Esta dissertação visa estudar a aplicabilidade e a importância prognóstica de métodos matemáticos não lineares no estudo das variações da freqüência cardíaca bem como no das mudanças morfológicas em sinais de eletrocardiograma. Apresentaremos uma revisão geral desse assunto focando em técnicas de análise não linear para o estudo de sinais de eletrocardiograma (ECG) visando construir uma base de conhecimentos que permita, no futuro, a abordagem de novos aspectos dessas metodologias. Como resultado do aprendizado, é gerado um programa que utiliza algumas das técnicas descritas ao longo da dissertação. Ao final da dissertação, abordaremos as vantagens e desvantagens dos métodos não lineares, concluindo que são ferramentas promissoras para a análise de sinais de ECG. / This dissertation presents a study about the applicability and the prognostic importance of nonlinear mathematical methods in the variations of heart frequency as well as in the morphological changes in the electrocardiogram signs. We will present a general revision of this subject focusing on application of nonlinear analysis for the study of electrocardiogram (ECG) signs in order to provide a base of knowledge that allows, in the future, the approach of new aspects of these methodologies. As a result this work, it was built a program that uses nonlinear analysis described along the dissertation. At the end of this document, we describe the advantages and disadvantages of the nonlinear methods, concluding that they are promising tools in the analysis of ECG signs.

Cardiovascular diseases are the leading cause of death worldwide, and are estimated to kill over 17 million people each year, about 31% of all deaths. In the clinic, the first diagnostic procedure for a suspected cardiac abnormality is often acquisition of an electrocardiogram (ECG), which measures the electrical potential of the heart at the body surface. Understanding the mechanisms underlying generation of the ECG waveforms is crucial for optimal clinical benefit. Computer simulations possess several strengths as a tool to gain this understanding, particularly in terms of human-specificity, flexibility, repeatability, and ethics. The ventricles make up the majority of the cardiac volume and are therefore responsible for the majority of ECG waveforms. Ventricular disorders are the most life-threatening, because the ventricles are responsible for pumping blood to the body. Due to their size it has only recently become possible to perform biophysically detailed simulations of the ventricles and torso using supercomputers. In this thesis, multiscale, mathematical models of the ventricles and torso using the Chaste software library are simulated on high performance computing systems. A description is included of the performance enhancements made in Chaste to improve resource efficiency and accelerate job turnaround, particularly in data storage and the auxiliary tasks of post-processing and data conversion. A novel model of ventricular activation is presented and parametrized using multi-modal human data, and successfully used to simulate normal and pathological QRS complexes. Similarly, repolarization gradients are imposed based on the literature and result in a variety of T waves. Finally, the developed human whole-ventricular and torso models are utilized to gain new insights into possible ionic mechanisms underlying the clinical manifestations of the early repolarization syndrome. Overall, this thesis presents a novel framework for simulation of the human ECG using high performance computers, with possible applications in basic science and computational medicine.

A interpretação dos gráficos gerados em exames com eletrocardiogramas (ECG) requer profissionais da área da saúde treinados para identificar as oscilações elétricas que resultam da atividade do coração. Ainda assim, pequenas alterações podem não ser percebidas, ou desprezadas, eliminando chances potenciais de detecção de patologias em estágios iniciais. A grande maioria dos procedimentos automatizados para a análise de ECGs é baseada em técnicas de filtragem digitais e estatísticas, nas quais geralmente se verifica a desvantagem não apenas do custo computacional, como também a perda da qualidade do sinal e o consequente comprometimento das informações extraídas. O presente trabalho lança mão de filtros com premissas geométricas que preservam essas informações e ainda contribuem para a redução no número de pontos redundantes contidos em um ECG. Também propõe a criação de uma identidade cardíaca capaz de traduzir o padrão morfológico único e característico de cada paciente. Foram analisados ECGs de 52 indivíduos saudáveis, e a redução de pontos alcançada foi de mais de 95%. Por fim, o desenvolvimento de uma ferramenta gráfica apresentou uma nova abordagem que viabiliza tanto uma análise personalizada do ECG, como também um acompanhamento da condição cardíaca ao longo da vida. / An interpretation of the graphs generated on electrocardiograms exams (ECG) requires trained healthcare professionals to identify the electrical oscillations that result from heart activity. Even so, small changes can not be perceived, and clinical changes may be neglected, eliminating potential chances of detection of pathologies still in early stages. The large majority of automated procedures for analysis of ECGs are based on digital and statistical filtering techniques, in which it usually occurs beyond computational cost, loss of signal quality and the resulting compromise of extracted information. The present work makes use of filters with geometric premises that preserve this information and also contribute to the reduction in the number of redundant points contained in an ECG. It also proposes the creation of a cardiac identity capable of translating the unique and characteristic morphological pattern of each patient. ECGs were analyzed from 52 healthy individuals, and the reduction of points achieved was greater than 95%. Finally, the development of a graphical tool presented a new approach that enables both a personalized ECG analysis and a monitoring of the cardiac condition throughout life.

Neste trabalho é descrito um sistema para aquisição e processamento do sinal de eletrocardiograma (ECG) para uso em experimentos de fisiologia cardíaca adaptativa de animais aquáticos (peixes). A aplicação imediata destina-se ao Laboratório de Zoofisiologia e Bioquímica Comparativa do Departamento de Ciências Fisiológicas da Universidade Federal de São Carlos. Um algoritmo de processamento do sinal de ECG é proposto, implementado e comparado com outros dois algoritmos, descritos na literatura especializada, tendo demonstrado ótimo desempenho. Um sistema de controle de experimentação, onde as condições do meio como temperatura e pressão de oxigênio, são mantidas constantes, também foi implementado. / In this work a system for signal acquisition and digital processing of the electrocardiogram (ECG) for adaptive cardiac physiology of fishes is described. The instrumentation has been developed to be used in the \"Laboratório de Zoofisiologia e Bioquímica do Departamento de Ciências Fisiológicas da Universidade Federal de São Carlos\". A new algorithm for signal processing of ECO is proposed, implemented and compares favourable with two others described in the literature. Also, a control system to keep constant the temperature and pressure has been designed.

Cardiologists can gain useful insight into a patient's condition when they are able to correlate the patent's symptoms and activities. For this purpose, a Holter Monitor is often used - a portable electrocardiogram (ECG) recorder worn by the patient for a period of 24-72 hours. Preferably, the monitor is not cumbersome to the patient and thus it should be designed to be as small and light as possible; however, the storage requirements for such a long signal are very large and can significantly increase the recorder's size and cost, and so signal compression is often employed. At the same time, the decompressed signal must contain enough detail for the cardiologist to be able to identify irregularities. "Lossy" compressors may obscure such details, where a "lossless" compressor preserves the signal exactly as captured.<p>The purpose of this thesis is to develop a platform upon which a Holter Monitor can be built, including a hardware-assisted lossless compression method in order to avoid the signal quality penalties of a lossy algorithm. <p>The objective of this thesis is to develop and implement a low-complexity lossless ECG encoding algorithm capable of at least a 2:1 compression ratio in an embedded system for use in a Holter Monitor. <p>Different lossless compression techniques were evaluated in terms of coding efficiency as well as suitability for ECG waveform application, random access within the signal and complexity of the decoding operation. For the reduction of the physical circuit size, a System On a Programmable Chip (SOPC) design was utilized. <p>A coder based on a library of linear predictors and Rice coding was chosen and found to give a compression ratio of at least 2:1 and as high as 3:1 on real-world signals tested while having a low decoder complexity and fast random access to arbitrary parts of the signal. In the hardware-assisted implementation, the speed of encoding was a factor of between four and five faster than a software encoder running on the same CPU while allowing the CPU to perform other tasks during the encoding process.

Cardiologists can gain useful insight into a patient's condition when they are able to correlate the patent's symptoms and activities. For this purpose, a Holter Monitor is often used - a portable electrocardiogram (ECG) recorder worn by the patient for a period of 24-72 hours. Preferably, the monitor is not cumbersome to the patient and thus it should be designed to be as small and light as possible; however, the storage requirements for such a long signal are very large and can significantly increase the recorder's size and cost, and so signal compression is often employed. At the same time, the decompressed signal must contain enough detail for the cardiologist to be able to identify irregularities. "Lossy" compressors may obscure such details, where a "lossless" compressor preserves the signal exactly as captured.<p>The purpose of this thesis is to develop a platform upon which a Holter Monitor can be built, including a hardware-assisted lossless compression method in order to avoid the signal quality penalties of a lossy algorithm. <p>The objective of this thesis is to develop and implement a low-complexity lossless ECG encoding algorithm capable of at least a 2:1 compression ratio in an embedded system for use in a Holter Monitor. <p>Different lossless compression techniques were evaluated in terms of coding efficiency as well as suitability for ECG waveform application, random access within the signal and complexity of the decoding operation. For the reduction of the physical circuit size, a System On a Programmable Chip (SOPC) design was utilized. <p>A coder based on a library of linear predictors and Rice coding was chosen and found to give a compression ratio of at least 2:1 and as high as 3:1 on real-world signals tested while having a low decoder complexity and fast random access to arbitrary parts of the signal. In the hardware-assisted implementation, the speed of encoding was a factor of between four and five faster than a software encoder running on the same CPU while allowing the CPU to perform other tasks during the encoding process.

The purpose of the investigations was to compare cardiovascular parameters between non-athletes and well-trained athletes and assess the functional state peculiarities of health strengthen individual’s cardiovascular system after significantly extended physical loads. 26 non-athletes adults, 25 members of Lithuanian National Teams, representing various disciplines and 20 healthy adults, attending health strengthen groups at Kaunas city sport clubs were tested. This research work was performed in three stages: 1) individuals of the first and second groups gradually underwent increasing physical load which was extended every minute with a use of veloergometer (provocative physical load test); 2) individuals of the first and second groups (non-athletes and well-trained individuals) underwent Roufier physical load test; 3) this stage included testing of adults, attending health strengthen groups at Kaunas city sport clubs, who performed considerably extended exercises load and variability. According to the opinion of the health strengthen training instructors, overall the extent of exercises performed by our tested individuals was around 50 % and variability of exercises was 30 % higher comparing with normal trainings. All employed exercises were known by individuals and they were performing them during their trainings, but while testing they were performed during one training. In process of test, individuals were motivated to verify if their training load was optimal, if higher... [to full text]

Pasinaudojant Henkelio matricomis tiriamas elektrokardiogramos ir jos parametrų kompleksiškumas. Po to, elektrokardiogramos fragmentai aprašomi eksponenčių baigtine sume. Taip pat pasiūlytas algoritmas, kaip pasinaudojant koreliacija dvylika standartinių derivacijų pakeisti trimis laisvai pasirenkamomis. / The method how to reinstate standard ECG lead by means of correlation and by three freely chosen ECG leads is suggested in this work. Next method is to evaluate complexity, to analyze, how many components are needed to record ECG and ECG parameters. Also we try to describe ECG fragment using exponential sum.

Orientador: Simone Biagio Chiacchio / Resumo: A mortalidade durante os períodos pré e pós-natal representa uma perda considerável na espécie equina. A compreensão das alterações cardiovasculares durante prenhez é fundamental para o manejo das fêmeas prenhes e dos fetos. As observações clínicas confirmam que as mudanças ocorrem, embora a natureza exata destas alterações não seja bem evidente na literatura equina. O monitoramento da frequência cardíaca no feto, não só possibilita a verificação da saúde fetal e viabilidade, mas também fornece informações sobre o estágio de desenvolvimento do sistema nervoso autônomo. Desta forma, os objetivos do presente estudo foram descrever o comportamento dos parâmetros eletrocardiográficos (ECG), valores normais da frequência cardíaca (FC) e índices de variabilidade da frequência cardíaca (VFC) nas éguas e nos neonatos. Para tal, foram utilizadas 10 éguas, de diferentes idades, pertencentes à raça Mini-Horse em todos os meses de gestação (11 meses) e após o parto. As éguas e os potros foram avaliados nos momentos, 24h, 7o, 14o, 21 o, 28 o e 35 o dia após o nascimento. A frequência cardíaca das éguas ao serem avaliadas em conjunto apresentou significância estatística (P<0,05), assim como as amplitudes das ondas S, T negativa e duração do intervalo PR. As amplitudes das ondas P1 e R variaram estaticamente entre os momentos subsequentes durante a gestação. Quanto aos neonatos foram temperatura foram diferentes quando avaliadas em conjunto e entre os momentos. No eletrocardiograma (ECG) ho... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Mortality during the pre and postnatal periods represents a considerable loss in the equine species. The understanding of cardiovascular changes during pregnancy is fundamental for the management of pregnant females and fetuses. Clinical observations confirm that changes occur, although the exact nature of these changes is not very evident in the equine literature. Heart rate monitoring in the fetus not only enables fetal health check and viability, but also provides information on the developmental stage of the autonomic nervous system. The aim of the present study was to describe the behavior of electrocardiographic parameters (ECG), normal heart rate (HR) and heart rate variability (HRV) in mares and neonates. For this, 10 mares, of different ages, belonging to the Mini-Horse breed were used in all gestation months (11 months) and after delivery. The mares and foals were evaluated at the times, 24h, 7o, 14o, 21o, 28o and 35 the day after birth. The mares heart rate when evaluated together showed statistical significance (P <0.05), as well as the amplitudes of the S wave, negative T and PR interval duration. The amplitudes of the P1 and R waves varied statically between the subsequent moments during gestation. As for the neonates were temperature were different when evaluated together and between moments. On the electrocardiogram (ECG) there was a difference in the amplitude of the waves P1 and P2 when evaluated together. The results were not influenced by the changes that ... (Complete abstract click electronic access below) / Doutor

A interpretação dos gráficos gerados em exames com eletrocardiogramas (ECG) requer profissionais da área da saúde treinados para identificar as oscilações elétricas que resultam da atividade do coração. Ainda assim, pequenas alterações podem não ser percebidas, ou desprezadas, eliminando chances potenciais de detecção de patologias em estágios iniciais. A grande maioria dos procedimentos automatizados para a análise de ECGs é baseada em técnicas de filtragem digitais e estatísticas, nas quais geralmente se verifica a desvantagem não apenas do custo computacional, como também a perda da qualidade do sinal e o consequente comprometimento das informações extraídas. O presente trabalho lança mão de filtros com premissas geométricas que preservam essas informações e ainda contribuem para a redução no número de pontos redundantes contidos em um ECG. Também propõe a criação de uma identidade cardíaca capaz de traduzir o padrão morfológico único e característico de cada paciente. Foram analisados ECGs de 52 indivíduos saudáveis, e a redução de pontos alcançada foi de mais de 95%. Por fim, o desenvolvimento de uma ferramenta gráfica apresentou uma nova abordagem que viabiliza tanto uma análise personalizada do ECG, como também um acompanhamento da condição cardíaca ao longo da vida. / An interpretation of the graphs generated on electrocardiograms exams (ECG) requires trained healthcare professionals to identify the electrical oscillations that result from heart activity. Even so, small changes can not be perceived, and clinical changes may be neglected, eliminating potential chances of detection of pathologies still in early stages. The large majority of automated procedures for analysis of ECGs are based on digital and statistical filtering techniques, in which it usually occurs beyond computational cost, loss of signal quality and the resulting compromise of extracted information. The present work makes use of filters with geometric premises that preserve this information and also contribute to the reduction in the number of redundant points contained in an ECG. It also proposes the creation of a cardiac identity capable of translating the unique and characteristic morphological pattern of each patient. ECGs were analyzed from 52 healthy individuals, and the reduction of points achieved was greater than 95%. Finally, the development of a graphical tool presented a new approach that enables both a personalized ECG analysis and a monitoring of the cardiac condition throughout life.