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2.
Rev. bras. med. esporte ; 27(5): 509-513, July-Sept. 2021. graf
Article in English | LILACS | ID: biblio-1288622

ABSTRACT

ABSTRACT Introduction: Due to various uncertain and unexpected factors in life such as diseases, natural disasters, traffic accidents, and congenital disabilities, the number and proportion of lower limb amputations are still rising for many reasons, so the research on lower limb prostheses is particularly important. Objective: This work aimed to study the relationship between altitude exercise and cardiopulmonary function. Methods: A model of abnormal changes in cardiopulmonary function was established, and then 40 plateau exercisers were selected, all of whom arrived in Tibet in March 2017. The relationship between pulmonary circulation volume and internal pressure in the chest was observed and compared. The relationship between cardiopulmonary sensory reflex and exercise (high altitude) breathing and heart rate was analyzed. A comparison of the cardiopulmonary function of subjects of different genders was implemented. Moreover, the influence of different altitudes on the subjects' cardiopulmonary function and the subjects' cardiopulmonary function changes before departure and during the first, second, and third week after departure were observed and compared. Results: I. As the pressure in the thoracic cavity increased, the subjects' pulmonary circulation blood volume gradually decreased, and the decrease was most obvious in the stage of thoracic pressure −50 to 0. II. As the cardiorespiratory reflex coefficient increased, the subjects' breathing and heart rate compensatory acceleration appeared. III. Tracking and monitoring of the subjects' cardiopulmonary indicators revealed that with the increase in altitude, the subjects' average arterial pressure, respiratory frequency, and heart rate all showed an upward trend, while the blood oxygen saturation value showed a downward trend. IV. No matter how high the altitude was, the average arterial pressure, respiratory rate, and heart rate monitored of the subjects under exercise were significantly superior to the indicator values under resting state. In contrast, the blood oxygen saturation value showed the opposite trend. V. The subjects' average arterial pressure, respiration, and heart rate in the first week were higher than other periods, but the blood oxygen saturation was relatively lower. In the second and third weeks, the changes in cardiopulmonary function were relatively smooth (all P<0.05). VI. The changes in the index of the cardiopulmonary function of subjects of different genders were small (p>0.05). Conclusion: Through modeling, the results of the plateau environment on the cardiopulmonary function of the body were made clearer, and these research data provided theoretical references for the training of the sports field in the plateau area. Level of evidence II; Therapeutic studies - investigation of treatment results.


RESUMO Contexto: devido a vários fatores incertos e inesperados da vida, como doenças, desastres naturais, acidentes de trânsito e defeitos congênitos, o número e a proporção de amputações de membros inferiores ainda estão aumentando por muitos motivos, portanto, a pesquisa sobre próteses de membros inferiores é particularmente importante. Objetivo: Este trabalho teve como objetivo estudar a relação entre o exercício em altitude e a função cardiopulmonar. Métodos: Um modelo de alterações anormais da função cardiopulmonar foi estabelecido e, em seguida, 40 praticantes de exercícios de platô foram selecionados, todos chegaram ao Tibete em março de 2017. A relação entre o volume de circulação pulmonar e a pressão interna no tórax foi observada e comparada. A relação entre o reflexo sensorial cardiopulmonar e a respiração do exercício (altitude) e a frequência cardíaca foi analisada. A comparação da função cardiopulmonar de indivíduos de diferentes gêneros foi implementada. Além disso, a influência de diferentes altitudes na função cardiopulmonar dos indivíduos e as mudanças na função cardiopulmonar dos indivíduos antes da partida e durante a primeira, segunda e terceira semanas após a partida foram observadas e comparadas. Resultados: I. À medida que a pressão na cavidade torácica aumentou, o volume de sangue da circulação pulmonar dos indivíduos diminuiu gradualmente, e a diminuição foi mais óbvia no estágio de pressão torácica −50 a 0. II. À medida que o coeficiente do reflexo cardiorrespiratório aumentou, a respiração dos indivíduos e a aceleração compensatória da frequência cardíaca apareceram. III. O rastreamento e o monitoramento dos indicadores cardiopulmonares dos indivíduos revelaram que, com o aumento da altitude, a pressão arterial média, a frequência respiratória e a frequência cardíaca dos indivíduos mostraram uma tendência ascendente, enquanto o valor de saturação de oxigênio no sangue mostrou uma tendência descendente. 4. Por mais alta que fosse a altitude, a pressão arterial média, a frequência respiratória e a frequência cardíaca monitoradas dos indivíduos em exercício foram significativamente superiores aos valores do indicador em repouso, enquanto o valor da saturação de oxigênio no sangue apresentou tendência oposta. V. A pressão arterial média, respiração e frequência cardíaca dos indivíduos na primeira semana foram maiores do que em outros períodos de tempo, mas a saturação de oxigênio no sangue foi relativamente menor. Na segunda e terceira semanas, as mudanças na função cardiopulmonar foram relativamente suaves (todos P <0,05). VI. As mudanças no índice de função cardiopulmonar de sujeitos de diferentes gêneros foram pequenas (p> 0,05). Conclusão: Por meio da modelagem, os resultados do ambiente de planalto sobre a função cardiopulmonar do corpo ficaram mais claros, e os dados dessas pesquisas forneceram referenciais teóricos para o treinamento do campo esportivo na área de planalto. Nível de evidência II; Estudos terapêuticos- investigação dos resultados do tratamento.


resumen está disponible en el texto completo


Subject(s)
Humans , Male , Female , Adult , Exercise/physiology , Simulation Technique/methods , Exercise Test , Altitude , Models, Cardiovascular
3.
Article in Chinese | WPRIM | ID: wpr-888211

ABSTRACT

The subpulmonary ventricular exclusion (Fontan) could effectively improve the living quality for the children patients with a functional single ventricle in clinical. However, postoperative Fontan circulation failure can easily occur, causing obvious limitations while clinically implementing Fontan. The cavopulmonary assist devices (CPAD) is currently an effective means to solve such limitations. Therefore, in this paper the


Subject(s)
Algorithms , Child , Feedback , Heart-Assist Devices , Hemodynamics , Humans , Models, Cardiovascular
5.
Article in Chinese | WPRIM | ID: wpr-879224

ABSTRACT

Atherosclerosis is a complex and multi-factorial pathophysiological process. Researches over the past decades have shown that the development of atherosclerotic vulnerable plaque is closely related to its components, morphology, and stress status. Biomechanical models have been developed by combining with medical imaging, biological experiments, and mechanical analysis, to study and analyze the biomechanical factors related to plaque vulnerability. Numerical simulation could quantify the dynamic changes of the microenvironment within the plaque, providing a method to represent the distribution of cellular and acellular components within the plaque microenvironment and to explore the interaction of lipid deposition, inflammation, angiogenesis, and other processes. Studying the pathological mechanism of plaque development would improve our understanding of cardiovascular disease and assist non-invasive inspection and early diagnosis of vulnerable plaques. The biomechanical models and numerical methods may serve as a theoretical support for designing and optimizing treatment strategies for vulnerable atherosclerosis.


Subject(s)
Atherosclerosis , Biomechanical Phenomena , Computer Simulation , Humans , Inflammation , Models, Cardiovascular , Plaque, Atherosclerotic/diagnostic imaging
6.
Article in Chinese | WPRIM | ID: wpr-879223

ABSTRACT

Coronary artery diseases (CAD) have always been serious threats to human health. The measurement, constitutive modeling, and analysis of mechanical properties of the blood vessel wall can provide a tool for disease diagnosis, stent implantation, and artificial artery design. The vessel wall has both active and passive mechanical properties. The passive mechanical properties are mainly determined by elastic and collagen fibers, and the active mechanical properties are determined by the contraction of vascular smooth muscle cells (VSMC). Substantial studies have shown that, the two-layer model of the vessel wall can feature the mechanical properties well, and the circumferential, axial and radial strain and stress are of great significance in arterial wall mechanics. This study reviewed recent investigations of mechanical properties of the vessel wall. Challenges and opportunities in this area are discussed relevant to the clinical treatment of coronary artery diseases.


Subject(s)
Biomechanical Phenomena , Coronary Vessels , Humans , Models, Cardiovascular , Myocytes, Smooth Muscle , Stress, Mechanical
7.
Clinics ; 75: e1339, 2020. graf
Article in English | LILACS | ID: biblio-1089602

ABSTRACT

OBJECTIVES: Cerebral ischemia seriously threatens human health and is characterized by high rates of incidence, disability and death. Developing an ideal animal model of cerebral ischemia that reflects the human clinical features is critical for pathological studies and clinical research. The goal of this study is to establish a local cerebral ischemia model in rhesus macaque, thereby providing an optimal animal model to study cerebral ischemia. METHODS: Eight healthy rhesus monkeys were selected for this study. CT scans were performed before the operation to exclude cerebral vascular and intracranial lesions. Under guidance and monitoring with digital subtraction angiography (DSA), a microcatheter was inserted into the M1 segment of the middle cerebral artery (MCA) via the femoral artery. Then, autologous white thrombi were introduced to block blood flow. Immediately following embolization, multisequence MRI was used to monitor cerebrovascular and brain parenchymal conditions. Twenty-four hours after embolization, 2 monkeys were sacrificed and subjected to perfusion, fixation and pathological examination. RESULTS: The cerebral ischemia model was established in 7 rhesus monkeys; one animal died during intubation. DSA and magnetic resonance angiography (MRA) indicated the presence of an arterial occlusion. MRI showed acute local cerebral ischemia. HE staining revealed infarct lesions formed in the brain tissues, and thrombi were present in the cerebral artery. CONCLUSION: We established a rhesus macaque model of local cerebral ischemia by autologous thrombus placement. This model has important implications for basic and clinical research on cerebral ischemia. MRI and DSA can evaluate the models to ensure accuracy and effectiveness.


Subject(s)
Humans , Animals , Male , Cerebral Infarction/diagnostic imaging , Brain Ischemia/diagnostic imaging , Angiography, Digital Subtraction , China , Macaca mulatta , Models, Biological , Models, Cardiovascular
8.
Clinics ; 75: e1293, 2020. tab, graf
Article in English | LILACS | ID: biblio-1055882

ABSTRACT

Exercising prior to experimental infarction may have beneficial effects on the heart. The objective of this study was to analyze studies on animals that had exercised prior to myocardial infarction and to examine any benefits through a systematic review and meta-analysis. The databases MEDLINE, Google Scholar, and Cochrane were consulted. We analyzed articles published between January 1978 and November 2018. From a total of 858 articles, 13 manuscripts were selected in this review. When animals exercised before experimental infarction, there was a reduction in mortality, a reduction in infarct size, improvements in cardiac function, and a better molecular balance between genes and proteins that exhibit cardiac protective effects. Analyzing heart weight/body weight, we observed the following results - Mean difference 95% CI - -0.02 [-0.61,0.57]. Meta-analysis of the infarct size (% of the left ventricle) revealed a statistically significant decrease in the size of the infarction in animals that exercised before myocardial infarction, in comparison with the sedentary animals -5.05 [-7.68, -2.40]. Analysis of the ejection fraction, measured by echo (%), revealed that animals that exercised before myocardial infarction exhibited higher and statistically significant measures, compared with sedentary animals 8.77 [3.87,13.66]. We conclude that exercise performed prior to experimental myocardial infarction confers cardiac benefits to animals.


Subject(s)
Animals , Male , Female , Mice , Rats , Physical Conditioning, Animal , Ventricular Function/physiology , Myocardial Infarction/physiopathology , Myocardial Infarction/therapy , Rats, Wistar , Rats, Sprague-Dawley , Disease Models, Animal , Heart , Heart Ventricles/physiopathology , Models, Cardiovascular
9.
Rev. bras. cir. cardiovasc ; 35(2): 134-140, 2020. tab, graf
Article in English | LILACS | ID: biblio-1101474

ABSTRACT

Abstract Objective: To analyze the impact of vacuum-assisted venous drainage (VAVD) on arterial pump flow in a simulated pediatric cardiopulmonary bypass circuit utilizing a centrifugal pump (CP) with an external arterial filter. Methods: The simulation circuit consisted of a Quadrox-I Pediatric oxygenator, a Rotaflow CP (Maquet Cardiopulmonary AG, Rastatt, Germany), and a custom pediatric tubing set primed with Lactated Ringer's solution and packed red blood cells. Venous line pressure, reservoir pressure, and arterial flow were measured with VAVD turned off to record baseline values. Four other conditions were tested with progressively higher vacuum pressures (-20, -40, -60, and -80 mmHg) applied to the baseline cardiotomy pressure. An arterial filter was placed into the circuit and arterial flow was measured with the purge line in both open and closed positions. These trials were repeated at set arterial flow rates of 1500, 2000, and 2500 mL/min. Results: The use of progressively higher vacuum caused a reduction in effective arterial flow from 1490±0.00 to 590±0.00, from 2020±0.01 to 1220±0.00, and from 2490±0.0 to 1830±0.01 mL/min. Effective forward flow decreased with increased levels of VAVD. Conclusion: The use of VAVD reduces arterial flow when a CP is used as the main arterial pump. The reduction in the forward arterial flow increases as the vacuum level increases. The loss of forward flow is further reduced when the arterial filter purge line is kept in the recommended open position. An independent flow probe is essential to monitor pump flow during cardiopulmonary bypass.


Subject(s)
Humans , Child , Cardiopulmonary Bypass , Drainage , Equipment Design , Hemodynamics , Models, Cardiovascular
10.
Article in Chinese | WPRIM | ID: wpr-774220

ABSTRACT

Valve transplantation is often used in the treatment of aortic valve insufficiency. However, after surgery, the reconstructed aortic roots have an expansion phenomenon, in which the lack of valve height causes the aortic valve to close again. In this paper, the effects of different aortic valve height design on valve opening and closing performance were studied. The optimal surgical plan was obtained by numerical simulation, providing technical support and theoretical basis. In this paper, six groups of three-dimensional geometric models with a valve height increment of ± 0.5 mm were established with a root diameter of 26.0 mm and a valve height of 14.0 mm. Through the structural mechanics calculation and analysis of the parameters such as maximum stress, valve area and contact force of the model, reasonable geometrical dimensions are obtained. The study found that the maximum stress values of the six groups of models ranged from 640 to 690 kPa, which was consistent with the results of the literature; the three-group models with valve heights of 13.5 mm, 14.0 mm, and 14.5 mm were within a reasonable range. The contact force value of the 6 groups of leaflets increased with the increase of valve height. Studies have shown that the height of the aortic valve has an effect on the aortic valve closure performance. A valve height that is too small or too large will reduce the aortic systolic valve area and affect the aortic function.


Subject(s)
Aortic Valve , Physiology , General Surgery , Aortic Valve Insufficiency , General Surgery , Heart Valve Prosthesis , Humans , Models, Cardiovascular
11.
Article in Chinese | WPRIM | ID: wpr-774195

ABSTRACT

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.


Subject(s)
China , Computer Simulation , Equipment Design , Heart Failure , Therapeutics , Heart-Assist Devices , Hemolysis , Humans , Models, Cardiovascular
12.
Article in Chinese | WPRIM | ID: wpr-774182

ABSTRACT

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.


Subject(s)
Computer Simulation , Heart Failure , General Surgery , Heart Ventricles , Heart-Assist Devices , Humans , Models, Cardiovascular , Suction
13.
Article in Chinese | WPRIM | ID: wpr-774159

ABSTRACT

Based on the noninvasive detection indeices and fuzzy mathematics method, this paper studied the noninvasive, convenient and economical cardiovascular health assessment system. The health evaluation index of cardiovascular function was built based on the internationally recognized risk factors of cardiovascular disease and the noninvasive detection index. The weight of 12 indexes was completed by the analytic hierarchy process, and the consistency test was passed. The membership function, evaluation matrix and evaluation model were built by fuzzy mathematics. The introducted methods enhanced the scientificity of the evaluation system. Through the Kappa consistency test, McNemer statistical results ( = 0.995 > 0.05) and Kappa values (Kappa = 0.616, < 0.001) suggest that the comprehensive evaluation results of model in this paper are relatively consistent with the clinical, which is of certain scientific significance for the early detection of cardiovascular diseases.


Subject(s)
Cardiovascular Diseases , Diagnosis , Cardiovascular System , Fuzzy Logic , Humans , Models, Cardiovascular , Research
14.
Article in English | WPRIM | ID: wpr-761807

ABSTRACT

A heart simulator, UT-Heart, is a finite element model of the human heart that can reproduce all the fundamental activities of the working heart, including propagation of excitation, contraction, and relaxation and generation of blood pressure and blood flow, based on the molecular aspects of the cardiac electrophysiology and excitation-contraction coupling. In this paper, we present a brief review of the practical use of UT-Heart. As an example, we focus on its application for predicting the effect of cardiac resynchronization therapy (CRT) and evaluating the proarrhythmic risk of drugs. Patient-specific, multiscale heart simulation successfully predicted the response to CRT by reproducing the complex pathophysiology of the heart. A proarrhythmic risk assessment system combining in vitro channel assays and in silico simulation of cardiac electrophysiology using UT-Heart successfully predicted druginduced arrhythmogenic risk. The assessment system was found to be reliable and efficient. We also developed a comprehensive hazard map on the various combinations of ion channel inhibitors. This in silico electrocardiogram database (now freely available at http://ut-heart.com/) can facilitate proarrhythmic risk assessment without the need to perform computationally expensive heart simulation. Based on these results, we conclude that the heart simulator, UT-Heart, could be a useful tool in clinical medicine and drug discovery.


Subject(s)
Blood Pressure , Cardiac Electrophysiology , Cardiac Resynchronization Therapy , Cardiotoxicity , Clinical Medicine , Computer Simulation , Drug Discovery , Drug Evaluation, Preclinical , Electrocardiography , Heart , Humans , In Vitro Techniques , Ion Channels , Models, Cardiovascular , Relaxation , Risk Assessment
15.
Rev. bras. cir. cardiovasc ; 33(3): 224-232, May-June 2018. tab, graf
Article in English | LILACS | ID: biblio-958406

ABSTRACT

Abstract Objective: Hemodilution is a concern in cardiopulmonary bypass (CPB). Using a smaller dual tubing rather than a single larger inner diameter (ID) tubing in the venous limb to decrease prime volume has been a standard practice. The purpose of this study is to evaluate these tubing options. Methods: Four different CPB circuits primed with blood (hematocrit 30%) were investigated. Two setups were used with two circuits for each one. In Setup I, a neonatal oxygenator was connected to dual 3/16" ID venous limbs (Circuit A) or to a single 1/4" ID venous limb (Circuit B); and in Setup II, a pediatric oxygenator was connected to dual 1/4" ID venous limbs (Circuit C) or a single 3/8" ID venous limb (Circuit D). Trials were conducted at arterial flow rates of 500 ml/min up to 1500 ml/min (Setup I) and up to 3000 ml/min (Setup II), at 36°C and 28°C. Results: Circuit B exhibited a higher venous flow rate than Circuit A, and Circuit D exhibited a higher venous flow rate than Circuit C, at both temperatures. Flow resistance was significantly higher in Circuits A and C than in Circuits B (P<0.001) and D (P<0.001), respectively. Conclusion: A single 1/4" venous limb is better than dual 3/16" venous limbs at all flow rates, up to 1500 ml/min. Moreover, a single 3/8" venous limb is better than dual 1/4" venous limbs, up to 3000 ml/min. Our findings strongly suggest a revision of perfusion practice to include single venous limb circuits for CPB.


Subject(s)
Humans , Oxygenators/standards , Cardiopulmonary Bypass/instrumentation , Cannula/standards , Pediatrics/instrumentation , Reference Standards , Temperature , Time Factors , Venous Pressure/physiology , Blood Flow Velocity/physiology , Cardiopulmonary Bypass/methods , Reproducibility of Results , Equipment Design , Equipment Safety , Hemodilution , Models, Cardiovascular
16.
Rev. bras. cir. cardiovasc ; 31(6): 449-453, Nov.-Dec. 2016. tab, graf
Article in English | LILACS | ID: biblio-843449

ABSTRACT

Abstract Objective: Introduce the low-cost and easy to purchase simulator without biological material so that any institution may promote extensive cardiovascular surgery training both in a hospital setting and at home without large budgets. Methods: A transparent plastic box is placed in a wooden frame, which is held by the edges using elastic bands, with the bottom turned upwards, where an oval opening is made, "simulating" a thoracotomy. For basic exercises in the aorta, the model presented by our service in the 2015 Brazilian Congress of Cardiovascular Surgery: a silicone ice tray, where one can train to make aortic purse-string suture, aortotomy, aortorrhaphy and proximal and distal anastomoses. Simulators for the training of valve replacement and valvoplasty, atrial septal defect repair and aortic diseases were added. These simulators are based on sewage pipes obtained in construction material stores and the silicone trays and ethyl vinyl acetate tissue were obtained in utility stores, all of them at a very low cost. Results: The models were manufactured using inert materials easily found in regular stores and do not present contamination risk. They may be used in any environment and maybe stored without any difficulties. This training enabled young surgeons to familiarize and train different surgical techniques, including procedures for aortic diseases. In a subjective assessment, these surgeons reported that the training period led to improved surgical techniques in the surgical field. Conclusion: The model described in this protocol is effective and low-cost when compared to existing simulators, enabling a large array of cardiovascular surgery training.


Subject(s)
Humans , Teaching Materials/economics , Education, Medical, Graduate/methods , Cardiac Surgical Procedures/economics , Cardiac Surgical Procedures/education , Models, Cardiovascular , Education, Medical, Graduate/economics
17.
Rev. bras. cir. cardiovasc ; 31(5): 343-350, Sept.-Oct. 2016. tab, graf
Article in English | LILACS | ID: biblio-829751

ABSTRACT

Abstract Objective: Usually only FDA-approved oxygenators are subject of studies by the international scientific community. The objective of this study is to evaluate two types of neonatal membrane oxygenators in terms of transmembrane pressure gradient, hemodynamic energy transmission and gaseous microemboli capture in simulated cardiopulmonary bypass systems. Methods: We investigated the Braile Infant 1500 (Braile Biomédica, São José do Rio Preto, Brazil), an oxygenator commonly used in Brazilian operating rooms, and compared it to the Dideco Kids D100 (Sorin Group, Arvada, CO, USA), that is an FDA-approved and widely used model in the USA. Cardiopulmonary bypass circuits were primed with lactated Ringer's solution and packed red blood cells (Hematocrit 40%). Trials were conducted at flow rates of 500 ml/min and 700 ml/min at 35ºC and 25ºC. Real-time pressure and flow data were recorded using a custom-based data acquisition system. For gaseous microemboli testing, 5cc of air were manually injected into the venous line. Gaseous microemboli were recorded using the Emboli Detection and Classification Quantifier. Results: Braile Infant 1500 had a lower pressure drop (P<0.01) and a higher total hemodynamic energy delivered to the pseudopatient (P<0.01). However, there was a higher raw number of gaseous microemboli seen prior to oxygenator at lower temperatures with the Braile oxygenator compared to the Kids D100 (P<0.01). Conclusion: Braile Infant 1500 oxygenator had a better hemodynamic performance compared to the Dideco Kids D100 oxygenator. Braile had more gaseous microemboli detected at the pre-oxygenator site under hypothermia, but delivered a smaller percentage of air emboli to the pseudopatient than the Dideco oxygenator.


Subject(s)
Humans , Infant, Newborn , Oxygenators, Membrane/standards , Cardiopulmonary Bypass/methods , Embolism, Air/prevention & control , Hemodynamics/physiology , Equipment Design , Models, Cardiovascular
18.
Arch. cardiol. Méx ; 86(3): 260-270, jul.-sep. 2016. tab, graf
Article in Spanish | LILACS | ID: biblio-838383

ABSTRACT

Resumen Objetivo Tras las evidencias acumuladas mediante el uso de técnicas de angioplastia con stents, surge la polémica sobre los factores que inciden en la respuesta final, ya que hay estudios que reportan reestenosis de la luz en el 30-40% alrededor de 6 meses luego de ser implantados, vinculándose como una de las causas al diseño del dispositivo. Este artículo propone la caracterización funcional de stents endovasculares, analizando su influencia mecánica en el sistema vascular y prediciendo los factores de trauma implícitos en el lecho de los vasos. Métodos Utilizando modelos computacionales de prótesis endovasculares tipo stents, mediante técnicas Finite Elements Analysis, se procedió al análisis estructural de dichos dispositivos con el fin de predecir el comportamiento mecánico y el trauma vascular. Para ello, las prótesis fueron consideradas estructuras tubulares compuestas por múltiples eslabones que están sometidos a cargas de presión, que se reflejan como concentradores de esfuerzos. Resultados El estudio permitió visualizar cómo se ajusta la geometría del stent a las diferentes cargas, obteniéndose una aproximación a la respuesta de interacción "sólido-sólido" entre el stent y la pared arterial. Así, se caracterizó el patrón de esfuerzos y se planteó un modelo conceptual que explica su incidencia mecánica en la interacción stent-vaso, para inferir en la funcionalidad del diseño del dispositivo. Conclusiones El modelo conceptual planteado permite determinar la relación entre las condiciones de interacción mecánicas del stent, y advierte sobre los efectos en lo que sería la operación del dispositivo en el ambiente vascular.


Abstract Objective The accumulated evidence on angioplasty techniques with stents has raised a controversy about the factors that influence the final vascular response. Indeed, several studies have shown there might be re-stenosis between 30% to 40% about 6 months after placement, relating to the design of the device as one of the main causes. This paper proposes the functional characterization of endovascular stents, analyzing its mechanical influence in the vascular system and predicting implicit traumatic factors in the vessel. Methods A structural analysis was made for several computational models of endovascular stents using Finite Element Analysis in order to predict the mechanical behavior and the vascular trauma. In this way, the stents were considered as tubular devices composed of multiple links under radial pressure loads, reflecting stress concentration effects. Results The analysis allowed to visualize how the geometry of stents is adjusted under several load conditions, in order to obtain the response of "solid-solid" interaction between the stent and the arterial wall. Thus, an analysis was performed in order to calculate stress, and a conceptual model that explains its mechanical impact on the stent-vessel interaction, was raised, to infer on the functionality from the design of the devices. Conclusions The proposed conceptual model allows to determine the relationship between the conditions of mechanical interaction of the stents, and warns about the effects in what would be the operation of the device on the vascular environment.


Subject(s)
Humans , Blood Vessels/injuries , Stents/adverse effects , Finite Element Analysis , Models, Cardiovascular , Biomechanical Phenomena
19.
Rev. bras. cir. cardiovasc ; 31(2): 151-157, Mar.-Apr. 2016. tab, graf
Article in English | LILACS | ID: lil-792647

ABSTRACT

Abstract Objective: This work describes the experimental validation of a cardiac simulator for three heart rates (60, 80 and 100 beats per minute), under physiological conditions, as a suitable environment for prosthetic heart valves testing in the mitral or aortic position. Methods: In the experiment, an aortic bileaflet mechanical valve and a mitral bioprosthesis were employed in the left ventricular model. A test fluid of 47.6% by volume of glycerin solution in water at 36.5ºC was used as blood analogue fluid. A supervisory control and data acquisition system implemented previously in LabVIEW was applied to induce the ventricular operation and to acquire the ventricular signals. The parameters of the left ventricular model operation were based on in vivo and in vitro data. The waves of ventricular and systemic pressures, aortic flow, stroke volume, among others, were acquired while manual adjustments in the arterial impedance model were also established. Results: The acquired waves showed good results concerning some in vivo data and requirements from the ISO 5840 standard. Conclusion: The experimental validation was performed, allowing, in future studies, characterizing the hydrodynamic performance of prosthetic heart valves.


Subject(s)
Humans , Aortic Valve/physiopathology , Prosthesis Design , Bioprosthesis , Heart Valve Prosthesis , Mitral Valve/physiopathology , Stroke Volume/physiology , Cardiac Output/physiology , Ventricular Function, Left/physiology , Heart Rate , Models, Cardiovascular
20.
Rev. bras. cir. cardiovasc ; 31(2): 171-173, Mar.-Apr. 2016. tab, graf
Article in English | LILACS | ID: lil-792644

ABSTRACT

Abstract Objective: To complement the ISO 5840 standards concerning the duration of left ventricular systole and diastole as a function of changes in heart rates according to in vivo studies from the physiologic literature review. Methods: The systolic and diastolic durations from three in vivo studies were compared with the durations of systole proposed by the ISO 5840:2010 and ISO 5840-2:2015 for hydrodynamic performance assessment of prosthetic heart valves. Results: Based on the in vivo studies analyzed, the systolic durations proposed by the ISO 5840 standard seemed consistent for 45 and 120 beats per minute (bpm), and showed diverse results for the 70 bpm condition. Conclusion: Information on the realistic validation of the operation of left ventricular models for different heart rates were obtained.


Subject(s)
Humans , Heart Valve Prosthesis/standards , Heart Rate/physiology , Systole/physiology , Pulsatile Flow , Guidelines as Topic/standards , Diastole/physiology , Hydrodynamics , Models, Cardiovascular
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