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1
Malina, Ondřej. „Detekce začátku a konce komplexu QRS s využitím hlubokého učení“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442595.
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This thesis deals with the issue of automatic measurement of the duration of QRS complexes in ECG signals. Special emphasis is then placed on the possibility of automatic detection of QRS complexes while exciting cardiac tissue with a pacemaker. The content of this work is divided into four logical units, where the first part deals with the heart as an organ. It describes the origin and spread of excitement in the heart, its possible pathologies and their manifestations in ECG recording, it also deals with pacing and measuring ECG recording during simultaneous pacing. The second part of the thesis contains a brief introduction to the topic of machine and deep learning. The third part of the thesis contains a search of current approaches using methods based on deep learning to solve the detection of QRSd. The fourth part deals with the design and implementation of its own model of deep learning, able to detect the beginnings and ends of QRS complexes from ECG recordings. It describes the data preprocessing implemented in the MATLAB programming environment. The actual implementation of the model was performed in the Python using the PyTorch and NumPy moduls.
2
Farber, Dawn L. (Dawn Lee). „Multi-channel QRS detector“. Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10868.
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3
Hanna, Rafik. „VALIDATION OF QUICKSCAT RADIOMETER (QRAD) MICROWAVE BRIGHTNESS TEMPERTURE MEASURMENTS“. Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3990.
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After the launch of NASA's SeaWinds scatterometer in 1999, a radiometer function was implemented in the Science Ground Data Processing Systems to allow the measurement of the earth's microwave brightness temperature. This dissertation presents results of a comprehensive validation to assess the quality of QRad brightness temperature measurements using near-simultaneous ocean Tb comparisons between the SeaWinds on QuikSCAT (QRad) and WindSat polarimetric radiometer on Coriolis. WindSat was selected because it is a well calibrated radiometer that has many suitable collocations with QuikSCAT; and it has a 10.7 GHz channel, which is close to QRad frequency of 13.4 GHz. Brightness temperature normalizations were made for WindSat before comparison to account for expected differences in Tb with QRad because of incidence angle and channel frequency differences. Brightness temperatures for nine months during 2005 and 2006 were spatially collocated for rain-free homogeneous ocean scenes (match-ups) within 1° latitude x longitude boxes and within a ± 60 minute window. To ensure high quality comparison, these collocations were quality controlled and edited to remove non-homogenous ocean scenes and/or transient environmental conditions, including rain contamination. WindSat and QRad Tb's were averaged within 1° boxes and these were used for the radiometric inter-calibration analysis on a monthly basis. Results show that QRad calibrations are stable in the mean within ± 2K over the yearly seasonal cycle.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering PhD
4
Kuna, Zdeněk. „Detekce komplexů QRS v signálech EKG“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218655.
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This project considers methods of construction QRS detectors. It focus in detection complexes of QRS single leads and space speed, which are calculated from three orthogonal leads. In theory was refer to various methods, which lead to design detector. It were designed two algoritms (constant and adaptive detecting threshold), which were implemented into detector and the signal was preprocessed by Hilbert transformation. Toward algoritms were completed by modification, which improved detection effectivity. Function of algoritms were tested in all signals of CSE (V2,V5,aVF).
5
Zedníček, Vlastimil. „Detekce QRS založená na vlnkové transformaci“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220878.
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This thesis deals with implementation of detector QRS complex with use of wavelet transform. The first part is focused on formation and possibility to measure cardiac activity. The other part of thesis we will familiarise with the different possibilities of detection QRS complex and we intimately focus on wavelet transform that will be used for a project of detection QRS complex. The practical part of thesis focuses on the project of detector in programming language Matlab and his different setting. This projected detector has been tested with CSE database. Achieved results of projected detector are evaluated with the results of others authors.
6
Zhorný, Lukáš. „Detekce komplexů QRS v signálech EKG“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413175.
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This thesis deals with the detection of QRS complexes from electrocardiograms using time-frequency analysis. Detection procedures are based on wavelet and Stockwell transform. The theoretical part describes the basics of electrocardiography, then introduces common approaches to time-frequency analysis, such as short-time Fourier transform (STFT), wavelet transform and Stockwell transform. These algorithms were tested on a set of electrograms from the MIT-BIH and CSE-MO1 arrhythmia database. For the CSE database worked best the method based on the wavelet transform with the filter bank Symlet4, with the resulting value of sensitivity 100 % and positive predictivity 99.86%. For the MIT database had the best performance the detector using the Stockwell transform with values of sensitivity 99.54% and positive predictivity 99.68%. The results were compared with the values of other authors mentioned in the text.
7
Kocian, Ondřej. „Detekce komplexů QRS s využitím vlnkové transformace“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217974.
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This project investigates methods of construction the wavelet-based QRS-complex detector. QRS-complex detection is very important, because it helps automatically calculate heart rate and in some cases it is used for compression ECG signal. The design of QRS detector can be made with many methods, in this project were mentioned and consequently tested only a few variants. The principle of designed detector used a wavelet-based decomposition of the original ECG signal to several frequency-coded bands. These bands are consequently transformed to absolute values and with the help of the threshold value are marked positions of assumed QRS complexes. Then are these assumed positions from all bands compared between themselves. If the position is confirmed at least at one nearby band, then is this position marked as true QRS complex. To increase efficiency of designed detector, two modifications were additionally mentioned. The first one, using the envelope of the signal, had rather negative effect on detectors efficiency. The second modification, using combined signal from three pseudoorthogonal leads, had reversely very good effect on detectors efficiency. In the end, the designed detector and all its modifications were tested on signals from CSE library (exactly on leads II, V2 and V6).
8
Loviška, David. „Detekce QRS komplexu s využitím vlnkové transformace“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218652.
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The aim of diploma thesis named “QRS detection using wavelet transform” is to simplify and accelerate the work of doctors. This can be achieved by using application for QRS detection, which can use one of four proposed algorithms. Application shows basic informations about inserted electrocardiogram. Part of this program is a graphical window with displayed record and with coloured marks on detected QRS complexes. By another algorythm are marks color-coded due to accurancy percentil of every detected complex. This program is designed for a several hours record from Holter ECG monitoring.
9
Hanus, Rostislav. „Detekce QRS založená na počítání průchodů nulou“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219638.
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This master’s thesis deals with the detection of QRS complex detection using zero crossing counts. QRS detection is an important part of the analysis of ECG signal. From the point of determining the R wave detection is based on the other waves and intervals necessary for the diagnosis of heart. This method is very effective even for very noisy signals. Implementation of the method in Matlab, and the success of detection is tested on the CSE and MIT-BIH database. The optimization algorithm is an optional value for the detector.
10
Hylmar, Petr. „Detekce QRS založená na počítání průchodů nulou“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220865.
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This master's thesis describes basics principles of QRS complex detection. It is focused on QRS detection using zero crossing counts method. There are described princips and program realization of this method. The other part is focused on genetic optimalization algorithm. There are presented obtained optimalization results on standard CSE and MIT-BIH database. The quality of the detector is compared with other authors. The optimalized QRS detector achieves comparable results with other authors. The part of the thesis is graphical user interface which supply view on modified ECG signal and detection results.
11
Spáčil, Jakub. „Optimální detekce hranic QRS komplexu v EKG signálech“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218719.
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This diploma thesis deals with location optimal wavelet for detecton charakterics points of QRS complex in ECG signals. The first part of this thesis deals with description of heart, genesis of electric signals on heart and problem of noise. The second part describes the wavelet transform and the designed program and the third part evaluate detection results. The created program is working with 10 ECG signals from the CSE database and is testing 12 different mother wavelets. The program was developed in Matlab environment and is based on the finding zero-points in the transformed signal.
12
Hráček, Roman. „Softwarový balík pro frekvenční metody detekce QRS komplexu“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221390.
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13
Daňová, Ľudmila. „Automatická detekce srdečních patologií pomocí vysokofrekvenčních složek komplexu QRS“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-432856.
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The aim of this thesis is to analyse high-frequency ECG to detect some heart diseases. This is performed with averaging of selected QRS complexes for each lead of the signal; these are thenfilteredin range 500-1 000 Hz. After that the envelope of the signal is done and here the peaks are detected. Based on mutual positions of this peaks, it is possible to detectwhat kind od signal we treat.
14
Oliveira, Alexandre Tomazati. „Detecção do complexo QRS em sinais cardiacos utilizando FPGA“. [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264060.
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Orientador: Euripedes Guilherme de Oliveira NobregaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-15T01:47:19Z (GMT). No. of bitstreams: 1 Oliveira_AlexandreTomazati_M.pdf: 3226409 bytes, checksum: 06c44b66428a69ae6b8214fd07432ae6 (MD5) Previous issue date: 2009
Resumo: O eletrocardiograma (ECG) é uma ferramenta utilizada para o diagnóstico de cardiopatias e outras doenças. Este trabalho tem como objetivo a detecção do complexo QRS, com foco na onda R, que representa a contração dos ventrículos. Para isso, são apresentadas duas técnicas de processamento do sinal de ECG. A primeira utiliza o algoritmo proposto por Pan & Tompkins que consiste em um banco de filtros digitais. A segunda faz uso da transformada wavelet discreta, que permite a localização de características de sinais tanto no tempo quanto na frequência. É apresentado um comparativo da eficácia dos dois algoritmos com base na sua implementação através de FPGA, utilizando dois métodos, o processamento serial em microcontrolador programado em C e o paralelo inteiramente em VHDL, com o intuito de comparar os tempos de processamento. Os resultados sugerem que trabalhos futuros poderão ser baseados na investigação de outras famílias wavelets para a detecção do complexo QRS em sinais de ECG, bem como explorar outros métodos de implementação de filtros em FPGA.
Abstract: The electrocardiogram (ECG) is a tool used for diagnosis of diseases related to the heart. This work has the purpose of detecting QRS complex, focusing on the R wave, which represents the ventricles'contraction. It is presented two techniques of processing ECG signals. The first uses Pan & Tompkins algorithm based on digital filtering. The second uses the discrete wavelet transform, which represents the characteristics of the signal simultaneously in time and frequency. It is presented a comparison of the efficacy of both algorithms, which are implemented in FPGA, using serial processing based on a C programmed microcontroller, and parallel processing entirely in VHDL, with the purpose of comparing the time of processing. The results suggest that future work can be based on the investigation of other wavelets family for detecting QRS complex in ECG signals and other methods of implementing filters in FPGA.
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
15
Saraiva, Aratã Andrade. „Detecção do complexo QRS através de morfologia matemática multiescalar“. Universidade Tecnológica Federal do Paraná, 2012. http://repositorio.utfpr.edu.br/jspui/handle/1/437.
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Este trabalho apresenta a morfologia matemática multiescalar com quatro escalas aplicada no sinal de eletrocardiografia para a detecção do complexo QRS. Para o desenvolvimento deste trabalho pluridisciplinar de Engenharia Biomédica foram utilizados conhecimentos de Cardiologia, Eletrocardiografia, Bioestatística, Processamento Digital de Sinais Biomédicos, Teoria de Detecção de Sinais, Análise ROC e Índices de Desempenho de Classificadores, interagindo com áreas da edicina, da Estatística, da Matemática, da Engenharia da Computação e da Engenharia Elétrica. Testes foram realizados com o banco de sinais de ECG do MIT/BIH. O desempenho do método foi avaliado através da curva ROC e do índice DER. Os resultados foram comparados com a morfologia multiescalar de uma, duas e de três escalas. Nos resultados foi observado que o método de morfologia multiescalar com quatro escalas, aplicado nas condições estabelecidas, apresentou índices melhores de detecção do complexo QRS, confirmando seu potencial no processamento de sinais biomédicos, dando suporte na manipulação do complexo QRS e oferecendo melhorias na detecção.This work presents the multiscale mathematical morphology with four scales applied in the ECG signal for detection of the QRS complex. To develop this Biomedical Engineering multidisciplinary work were used knowledge of Cardiology, Electrocardiography, Biostatistics, Biomedical Digital Signal Processing, Signal Detection Theory, ROC Analysis and Performance Classifiers Indexes, interacting with areas of Medicine, Statistics, Mathematics, Computer Engineering and Electrical Engineering. The tests were realized with MIT/BIH ECG signals database. The performance of the method was evaluated using ROC curves and the DER index. The results were compared with the multiscale mathematical morphology of one, two and three scales. In the results was observed that the multiscale mathematical morphology with four scales presented better indexes detection of the QRS complex, confirming its potential in biomedical signal processing, supporting the handling of the QRS complex and offering improvements in detection.
16
Daňová, Ľudmila. „Automatická detekce srdečních patologií pomocí vysokofrekvenčních složek komplexu QRS“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442483.
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The aim of this thesis is to analyse high-frequency ECG to detect some heart diseases. This is performed with averaging of selected QRS complexes for each lead of the signal; these are then filtered in range 500-1 000 Hz. After that the envelope of the signal is done and here the peaks are detected. Based on mutual positions of this peaks, it is possible to detect what kind od signal we treat.
17
Engström, Magnus, und Nadia Soheily. „EKG-analys och presentation“. Thesis, KTH, Data- och elektroteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154539.
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Tolkningen av EKG är en viktig metod vid diagnostisering av onormala hjärttillstånd och kan användas i förebyggande syfte att upptäcka tidigare okända hjärtproblem. Att enkelt kunna mäta sitt EKG och få det analyserat och presenterat på ett pedagogiskt sätt utan att behöva rådfråga en läkare är något det finns ett konsumentbehov av. Denna rapport beskriver hur en EKG-signal behandlas med olika algoritmer och metoder i syfte att detektera hjärtslag och dess olika parametrar. Denna information används till att klassificera varje hjärtslag för sig och därmed avgöra om användaren har en normal eller onormal hjärtfunktion. För att nå dit har en mjukvaruprototyp utvecklats där algoritmerna implementerats. En enkätundersökning gjordes i syfte att undersöka hur utdata från mjukvaruprototypen skulle presenteras för en vanlig användare utan medicinsk utbildning. Sju filer med EKG-signaler från MIT-BIH Arrhythmia Database användes för testning av mjukvaruprototypen. Resultatet visade att prototypen kunde detektera en rad olika hjärtfel som låg till grund vid fastställning om hjärtat slog normalt eller onormalt. Resultatet presenterades på en mobilapp baserad på enkätundersökningen.The interpretation of the ECG is an important method in the diagnosis of abnormal heart conditions and can be used proactively to discover previ-ously unknown heart problems. Being able to easily measure the ECG and get it analyzed and presented in a clear manner without having to consult a doctor is improtant to satisfy consumer needs. This report describes how an ECG signal is treated with different algo-rithms and methods to detect the heartbeat and its various parameters. This information is used to classify each heartbeat separately and thus determine whether the user has a normal or abnormal cardiac function. To achieve this a software prototype was developed in which the algorithms were implemented. A questionnaire survey was done in order to examine how the output of the software prototype should be presented for a user with no medical training. Seven ECG files from MIT-BIH Arrhythmia database were used for validation of the algorithms. The developed algorithms could detect of if any abnormality of heart function occurred and informed the users to consult a physician. The presentation of the heart function was based on the result from the questioner.
18
Price, Nicholas F. „Deriving the Time-Course of the Dominant Frequency of Atrial Fibrillation from a Long Term in vivo Sheep Model using QRST Removal Techniques“. University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1319763800.
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19
Koc, Bengi. „Detection And Classification Of Qrs Complexes From The Ecg Recordings“. Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12610328/index.pdf.
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Electrocardiography (ECG) is the most important noninvasive tool used for diagnosing heart diseases. An ECG interpretation program can help the physician state the diagnosis correctly and take the corrective action. Detection of the QRS
complexes from the ECG signal is usually the first step for an interpretation tool. The main goal in this thesis was to develop robust and high performance QRS detection algorithms, and using the results of the QRS detection step, to classify these beats according to their different pathologies. In order to evaluate the performances, these algorithms were tested and compared in Massachusetts Institute of Technology Beth Israel Hospital (MIT-BIH) database, which was developed for research in cardiac electrophysiology.
In this thesis, four promising QRS detection methods were taken from literature and implemented: a derivative based method (Method I), a digital filter based method (Method II), Tompkin&rsquos method that utilizes the morphological features of the ECG signal (Method III) and a neural network based QRS detection method (Method IV). Overall sensitivity and positive predictivity values above 99% are achieved with each method, which are compatible with the results reported in literature. Method III has the best overall performance among the others with a sensitivity of 99.93% and a positive predictivity of 100.00%. Based on the detected QRS complexes, some features were extracted and classification of some beat types were performed. In order to classify the detected beats, three methods were taken from literature and implemented in this thesis: a Kth nearest neighbor rule based method (Method I), a neural network based method (Method II) and a rule based method (Method III). Overall results of Method I and Method II have sensitivity values above 92.96%. These findings are also compatible with those reported in the related literature. The classification made by the rule based approach, Method III, did not coincide well with the annotations provided in the MIT-BIH database. The best results were achieved by Method II with the overall sensitivity value of 95.24%.
20
Aro, A. (Aapo). „Electrocardiographic risk markers of sudden cardiac death in middle-aged subjects“. Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526201795.
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Abstract Sudden cardiac death (SCD) is a major medical and public health concern responsible for 50% of cardiovascular deaths and as much as 15% to 20% of overall mortality. Coronary heart disease is the underlying cause of most of these deaths, and in 50% of such cases, SCD is the first manifestation of the disease. Researchers have investigated numerous noninvasive methods to more accurately identify individuals at high risk of SCD, but most such studies have focused on patients with specific heart disease. The standard 12-lead electrocardiogram (ECG) is a widely available tool to analyze the electrical activity of the heart, but few epidemiological studies have successfully identified specific electrocardiographic risk markers of SCD at the population level. This thesis aims to clarify the prognostic implications of several ECG patterns in the general population. We evaluated the 12-lead ECGs of 10899 middle-aged Finnish subjects (52% male) recorded between 1966 and 1972, and followed the subjects for 30 ± 11 years. The prevalence of a prolonged QRS duration ≥ 110 ms and nonspecific intraventricular conduction delay (IVCD; defined as QRS ≥ 110 ms with no partial or complete bundle branch block) in the population was 1.3% and 0.6%, respectively. Both were significantly associated with an elevated risk of all-cause mortality and cardiovascular mortality. QRS duration ≥ 110 ms doubled the risk of SCD, and IVCD was associated with a three-fold higher risk of SCD. Two percent of the subjects presented with wide frontal QRS-T angle ≥ 100° (the angle between the QRS axis and the T-wave axis in the frontal plane). A wide QRS-T angle was associated with higher overall mortality and more than doubled the risk of SCD, which was mainly due to an abnormal T-wave axis. Inverted T-waves in the right precordial leads (V1–V3) or beyond were present in 0.5% of the population. No increase in mortality or SCD was associated with right precordial T-wave inversions. In contrast, inverted T-waves in other leads than V1–V3 were associated with higher risk of cardiovascular mortality and SCD. Altogether 2.1% of the study participants presented with a prolonged PR interval > 200 ms. No rise in overall mortality, SCD, or hospitalizations due to heart failure, atrial fibrillation, or stroke was observed among these subjects during the follow-up period. In conclusion, of the electrocardiographic parameters studied, prolonged QRS duration, IVCD, and wide QRS-T angle are associated with SCD in the general population, and such changes in an ECG should therefore alert the physician to more closely evaluate and follow the patient. On the other hand, a prolonged PR interval and right precordial T-wave inversions seem to have no prognostic implications in the absence of other features suggestive of underlying heart diseaseTiivistelmä Sydänperäinen äkkikuolema on yleisin kuolinsyy länsimaissa, missä puolet sydänkuolemista ja 15–20 % kokonaiskuolleisuudesta johtuu äkillisestä sydänpysähdyksestä. Sepelvaltimotauti on yleisin taustalla oleva syy, ja jopa puolessa sepelvaltimotautikuolemista äkkikuolema on taudin ensimmäinen oire. Jo pitkään on yritetty kehittää menetelmiä, joilla voitaisiin tunnistaa suurimmassa äkkikuoleman vaarassa olevat. 12-kanavainen EKG on laajalti käytössä oleva tutkimus, jolla tutkitaan sydämen sähköistä toimintaa, mutta sydänperäistä äkkikuolemaa spesifisti väestössä ennustavia EKG-poikkeavuuksia ei ole juuri pystytty osoittamaan. Tämän väitöskirjatyön tarkoituksena oli tutkia, miten EKG:ssä nähtävät ilmiöt kuten QRS kompleksin kesto, QRS-kompleksin ja T-aallon välinen kulma, kääntyneet T-aallot sekä PR-aika korreloivat ennusteeseen väestötasolla. Tutkimme 10899 suomalaisen keski-ikäisen henkilön (52 % miehiä) EKG:t, jotka oli rekisteröity 1966–1972, ja seurasimme tutkittavia keskimäärin 30 (± 11) vuotta. Leventynyt QRS kompleksi ≥ 110 ms löytyi 1.3 %:lta ja epäspesifi kammionsisäinen johtumishäiriö eli IVCD (QRS ≥ 110 ms ilman osittaista tai täydellistä haarakatkosta) 0.6 %:lta tutkituista. Molemmat muutokset liittyivät lisääntyneeseen kokonaiskuolleisuuteen sekä sydänkuoleman riskiin. QRS kompleksin kesto ≥ 110 ms assosioitui lisäksi kaksinkertaiseen ja IVCD kolminkertaiseen äkkikuolemariskiin. 2 %:lla tutkituista sydänlihaksen depolarisaation suuntaa kuvaavan QRS-kompleksin akselin ja repolarisaatiota kuvaavan T-aallon akselin välinen frontaalitason QRS-T kulma oli leveä ≥ 100°. Näillä henkilöillä kokonaiskuolleisuus oli lisääntynyt, ja sydänperäisen äkkikuoleman riski oli yli kaksinkertainen verrattuna henkilöihin jolla QRS-T kulma oli < 100°. Oikeanpuoleisissa rintakytkennöissä V1–V3 todettiin negatiiviset T-aallot 0.5 %:lla tutkituista, mutta näillä ei ollut vaikutusta kuolleisuuteen. Sen sijaan henkilöillä, joilla todettiin negatiiviset T-aallot muissa kytkennöissä, oli yli kaksinkertainen sydänkuoleman ja äkillisen sydänpysähdyksen vaara muihin tutkittuihin verrattuna. Osallistujista 2.1 %:lla todettiin pidentynyt PR-aika > 200 ms. Tämä ei kuitenkaan vaikuttanut henkilöiden kuolleisuuteen eikä sydämen vajaatoiminnasta, eteisvärinästä tai aivoverenkiertohäiriöistä johtuvien sairaalahoitojen määrään. Tutkituista EKG:n poikkeavuuksista siis pidentynyt QRS-kompleksin kesto, IVCD ja leveä QRS-T kulma liittyvät selvästi lisääntyneeseen äkillisen sydänpysähdyksen riskiin. Sen sijaan pidentynyt PR-aika tai T-inversiot oikeanpuoleisissa rintakytkennöissä ilman muuta viitettä sydänsairaudesta eivät vaikuta ennusteeseen keski-ikäisessä väestössä
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Heczko, Marian. „Analýza EKG signálů“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-218152.
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The topic of this master's thesis is the analysis of ECG signals using wavelet transform. In the introductory chapters there is a brief description of heart anatomy, the emergence and spread of potentials, which evocating activities of myocardium. There is an overview of techniques used for ECG signals analysis and explanation of ECG curve diagnostic importance. Work also containts an ECG signal analysis common procedure explanation and different approaches brief overview. The main part of this work is an application detecting significant intervals in the ECG signal, developed in Matlab. In several chapters the detection procedure is described in more details and gave reasons for chosen methods. In the last chapter there is a preview of several signals as a result of developed application, together with evaluation of the tests carried out at the CSE database. Detector sensitivity was quantified over 99,10%.
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Ieong, Chio In. „ECG QRS complex detection with programmable hardware = 心電圖QRS複合波檢測算法及可編程器件實現“. Thesis, University of Macau, 2008. http://umaclib3.umac.mo/record=b1939516.
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Syed, Shah Nemath Farhan. „IMPLEMENTATION OF INTERACTIVE REMOTE PHYSIOLOGICAL MONITORING AND FEEDBACK TRAINING SYSTEM“. University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1164666232.
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Gao, Qiang. „A FPGA based low-cost high speed QRD-RLS array processing“. Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=16922.
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Over the last 30 years, Digital Signal Processing algorithm implementation has been driven by the continued progress and availability of high speed FPGA/ASIC circuit technology. The classic method of CORDIC (Coordinate Rotation DIgital Computer) arithmetic has been widely implemented as part of the computational requirements of the well known QR decomposition - Recursive Least Squares (RLS) algorithm. This thesis presents a novel FPGA implementation of a complex arithmetic valued QR decomposition which can function in adaptive filter applications and implement the adaptive filter weight extraction without using the traditional back-substitution method. In order to operate Givens rotation on a complex valued system, Double Angle Complex Rotation (DACR) is adopted to simplify the computational requirement of the classic Complex Givens Rotation (CGR). A new modified ‘processor-like’ architecture of a DACR based QR-RLS is presented. It features a single arithmetic Processing Element (PE) that has been extensively pipelined and efficiently shared for the implementation of the Givens transform associated with the QR algorithm. Annihilation-Reordering look-ahead Transformation (ART) was used to pipeline and hence speed up the real valued QR-RLS adaptive signal processing array without changing the filter’s convergence behavior. This thesis extends the ART technique to cope with a complex valued QR-RLS computation array, results in a novel Complex valued Annihilation-Reordering look-ahead Transformation (C-ART). The complex Givens rotation implemented in CORDIC arithmetic is suitable for the cut-set pipelining thus increasing the throughput.
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Bergenholm, Linnéa. „Predicting QRS and PR interval prolongations in humans using nonclinical data“. Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/92121/.
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Risk of cardiac conduction slowing (QRS/PR interval prolongations in monitored electrocardiograms) is assessed in nonclinical studies, where the current AstraZeneca strategy involves ensuring high margins to in vitro effects and statistical tests to identify in vivo effects. This thesis aims to improve QRS/PR risk assessment using pharmacokinetic-pharmacodynamic modelling for describing QRS/PR effects and evaluating translation to human effects. Data for six compounds were collected from the literature and previously performed in vitro (sodium/calcium channel), in vivo (guinea pig/dog) and clinical AstraZeneca studies. Mathematical models were developed and evaluated to describe and compare effects across compounds and species. Key results were that proportional drug effect models often suffice for small QRS/PR changes (up to 20%), while larger effects require nonlinear models. Heartrate correction and circadian rhythm models reduced residuals primarily for describing baseline PR intervals, with highest impact in humans followed by dogs and guinea pigs. Meaningful (10%) human QRS/PR changes correlated to low levels of sodium channel block (3-7%) and calcium channel binding (13-21%) and to small effects in guinea pigs and dogs (QRS 2.3-4.6% and PR 2.3-10%). This suggests that worst case human effects can be predicted by assuming four times greater effects at the same concentration from dog/guinea pig. Small changes in vitro and in vivo consistently translate to meaningful PR/QRS changes in humans across compounds. Accurate characterisation of concentration-effect relationships therefore require a model-based approach. Although the presented work is limited by the small number of investigated compounds, it provides a starting point for predicting human risk using routine QRS/PR data to improve the safety of new drugs.
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Oliveira, Francisco Ivan de. „Transformada de Hilbert Sobre Bases de Wavelets: DetecÃÃo de Complexos QRS“. Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8599.
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nÃo hÃA tarefa mais importante em processamento de sinais de eletrocardiograma (ECG) à a determinaÃÃo exata do complexo de QRS, em particular, a detecÃÃo dos picos de onda R atravÃs de sistemas e anÃlises computadorizadas. à essencial, especialmente, para uma medida correta da variabilidade do ritmo cardÃaco (HRV). Um grande obstÃculo a ser superado para uma detecÃÃo confiÃvel à a sensibilidade do eletrocardiograma a diversas fontes de distÃrbio, tais como, a interferÃncia à rede elÃtrica, os artefatos do movimento, flutuaÃÃo da linha base e o ruÃdo dos mÃsculos. Este trabalho utiliza as propriedades matemÃticas da transformaÃÃo de Hilbert sobre wavelets para desenvolver um novo algoritmo capaz de diferenciar as ondas R das demais (P, Q, S, T e U) e facilitar a detecÃÃo dos complexos QRS. Uma taxa de detecÃÃo do complexo QRS de 99,92% à alcanÃada para a base de dados de arritmias do MIT-BIH. A tolerÃncia a ruÃdo do mÃtodo proposto foi tambÃm testada usando os registros padrÃo da base de dados MIT-BIH Noise Stress Test. A taxa da detecÃÃo do detector ficou aproximadamente 99,35% mesmo para as relaÃÃes sinal-ruÃdo (SNR) tÃo baixo quanto 6dB.
The most important task in the ECG signal processing is the accurate determina-tion of QRS complex, in particular, accurate detection of the R wave peaks, is essential in computer-based ECG analysis especially for a correct measurement of Heart Rate Variability (HRV). A great hurdle to be overcome in reliable detection is the sensibility of the electrocar-diogram to several disturbance sources such as powering source interference, movement arti-facts, baseline wandering and muscle noise. This study uses the Hilbert Transform pairs of wavelet bases for QRS detection. From the properties of these mathematical tools it was pos-sible to develop an algorithm which is able to differentiate the R waves from the others (P, Q, S, T and U waves).The performance of the algorithm was verified using the records MIT-BIH arrhythmia and normal databases. A QRS detection rate of 99.92% was achieved against MIT-BIH arrhythmia database. The noise tolerance of the proposed method was also tested using standard records from the MIT-BIH Noise Stress Test Database. The detection rate of the detector remains about 99.35% even for signal-to-noise ratios (SNR) as low as 6dB.
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Zanfelici, Tatiane Oliveira. „Validação do Questionnaire on Resources and Stress - Short Form (QRS-F)“. Universidade Federal de São Carlos, 2013. https://repositorio.ufscar.br/handle/ufscar/2917.
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Previous issue date: 2013-07-31Universidade Federal de Sao Carlos
Family members of people with disabilities may be exposed to various stressors, among them the disability itself, becoming potential targets of stress. In this context, several models have been designed for the study of stress, among which highlights the Cognitive Assessment and the ABC-X, which comprise the coping strategies as a way to mediate the perception of stressors. Researches conducted with several family members have pointed out that the constant stress can lead to more roughness family relationships, and fewer opportunities for stimulation of child development, which contribute to enhance family relationships with any child, including those with disabilities. For the evaluation of the parental stress variable, studies show the use of different instruments, including the Questionnaire on Resources and Stress - QRS-F which stand out for being directed especially to families of children with disabilities and chronic illnesses. Given the above, this study proposed two objectives: 1) the cross-cultural adaptation of the QRS-F, since the translations available in Brazil do not have this treatment, or definitely modified the structure of the questionnaire, 2) a study of the evidence of psychometric validity of the instrument . The first study involved five independent translators, five professionals on the thematic area of the instrument and seven relatives of people with autism. The questionnaire underwent procedures of translation and retranslation, as well translations adjustments, resulting in altered or partially altered. The evaluation of the expert committee regarding the relevance of the questions in the conceptual levels, language and experimental indicated substantial kappa at all levels of assessment, indicating that the translation was adequate for the pilot application. The second study involved 57 mothers, fathers, grandparents and sister of children with and without various disabilities. Their analyzes showed significant correlations with the measure of stress obtained by Symptom Inventory Lipp Stress and the instrument that assessed coping resources, the Coping Strategies Inventory, indicating associations with the dimensions of the QRS-F Parental Problems, Pessimism and Physical Incapacity . The reliability coefficient obtained by the proof of Kuder-Richardson pointed a ratio considered adequate (KR-20 = .64). The test criterion validity indicated higher scores related to the dimension of the QRS-F called Pessimism, when compared groups of respondents relatives of people with and without various disabilities. It was considered that this version of the QRS-F, now called Questionnaire of Resources and Stressors, possesses the attributes necessary to be considered a valid tool in research in the area of parental stress in Brazil. It is suggested to do a further study, covering a broader sample of respondents, which allow the realization of more sophisticated analyzes, but indispensable for the consolidation of this instrument.
Membros de famílias de pessoas com deficiências podem estar expostos a vários estressores, dentre os quais as necessidades desencadeadas pelas próprias condições, tornando-se alvos potenciais de situações de estresse. Neste contexto, diversos modelos foram concebidos para o estudo do estresse, dentre os quais se destaca a Avaliação Cognitiva e o ABC-X, os quais compreendem as estratégias de enfrentamento como uma maneira de se mediar a percepção dos estressores. Pesquisas realizadas com diversos membros da família tem apontado que o estresse constante pode conduzir a relações familiares de mais aspereza, bem como menores oportunidades de estimulação do desenvolvimento infantil, às quais contribuem para potencializar a relações familiares com qualquer criança, inclusive aquelas com deficiências. Para a avaliação da variável estresse parental, as pesquisas apontam o emprego de variados instrumentos, dos quais o Questionnaire on Resources and Stress QRS-F se destaca por direcionar-se especialmente às famílias de crianças com deficiências e doenças crônicas. Diante do exposto, este estudo propôs dois objetivos: 1) a adaptação transcultural do QRS-F, visto que as traduções disponíveis no Brasil não possuem esse tratamento, ou modificaram definitivamente a estrutura do questionário; 2) um estudo das evidências de validade psicométricas do instrumento. Participaram do primeiro estudo cinco tradutores independentes, cinco profissionais da área temática do instrumento e sete familiares de pessoas com autismo. O questionário passou por procedimentos de tradução e retradução, bem como ajuizamento das traduções, resultando em traduções alteradas ou parcialmente alteradas. A avaliação do comitê de especialistas quanto à pertinência das questões nos níveis conceituais, idiomáticos e experimentais indicou kappa substancial em todos os níveis de avaliação, indicando que a tradução estava adequada para a aplicação piloto. No segundo estudo, participaram 57 mães, pais, avós e irmã de crianças com e sem variadas deficiências. Suas análises indicaram correlações significativas com a medida de estresse obtidas pelo Inventário de Sintomas de Stress de Lipp e o instrumento que avaliou recursos de coping, o Inventário de Estratégias de Enfrentamento, indicando associações com as dimensões do QRS-F Problemas Parentais, Pessimismo e Incapacidade Física. O coeficiente de fidedignidade obtido pela prova de Kuder-Richardson apontou um índice considerado adequado (KR-20 = 0,64). O teste de validade de critério indicou maiores pontuações especialmente quanto à dimensão do QRS-F denominada Pessimismo, quando comparados os grupos de respondentes familiares de pessoas com e sem variadas deficiências. Considerou-se que esta versão do QRS-F, agora denominada Questionário de Recursos e Estressores, possui os atributos necessários para ser considerado um instrumento válido em pesquisa na área de estresse parental no Brasil. Sugere-se a realização de estudos posteriores que contemplem uma amostra mais ampla de respondentes, os quais possibilitem a realização de análises mais sofisticadas, porém indispensáveis para a consolidação deste instrumento.
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Oliveira, Francisco Ivan de. „Transformada de Hilbert sobre bases de wavelets: detecção de complexos QRS“. reponame:Repositório Institucional da UFC, 2007. http://www.repositorio.ufc.br/handle/riufc/4068.
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OLIVEIRA, F. I. de. Transformada de Hilbert sobre bases de wavelets: detecção de complexos QRS. 2007. 210 f. Dissertação (Mestrado em Teleinformática) - Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2007.Submitted by Marlene Sousa (mmarlene@ufc.br) on 2012-11-23T11:47:08Z No. of bitstreams: 1 2007_dis_fideoliveira.pdf: 5612143 bytes, checksum: d20cfac31f2621246c16a921784765e1 (MD5)
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The most important task in the ECG signal processing is the accurate determina-tion of QRS complex, in particular, accurate detection of the R wave peaks, is essential in computer-based ECG analysis especially for a correct measurement of Heart Rate Variability (HRV). A great hurdle to be overcome in reliable detection is the sensibility of the electrocar-diogram to several disturbance sources such as powering source interference, movement arti-facts, baseline wandering and muscle noise. This study uses the Hilbert Transform pairs of wavelet bases for QRS detection. From the properties of these mathematical tools it was pos-sible to develop an algorithm which is able to differentiate the R waves from the others (P, Q, S, T and U waves).The performance of the algorithm was verified using the records MIT-BIH arrhythmia and normal databases. A QRS detection rate of 99.92% was achieved against MIT-BIH arrhythmia database. The noise tolerance of the proposed method was also tested using standard records from the MIT-BIH Noise Stress Test Database. The detection rate of the detector remains about 99.35% even for signal-to-noise ratios (SNR) as low as 6dB.
A tarefa mais importante em processamento de sinais de eletrocardiograma (ECG) é a determinação exata do complexo de QRS, em particular, a detecção dos picos de onda R através de sistemas e análises computadorizadas. É essencial, especialmente, para uma medida correta da variabilidade do ritmo cardíaco (HRV). Um grande obstáculo a ser superado para uma detecção confiável é a sensibilidade do eletrocardiograma a diversas fontes de distúrbio, tais como, a interferência à rede elétrica, os artefatos do movimento, flutuação da linha base e o ruído dos músculos. Este trabalho utiliza as propriedades matemáticas da transformação de Hilbert sobre wavelets para desenvolver um novo algoritmo capaz de diferenciar as ondas R das demais (P, Q, S, T e U) e facilitar a detecção dos complexos QRS. Uma taxa de detecção do complexo QRS de 99,92% é alcançada para a base de dados de arritmias do MIT-BIH. A tolerância a ruído do método proposto foi também testada usando os registros padrão da base de dados MIT-BIH Noise Stress Test. A taxa da detecção do detector ficou aproximadamente 99,35% mesmo para as relações sinal-ruído (SNR) tão baixo quanto 6dB.
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Ondráček, Vladimír. „Měření QT intervalu v elektrokadiografických záznamech“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218650.
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This diploma thesis focuses on determination of the QT interval in ECG. The thoretical part desribes physiology of the heart, electronic activity of the heart and possible methods of ECG measurement. The theoretical part also describes methods of signal processing, the processed signal is then used for determination of the QT interval. The practical part focuses on two chosen methods of QT interval determination and on implementation of the methods in a computer program. The results part is evaluation of measured QT intervals and a comparision of the results with reference values.
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Lambert, Olivier. „Elargissement progressif du complexe q. R. S a l'effort“. Nancy 1, 1992. http://www.theses.fr/1992NAN1A004.
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Cheng, Pak-ho, und 鄭柏濠. „P wave characteristics and QRS duration in patients after Fontan-type procedures“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B43781627.
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Cheng, Pak-ho. „P wave characteristics and QRS duration in patients after Fontan-type procedures“. Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43781627.
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Dobos, Rebecca. „Extremitetelektrodernas inverkan på QRS-amplituden och den elektriska axeln i ett elektrokardiogram“. Thesis, Örebro universitet, Institutionen för hälsovetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-69414.
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Janjarasjitt, Suparerk. „A NEW QRS DETECTION AND ECG SIGNAL EXTRACTION TECHNIQUE FOR FETAL MONITORING“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1144263231.
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Andrade, Cândido Moreira. „O modelo QRSP para a quantificação do risco na saída de veículos da pista em rodovias“. Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18144/tde-10112011-172114/.
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Uma parcela significativa dos acidentes de trânsito nas rodovias ocorre devido à saída de veículos da pista, o que pode resultar em choques com obstáculos fixos, quedas em espaços vazios, tombamento, capotagem, etc. Esse tipo de acidente é, em geral, grave, em razão das altas velocidades desenvolvidas nas rodovias. Cerca de 1/3 dos acidentes rodoviários com vítimas fatais nos Estados Unidos resultam de saída de pista. No Brasil, estima-se que 30% dos acidentes rodoviários estão relacionados com saída da pista, sendo esse valor da ordem de 25% nos casos dos acidentes com vítimas fatais. Neste trabalho é apresentado o Modelo QRSP (formado pelas letras iniciais das palavras: Quantificação - Risco - Saída - Pista) em rodovias. O modelo permite quantificar o nível de proteção existente em cada segmento particular da rodovia (análise microscópica) e, a partir dessa informação, quantificar o nível de proteção considerando trechos longos (análise macroscópica). No modelo desenvolvido, a avaliação é feita considerando separadamente os dois lados da pista (direito e esquerdo), podendo os resultados serem compostos no caso da quantificação de trechos longos. O modelo foi desenvolvido para o caso de rodovias de múltiplas faixas por sentido (denominadas comumente de pista dupla), podendo, no entanto, também ser empregado no caso das rodovias de duas faixas e duplo sentido (rodovias de pista simples). O modelo QRSP permite determinar parâmetros não fornecidos pelos métodos ABNT (2007) - norma brasileira - e AASHTO (2002) - norma americana, proporcionando, dessa forma, uma melhor quantificação do risco na saída de veículos da pista. A análise dos resultados fornecidos pelo modelo QRSP mostra que o mesmo representa a realidade de maneira satisfatória. As informações quantitativas fornecidas pelo modelo são de grande utilidade na elaboração de projetos de melhoria das características das laterais de rodovias existentes, bem como na preparação de projetos de novas rodovias.A significant portion of road traffic accidents on highways occurs because of the exit of vehicles from the runway, which may result in collisions with fixed obstacles, falls in empty spaces, overturning, roll over, etc. This kind of accident is in general quite severe, due to the high speeds on highways. Approximately one third of road accidents with fatalities in the United States result from the runway exit. In Brazil, it is estimated that 30% of road accidents are also related to the runway exit, bringing this value at 25% in the cases of accidents with fatal victims. The QRRE that stands for Quantification the Risk in the Runway Exit of vehicles on highways is presented in this research. The model allows to quantify the level of protection in each particular segment of the highway (microscopic analysis) and from this information, it permits to quantify the level of protection considering long segments (macroscopic analysis). In the developed model, the assessment is done considering separately the left and right sides of the runway, and the results can be compounded in the case of long segments quantification. The model was developed for the case of multilanes highways in each direction, however, this model can also be used in the case of two lanes highways with two-ways direction. The QRRE model allows to determine parameters that are not provided by the methods ABNT (2007) - Brazilian standard, - and AASHTO (2002) - American standard, which provides a better measurement of risk in the exit of vehicles from the runway. The results obtained by QRRE model show that it clearly represents the reality. The quantitative information provided by the model are useful for the development of projects in order to improve the characteristics of the roadside highways available, and the development of projects for new highways.
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Qbeia, Safaa. „Jämförelse mellan två mätmetoder för qrs-duration i vila och maxbelastning vid arbetsprov“. Thesis, Malmö universitet, Fakulteten för hälsa och samhälle (HS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-42928.
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Elektrokardiografi är en medicinsk teknik som används för att registrera hjärtats elektriska aktivitet. QRS-tiden avspeglar hur snabbt kammarmuskulaturen depolariseras. QRS-tiden mäts från början av Q-vågen till slutet av S-vågen och har ett normalt värde som ligger på <120 millisekunder (ms) hos vuxna. Ett breddökat QRS-komplex (>120 ms) kan uppstå på grund av defekta retledningsbanor som vänstersidigt skänkelblock/högersidigt skänkelblock då kammarnas depolarisation sker långsammare. QRS-tiden kan även förlängas vid användning av vissa antiarytmiska läkemedel som Tambocor. Många studier har visat att Tambocor kan medföra en viss QRS-breddökning vid fysisk ansträngning. QRS-breddökning är en avgörande prognostisk markör för Tambocor-utsättning eller dosjustering då en förlängd QRS-tid kan leda till livshotande arytmier såsom ventrikelflimmer. I studien utfördes QRS-mätningar på friska patienter, patienter med Tambocor-behandling och patienter med vänstersidigt/högersidigt skänkelblock. Syftet med studien var att undersöka om QRS-tiden i vila och maxbelastning vid arbetsprov skiljer sig statistiskt och kliniskt åt när mätning sker med två olika metoder. QRS-mätning med båda metoderna utfördes digitalt via ECView program. Metod 1 baserade på att välja ett QRS-komplex som ser bredast ut och har bra teknisk kvalitet för att kunna mäta på. Metod 2 baserade på att mäta på avledningen som har tidigast Q och på avledningen som har senast S. Resultatet visade en stark positiv korrelation mellan metoderna både i vila och vid maxbelastning. One sample T test visade att metod 2 ger signifikant högre värde än metod 1. Bland-Altman diagram visade en god överenstämmelse mellan metoderna. Resultatet visade även att det kliniska beslutet för medicinutsättning/dosjustering hade påverkats hos två patienter med Tambocor-behandling beroende på vilken metod som används. Slutsatsen är att metoderna skiljer sig signifikant åt och fler studier behövs för att bekräfta om skillnaden är klinisk signifikant
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Klingspor, Måns. „Hilbert Transform : Mathematical Theory and Applications to Signal processing“. Thesis, Linköpings universitet, Matematik och tillämpad matematik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-122736.
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The Hilbert transform is a widely used transform in signal processing. In this thesis we explore its use for three different applications: electrocardiography, the Hilbert-Huang transform and modulation. For electrocardiography, we examine how and why the Hilbert transform can be used for QRS complex detection. Also, what are the advantages and limitations of this method? The Hilbert-Huang transform is a very popular method for spectral analysis for nonlinear and/or nonstationary processes. We examine its connection with the Hilbert transform and show limitations of the method. Lastly, the connection between the Hilbert transform and single-sideband modulation is investigated.
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GOMES, Gabriel de Souza Pereira. „Uma solução embarcada leve para localização de complexos QRS e filtragem ECG utilizando wavelets“. reponame:Repositório Institucional da UNIFEI, 2018. http://repositorio.unifei.edu.br/xmlui/handle/123456789/1652.
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Este trabalho é parte do projeto FINEP sob o convênio 01.13.0387, cujo objetivo geral é a construção de um microssistema de eletrocardiografia portátil de baixo custo para monitoramento remoto. Dentro desse contexto, a dissertação aqui apresentada propõe uma solução leve (uma vez que pode ser implementada em um arduino sem necessidade de memória extra), fundamentada em wavelet e análise de limiar para filtragem de sinais ECG e detecção de complexos QRS em sistemas embarcados de monitoramento de sinais eletrocardiográficos. O algoritmo desenvolvido requer menos recursos computacionais (por exemplo, não requer unidade de ponto flutuante) e, mesmo assim, mantém um alto nível de precisão (99,2%) e alta robustez quando comparado com soluções similares. O método foi avaliado primeiramente utilizando a base de dados padrão de arritmia do MIT BIH (Instituto de Tecnologia de Massachussets Hospital Beth Israel) e depois implementado na placa BlackHeart, que é o hardware desenvolvido no projeto no qual este trabalho se enquadra, sendo ele composto por uma placa baseada em um microcontrolador Arduino Leonardoc, contando também com uma interface de eletrododo. O método aqui apresentado foi validado e comparado a três outros algoritmos, sendo um deles o famoso método de Pan-Tompkins.
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Oliveira, Bruno Rodrigues de [UNESP]. „Deteccão de complexos QRS em eletrocardiogramas baseada na decomposição em valores singulares em multirresolução“. Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/134101.
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000857500.pdf: 4743253 bytes, checksum: da5d2724b71f588ae56be27cfaf9a5bd (MD5)O Eletrocardiograma (ECG) e um exame de extrema importância para avaliar a saúde do coração de um individuo. A analise de seu traçado possibilita diagnosticar uma serie de doenças e anomalias. Para isso, sistemas computacionais precisam segmentar os sinais de ECG, cujo primeiro passo e a detecção dos complexos QRS (ondas Q, R e S). Mui- tos métodos tem sido propostos para tal finalidade. Os primeiros utilizavam técnicas de filtragem e diferenciação, mas recentemente alguns pesquisadores tem concebido metodologias baseadas na analise de multirresolução da transformada Wavelet. Seguindo caminho semelhante, neste trabalho e proposta uma metodologia baseada na decomposição em valores singulares em multirresolução (MRSVD), para solução do problema de detecção dos complexos QRS de um sinal de ECG, que pode ser dividida em quatro etapas essenciais: pré-processamento, inspeção, decisão e correção. Em quase todas elas ha implementações inovadoras: na primeira utiliza-se, de forma inédita, a MRSVD; na segunda etapa exploram-se características fisiológicas do músculo cardíaco para certificar-se de que um determinado segmento compreende ou não uma onda R autentica; na ultima, são corrigidas as detecções baseadas nas amplitudes das ondas R. A avaliação da qualidade de detecção, para os experimentos realizados, mostra que o algoritmo proposto atingiu taxa de previsibilidade de 99, 20%, taxa de sensibilidade de 99, 70% e erro de apenas 1,10%, contra 97, 10%, 99, 00% e 3, 70%, respectivamente, obtidas por outro método
The electrocardiogram (ECG) is a test of utmost importance to evaluate the heart health of a person. The analysis of its layout enables diagnose a number of diseases and abnor- malities. For computer systems that need to segment the ECG signal, the first step the detection of QRS complexes. The earliest methods used filtering techniques and differen- tiation. Recently some researchers have designed methodologies based the multiresolution analysis the wavelet transform. Following similar path, this work proposes a methodology based on singular value decomposition in multiresolution (MRSVD), to solve the prob- lem of detection of QRS complexes of an ECG signal, which can be divided in four key stages: preprocessing, inspection, decision and correction. In of all, there are innovative proposals: in the first, it is used, in an unprecedented manner, the MRSVD; the second stage explores the physiological characteristics of the heart muscle, to make sure that a particular segment comprises or not a genuine R wave and, the last, corrects detections based on the amplitudes of the R wave. The evaluation of quality of detection for the experiments shows that the proposed algorithm has reached a predictive and sensitivity rates of of 99.20% and 99.70%, respectively, and error of only 1.10%, in comparation to another method which obtained 97, 10%, 99, 00% and 3, 70%, respectively
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Oliveira, Bruno Rodrigues de. „Deteccão de complexos QRS em eletrocardiogramas baseada na decomposição em valores singulares em multirresolução /“. Ilha Solteira, 2015. http://hdl.handle.net/11449/134101.
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Orientador: Jozué Vieira FilhoBanca: Marco Aparecido Queiroz Duarte
Banca: Roberto Kawakami Harrop Galvão
Resumo: O Eletrocardiograma (ECG) e um exame de extrema importância para avaliar a saúde do coração de um individuo. A analise de seu traçado possibilita diagnosticar uma serie de doenças e anomalias. Para isso, sistemas computacionais precisam segmentar os sinais de ECG, cujo primeiro passo e a detecção dos complexos QRS (ondas Q, R e S). Mui- tos métodos tem sido propostos para tal finalidade. Os primeiros utilizavam técnicas de filtragem e diferenciação, mas recentemente alguns pesquisadores tem concebido metodologias baseadas na analise de multirresolução da transformada Wavelet. Seguindo caminho semelhante, neste trabalho e proposta uma metodologia baseada na decomposição em valores singulares em multirresolução (MRSVD), para solução do problema de detecção dos complexos QRS de um sinal de ECG, que pode ser dividida em quatro etapas essenciais: pré-processamento, inspeção, decisão e correção. Em quase todas elas ha implementações inovadoras: na primeira utiliza-se, de forma inédita, a MRSVD; na segunda etapa exploram-se características fisiológicas do músculo cardíaco para certificar-se de que um determinado segmento compreende ou não uma onda R autentica; na ultima, são corrigidas as detecções baseadas nas amplitudes das ondas R. A avaliação da qualidade de detecção, para os experimentos realizados, mostra que o algoritmo proposto atingiu taxa de previsibilidade de 99, 20%, taxa de sensibilidade de 99, 70% e erro de apenas 1,10%, contra 97, 10%, 99, 00% e 3, 70%, respectivamente, obtidas por outro método
Abstract: The electrocardiogram (ECG) is a test of utmost importance to evaluate the heart health of a person. The analysis of its layout enables diagnose a number of diseases and abnor- malities. For computer systems that need to segment the ECG signal, the first step the detection of QRS complexes. The earliest methods used filtering techniques and differen- tiation. Recently some researchers have designed methodologies based the multiresolution analysis the wavelet transform. Following similar path, this work proposes a methodology based on singular value decomposition in multiresolution (MRSVD), to solve the prob- lem of detection of QRS complexes of an ECG signal, which can be divided in four key stages: preprocessing, inspection, decision and correction. In of all, there are innovative proposals: in the first, it is used, in an unprecedented manner, the MRSVD; the second stage explores the physiological characteristics of the heart muscle, to make sure that a particular segment comprises or not a genuine R wave and, the last, corrects detections based on the amplitudes of the R wave. The evaluation of quality of detection for the experiments shows that the proposed algorithm has reached a predictive and sensitivity rates of of 99.20% and 99.70%, respectively, and error of only 1.10%, in comparation to another method which obtained 97, 10%, 99, 00% and 3, 70%, respectively
Mestre
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Tsai, Chiou-Wei, Richard E. Cagley und Ronald A. Iltis. „JOINT INTERFERENCE SUPPRESSION AND QRD-M DETECTION FOR SPATIAL MULTIPLEXING MIMO SYSTEMS IN A RAYLEIGH FADING CHANNEL“. International Foundation for Telemetering, 2006. http://hdl.handle.net/10150/604390.
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ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, CaliforniaSpatial multiplexing (SM) systems have received significant attention because the architecture offers high spectral efficiency. However, relatively little research exists on optimization of SM systems in the presence of jamming. In a spatially uncoded SM system, such as V-BLAST, the channel state information is assumed to be unavailable a priori at both transmitter and receiver. Here, Kalman filtering is used to estimate the Rayleigh fading channel at the receiver. The spatial correlation of the jammer plus noise is also estimated, and spatial whitening to reject the jammers is employed in both the Kalman channel estimator and detector. To avoid the exponential complexity of maximum-likelihood (ML) detection, the QRD-M algorithm is employed. In contrast to sphere decoding, QRD-M has fixed decoding complexity of order O(M), and is thus attractive for hardware implementation. The performance of the joint Kalman filter channel estimator, spatial whitener and QRD-M detector is verfied by simulations.
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Romeyke, Martin [Verfasser]. „Elektrokardiographische Veränderungen und die Bedeutung von QRS-Fragmentation bei Patienten mit manifester chronischer Herzinsuffizienz / Martin Romeyke“. Lübeck : Zentrale Hochschulbibliothek Lübeck, 2016. http://d-nb.info/1083851039/34.
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Neto, Francisco Rodrigues dos Santos. „Análise de um novo critério de interpretação no diagnóstico diferencial das taquicardias de complexo QRS largo“. Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-23092015-154252/.
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Introdução: O diagnóstico diferencial entre as taquicardias de complexo QRS largo é de grande importância, pois o diagnóstico incorreto pode acarretar terapias inadequadas e potencialmente fatais. Critérios eletrocardiográficos têm sido utilizados para diferenciar a taquicardia ventricular da supraventricular com aberrância de condução, usando-se medidas dos intervalos das ondas do QRS em milissegundos e padrões eletrocardiográficos peculiares, mas sua consequência direta é a dificuldade na memorização e em sua aplicabilidade clínica. Objetivo: O objetivo deste estudo foi avaliar a acurácia diagnóstica de um novo critério eletrocardiográfico baseado no reconhecimento da negatividade do complexo QRS nas derivações DI, DII, V1 e V6, para o diagnóstico diferencial das taquicardias com QRS largo. Métodos: Foram avaliados 120 eletrocardiogramas de taquicardia ventricular ou taquicardia supraventricular com aberrância de condução por meio de dois métodos de avaliação: algoritmo de Brugada, que é composto por quatro passos, e um critério novo, composto por três passos para o diagnóstico. Os diagnósticos foram realizados com e sem conhecimento do dado clínico. As avaliações foram feitas por seis examinadores, sendo dois experientes na área (Grupo I), dois cardiologistas clínicos (Grupo II) e dois residentes de cardiologia na emergência (Grupo III). O padrão-ouro para o diagnóstico final foi o estudo eletrofisiológico. Resultados: Dos 120 pacientes, 68% apresentavam taquicardia ventricular e 32% taquicardia supraventricular com aberrância de condução. A idade dos pacientes variou de 17 a 85 anos, com média de 49,1 anos. A sensibilidade global foi maior (87,2%) quando o algoritmo de Brugada foi utilizado. A especificidade global foi maior (85,1%) com o critério novo. O valor preditivo positivo para taquicardia ventricular foi alto em ambos os métodos (90,9% no critério novo e 85,8% no algoritmo de Brugada). Os dois métodos tiveram boa acurácia (73,8% utilizando o critério novo e 81,4% o algoritmo de Brugada). O conhecimento do dado clínico não aumentou a acurácia diagnóstica. Entre os avaliadores mais experientes (Grupos I e II), a acurácia diagnóstica foi superior utilizando o algoritmo de Brugada em relação ao critério novo (84,6 e 85,8% vs. 74,2 e 74,6%). Para os avaliadores menos experientes (Grupo III), os dois métodos foram bastante semelhantes em termos de acurácia diagnóstica (73,7% no algoritmo de Brugada e 72,9% no critério novo), mas, para esses avaliadores, o critério novo apresentou maior especificidade que o algoritmo de Brugada (85,5% vs. 65,8%). Esses valores não mostraram alterações significativas com o conhecimento do dado clínico. O percentual de discordância entre os avaliadores foi maior utilizando o algoritmo de Brugada em relação ao critério novo (60,8% vs. 30%), e essa diferença persistiu com o conhecimento do dado clínico. Conclusão: O novo critério eletrocardiográfico apresentou boa acurácia no diagnóstico diferencial das taquicardias com QRS largo, podendo ser utilizado por médicos não especialista como alternativa ao algoritmo de Brugada. O conhecimento do dado clínico (presença ou não de cardiopatia) não aumentou a acurácia diagnóstica nos dois métodosIntroduction: The differential diagnosis of wide QRS complex tachycardia is of great importance because an incorrect diagnosis can lead to inappropriate and potentially deadly therapies. Electrocardiographic criteria have been used in an attempt to differentiate ventricular tachycardia from supraventricular tachycardia with aberrant conduction, measuring the QRS interval in milliseconds and peculiar electrocardiographic patterns, but its direct consequence is the difficulty in memorizing and its clinical applicability. Objective: The objective of this study was to evaluate the diagnostic accuracy of a new electrocardiographic criteria based on recognition of QRS complex negativity in leads DI, DII, V1 and V6 for the differential diagnosis of wide QRS tachycardias. Methods: We evaluated 120 ventricular tachycardia or supraventricular tachycardia with aberrant conduction electrocardiograms using two assessment methods: the Brugada algorithm, which consists of four steps, and a new proposed criterion, consisting of three steps to diagnosis. The diagnoses were performed with and without knowledge of the clinical data. Evaluations were made by six examiners, two experts in the area (Group I), two clinical cardiologists (Group II) and two in emergency cardiology residents (Group III). The gold standard for final diagnosis was the electrophysiological study. Results: Of the 120 patients, 68% presented with ventricular tachycardia and 32% presented with supraventricular tachycardia with aberrant conduction. The patients\' ages ranged from 17 to 85 years, with a mean age of 49.1 years. Global sensitivity was higher (87.2%) when Brugada algorithm was used. Global specificity was higher (85.1%) if the new criterion was used. Both methods presented a high positive predictive value for ventricular tachycardia (90.9% for the new criterion and 85.8% for the Brugada algorithm). Also, both methods had good accuracy (73.8% with the new criterion and 81.4% with the Brugada algorithm). Knowledge of clinical data did not increase diagnostic accuracy. Among the most experienced evaluators (Groups I and II), the diagnostic accuracy was superior using the Brugada algorithm compared with the new criterion (84.6 and 85.8% vs. 74.2 and 74.6%). For the less experienced evaluators (Group III), the two methods had very similar diagnostic accuracy (73.7% for the Brugada algorithm and 72.9% for the new criterion), but for those evaluators, the new criteria showed greater specificity than Brugada algorithm (85.5% vs. 65.8 %%). These values did not change significantly with knowledge of the clinical data. The percentage of disagreement among reviewers was higher for the Brugada algorithm than for the new criterion (60.8% and 30%, respectively), and this difference persisted with knowledge of the clinical data. Conclusion: The new electrocardiographic criteria showed good accuracy in the differential diagnosis of wide QRS tachycardias, and can be used by physicians not expert as an alternative to Brugada algorithm. Knowledge of clinical data (presence or absence of heart disease) did not increase the diagnostic accuracy for both methods
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NISHIDA, Erica Noronha. „Propriedades da Filtragem de Savitzky-Golay Aplicadas na Identificação de Complexos QRS em Sinais de Eletrocardiograma“. reponame:Repositório Institucional da UNIFEI, 2017. http://repositorio.unifei.edu.br/xmlui/handle/123456789/954.
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Essa dissertação apresenta as propriedades da filtragem de Savitzky-Golay e sua aplicação em uma das etapas de um algoritmo de detecção do complexo QRS em um sinal de eletrocardiograma (ECG). Esse algoritmo também foi implementado em um sistema eletrocardiógrafo portátil em desenvolvimento pelo Grupo de Microeletrônica UNIFEI. Nessa aplicação foi utilizada a filtragem diferencial de Savitzky-Golay devido, principalmente, a suas características de supressão de ruídos em uma frequência estabelecida (60Hz) e a utilização de coeficientes inteiros. Tais características permitiram a simplificação de etapas, redução de tempo e memória de processamento, além da diminuição de etapas de filtragem analógica e digital no sistema. Eficiência, exatidão e imunidade a ruído são comprovados através de figuras de mérito analisadas a partir de sinais padrão de ECG.
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Bignoto, Tiago Costa. „Correlação entre escore de Selvester e realce tardio na tomografia computadorizada do coração em portadores de miocardiopatia hipertrófica“. Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/98/98131/tde-17092018-095537/.
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A Miocardiopatia hipertrófica foi descrita há mais de 50 anos e é a cardiopatia de causa genética mais comum no mundo. Pacientes portadores de miocardiopatia hipertrófica podem apresentar maior risco de eventos arrítmicos graves e morte súbita. Assim torna-se importante o desenvolvimento de técnicas de rastreio desse subgrupo de pacientes para, quando necessário, indicar tratamento específico como o implante de CDI. O realce tardio é a manifestação de fibrose nos exames de imagem como tomografia computadorizada do coração e/ou ressonância cardíaca em pacientes com cardiopatias e quando presente em grandes quantidades, pode estar relacionado a maior incidência de eventos fatais. O eletrocardiograma é ferramenta de baixo custo, não invasiva e difundida nos serviços de saúde brasileiros. O objetivo desse estudo é avaliar a correlação entre a presença e localização de realce tardio na tomografia computadorizada do coração e o achado de fibrose pelo escore de Selvester no eletrocardiograma de repouso de portadores de MCPH, determinar a prevalência de fibrose miocárdica entre os pacientes, comparando a sensibilidade, especificidade, valor preditivo positivo e negativo do escore de Selvester. Foram analisados 112 pacientes do ambulatório de miocardiopatia do Instituto Dante Pazzanese de Cardiologia portadores de miocardiopatia hipertrófica sendo incluídos 75 desses. Foram divididos em dois grupos: Portadores de CDI com 60 pacientes e sem CDI com 15 pacientes. Foram coletados dados clínicos, ecocardiográficos, eletrocardiografia digital e tomografia computadorizada do coração. Foram realizados os cálculos do escore de Selvester e a mensuração e localização de realce tardio nos cortes tomográficos dos pacientes. A correlação dos resultados foi analisada pelo método de regressão linear. As características e frequências mais marcantes do grupo foram sexo masculino 49,4%, idade 41,63 ± 15,16, classe funcional I/II - NYHA 90,6%, fibrilação atrial 21,3%, baixa prevalência de comorbidades como hipertensão arterial 37,3%, diabetes 4%, dislipidemia 17,3%, clearence de creatinina > 60mL/min em 100% e ausência de doença coronariana estabelecida, fração de ejeção do ventrículo esquerdo preservada de 69,9 ± 5,46, medida do septo interventricular de 21,04 ± 6,23 e prevalência de gradiente > 30mmHg na via de saída do ventrículo esquerdo de 37,3%. Dos fatores de risco clássicos, morte súbita familiar e história de síncope eram as mais prevalentes com 57,3% cada, o uso do beta-bloqueador ocorreu em 89,3%. A massa de fibrose pela tomografia computadorizada foi de 9,87 ± 10,79 equivalendo a porcentagem de 5,66 ± 6,16, tendo prevalência em 88% da amostra. Já pelo escore de Selvester, encontramos 8,44 ± 7,39 de porcentagem de fibrose com prevalência de 76%. Na análise de kappa para a variável categórica fibrose entre o escore de Selvester e a tomografia computadorizada do coração, foi encontrada fraca correlação com r = 0,38 (p < 0,01). Enquanto variável contínua aplicando o método de regressão linear, foi encontrada correlação forte com r = 0,7 (p < 0,01). A sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo do escore de Selvester para o diagnóstico de fibrose foram de, respectivamente, 84,8%, 88,8%, 98,2% e 44,4%. A localização da fibrose apresentou correlação fraca entre os métodos com r = 0,16 (p < 0,01). Os dados desse estudo indicam que há moderada correlação entre o escore de Selvester e o realce tardio pela tomografia computadorizada na quantificação de fibrose em pacientes portadores de miocardiopatia hipertrófica.Hypertrophic cardiomyopathy is considered the most common genetic cardiovascular disease and has been recognized for 50 years. Patients with hypertrophic cardiomyopathy may present risk of arrhythmic events and sudden cardiac death. Thus, it is important to develop screening techniques for this subgroup of patients to indicate, when necessary, specific treatment as implantable cardioverter defibrillator. Late enhancement is fibrosis manifestation in images exam as multidetector computed tomography and/or magnetic cardiac resonance and if present in large quantities may be related to a higher incidence of fatal events. The electrocardiogram is a low-cost, non-invasive tool that is present in most Brazilian health services. The purpose of this study was to test the presence and location correlation between the Selvester and the late enhancement in the multidetector computed tomography, to determine the prevalence of myocardial fibrosis among patients, comparing the sensitivity, specificity, positive and negative predictive value of the Selvester QRS score. A total of 112 patients from the Institute of Cardiology Dante Pazzanese outpatient clinic with hypertrophic cardiomyopathy were analyzed, and 75 of them were included. They were divided into two groups: ICD patients with 60 patients and no ICD with 15 patients. Clinical, echocardiographic, digital electrocardiography and computed tomography of the heart were collected. The Selvester score was calculated and the measurement and location of late enhancement in the tomographic sections of the patients were performed. The correlation of the results was analyzed by the linear regression. The most remarkable features and frequencies of the group were male gender 49.4%, age 41.63 ± 15.16 years, functional class I / II - NYHA 90.6%, atrial fibrillation 21.3%, low prevalence of comorbidities as hypertension 37.3%, diabetes 4%, dyslipidemia 17.3%, creatinine clearance > 60mL/min in 100% and absence of known coronary artery disease, left ventricular ejection fraction preserved 69.9 ± 5.46, measured of the interventricular septum 21.04 ± 6.23 and prevalence of gradient > 30mmHg in the left ventricular outflow tract 37.3%. Classic risk factors as sudden family death and history of syncope were the most prevalent 57.3% each, the use of beta-blocker occurred in 89.3%. The mass of fibrosis by multidetector computed tomography was 9.87 ± 10.79g, representing a percentage of 5.66 ± 6.16, with a prevalence of 88% of the sample. Selvester QRS score, was found 8.44 ± 7.39 percent of fibrosis with a prevalence of 76%. In the kappa analysis for the categorical variable between the Selvester score and the computed tomography of the heart, we found a weak correlation r = 0.38 (p <0.01), as a continuous variable applying the linear regression, a strong correlation was found r = 0.7 (p <0.01). The sensitivity, specificity, positive predictive value and negative predictive value of the Selvester QRS score for the diagnosis of fibrosis were 84.8%, 88.8%, 98.2% and 44.4%, respectively. The location of the fibrosis showed weak correlation between the methods r = 0.16 (p <0.01). The results of this study indicate there is a moderate correlation between the Selvester QRS score and the late enhancement by multidetector computed tomography in the quantification of fibrosis in patients with hypertrophic cardiomyopathy.
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Hanzelka, Adam. „Rozměřování experimentálních záznamů EKG“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220063.
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This master's thesis deals with an analysis of principles of ECG signals detection and delineation. The theoretical part describes heart electrophysiology and electrocardiography basics. Next, the most important QRS detection and ECG delineation algorithms are introduced. Especially the wavelet transform methods are described. In the practical part proper delineation algoriythm was realized. It was tested on the standard CSE database, then it was modified on data of isolated rabbit heartsand the results are published in the conclusion.
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Bajgar, Jiří. „Detekce P vlny v EKG signálech“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221317.
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The aim of this diploma thesis is to introduce methods of detection of the QRS complex and the subsequent detection of P waves. The intention is to create a program by specified method in the software Matlab which will be able to implement this method. The thesis describes the basic and important methods of detection and subsequent algorithm to detect P waves. Solution of the algorithm is tested on real data. It also describes the automatic signal evaluation and the results of this automatic function.
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Bucsuházy, Kateřina. „Rozměření experimentálních záznamů EKG“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221318.
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This master thesis deals with QRS complex detection and ECG delineation. The theoretical part of this work describes wavelet transform, some of QRS detection approaches and some of ECG delineation approaches. For algorithm realization in Matlab is used redundant dyadic discrete wavelet transform. Algorithm is designed for experimental electrocardiograms of isolated rabbit hearts and it is evaluated through manually determined references.
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Metzger, Frauke [Verfasser]. „Die Breite des stimulierten QRS-Komplexes bei Patienten mit koronarer Herzkrankheit und überlebtem plötzlichem Herztod / Frauke Metzger“. Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2013. http://d-nb.info/1037430395/34.
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Terho, H. (Henri). „Electrocardiographic risk markers for cardiac events in middle-aged population“. Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526223841.
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Abstract Cardiovascular diseases are the leading cause of death in developed countries. Approximately 50% of these events are due to sudden cardiac death (SCD) and often without preceding diagnosis of cardiac disease. Many risk factors for cardiac events have been identified and prevention strategies have improved markedly. The aim of this thesis was to evaluate the usability of the 12-lead electrocardiogram (ECG) to predict cardiac events. The study population consisted of 10,904 middle-aged general population subjects with ECG recordings between the years 1966–1972 with a long follow-up (30±11 years). The first part of the thesis (I) focused on the prevalence and prognostic significance of fragmented QRS complex (fQRS). The prevalence of fQRS was 19.7%. Fragmented QRS complex did not predict mortality in subjects with no history of cardiac disease. Among subjects with underlying cardiac disease and lateral fQRS, the risk of cardiac death was 2.5-fold (P=0.001) and the risk of SCD was almost 3-fold (P=0.004). Other major electrocardiographic abnormalities were assessed in subjects without known cardiac disease for the risk of cardiac death, SCD and hospitalization due to coronary artery disease (II, III). Abnormal ECG was moderately associated with cardiac death after 10 and 30 years of follow-up (hazard ratio 1.7, P=0.009; hazard ratio 1.3, P>0.001, respectively) (II). The risk of hospitalization was not associated with abnormal ECG findings. Abnormal ECG moderately predicted SCD during 10 and 30 years of follow-up (hazard ratio 1.6, P=0.052; hazard ratio 1.3, P=0.007) (III). The risk of SCD was 3-fold when ≥2 ECG abnormalities were present. In conclusion, lateral fQRS in middle-aged subjects with underlying cardiac disease was associated with increased risk of death. Certain abnormal ECG findings associated with the risk of non-arrhythmic cardiac mortality and arrhythmic death. The risk of arrhythmic mortality was substantially elevated when multiple ECG abnormalities were present in middle-aged populationTiivistelmä Sydänsairaudet ovat yleisin kuolinsyy kehittyneissä maissa. Noin 50 % näistä kuolemista aiheutuu äkillisestä sydänpysähdyksestä, suuri osa ilman aiempaa tietoa sairaudesta. Useita sydänsairauksien riskitekijöitä on tunnistettu ja ennaltaehkäisy on kehittynyt merkittävästi. Väitöstutkimuksen tavoitteena on tutkia 12-kytkentäisen sydänsähkökäyrän (EKG) käyttökelpoisuutta sydänsairauksien ilmenemisen ennustamisessa. Tutkimusväestöön kuului 10,904 keski-ikäistä suomalaista henkilöä. Aineisto kerättiin vuosina 1966-1972 ja seuranta-aika oli 30 (±11) vuotta. Ensimmäisessä osajulkaisussa (I) tutkimme QRS-kompleksin fragmentaation vallitsevuutta ja sen vaikutusta ennusteeseen väestössä. Fragmentoituneen QRS-kompleksin esiintyvyys oli 19.7 %. Fragmentoitunut QRS-kompleksi ei lisännyt kuolemanriskiä henkilöillä, joilla ei ollut sydänsairautta. Henkilöillä, joilla oli todettu sydänsairaus, lateraalinen fQRS lisäsi sydänperäistä kuolleisuutta 2.5-kertaiseksi (P=0.001) ja rytmihäiriöperäistä kuolleisuutta 3-kertaiseksi (P=0.004). Tutkimme muiden poikkeavien EKG-löydösten ennustearvoa kuolleisuuteen ja sairaalahoidon tarpeeseen sepelvaltimokohtauksen vuoksi (II, III). Poikkeavien EKG-muutosten esiintymiseen liittyi lisääntyneen sydänperäisen kuoleman riski sekä 10 vuoden (riskitiheyssuhde 1.7, P=0.009) että 30 vuoden seurannassa (riskitiheyssuhde 1.3, P>0.001) (II). Poikkeavat EKG-muutokset eivät ennustaneet sairaalahoitojaksoja. Poikkeava EKG ennusti rytmihäiriöperäisen kuoleman riskiä sekä 10 vuoden (riskitiheyssuhde 1.6, P=0.052) että 30 vuoden seurannassa (riskitiheyssuhde 1.3, P=0.007) (III). Äkkikuoleman riski oli 3-kertainen henkilöillä, joilla todettiin ≥ 2 EKG-poikkeavuutta. Tutkimuksen yhteenvetona voidaan todeta, että fQRS lateraalisissa kytkennöissä lisäsi sydänperäisen kuoleman riskiä henkilöillä, joilla on todettu sydänsairaus. Tiettyihin poikkeaviin EKG-muutoksiin liittyi lisääntynyt ei-rytmihäiriöperäisen ja rytmihäiriöperäisen kuoleman riski. Useiden tutkittujen EKG-muutosten ilmentyminen samanaikaisesti lisäsi merkittävästi rytmihäiriöperäisen kuoleman riskiä keski-ikäisessä väestössä