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Estudo do eletrocardiograma sob uma abordagem matemática.; Electrocardiogram evaluation under a mathematical approach.

Melco, Tito Coutinho
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/11/2006 PT
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37.19%
O eletrocardiograma transMITe informações com relação à passagem do pulso elétrico pelo coração e, conseqüentemente, do funcionamento deste. Desde o início da sua utilização, possibilitada pelo trabalho de Willem Einthoven criando a primeira máquina capaz de medir o pulso elétrico de forma não invasiva e com sensibilidade forte o bastante para ser capaz de produzir um gráfico proveitoso, o eletrocardiograma é muito utilizado para avaliação clínica de pacientes. Entretanto a evolução das máquinas que o descrevem não foi muito além do que o elaborado por Einthoven no início do século 20. As máquinas capazes de captar o eletrocardiograma se tornaram menores (até portáteis para algumas aplicações), gráficos passaram a ser disponibilizados em telas de vídeo (ao invés das fitas de papel) e, como maior evolução, as máquinas que observam o eletrocardiograma passaram a conseguir captar a ocorrência de um ciclo cardíaco com alta confiabilidade e, atualmente, passaram a medir também o parâmetro ST com precisão deliMITada (necessitando ajuda do operador para ajuste em alguns casos). É baseado nestes fatos que esta dissertação procura estudar algoritmos matemáticos, de forma mais focada nos modelos do impulso elétrico durante os ciclos cardíacos...

O eletrocardiograma de alta resolução no domínio do tempo em portadores de insuficiência cardíaca congestiva; The signal-averaged electrocardiogram in pacients with congestive heart failure

Grell, Ernani de Sousa
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 20/02/2003 PT
Relevância na Pesquisa
27.03%
Foi avaliada a incidência de potencial tardio pelo eletrocardiograma de alta resolução no domínio do tempo em portadores de insuficiência cardíaca congestiva de diferentes etiologias com o objetivo de se estudarem as correlações clínicas e prognósticas entre pacientes com potencial tardio presente e ausente na referida patologia. Foram estudados 288 pacientes com insuficiência cardíaca congestiva, de idades entre 16 a 70 anos (média 51,51; desvio padrão 11,24), 215 do sexo masculino (74,65%) e 73 do sexo feminino (25,35%). As etiologias da insuficiência cardíaca congestiva foram: a cardiopatia hipertensiva em 78 pacientes (27,08%); a cardiopatia isquêmica em 65 (22,57%); a Doença de Chagas em 42 (14,58%); a valvopatia em 12 (4,17%); a cardiomiopatia alcoólica em 9 (3,13%); a cardiomiopatia periparto em 6 (2,08%); a miocardite viral em 3 (1,04%). Em 73 pacientes (25,35%), a etiologia não foi identificada e a cardiomiopatia dilatada foi considerada idiopática. Foram estudados a idade, o sexo, a etiologia da insuficiência cardíaca, as variáveis do eletrocardiograma (área eletricamente inativa e bloqueios de ramo), do ecocardiograma transtorácico (diâmetro do átrio esquerdo, diâmetro sistólico e diastólico do ventrículo esquerdo)...

Data mining em banco de dados de eletrocardiograma; Data mining in electrocardiogram databases

Ferreira, José Alves
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 23/04/2014 PT
Relevância na Pesquisa
36.79%
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...

Electrocardiografia clínica em canídeos : estudo retrospectivo de 118 casos

Guerreiro, Carlota Graça Valente Torres
Fonte: Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária Publicador: Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária
Tipo: Trabalho de Conclusão de Curso
Publicado em 10/07/2009 POR
Relevância na Pesquisa
26.93%
Dissertação de Mestrado Integrado em Medicina Veterinária; Com base no estágio curricular realizado no Instituto Veterinário do Parque, apresenta-se esta Dissertação de Mestrado Integrado em Medicina Veterinária, que tem como tema a Electrocardiografia Clínica em Canídeos. Por ter sido possível, durante o referido estágio, acompanhar uma elevada casuística da especialidade de Cardiologia e, pelo facto de as alterações electrocardiográficas e do ritmo cardíaco constituírem condições de extrema importância, muitas vezes subvalorizadas, decidiu-se abordar este tema de uma forma mais pormenorizada. Para o reconhecimento da etiologia das arritmias, a consequente instituição terapêutica e o estabelecimento do prognóstico, tomam-se como procedimentos o entendimento da história clínica do canídeo, o exame físico minucioso e o recurso a outros exames complementares, como a ecocardiografia. Ainda assim, o diagnóstico definitivo das arritmias encontra no registo electrocardiográfico o seu principal recurso. Ao longo de todo o estágio realizado, 118 canídeos foram submetidos a um exame electrocardiográfico. Mais de metade destes cães pertenciam ao sexo masculino, com uma idade média de, aproximadamente...

Detection of incipient left ventricular hypertrophy in mild to moderate arterial hypertension with normal electrocardiogram and echocardiogram: a new use for signal-averaged electrocardiography

Ginefra,Paulo; Barbosa,Eduardo C.; Benchimol-Barbosa,P. R.; Bomfim,Alfredo S.; Boghossian,Sílvia H.; Salgado,Angelo A.; Brasil,Flávia G.; Freitas,Elizabete A.; Albanesi Filho,Francisco M.
Fonte: Sociedade Brasileira de Cardiologia - SBC Publicador: Sociedade Brasileira de Cardiologia - SBC
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2003 EN
Relevância na Pesquisa
36.79%
OBJECTIVE: To assess signal-averaged electrocardiogram (SAECG) for diagnosing incipient left ventricular hypertrophy (LVH). METHODS: A study with 115 individuals was carried out. The individuals were divided as follows: GI - 38 healthy individuals; GII - 47 individuals with mild to moderate hypertension and normal findings on echocardiogram and ECG; and GIII - 30 individuals with hypertension and documented LVH. The magnitude vector of the SAECG was analyzed with the high-pass cutoff frequency of 40 Hz through the bidirectional four-pole Butterworth high-pass digital filter. The mean quadratic root of the total QRS voltage (RMST) and the two-dimensional integral of the QRS area of the spectro-temporal map were analyzed between 0 and 30 Hz for the frequency domain (Int FD), and between 40 and 250 Hz for the time domain (Int TD). The electrocardiographic criterion for LVH was based on the Cornell Product. Left ventricular mass was calculated with the Devereux formula. RESULTS: All parameters analyzed increased from GI to GIII, except for Int FD (GII vs GIII) and RMST log (GII vs GIII). Int TD showed greater accuracy for detecting LVH with an appropriate cutoff > 8 (sensitivity of 55%, specificity of 81%). Positive values (> 8) were found in 56.5% of the G II patients and in 18.4% of the GI patients (p< 0.0005). CONCLUSION: SAECG can be used in the early diagnosis of LVH in hypertensive patients with normal ECG and echocardiogram.

A routine electrocardiogram cannot be used to determine the size of myocardial infarction in the rat

Bonilha,A.M.M.; Saraiva,R.M.; Kanashiro,R.M.; Portes,L.A.; Antonio,E.L.; Tucci,P.J.F.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2005 EN
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36.79%
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.

Thallium-201 myocardial imaging in evaluation of asymptomatic individuals with ischaemic ST segment depression on exercise electrocardiogram.

Caralis, D G; Bailey, I; Kennedy, H L; Pitt, B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1979 EN
Relevância na Pesquisa
27.03%
Asymptomatic adults with normal physical examination, normal resting electrocardiogram, and normal routine laboratory evaluation who have a positive exercise electrocardiogram and abnormal exercise thallium-201 myocardial image have a very high probability of angiographically significant coronary artery disease. If, on the other hand, the exercise electrocardiogram is positive for "ischaemic" ST segment changes, but the exercise thallium image is normal, the probability for coronary disease is low. The exercise electrocardiogram combined with thallium-201 myocardial image are safe non-invasive methods which can be performed on an out-patient basis.

Effect of positive acceleration (+gz) on electrocardiogram of subjects with vasoregulatory abnormality.

Khanna, P K; Balasubramanian, K V; Dham, S K; Rai, K; Hoon, R S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1977 EN
Relevância na Pesquisa
26.93%
ST-T wave changes in the electrocardiogram detected during routine examination and aggravated by erect posture, hyperventilation, and exercise in apparently healthy young individuals have been termed vasoregulatory abnormalities. No evidence of ischaemic heart disease has been found in such subjects. Ten young healthy air crew with vasoregulatory abnormalities were subjected to maximal exercise on treadmill and procedure repeated after 120 mg propranolol daily for 3 days. After one week, they were subjected to a stress of positive acceleration (+gz) in a human centrifuge at 2-5 g and 3-5 g for 15 seconds each at a constant rate of rise of 0-1 g/s and the electrocardiogram was monitored during and in the post-acceleration phase. The procedure was repeated after propranolol 120 mg daily for 3 days. The stress of positive acceleration resulted in pronounced prominence of P waves and inversion of T waves (as has been reported in normal subjects) with minimal ST depression in the electrocardiogram. ST segment depression during exercise, at heart rates corresponding to those achieved during peak centrifuge runs, was significantly more pronounced. The ST, P, and T wave changes were returned to normal after propranolol. It is concluded that minimal ST segment depression after stress of positive acceleration as compared with conspicuous ST segment depression during exercise at corresponding heart rates...

Comparison of the value of novel rapid measurement of myoglobin, creatine kinase, and creatine kinase-MB with the electrocardiogram for the diagnosis of acute myocardial infarction.

Lee, H. S.; Cross, S. J.; Garthwaite, P.; Dickie, A.; Ross, I.; Walton, S.; Jennings, K.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1994 EN
Relevância na Pesquisa
27.15%
OBJECTIVE--To determine whether serum myoglobin, creatine kinase, and creatine kinase-MB measured at admission by rapid, compact, and easy to use automated quantitative analysers (results within 10 min) helped the early identification of acute myocardial infarction. The results were compared with the data obtained from the electrocardiograms recorded at admission. DESIGN--A prospective study. SETTING--Coronary care unit. PATIENTS--94 consecutive patients with suspected myocardial infarction. Myocardial infarction was subsequently confirmed in 44 patients and excluded in 50. METHODS--All admission serum myoglobin, creatine kinase, and creatine kinase-MB were measured by clinical staff using analysers in the coronary care unit. An admission electrocardiogram was obtained from all patients. RESULTS--The sensitivity, specificity, and predictive accuracy for diagnosing myocardial infarction were: electrocardiogram 68%, 100%, and 85%; myoglobin 57%, 100%, and 80%; creatine kinase (threshold of 190 U/l) 34%, 98%, and 68%; creatine kinase-MB (threshold of 25 U/l) 43%, 100%, and 73%. When the electrocardiographic and myoglobin data were combined the sensitivity improved to 91%, diagnostic accuracy to 96%, with specificity of 100%. The results for the electrocardiogram and creatine kinase-MB were 80%...

Comparison of automatic QT measurement techniques in the normal 12 lead electrocardiogram.

McLaughlin, N. B.; Campbell, R. W.; Murray, A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1995 EN
Relevância na Pesquisa
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OBJECTIVE--To undertake a quantitative assessment of different automatic QT measurement techniques and investigate the influence of electrocardiogram filtering and algorithm parameters. DESIGN--Four methods for identifying the end of the T wave were compared: (1) threshold crossing of the T wave (TH); (2) threshold crossing of the differential of the T wave (DTH); (3) intercept of an isoelectric level and the maximum T wave slope (SI); and (4) intercept of an isoelectric level and the line passing through the peak and the point of maximum slope of the T wave (PSI). Automatic QT measurements were made by all techniques following different electrocardiogram filtering and, when appropriate, with four different isoelectric levels and with three different threshold levels. SUBJECTS--12 simultaneous standard electrocardiogram leads, containing at least two electrocardiogram complexes, were recorded from 25 healthy volunteers relaxing in a semirecumbent position. MAIN OUTCOME MEASURE--Mean and standard deviation of differences between reference and automatic QT measurements were compared for the four techniques. RESULTS--The mean automatic QT measurements varied by up to 62 ms, which was greater than has been found between manual measurements by experienced clinicians. Technique TH was particularly poor. The other techniques produced consistent results for most electrocardiogram filter...

Limited value of the resting electrocardiogram in assessing patients with recent onset chest pain: lessons from a chest pain clinic.

Norell, M; Lythall, D; Coghlan, G; Cheng, A; Kushwaha, S; Swan, J; Ilsley, C; Mitchell, A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1992 EN
Relevância na Pesquisa
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OBJECTIVE--To evaluate a clinic set up specifically to assess patients with recent onset chest pain, particularly those presenting with a normal resting electrocardiogram. DESIGN--Retrospective review of case notes. SETTING--Cardiac department of a tertiary referral cardiothoracic centre. PATIENTS--250 consecutive patients with recent onset chest pain seen within 24 hours of general practitioner referral. OUTCOME MEASURES--Clinical diagnosis and management. RESULTS--40% of patients were seen within seven days of the onset of symptoms. Twenty seven per cent had non-cardiac symptoms and could be discharged while 60% were considered to have cardiac pain. Sixty six patients (26%) were admitted directly from the clinic and 48 of these underwent coronary angiography within three weeks. Seventy patients (28%) have so far undergone intervention (angioplasty or coronary artery surgery), 22 within one month of presentation. One hundred and nine patients (44%) presented with a normal resting electrocardiogram, 21 of whom were considered to have unstable angina. Forty one of these patients were investigated of whom 37 were found to have significant coronary disease and 26 have undergone intervention. CONCLUSIONS--This experience highlights the inadequacy of a routine electrocardiogram reporting service in patients with recent onset of chest pain. An alternative facility offering immediate and complete cardiac assessment produced patient benefit with early diagnosis and intervention. Investigation of these patients...

Relations between resting ventricular long axis function, the electrocardiogram, and myocardial perfusion imaging in syndrome X.

Henein, M. Y.; Rosano, G. M.; Underwood, R.; Poole-Wilson, P. A.; Gibson, D. G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1994 EN
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OBJECTIVE--To investigate interrelations between ventricular long axis function, resting electrocardiogram, and myocardial perfusion imaging in a group of patients with syndrome X in order to define possible underlying mechanisms. DESIGN--Prospective echocardiographic, electrocardiographic, and myocardial perfusion imaging. SETTING--A tertiary referral centre for cardiac diseases with invasive and non-invasive facilities. PATIENTS--50 consecutive patients with syndrome X selected on the basis of a history of angina, ST segment depression on exercise, and normal coronary arteriograms and 21 controls of similar age. RESULTS--Long axis motion of one or both ventricles assessed by echocardiography was abnormal in 37 patients. The onset of systolic shortening was delayed by > 130 ms (upper limit of normal 95% confidence interval) in eight patients, and was associated with prolonged shortening during the isovolumic relaxation period in seven (p < 0.01) (systolic abnormalities). The onset of diastolic lengthening was delayed by > 80 ms in 20. Early diastolic peak lengthening rate was < 4.5 cm.s-1 in 13 patients, and the relative amplitude of lengthening during atrial systole was > 45% in 18. On the resting electrocardiogram septal q waves were absent in 12 patients. This was associated with long axis systolic disturbances in seven patients (p < 0.05). T waves were abnormal in 10 and associated with delayed onset of early diastolic lengthening in all (p < 0.001). Late diastolic long axis disturbances were not associated with any consistent electrocardiographic abnormality. Myocardial perfusion imaging was abnormal in six of 33 patients...

Time course of ventricular arrhythmias and the signal averaged electrocardiogram in the post-infarction period: a prospective study of correlation.

Turitto, G; Caref, E B; Macina, G; Fontaine, J M; Ursell, S N; el-Sherif, N
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1988 EN
Relevância na Pesquisa
27.03%
The incidence and time course of complex ventricular arrhythmias and of the abnormal signal averaged electrocardiogram were studied prospectively in 90 patients in the first two months after acute myocardial infarction. Serial recordings of both 24 hour ambulatory and signal averaged electrocardiograms were obtained 0-5 days (phase 1), 6-30 days (phase 2), and 31-60 days (phase 3) after infarction. A total of 264 ambulatory electrocardiograms and 264 signal averaged electrocardiograms were available for analysis. Complex ventricular arrhythmias were seen in 31%, 17%, and 38% of patients during phases 1, 2, and 3 respectively, and abnormal signal averaged electrocardiogram in 13%, 24%, and 16%. The incidence of complex ventricular arrhythmias was not significantly different in patients with or without an abnormal signal averaged electrocardiogram in the entire study period nor in any of the three phases after infarction. During phase 2 when abnormal signal averaged electrocardiograms were most common complex ventricular arrhythmias were least common. This lack of correlation suggests that the abnormal signal averaged electrocardiogram and complex ventricular arrhythmias after infarction have different electrophysiological bases.

Value of the resting 12 lead electrocardiogram and vectorcardiogram for locating the accessory pathway in patients with the Wolff-Parkinson-White syndrome.

Lemery, R; Hammill, S C; Wood, D L; Danielson, G K; Mankin, H T; Osborn, M J; Gersh, B J; Holmes, D R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1987 EN
Relevância na Pesquisa
27.19%
The resting 12 lead electrocardiogram and vectocardiogram were reviewed in 47 patients with the Wolff-Parkinson-White syndrome (a) who had pre-excitation on the resting 12 lead electrocardiogram, (b) who had a single anterograde conducting accessory pathway assessed and located during preoperative electrophysiological study and during epicardial mapping at operation, and (c) in whom surgical division of the accessory pathway resulted in loss of pre-excitation. The site of the accessory pathway established during operation was compared with that established by evaluating the polarity of the delta wave and QRS complex on the resting 12 lead electrocardiogram. The electrocardiogram was assessed by the Rosenbaum criteria (Wolff-Parkinson-White type A, left-sided pathway; or type B, right-sided pathway), the Gallagher criteria (atrial pacing resulting in maximal pre-excitation), and the World Health Organisation criteria (a composite of previous studies). The Gallagher and World Health Organisation criteria were derived from patients demonstrating maximal pre-excitation that often required atrial pacing. The present study was designed to determine whether these criteria could be accurately applied to the resting 12 lead electrocardiogram on which the degree of pre-excitation was variable. The Rosenbaum criteria correctly identified a left sided accessory pathway in 26 of 34 patients and a right-sided accessory pathway in nine of 13 patients. The Gallagher and World Health Organisation criteria correctly identified the location in only 15 (32%) of the 47 patients. The resting vectorcardiogram was inaccurate for locating the accessory pathway. Although published criteria are useful for identifying the site of the accessory pathway from an electrocardiogram obtained when rapid atrial pacing is being used to achieve maximal pre-excitation...

A normal electrocardiogram precludes the need for left ventriculography in the assessment of coronary artery disease

Khan, M; Sinha, S; Hayton, S; Fynn, S; Henderson, R; Bennett, D
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1998 EN
Relevância na Pesquisa
27.03%
Objective—To assess whether a normal electrocardiogram can identify good left ventricular function and obviate the need for routine left ventriculography in patients undergoing cardiac catheterisation for suspected coronary artery disease.
Design—A prospective study of patients undergoing cardiac catheterisation.
Setting—A regional cardiac centre.
Patients—The electrocardiograms, coronary angiograms, and left ventriculograms of 391 consecutive patients undergoing investigations for suspected coronary artery disease were entered into the study. Patients with arrhythmias and cardiac pathologies other than coronary artery disease were excluded.
Main outcome measures—The electrocardiogram was assessed using a 29 point QRS scoring system, and classified by two cardiologists and a trainee cardiologist as normal or abnormal. Left ventricular function was assessed by digital ventriculography.
Results—The sensitivity, specificity, and negative predictive value of a QRS score of 0 (normal QRS complexes) for discriminating good left ventricular function (ejection fraction ⩾ 50%) were 92.6%, 41.5%, and 97.2%, respectively. The figures for a normal electrocardiogram as assessed by a doctor were 96.3%, 40.4%, and 98.6% for cardiologist A; 96.3%...

How reliable is the electrocardiogram in detecting left ventricular hypertrophy in hypertension?

Vijan, S. G.; Manning, G.; Millar-Craig, M. W.
Fonte: BMJ Group Publicador: BMJ Group
Tipo: Artigo de Revista Científica
Publicado em /07/1991 EN
Relevância na Pesquisa
27.03%
This paper assesses the sensitivity and specificity of the electrocardiogram in detecting left ventricular hypertrophy in 75 hypertensive patients. Each patient underwent a 12 lead electrocardiogram and echocardiogram. Left ventricular mass index, using echocardiogram, was calculated according to the Penn convention and left ventricular hypertrophy was assessed by standard electrocardiographic criteria. The electrocardiogram was found to be very specific but insensitive in the detection of left ventricular hypertrophy as compared with the echocardiogram. Other non-voltage dependent markers appeared to have similar reliability. We conclude that the electrocardiogram may be unreliable in the detection of left ventricular hypertrophy in hypertensive patients. Accurate assessment of left ventricular hypertrophy, in these patients should be by echocardiography.

Use of Computers Simulation as an Aid in Understanding the Electrocardiogram in Ischemia and Infarction

Geselowitz, David B.; Miller, Walter T.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 05/10/1977 EN
Relevância na Pesquisa
36.79%
We have developed a digital computer model for the simulation of the body surface electrocardiogram (ECG) during ventricular activation and recovery. The ventricles of the heart are represented in detail by a three dimensional array of 4000 points which is subdivided into 23 regions. Excitation sequence and cellular action potential data taken from the literature are used to determine the moments of 23 dipoles, corresponding to the 23 regions, at each instant of time during simulated cardiac cycles for normal and ischemic conditions. The 23 dipoles are then used to calculate the potentials on the surface of a homogeneous volume conductor with the shape of an adult male torso. Calculated torso isopotential surface maps and standard 12 lead ECGs during ventricular activation and recovery are in good agreement with human data reported in the literature. The heart is represented in sufficient detail to allow variations in the location and size of the ischemic injury and in the distribution of ischemia within the injured region.

Fetal blood sampling in addition to intrapartum ST-analysis of the fetal electrocardiogram: evaluation of the recommendations in the Dutch STAN® trial; Fetal blood sampling in addition to intrapartum ST-analysis of the fetal electrocardiogram: evaluation of the recommendations in the Dutch STAN(R) trial

Becker, J.; Westerhuis, M.; Sterrenburg, K.; Van den Akker, E.; van Beek, E.; Bolte, A.; Van Dessel, T.; Drogtrop, A.; van Geijn, H.; Graziosi, G.; van Lith, J.; Mol, B.; Moons, K.; Nijhuis, J.; Oei, S.; Oosterbaan, H.; Porath, M.; Rijnders, R.; Schuitema
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
Relevância na Pesquisa
37.03%
Objectives:  To evaluate the recommendations for additional fetal blood sampling (FBS) when using ST-analysis of the fetal electrocardiogram. Design:  Prospective cohort study. Setting:  Three academic and six non-academic teaching hospitals in the Netherlands. Population:  Labouring women with a high-risk singleton pregnancy in cephalic position beyond 36 weeks of gestation. Methods:  In labouring women allocated to the STAN® arm of a previously published randomised controlled trial who underwent one or more FBS during delivery, we assessed whether FBS was performed according to the trial protocol and how fetal acidosis, defined as an FBS pH < 7.20, was related to ST-waveform analysis. Main outcome measures:  The number of FBS showing fetal acidosis, related to the different STAN® criteria where additional FBS is recommended. Results:  Among 2827 women monitored with STAN®, 297 underwent FBS, of whom 171 (57.6%) were performed according to the predefined criteria and 126 were performed in absence of these criteria. In the first group, rates of fetal acidosis (pH < 7.20) were two of 18, none of nine, 12 of 111 and three of 33 when FBS was taken for abnormal cardiotocogram (CTG) at the start, intermediary CTG at the start...

Is intrapartum fever associated with ST-waveform changes of the fetal electrocardiogram? A retrospective cohort study

Becker, J.; van Rijswijk, J.; Versteijnen, B.; Evers, A.; Van den Akker, E.; van Beek, E.; Bolte, A.; Rijnders, R.; Mol, B.; Moons, K.; Porath, M.; Drogtrop, A.; Schuitemaker, N.; Willekes, C.; Westerhuis, M.; Visser, G.; Kwee, A.
Fonte: Blackwell Publishing Publicador: Blackwell Publishing
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
36.93%
OBJECTIVE: To investigate the association between maternal intrapartum fever and ST-waveform changes of the fetal electrocardiogram. DESIGN: Retrospective cohort study. SETTING: Three academic and six non-academic teaching hospitals in the Netherlands. POPULATION: Labouring women with a high-risk singleton pregnancy in cephalic position beyond 36 weeks of gestation. METHODS: We studied 142 women with fever (≥38.0°C) during labour and 141 women with normal temperature who had been included in two previous studies. In both groups, we counted the number and type of ST-events and classified them as significant (intervention needed) or not significant, based on STAN(®) clinical guidelines. MAIN OUTCOME MEASURES: Number and type of ST-events. RESULTS: Both univariable and multivariable regression analysis showed no association between the presence of maternal intrapartum fever and the number or type of ST-events. CONCLUSIONS: Maternal intrapartum fever is not associated with ST-segment changes of the fetal electrocardiogram. Interpretation of ST-changes in labouring women with fever should therefore not differ from other situations.; JH Becker, J van Rijswijk, B Versteijnen, ACC Evers, ESA van den Akker, E van Beek, AC Bolte, RJP Rijnders...

Feature extraction of electrocardiogram signals by applying adaptive threshold and principal component analysis

Rodríguez,R.; Mexicano,A.; Bila,J.; Cervantes,S.; Ponce,R.
Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2015 EN
Relevância na Pesquisa
36.79%
This paper presents a novel approach for QRS complex detection and extraction of electrocardiogram signals for different types of arrhythmias. Firstly, the ECG signal is filtered by a band pass filter, and then it is differentiated. After that, the Hilbert transform and the adaptive threshold technique are applied for QRS detection. Finally, the Principal Component Analysis is implemented to extract features from the ECG signal. Nineteen different records from the MIT-BIH arrhythmia database have been used to test the proposed method. A 96.28% of sensitivity and a 99.71% of positive predictivity are reported in this testing for QRS complexity detection, being a positive result in comparison with recent researches.