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Heart rate fluctuations Measurement and analysis of neurocardiological signals

Zoltán Gingl Department of Experimental Physics University of Szeged, Hungary www.noise.physx.u-szeged.hu. Heart rate fluctuations Measurement and analysis of neurocardiological signals. About the noise group. University of Szeged, Dept. Experimental Physics Founder: Prof.L.B. Kish (1988)

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Heart rate fluctuations Measurement and analysis of neurocardiological signals

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  1. Zoltán Gingl Department of Experimental Physics University of Szeged, Hungary www.noise.physx.u-szeged.hu Heart rate fluctuationsMeasurement and analysis of neurocardiological signals

  2. About the noise group • University of Szeged, Dept. Experimental Physics • Founder: Prof.L.B. Kish (1988) • 3 senior researchers, 1 PhD student, 8-10 students • Research and education • Noise and fluctuations in various systems • Measurements, development of measurement devices • Analog and numerical simulations • Theories • Education (measurements, electronics, laboratory practices)

  3. Our current interest • Noise in a constructive role • Stochastic resonance, dithering • Utilising jitter noise in excimer lasers • Taguchi and carbon nanotube gas sensor resistance fluctuations (FES) • Medical research • Analysis of fluctuations • Signal processing methods • Development of special instuments

  4. Signals of human body • Random internal and external excitations • Deterministic and noisy components simultaneously • Response will contain noise as well • Information source Aim: measurement and analysis of neurocardiological signals (ECG,blood pressure, respiration, blood flow, etc.)‏

  5. Can a noise researcher help medical doctors? • Enhancing flexibility: many nice existing instuments, but always limitations due to the fixed functions • Experience in signal processing: statistical and spectral analysis • Development of physical and mathematical models, calculations, simulation

  6. Can a noise researcher help medical doctors? • Software development supporting special signal acquisition and processing • Firmware for the instrument • Analysis on the PC (LabVIEW, C++, C#)

  7. Can a noise researcher help medical doctors? • Hardware development: almost all medical equipment has analog outputs: digitised by intelligent USB data acqusision systems

  8. Today’s measurement and analysis • Measurement • Smaller • Faster • More precise • Analog signal processing, A/D conversion • Analysis • Same signal as before, but more info obtained • High processing power • Digital signal processing techniques

  9. Data conversion and low level processing: mixed signal processor C8051F060 (www.silabs.com)

  10. Heart rate modulation mechanism

  11. What matters? • Nervous system (sympathetic and parasympathetic responses) • Blood vessels • Heart muscle • Coronary artery

  12. ECG, blood pressure signals RRi SBPi

  13. Measurement methods • ECG: signal amplification • Blood pressure: sensor or indirect methods • Blood flow • Respiration

  14. RR time dependence and spectrum

  15. Smaller fluctuations - higher risk of sudden cardiac death

  16. The sdRR is a very simple but good predictor and indicator • Diabetes • Cardiac diseases • Coronary arterial diseases

  17. The PSD of the RR • Sympathetic activity (0.04-0.15Hz) • Respiration (0.15-0.4Hz)

  18. Spectra: normal vs. neuropath

  19. Long term behaviour

  20. Very low frequency spectrum

  21. The Poincare plot(to smoke or not to smoke, that is the question…)

  22. Poicare plot:Heart rate irregularities

  23. Baroreflex sensitivity • Forced or spontaneous excitations • Neuropathy, diabetes • Cardiac disfunctions • Blood vessels get too rigid • Blood pressure wave reflection can be too fast

  24. Baroreflex mechanism in humans(Hidaka et al., Phys Rev Lett, 85 (2000) 17)

  25. ECG and BP influenced by respiration

  26. Forced respiration

  27. Simple respiration monitoringpneumobelt

  28. Muscle sympathetic nervous activity (MSNA) • Random bursts correlated with heart activity • Especially useful when the regluation does not function well • Parasympathetic response: 0.2-0.3sec • Sympathetic response: 3-10 sec

  29. Blood flow fluctuations

  30. Analysis of blood flow • 0.0095-0.02Hz, endothelium • 0.02-0.06Hz, thermoregulation, metabolic, neurogenic activity • 0.06-0.15Hz, blood pressure regulation • 0.15-0.4Hz, respiration • 0.4-1.6Hz, heart rate • Heating: excitation of different mechanisms • Check how they change in time • Wavelet analysis (time dependent spectral analysis

  31. Analysis of blood flow

  32. Intracardial ECG during fibrillation • Many electrodes at different locations • Spatial analysis • Spectral analysis • Identification of sources of fibrillation • Developed software (LabVIEW VI)

  33. Movement of the heart walls • Echocardiography • Heart wall velocity calculation • Our contribution: correlation analysis software • Muscle degradation analysis

  34. Velocities and cross correlation

  35. ST elevation: insufficient oxigen

  36. ST elevation analysis software(Norbert Csík)‏

  37. Summary • Many different signals can be measured • Non-invasive methods are preferred • Analog and digital electronics to support instrumentation • Fluctuating signals: random and deterministic components • Advanced signal processing: enhanced information extraction • Research and applications • Promising future – even more information from the same signals www.noise.physx.u-szeged.hu gingl@physx.u-szeged.hu

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