Elektrokardiografi, EKG är den mest använda kardiovaskulära undersökningen för studering av hjärtats funktion, patologi i hjärtats retledningssystem och rytm. För att registrera och undersöka hjärtats elektriska aktivitet, används de standardiserade 12-avledningssystemet (12-SL) med distal placering av extremitetsavledningarna på underarmar och underben. På grund av muskelstörningar som kan förekomma under bland annat ett arbetsprov, är 12-SL inte alltid optimalt. Därför har andra modifierade system för elektrodplacering av extremitetselektroderna som Mason- Likar och Lund-avledningssystemet, ersatt med en omplacering proximalt på överarmar och höftkam. Tidigare studier har visat en förändring i EKG-registreringen som kan leda till falska patologier eller missvisande av det befintliga patologierna. Studier har även visat en förändring i EKG-registreringar som kan uppkomma vid olika kroppspositioner. Syftet med denna studie var därför att studera den potentiella skillnaden som uppstår mellan 12-SL och en proximal omplacering enligt Lund-systemet med en kroppspositionsändring. Studien inkluderade 31 deltagare remitterade till ett ordinärt arbetsprov, där en registrering skedde vid distal- och proximal koppling samt med patienten i sittande läge. Utifrån erhållna EKG-registreringar jämfördes R-vågsamplituden, QRS-durationen samt PQ tiden. Studien visade en statistisk signifikant skillnad i alla extremitetsavledningar vid en förflyttning av elektroderna för R-vågamplituden samt för avledning V5 och –aVL vid ändring av kroppsposition. Ingen signifikant förändring kunde observeras för PQ-tiden och QRS-durationen. / Electrocardiography, ECG is the most used cardiovascular method to study cardiac function, pathology of the heart's retinal system and rhythm. To record and investigate the electrical activity of the heart, the standard 12-lead system (12-SL) with distal placement of the limb leads on the forearms and lower legs are commonly used. Due to muscular artifact that can occur in connection with exercise ECGs, 12-SL is not always optimal for use. Therefore, other systems such as Mason-Likar and the Lund-system have replaced with a proximal repositioning of the limb electrodes. Previous studies have shown a change in ECG registration that can lead to false pathology and alarms when modifying the standardized 12-lead system. Previous studies have also shown a possible change in ECG-registrations that can occur with a different body positions. The purpose of this research was to study the potential change that arises between 12-SL and a proximal relocation according to the Lund system with a difference in a body position. The study included 31 participants referred to the regular work test, where a registration was made at distal and proximal connection as well as with the patient in a sitting position. Based on the obtained ECG, the R- wave amplitudes, QRS- durations and PQ- intervals was measured and compared. Results showed a statistically significant difference in all limb leads at and displacements of the electrodes for the R-wave amplitude as well as for the V5 and -aVL with a different body position. No significant change was observers for the PQ- time and QRS- duration.

Dissertation-Publikation.

Tato práce se zabývá možností využití vlnkové transformace v aplikacích, které se zabývají potlačením šumu. Především se jedná o oblast filtrace signálu EKG. Úkolem je zhodnotit vliv různých parametrů nastavení samotné filtrace a zjistit jaký vliv má různé nastavení prahování wavelet koeficientů. Výsledkem práce je také stanovení hodnot prahů, stanovení nejlepšího způsobu rozkladu signálu a volba rekonstrukčních bank filtrů. Text obsahuje výsledky Wienerovy filtrace, při které byly testovány různé banky rozkladových a rekonstrukčních filtrů.Všechny popsané filtrační metody byly testovány na reálných záznamech EKG s aditivním myopotenciálním šumem. Algoritmy byly realizovány v prostředí MATLAB.

The aim of this thesis is segmentation of P waves in ECG signals. The theoretical part of the thesis describes the physiology of the heart and the basics of deep learning methods. Preprocessing of the signals is performed and neural network U-Net is implemented in the Python software environment in the practical part. Afterwards, optimization of network architecture is performed in order to reduce model complexity. Lastly the success rate of the model is evaluated.

This diploma thesis is focused on testing ECG monitors and ECG instruments. There are discussed origin and charakteristics of ECG signal. The ECG signal is presented by standard leads. This is the reason, why the way of making leads is mentioned. One chapter is aimed at generating ECG signal. There are set requierements for the ECG generator. These requierements results from ECG instrument possibilities and from ECG signal character. Next part of this diploma thesis includes hardware design of each part of the system. The system was designed with respect to mobility and 12-leads systems compatibility. Finaly the thesis includes design of the controll software.

Main objective of this thesis was to learn about possibility of suppression of narrow band disturbances. We focused on use of Lynn’s filters. The objective was to realize these filters with respect to a fast algorithm of filtering. Concretely, for suppression of drift we realized the fast high pass filter with flexible cut off frequency. Then we realized filter for suppression of electrical network disturbance. We have realized these filters for sampling frequencies 250 and 500 Hz and we tested them with real ECG signals. Then we have evaluated their efficiency.

Objective of this diploma work was to study methods of adaptive filtering and their use in suppression of noise in biological signals. Adaptive filtering represents effective means of suppression of parasitic nonstationary disturbances in a useful signal. The task was to design various types of adaptive filters and implement an adaptation algorithm in Matlab programming environment. It namely included suppression of powerline noise at 50 Hz and 100 Hz in ECG signals with minimization useful components disturbing. The realized filters were verified on real ECH signals and their efficiency was evaluated.

Master’s thesis deals with the measurement of biological signals for the effect of psychological burden. To monitor this effect was elected Stroop test, which is in the psychology used to detect disorders of attention and concentration. EEG and ECG signals during Stroop test were obtained using the EEG recording systém, in the context of research evoked potentials. As a part of the work it has been designed custom application for analyzing and interpreting data and statistical analysis by t-test.

This work concerns with problems of the QT sequences detection in ECG signal. The first part introduces electrophysiology of heart and his electrical manifestation. For main detection were used two algorithms, which were afterwards modified and programmed in Matlab. The work includes developed custom applications for measurement and evaluation of the length of QT interval. The final lengths of the QT interval, which we got from this two methods, were compared with reference length.

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.