed a slight decrease with the medians ranging from 240,000 to 200,000/mm3. No difficulty was observed during perfusion terminations, nor were there any immediate deaths, and all patients except one, were discharged in good condition. CONCLUSION: The Spiral Pump, as blood propeller during cardiopulmonary bypass, demonstrated to be reliable and safe, comprising in a good option as original and national product for this kind of application.

Clinical evaluation of the Spiral Pump® after improvements to the original project in patients submitted to cardiac surgeries with cardiopulmonary bypass / Avaliação clínica da bomba espiral (Spiral Pump®) após aperfeiçoamentos introduzidos ao projeto original em pacientes submetidos a cirurgias cardíacas com circulação extracorpórea

Objective: The objective of this paper is to present the results from Spiral Pump clinical trial after design modifications performed at its previous project. This pump applies axial end centrifugal hydraulic effects for blood pumping during cardiopulmonary bypass for patients under cardiac surgery. Methods: This study was performed in 52 patients (51% males), between 20 to 80 (67±14.4) years old weighing 53 to 102 (71.7±12.6) kg, mostly under myocardial revascularization surgery (34.6%) and valvular surgery (32.8%). Besides the routine evaluation of the data observed in these cases, we monitored pump rotational speed, blood flow, cardiopulmonary bypass duration, urine free hemoglobin for blood cell trauma analysis (+ to 4+), lactate desidrogenase (UI/L), fibrinogen level (mg/dL) and platelet count (nº/mm3). Results: Besides maintaining appropriate blood pressure and metabolic parameters it was also observed that the Free Hemoglobin levels remained normal, with a slight increase after 90 minutes of cardiopulmonary bypass. The Lactate Dehydrogenase showed an increase, with medians varying between 550-770 IU/L, whereas the decrease in Fibrinogen showed medians of 130-100 mg/dl. The number of platelets showed a slight decrease with the medians ranging from 240,000 to 200,000/mm3. No difficulty was observed during perfusion terminations, nor were there any immediate deaths, and all patients except one, were discharged in good condition. CONCLUSION: The Spiral Pump, as blood propeller during cardiopulmonary bypass, demonstrated to be reliable and safe, comprising in a good option as original and national product for this kind of application. .

Objetivos: Apresentar resultados da aplicação da bomba espiral que emprega efeitos hidráulicos centrífugo e axial de bombeamento como elemento propulsor do circuito de circulação extracorpórea em pacientes submetidos a cirurgias cardíacas após modificações introduzidas no design do projeto original. Métodos: O estudo foi realizado em 52 pacientes (51% masculinos), com idade entre 20 a 80 (67±14,4) anos, peso 53 a 102 (71,7±12,6) kg, submetidos na maioria a cirurgia de revascularização miocárdica (34,6%) e Orovalvar (32,8%). Além das avaliações rotineiras, foram registrados rotação, tempo de CEC e para análise do impacto traumático à crase sanguínea, hemoglobina livre na urina (+ a 4+), desidrogenase láctica, fibrinogênio (mg/dL) e contagem de plaquetas (nº/mm3). Resultados: Observou-se a manutenção de parâmetros pressóricos e metabólicos adequados. Quanto aos marcadores de danos à crase sanguínea, as alterações estiveram proporcionais ao tempo maior de circulação extracorpórea. Os níveis de Hemoglobina Livre permaneceram com valores normais, com ligeiro aumento a partir dos 90 minutos de circulação extracorpórea. A Desidrogenase Láctica mostrou aumento, variando as medianas entre 550 a 770 UI/L enquanto o Fibrinogênio mostrou queda das medianas de 130 a 100 mg/dl. O número de plaquetas mostrou ligeira queda das medianas variando entre 240.000 a 200.000/mm3. Não ocorreram dificuldades de saída de perfusão, não se observou óbito imediato e todos os pacientes, exceto 1, obtiveram alta hospitalar. Conclusão: A bomba espiral aplicada como bomba propulsora de sangue durante cirurgia cardíaca se mostrou confiável e segura, não causou impacto traumático ...

A system to help physicians with fracture detection in stents.

Fractures in stents are usually detected by visual analysis, which may be affected by the presence of noise and image deformations. The lack of research into automating stent fracture detection has motivated this work, in which techniques are developed to facilitate diagnosis by observation (Image Delineation Algorithm) and, when possible, to point out areas of possible fractures (Fracture Detection Algorithm). The use of classical elements and the development of additional computational techniques contributed to the process of image analysis, providing a possible way to aid medical diagnosis. The developed algorithms are applied to image samples from femoropopliteal arteries, and the results are compared to those of medical diagnosis. As a result, aside from the improvement of image display, a kappa concordance index of 0.878 for the detection of fractures confirms the method as satisfactory, with very good agreement with medical diagnosis.

A system to help physicians with fracture detection in stents

Fractures in stents are usually detected by visualanalysis, which may be affected by the presence of noiseand image deformations.The lack of research into automatingstent fracture detection has motivated this work, inwhich techniques are developed to facilitate diagnosis byobservation (Image Delineation Algorithm) and, whenpossible, to point out areas of possible fractures (FractureDetection Algorithm). The use of classical elements andthe development of additional computational techniquescontributed to the process of image analysis, providing apossible way to aid medical diagnosis.The developed algorithmsare applied to image samples from femoropoplitealarteries, and the results are compared to those of medicaldiagnosis. As a result, aside from the improvement ofimage display, a kappa concordance index of 0.878 forthe detection of fractures confirms the method as satisfactory,with very good agreement with medical diagnosis.

Avaliação de desempenho em um medidor eletromagnético de baixo custo desenvolvido para aplicações em simulação cardiovascular / Performance evaluation on low cost electromagnetic flow meter for cardiovascular simulation system application

Técnicas cirúrgicas, próteses e dispositivos implantáveis utilizados pela cardiologia estão em constante desenvolvimento. Alguns institutos de pesquisas e universidades desenvolvem simuladores hidrodinâmicos com capacidade de reproduzir os níveis de pressão e vazão do sistema cardiovascular humano, com pistões, válvulas, câmaras de complacência, dispositivos para ajustes e medição de pressão e vazão. Este artigo apresenta o desenvolvimento e a avaliação de um fluxômetro eletromagnético (FE). O custo elevado de um fluxômetro por ultrassom (FUS) pode inviabilizar algumas pesquisas com simuladores; desta forma, uma alternativa com menor custo é apresentada neste trabalho. Baseado na indução eletromagnética para medição de vazão em um fluido iônico, o FE desenvolvido mostrou ser uma solução de baixo custo. O transdutor foi montado em um tubo de plástico com diâmetro interno de 9,5 mm, excitado por um campo magnético de 0,35 T, possui 4 eletrodos que, ligados a um circuito eletrônico, fornecem tensão elétrica proporcional à velocidade do fluido. A equação da tensão induzida, técnicas para calibração, ensaios e resultados são apresentados. Para a realização dos ensaios, foram utilizados um simulador cardiovascular e um FUS como referência. Os dados foram obtidos por hardware e software da National Instruments. Dentre os resultados, destaca-se o baixo desvio padrão de 0,043 L/min do FE para uma vazão de 3,56 L/min. O maior erro porcentual relativo foi de 1,49 ± 1,25%. Em um dos gráficos de vazão do FE observou-se um comportamento não monotônico, confirmado por uma análise da resposta em freqüência, observando-se maior amplitude na segunda, terceira e quarta harmônicas. Os resultados indicaram que o FE pode substituir o FUS em aplicações com simuladores hidrodinâmicos.

Implantable devices, prosthesis and their associated surgical techniques in cardiology are constantly under development. Many research groups have been using hydrodynamic simulators as a tool to assist the development in cardiovascular area, capable to mimic pressure and flow found in human cardiovascular system. They are made with plastic tubes, compliances chambers, valves, moving diaphragms and clamps for pressure and flow adjustments. The high cost of ultrasonic flow meters (UF) may difficult, for some research groups, the development of their own mock systems. This paper presents a simple and low cost electromagnetic flow meter (EF) useful for those cardiovascular simulation systems. EF measures flow of ionic fluids based on electromagnetic induction. A special transducer was assembled directly on a plastic tube with 9.5 mm of inner diameter. The transducer has 4 electrodes and, when excited by a magnetic field of 0.35 tesla, detects electric tension that is proportional to the fluid velocity. In this paper, induced electric potential equation, calibration techniques, performance tests and results are presented. A cardiovascular simulation system was used as test setup with an UF (Transonic Systems Inc.) as comparative flow meter. The signals were acquired by a PCI-6036E card and processed with LabView® 7.1 (National Instruments). The results from EF showed a standard deviation (SD) of 0.043 L/min for a flow of 3.56 L/min. The largest relative error was of 1.49 ± 1.25%. In one flow signal from the EF, the non monotonic behavior suggests a rich harmonic signal, which was confirmed by an analysis in the frequency domain. In vitro performance tests indicated that our EF can substitute the commercial available UF for hydrodynamic simulator application.

Magnetic suspension of the rotor of a ventricular assist device of mixed flow type.

This work presents results of preliminary studies concerning application of magnetic bearing in a ventricular assist device (VAD) being developed by Dante Pazzanese Institute of Cardiology-IDPC (São Paulo, Brazil). The VAD-IDPC has a novel architecture that distinguishes from other known VADs. In this, the rotor has a conical geometry with spiral impellers, showing characteristics that are intermediate between a centrifugal VAD and an axial VAD. The effectiveness of this new type of blood pumping principle was showed by tests and by using it in heart surgery for external blood circulation. However, the developed VAD uses a combination of ball bearings and mechanical seals, limiting the life for some 10 h, making impossible its long-term use or its use as an implantable VAD. As a part of development of an implantable VAD, this work aims at the replacement of ball bearings by a magnetic bearing. The most important magnetic bearing principles are studied and the magnetic bearing developed by Escola Politécnica of São Paulo University (EPUSP-MB) is elected because of its very simple architecture. Besides presenting the principle of the EPUSP-MB, this work presents one possible alternative for applying the EPUSP-MB in the IDPC-VAD.

An electro-fluid-dynamic simulator for the cardiovascular system.

This work presents the initial studies and the proposal for a cardiovascular system electro-fluid-dynamic simulator to be applied in the development of left ventricular assist devices (LVADs). The simulator, which is being developed at University Sao Judas Tadeu and at Institute Dante Pazzanese of Cardiology, is composed of three modules: (i) an electrical analog model of the cardiovascular system operating in the PSpice electrical simulator environment; (ii) an electronic controller, based on laboratory virtual instrumentation engineering workbench (LabVIEW) acquisition and control tool, which will act over the physical simulator; and (iii) the physical simulator: a fluid-dynamic equipment composed of pneumatic actuators and compliance tubes for the simulation of active cardiac chambers and big vessels. The physical simulator (iii) is based on results obtained from the electrical analog model (i) and physiological parameters.