An ECG (electrocardiogram) simulator is an electronic tool that plays an essential role in the testing, design, and development of ECG monitors and other ECG equipment. Principally an ECG simulator provides ECG monitors with an electrical signal that emulates the human heart's electrical signal so that the monitor can be tested for reliability and important diagnostic capabilities. However, the current portable commercially available ECG simulators are lacking in their ability to fully test ECG monitors. Specifically, the portable simulators presently on the market do not produce authentic ECG signals but rather they endeavor to create the ECG signals mathematically. They even attempt to mathematically create arrhythmias (irregular heartbeats of which there are many different types). Arrhythmia detection is an important capability for any modern ECG monitor because arrhythmias are often the critical link to the diagnosis of heart conditions or cardiovascular disease. The focus of this thesis is the design and implementation of a portable ECG simulator. The important innovation of this prototype simulator is that it will not create its ECG signals mathematically, but rather it will store ECG data files on a memory module and use this data to produce an authentic ECG signal. The data files will consist of different types of ECG signals including different types of arrhythmias. The data files are obtained via the internet and require formatting and storing onto a memory chip. These files are then processed by a digital to analog converter and output on a four lead network to produce an authentic ECG signal. The system is built around the ultra-low power Texas Instruments MSP430 microcontroller.

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Both the fast Fourier transform and discrete wavelet transform have been used extensively for signal denoising. Therefore, comparing the two for the purpose of denoising an electrocardiogram is of high interest. In this report, we outline the theory that both methods are built on, as well as develop MATLAB codes able to denoise an electrocardiogram using both methods. It was shown that the discrete wavelet transform performed significantly better in this context, which shows why it is the preferred method.

Darbe tyrėme veloergometrinių mėginių metu užregistruotus elektrokardiogramos parametrus JT ir RR, kurie gali atspindėti organizmo būklę: reguliacinę, aprūpininančiąją ir vykdančiąją sistemas. Nors šie parametrai ir pakankamai informatyvūs, tačiau dažnai esant nedideliems širdies ir kraujagyslių sutrikimams jokių pokyčių neparodo. Todėl reikalingi nauji analizės metodai, kurie padėtų atskleisti kokybiškai naują informaciją glūdinčią EKG parametruose ir jų kaitoje. Sukūrėme taikomoją programą, kuri parašyta „Matlab“ aplinkoje. Ši programa grupuoja duomenis, atlieka reikiamus skaičiavimus ir rezultatus, įvairius grafikus, pateikia vartotojui ekrane. Tyrimo eigoje sukūrėme tris metodus: EKG parametrų kitimo greičio skaičiavimo ir vaizdavimo fazinėje plokštumoje; EKG parametro glodumo koeficiento skaičiavimo ir vaizdavimo; EKG parametro duomenų grupavimo metodą, Pirmajame metode pastebėjome EKG JT parametro fazinių plokštumų kitimo greičių skirtumus tarp ligonių ir sveikų asmenų grupių, antrajame EKG JT parametro glodumo koeficiento a, o trečiajame EKG JT parametro sudarytų porų diskriminantų vidurkių skirtumus. Norėdami įsitikinti gautų hipotezių teisingumu pritaikėme šių metodų rezultatams neparametrinį Manio-Vitnio-Vilkoksono testą (ZM) su reikšmingumo lygmeniu . Gavome, kad gautos hipotezės yra teisingos. Tai yra pastebėti skirtumai yra reikšmingi tarp sveikų asmenų ir asmenų su tam tikrais kardiologiniais nusiskundimais grupių. Atliktas darbas – tai tik dar vienas žingsnis... [toliau žr. visą tekstą] / For correct specification human’s physiological state, it is very important to evaluate the changes of main human organism systems. In this paper, the parameters that characterize the function of periphery, regulation and supplying systems, JT and RR interval have been studied. Interpolation of discrete data from the physical load obtained by provocative incremental bicycle ergometry stress test was made by cubic spline. The differences for various groups of person (sportsmen and patients with ischemic heart disease) were investigated. EKG parameters were applied in three methods: EKG parameters changes in speed computing and imaging in phase plane, EKG parameters smoothness level calculation, EKG parameters data grouping method. The study revealed that the JT interval’s changes in speed reliably differences between healthy and ill people. Also JT parameter’s smoothness level and JT parameter’s discriminants difference between the groups.

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O objetivo deste trabalho é filtrar sinais corrompidos por ruído Gaussiano ou impulsivo, preservando a amplitude e a morfologia do sinal original. Normalmente, um filtro linear é utilizado nesta tarefa, porém este filtro altera significativamente as amplitudes e as bordas dos sinais, bem como insere atrasos no sinal. Mostra-se neste trabalho que a difusão anisotrópica em conjunto com filtro mediana é muito mais eficaz do que os filtros lineares para esta aplicação. A difusão anisotrópica é uma filtragem iterativa, onde o sinal é filtrado repetidamente. A difusão anisotrópica é controlada por uma função denominada parada-na-aresta, por um parâmetro de escala e pelo número de iterações. Neste trabalho, testamos três bem conhecidas funções parada-na-aresta, concluindo que a função de parada na aresta de Malik e Perona consegue o maior fator de redução de ruído. Infelizmente, esta função é extremamente sensível ao número de iterações, onde o fator de redução de ruído deteriora-se rapidamente antes e depois do ponto ótimo. Como não se conhece o sinal sem ruído, não é possível determinar precisamente qual é o melhor momento de encerrar as iterações do filtro anisotrópico. Desenvolve-se neste trabalho um novo método de parada de difusão baseado na análise da resposta de freqüência do sinal filtrado. Também mostramos como determinar automaticamente um valor de escala adequado. Aplicamos a técnica proposta em eletrocardiograma (ECG). complexo QRS e as Contrações Ventriculares Prematuras (Premature Ventricular Contractions - PVCs) são informações importantes contidas no sinal de ECG. Quando esses sinais são adquiridos no mundo real, eles são freqüentemente corrompidos por eletromiogramas (EMG), artefatos ruidosos provenientes da atividade elétrica associada às contrações musculares. EMG é considerado o ruído de ECG mais difícil de ser eliminado. Ao filtrar o sinal de ECG para remover EMG, não se pode alterar a informação do complexo QRS e anomalia PVC, para não comprometer o diagnóstico clínico. O sinal EMG é modelado como sendo ruído Gaussiano ou, de uma forma mais realística, como ruído com distribuição alfa-estável com características impulsivas. Aplicamos a técnica proposta para filtrar sinais de eletrocardiograma reais do banco de dados de Massachusetts Institute of Technology - Beth Israel Hospital (MIT-BIH). Também é analisada nesta tese a filtragem de sinais provenientes de sensor piezoelétrico. Estes sinais são usados em sistemas reais de corte de aço duro. Em geral uma ferramenta de corte tem sensores piezoelétricos, usados para medição do esforço do corte. Quando a ferramenta de corte se encosta à peça a ser cortada, o sinal do sensor produz uma informação que decai erroneamente ao longo do tempo. Aplicamos a difusão anisotrópica em conjunto com o filtro mediana para determinar o decaimento do sinal do sensor piezoelétrico ao longo do tempo, e assim compensar esta distorção e melhorar o corte de aço duro. / This thesis aims to filter signals corrupted by Gaussian or impulsive noise, preserving the amplitude and the morphology of the original signal. Typically, a linear filter is used for this task, but this filter significantly alters the amplitudes and the edges of the signals and inserts delays in the signal. This work shows that the anisotropic diffusion in conjunction with median filter is much more effective than linear filters for this application. The anisotropic diffusion is an iterative filter, where the signal is filtered repeatedly. An edge-stopping function, a scale parameter and the number of iterations control the anisotropic diffusion. In this study, we tested three well-known edge-stopping functions, concluding that the Perona and Maliks function yields the largest noise reduction factor. Unfortunately, this function is extremely sensitive to the number of iterations, where the noise reduction factor deteriorates quickly before and after the optimal point. As we do not have access to the original noiseless signal, it is not possible to determine precisely the best moment to stop the iterations of the anisotropic filtering. We develop in this paper a new method to determine the best stopping time based on the analysis of the frequency response of the filtered signal. We also show how to determine automatically an adequate scale parameter. We apply the proposed technique to filter electrocardiogram (ECG). The QRS complex and Premature Ventricular Contractions (PVCs) are important information in the ECG signal. When these signals are acquired in the real world, they are often corrupted with noise artifacts from the electrical activity associated with muscle contractions called Electromyography (EMG). EMC is considered the most difficult noise to be eliminated from ECG. When the ECG signal is filtered to remove EMG, the information of the QRS complex and the PVC abnormality must not be altered, to not compromise the clinical diagnosis. We model the EMG signal as Gaussian noise or, more realistically, as alpha stable distribution noise with impulsive characteristics. We apply this technique to filter the real ECG signals from the Massachusetts Institute of Technology - Beth Israel Hospital database (MIT-BIH). This thesis also analyzes the filtering of signals from piezoelectric sensor. These signals are used in real systems for cutting hard steel. In general, a cutting tool has piezoelectric sensors, used to measure the cutting force. When the cutting tool touches the part to be cut, the signal from the sensor produces information that falsely decays over the time. We apply the anisotropic diffusion in conjunction with the median filter to determine the decay of the signal, and therefore offset this distortion and improve the hard steel cutting.

Neste estudo, foi proposta a exploração de um banco de dados, com informações de exames de eletrocardiogramas (ECG), utilizado pelo sistema denominado Tele-ECG do Instituto Dante Pazzanese de Cardiologia, aplicando a técnica de data mining (mineração de dados) para encontrar padrões que colaborem, no futuro, para a aquisição de conhecimento na análise de eletrocardiograma. A metodologia proposta permite que, com a utilização de data mining, investiguem-se dados à procura de padrões sem a utilização do traçado do ECG. Três pacotes de software (Weka, Orange e R-Project) do tipo open source foram utilizados, contendo, cada um deles, um conjunto de implementações algorítmicas e de diversas técnicas de data mining, além de serem softwares de domínio público. Regras conhecidas foram encontradas (confirmadas pelo especialista médico em análise de eletrocardiograma), evidenciando a validade dessa metodologia. / In this study, the exploration of electrocardiograms (ECG) databases, obtained from a Tele-ECG System of Dante Pazzanese Institute of Cardiology, has been proposed, applying the technique of data mining to find patterns that could collaborate, in the future, for the acquisition of knowledge in the analysis of electrocardiograms. The proposed method was to investigate the data looking for patterns without the use of the ECG traces. Three Data-mining open source software packages (Weka, Orange and R - Project) were used, containing, each one, a set of algorithmic implementations and various data mining techniques, as well as being a public domain software. Known rules were found (confirmed by medical experts in electrocardiogram analysis), showing the validity of the methodology.

A utilização das ressecções pulmonares em cães e gatos, quer sejam por lobectomia ou pneumonectomia, é realizada no intuito de cura ou paliação de processos broncopulmonares sempre que os meios conservadores de tratamento clínico sejam considerados ineficientes. Tendo em vista as significativas modificações que a pneumonectomia acarreta, novos estudos experimentais devem ser feitos para elucidar as vantagens desta intervenção cirúrgica, bem como aplicá-la com a devida segurança. O presente estudo tem como objetivo avaliar as alterações eletrocardiográficas e as alterações histopatológicas no pulmão esquerdo de cães submetidos à pneumonectomia direita. Foram utilizados dez cães, machos ou fêmeas, adultos, sem raça definida e pesando entre dez e trinta quilos. Foram avaliados os parâmetros clínicos do animal diariamente, as alterações em todas as derivações do eletrocardiograma e realizado estudo morfométrico de pulmão esquerdo bem como descrição das principais alterações histopatológicas. Foram descritos tópicos importantes da técnica cirúrgica que colaboram na prevenção de intercorrências trans e pós-operatórias. Todos os animais apresentaram boa evolução pós-operatória. Quanto à análise eletrocardiográfica, apenas um animal apresentou alteração de relevância clínica, sendo a ausência de alterações, a maioria dos casos. Presenciamos um caso de Complexos Ventriculares Prematuros decorrente à parada cardiorrespiratória revertida com sucesso. Verificamos diminuição da amplitude dos Complexos QRS nos primeiros 14 dias, retornado após 60 dias de pós-operatório. Quanto à descrição histopatológica, foram presenciados processos de hiperinsuflação ou alterações parenquimatosas não expressivas. Na análise morfométrica,as artérias intra-acinares indicaram aumento significante da porcentagem de espessura após pneumonectomia direita. As artérias com diâmetro 0-50 µm apresentaram os maiores valores tanto nos períodos pré e pós-operatório, mas a taxa de aumento (%) foi mais evidente nas artérias com diâmetro maior de 100 µm. / The intention of the use of pulmonary resections in dogs and cats, either lobectomy or pneumonectomy, is the cure or palliation of bronchopulmonary processes whenever the conservative clinical treatment means are considered ineffective. Bearing in mind the significant alterations that the pneumonectomy causes, new experimental studies must be done to elucidate the advantages of this surgical intervention, as well as perform it without any risk. The aim of the current study is to evaluate both the eletrocardiographical and the histopathological alterations in the lungs of dogs that were undergone a right pneumonectomy. Ten either male or female adult mongrel dogs weighing between ten and thirty kilos were investigated. The clinical parameters of the animals and the alterations in every eletrocardiogram derivation were evaluated day after day, and a left lung morphometrical study and the description of the main histopathological alterations were made, as well. Important topics of the surgical technique that contribute to prevent the trans and post-operative complications were described. All the animals presented a good post-operative outcome. As for the eletrocardiographical analysis, few of them were of clinical significance and in most cases there were no alterations. We observed a premature ventricular complex case resulted from a cardiorrespiratory arrest that was reverted to successfully. We found out decrease of QRS Complex Amplitude on the 0-14 days, and it returned to normal after sixty post-operative days. As for histopathological description, neither significant hiperinsuflation processes nor parenquimatous alterations were practically observed. In the morphometric analysis, the intra-acinar arteries showed, a significant increase of the thickness percentage after right pneumonectomy. The arteries with diameter 0-50µm presented the most values either period pre or post-operative, but increase rate (%) was more evident in the greater than 100 µm diameter arteries.

Orientador: Alessandra Melchert / Resumo: O presente estudo teve como objetivo avaliar a influência do escore corporal sobre parâmetros cardiovasculares (ecocardiográficos, eletrocardiográficos, tomográficos e radiográficos) em papagaios verdadeiros (Amazona aestiva) anestesiados e mantidos em cativeiro. Foram utilizadas 35 aves, sem distinção de sexo, agrupadas de acordo com a condição nutricional: Grupo Magro (n=11); Grupo Ideal (n=14); Grupo Obeso (n=10). Ao exame ecocardiográfico os papagaios obesos apresentaram menor o comprimento diastólico do VD em relação ao grupo magro. Os valores da fração de encurtamento (FE) do eixo transverso do ventrículo esquerdo (VE), FE do eixo longitudinal do VE e FE do eixo longitudinal do ventrículo direito (VD), para os papagaios obesos, apesar de não significativos, foram bastante inferiores aos dos animais em escore magro e normal. Na avaliação radiográfica e tomográfica, comparando as medidas dos diferentes grupos, não foram observadas diferenças significativas. No exame eletrocardiográfico foram determinados: frequência cardíaca (FC), ritmo cardíaco, duração e amplitude da onda P, duração do intervalo PR e complexo QRS (padrão rS), duração e amplitude da onda R, duração do intervalo RR e intervalo QT e QT corrigido (QTC), duração e amplitude da onda T, não se observando diferença significativa entre os grupos estudados. Concluiu-se que, assim como em mamíferos, alterações da condição nutricional em papagaios-verdadeiros (A. aestiva) acarretam em disfunções cardiovasculares, d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the influence of the body condition score (BCS) on cardiovascular parameters (echocardiographic, electrocardiographic, tomographic and radiographic) in parrots (Amazona aestiva) anesthetized and kept in captivity. Thirty-five birds were evaluated, regardless of gender, grouped according to the nutritional condition: Lean group (n = 11); Ideal group (n = 14); Obese group (n = 10). On echocardiographic examination, obese parrots presented lower diastolic length of the right ventricle (RV) than the lean group. The fractional shortening (FS) values of the left ventricle (LV) in transverse axis, LV FS and RV FS in longitudinal axis for the obese parrots, although not significant, were lower than those of the lean and normal animals. In the radiographic and tomographic evaluation, comparing the measurements of the different groups, no significant differences were observed. Cardiac frequency (HR), heart rate, duration and amplitude of the P wave, duration of the PR interval and QRS complex (rS pattern), duration and amplitude of the R wave, duration of the RR interval, QT and correct QT (QTc) intervals, duration and amplitude of the T wave were determined in the electrocardiographic exam. No significant difference was observed between the studied groups. It was concluded that, as in mammals, changes in nutritional status in parrots (A. aestiva) lead to cardiovascular dysfunctions, however, detected only on echocardiographic examination. The prop... (Complete abstract click electronic access below) / Doutor

The electrocardiogram (ECG) is a graphical representation of the electrical activity of the heart. The 12-lead ECG shows this activity in 12 "views" called "leads", relative to the location of sensors attached to the body surface. The ECG is a routinely applied cost effective diagnostic medical test, utilised in healthcare settings around the world. Although more than three hundred million ECGs are recorded each year, correctly interpreting them is considered a complex task. Failure to make correct interpretations can lead to injury or death and costs vast sums in litigation payments. Many automated attempts at interpreting ECGs have been implemented and continue to be developed and improved. Despite this, automated methods are still considered to be less reliable than expert human interpretation. As ECG interpretation is both a cognitive and visual task, eye-tracking holds great potential as an investigative methodology. This thesis aims to identify any cues in visual behaviour that may indicate differences in subsequent ECG interpretation accuracy. This is the first work that uses eye-tracking to analyse how practitioners interpret ECGs as a function of accuracy. In order to investigate these phenomenon, several experiments were carried out using eye-movements captured from clinical practitioners that interpret ECGs as part of their usual clinical role. The findings presented in this thesis have advanced research in the understanding of ECG interpretation. Specifically: Clinical history makes a difference to how people look at ECGs; different gaze patterns are often found in accurate and inaccurate interpretation groups. Grouping data to account for within ECG lead behaviour (eye-movement patterns within a lead) is more revealing than analysis at the level of the lead (eye-movements between leads). Findings suggest analysing visual behaviour at this level is crucial in order to detect behaviour in ECG interpretation. Further to this the thesis presents eye-tracking techniques that can be applied to wider areas of task performance. These methods work over complex stimuli, are able to deal post hoc with differently sized groups and generate appropriate areas of interest on a stimulus. These methods detect important differences in eye-movement behaviour between groups that are missed when applying standard inferential statistical techniques.