Navegando por Palavras-chave "Electrocardiogram"
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- ItemAcesso aberto (Open Access)Aplicação de redes neurais artificiais para o diagnóstico de arritmias cardíacas usando processamento de sinais de eletrocardiograma.(Universidade Federal de São Paulo, 2022-10-14) Lima, Victor Mendes Cunha [UNIFESP]; Santos, Sergio Ronaldo Barros dos [UNIFESP]; http://lattes.cnpq.br/0608523738367987; http://lattes.cnpq.br/9949464804738379Este trabalho trata da aplicação de redes neurais artificiais (RNAs) como método de diagnóstico de arritmias cardíacas, a exemplo de infarto no miocárdio, utilizando técnicas de processamento de sinais de eletrocardiograma obtidos a partir de um conjunto de dados com informações de diagnóstico de pacientes saudáveis e de pacientes com diversas patologias cardíacas. Os dados utilizados para treinamento e teste das RNAs foram obtidos a partir da extração dos espectros das derivações dos sinais de eletrocardiograma. Em seguida os espectros obtidos foram filtrados e, a partir deles, foram calculadas as potências espectrais em sete bandas de frequências distintas pelo método de Burg. Após a obtenção das potências espectrais fez-se a separação dos dados em grupo de treinamento e grupo de teste, usados para, respectivamente, treinar e testar as redes. Os treinamentos foram realizados por meio do algoritmo backpropagation e do algoritmo LMS. A rede com melhor desempenho apresentou taxa de acerto de 80,97%, enquanto a de pior desempenho apresentou taxa de acerto de 78,94%. Mesmo com valores abaixo do esperado, de acordo com outras literaturas, o método apresentou resultados próximos com diferentes separações de dados, revelando boa precisão.
- ItemAcesso aberto (Open Access)Desempenho do eletrocardiograma no diagnóstico da hipertrofia ventricular esquerda em hipertensos na presença de bloqueio de ramo esquerdo(Universidade Federal de São Paulo (UNIFESP), 2017-01-24) Burgos, Paula Freitas Martins [UNIFESP]; Povoa, Rui Manuel dos Santos [UNIFESP]; http://lattes.cnpq.br/2613638579389329; http://lattes.cnpq.br/2901686411251664; Universidade Federal de São Paulo (UNIFESP)Background: Left ventricular hypertrophy (LVH) is an important risk factor for cardiovascular events, and the electrocardiogram (ECG) usually starts its identification. Objective: To evaluate the impact of the left bundle branch block (LBB) in the diagnostic of LVH by ECG in hypertensive patients. Methods: We studied 2,240 hypertensive patients. All patients underwent ECG and echocardiography (ECHO). We evaluated the electrocardiographic criteria most often used for the diagnosis of LVH: Cornell voltage, Cornell product voltage, Sokolow-Lyon voltage, Sokolow-Lyon product, RaVL, RaVL product RaVL + SV3, relationship RV6 / RV5, strain pattern, left atrial enlargement and QT interval and the BRE was identified when: QRS duration ≥120ms; wave absence of "q" in DI, aVL, V5 and V6; R waves and extended with notches and / or slurrying medium in terminal DI, aVL, V5 and V6; wave "r" with slow growth V1 to V3 may occur QS; S extended waves with thickening and / or notches V1 and V2; intrinsecoid deflection in V5 and V6 ≥0,05 s, electrical axis between -30º and + 60º; ST depression and asymmetric T wave as opposed to medium-terminal delay. The LVH identification pattern was the mass indexed of left ventricular (LVMI), obtained by echocardiography in all participants. Results: The ages ranged 58.7 ± 11.3 years, 684 (30.5%) males and 1,556 (69.5%) females. In participants without LBB, the ECG sensitivity to the presence of LVH ranged from 7.6 to 40.9% and specificity from 70.2 to 99.2%. In participants with LBB, sensitivity to LVH ranged from 11.9 to 95.2% and specificity from 6.6 to 96.6%. Among the criteria for LVH with best performance, the highlight was the Sokolow-Lyon voltage to 3,0mV with sensitivity of 22.2% (95%CI 15.8 - 30.8) and specificity of 88.3% (95% CI 77.8 - 94.2). Conclusion: In hypertensive patients with LBB, the most commonly used criteria for detection of LVH on ECG showed significant decrease in sensitivity and specificity performance. In this scenario, the Sokolow-Lyon voltage 3,0mV showed better behavior.
- ItemSomente MetadadadosPharmacological evaluation of R(+)-pulegone on cardiac excitability: Role of potassium current blockage and control of action potential waveform(Elsevier B.V., 2014-09-01) Santos-Miranda, Artur; Gondim, Antonio Nei; Rodrigues Menezes-Filho, Jose Evaldo; Lins Vasconcelos, Carla Marina; Cruz, Jader Santos; Roman-Campos, Danilo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade Federal de Minas Gerais (UFMG); Univ Estado Bahia; Univ Fed SergipeIntroduction: R(+)-pulegone is a ketone monoterpene and it is the main constituent of essential oils in several plants. Previous studies provided some evidence that R(+)-pulegone may act on isolated cardiac myocytes. in this study, we evaluated in extended detail, the pharmacological effects of R(+)-pulegone on cardiac tissue.Methods: Using in vivo measurements of rat cardiac electrocardiogram (ECG) and patch-clamp technique in isolated myocytes we determinate the influence of R(+)-pulegone on cardiac excitability.Results: R(+)-pulegone delayed action potential repolarization (APR) in a concentration-dependent manner (EC50 = 775.7 +/- 1.48, 325.0 +/- 1.30, 469.3 +/- 1.91 mu M at 10, 50 and 90% of APR respectively). in line with prolongation of APR R(+)-pulegone, in a concentration-dependent manner, blocked distinct potassium current components (transient outward potassium current (I-to), rapid delayed rectifier potassium current (I-kr), inactivating steady state potassium current (I-ss) and inward rectifier potassium current (I-K1)) (EC50 = 1441 +/- 1.04; 605.0 +/- 1.22, 818.7 +/- 1.22; 1753 +/- 1.09 mu M for I-to, I-Kr, I-ss and I-K1, respectively). the inhibition occurred in a fast and reversible way, without changing the steady-state activation curve, but instead shifting to the left the steady-state inactivation curve (V-1/2 from -56.92 +/- 0.35 to 67.52 +/- 0.19 mV). in vivo infusion of 100 mg/kg R(+)-pulegone prolonged the QTc (similar to 40%) and PR (similar to 62%) interval along with reducing the heart rate by similar to 26%.Conclusion: Taken together, R(+)-pulegone prolongs the APR by inhibiting several cardiomyocyte current components in a concentration-dependent manner. This occurs through a direct block by R(+)pulegone of the channel pore, followed by a left shift on the steady state inactivation curve. Finally, R(+)-pulegone induced changes in some aspects of the ECG profile, which are in agreement with its effects on potassium channels of isolated cardiomyocytes. (C) 2014 Elsevier GmbH. All rights reserved.
- ItemAcesso aberto (Open Access)A routine electrocardiogram cannot be used to determine the size of myocardial infarction in the rat(Associação Brasileira de Divulgação Científica, 2005-04-01) Bonilha, Andre.Mateis Martins [UNIFESP]; Saraiva, Roberto Magalhães [UNIFESP]; Kanashiro-Takeuchi, Rosimeire Miyuki [UNIFESP]; Portes, Leslie Andrews [UNIFESP]; Antonio, Ednei Luiz [UNIFESP]; Tucci, Paulo José Ferreira [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Nine lead electrocardiograms of non-infarcted (N = 61) and infarcted (N = 71) female Wistar rats (200-250 g) were analyzed in order to distinguish left ventricle myocardial infarction (MI) larger than 40% (LMI) from MI smaller than 40% (SMI). MI larger than 40% clearly caused a deviation of ÂQRS and ÂT from normal values of 270-360 degrees to 90-270 degrees. Infarcted rats showed Q wave in D1 larger than 1 mm with 94% sensitivity and 100% specificity. The sum of QRS positivity in V1, V2 and V6 lower than 10 mm identified MI with 82% sensitivity and 100% specificity. The data showed that MI can be easily and reliably diagnosed by electrocardiogram in the rat. However, contradicting what is frequently believed, when specificity and sensitivity were analyzed focusing on MI size, none of these current electrocardiographic indices of MI size adequately discriminates LMI from SMI.