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Methods for the evaluation of heart rate and arterial blood pressure variability
Sedláčková, Gabriela ; Halámek, Josef (referee) ; Leinveber, Pavel (advisor)
The bachelor thesis deals with methods for description of heart rate variability and arterial blood pressure. An important mechanism for maintaining homoeostasis in the body is so called baroreflex feedback loop, which allows for a short-term regulation of blood pressure. The thesis contains description of methods which are currently used for baroreflex sensitivity evaluation. Analysis in time domain as well as in frequency domain was done using programs in Matlab environment. At the end of the thesis the influence of ventricular extrasystoles on output parameter is evaluated.
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Efficient implementation of Stockwell Transform for real-time embedded processing of physiologic signals
Holmes, D. ; Pinto, S.C. ; Felton, Ch. ; Smítal, L. ; Leinveber, P. ; Jurák, Pavel ; Gilbert, B. ; Haider, C.
Physiologic monitoring enables scientists and physicians to study both normal and pathologic signals of the body. While wearable technologies are available today, many of these technologies are limited to data collection only. Embedded processors have minimal computational capabilities. We propose an efficient implementation of the Stockwell Transform which can enable real-time time-frequency analysis of biological signals in a microcontroller. The method is built upon the fact that the Stockwell Transform can be implemented as a compact filter bank with pre-computed filter taps. Additionally, due to the long tails of the gaussian windowing function, low amplitude filter taps can be removed. The method was implemented on a TI MSP430 processor. Simulated ECG data was fed into the processor to demonstrate performance and evaluate computational efficiency.
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Biventricular pacing optimization by means of the dyssynchrony parameter
Jurák, Pavel ; Leinveber, P. ; Halámek, Josef ; Plešinger, Filip ; Postránecká, T. ; Lipoldová, J. ; Novák, M.
To improve Cardiac Resynchronization Therapy (CRT), different interventricular delay (VVD) settings can be used. However, relatively small VVD induced hemodynamic changes cannot be measured by standard echocardiographic methods. The QRS complex duration (QRSd) is mostly the main criterion. Here we introduce a new dyssynchrony parameter (DYS) that is able to more accurately detect improved electrical synchrony. Methods: 12-lead 5 kHz ECG during 3-10 minute rest period was measured in 46 patients with CRT OFF and CRT ON with VVD 0 ms (CRT0) and -20 ms (CRT20). We detected QRSd and the dyssynchrony parameter DYS as the time difference between 500-1000 Hz averaged envelopes positions in the V1 and V6 leads in the QRS complex region. Results: 32 of 46 patients had a positive CRT response manifested by QRSd shortening and a DYS decrease. 28 of 32 patients had a positive LV pre-excitation effect: additional QRSd shortening of 4.7+/-.9 ms and a DYS decrease of 12.6+/-7.5 ms. The correlation coefficient of QRSd and DYS changes (CRT 0 vs CRT 20) was 0.23 and indicates information diversity. The DYS parameter differs from QRSd and provides a significantly higher response to VVdelay changes (p <; 0.001).
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Methods for the evaluation of heart rate and arterial blood pressure variability
Sedláčková, Gabriela ; Halámek, Josef (referee) ; Leinveber, Pavel (advisor)
The bachelor thesis deals with methods for description of heart rate variability and arterial blood pressure. An important mechanism for maintaining homoeostasis in the body is so called baroreflex feedback loop, which allows for a short-term regulation of blood pressure. The thesis contains description of methods which are currently used for baroreflex sensitivity evaluation. Analysis in time domain as well as in frequency domain was done using programs in Matlab environment. At the end of the thesis the influence of ventricular extrasystoles on output parameter is evaluated.
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Porovnání metod pro výpočet srdečního výdeje ze signálu impedanční kardiografie
Jurák, Pavel ; Halámek, Josef ; Vondra, Vlastimil ; Kára, T. ; Nykodým, J. ; Číp, Ondřej ; Eisenberger, M. ; Leinveber, P. ; Fráňa, P. ; Meluzín, J. ; Souček, M.
The goal of the study is to compare various methods of non-invasive stroke volume (SV) assessment from a raw impedance cardiography (IC) signal. IC detects changes in cardiac haemodynamic function using thoracic electrical bioimpedance technology. Corresponding changes of impedance are used along with ECG and blood pressure to measure and calculate haemodynamics parameters
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