Analysis and Processing of Biomedical Signals and Data

Head of Department

Prof. Ivaylo Christov, DSc

  • E-mail: Ivaylo.Christovbiomed.bas.bg
  • Phone: (359 2) 9793635
  • Fax: (359 2) 8723787
  • Address: “Acad. G. Bonchev” Str., Block 105, Room 202
    Sofia 1113, Bulgaria

Staff

Main research topics

  • A complex approach for ECG signal acquisition, preprocessing, analysis and visualisation has been developed, including compact amplifier structures for synchronous recording of the 12 standard leads, digital procedures for total elimination of power-line interference without affecting the ECG spectrum components, suppression of drift and muscle disturbances. Algorithms have been elaborated for ECG wave boundary detection, for time and amplitude parameter measurement and for diagnostic classification.
  • Heart rate variability analysis methods have been improved and assessed, yielding higher spectrum width and accuracy. Various applications include early diagnostics of autonomic neuropathy in diabetic children, detection of mild hypertension, testing vegetative system reactivity, etc.
  • A method and instrumentation for electrochemotherapy of malignant tumours has been developed by the introduction and application of short bursts of biphasic pulses.
  • Effective and safety defibrillation waveforms have been investigated – biphasic, with automatic adjustment of the chopping-modulated pulses to patient transthoracic resistance. The waveforms have been optimized by modelling of the thorax and the transmembrane potential, and with a lot of clinical experiments. The pulses have been implemented in the new series of defibrillators with biphasic multipulse biowave technology.
  • Huge quantity of heart beat pattern recognition parameters have been measured in internationally approved and annotated databases. The measurements have been used for automatic heard beat classification in arrhythmia analysis. The classification has been performed by neural networks, K-th nearest neighbours rule, discriminant analysis, etc.
  • ECG heart beat detection methods have been created. They work with one or any number of leads. The statistical indices are higher than, or comparable to those, cited in the scientific literature.
  • A generalized index for cardiac risk assessment in emergency non-cardiac surgery has been derived from ECG ischaemia signs.
  • Method for analysis of the QT dispersion has been developed, based on precise automatic measurement of time-intervals in the electrocardiogram. Statistically significant decrease of the QT dispersion has been found, pointing toward improvement of the cardiac repolarization after successive cardiac bypass. Another study has proven negative correlation between the QT dispersion and the variability of flow-mediated vasodilatation of the brachial artery for patients having angina pectoris, myocardial ischemia and coronary artery disease, confirmed by angiography.

Research projects

Current projects

  1. Evaluation of the effect of non-invasive ventilatory therapy on neuro-vegetative status in patients with syndrome of obstructive sleep apnea by 16-channel device for high-resolution ECG and breathing signal
    Cooperation agreement between BAS and Schiller AG, Switzerland, 2013-2014.
  2. Design and development of a 16-channel ECG simulator for direct reproduction of standardized databases
    Cooperation agreement between BAS and Schiller AG, Switzerland, 2013-2014.
  3. Load dependent changes of T-wave and QRS-complex alternans during exercise ECG test
    Joint project with CNR – Italy and St George’s University of London, UK, 2010-2015.
  4. Analysis of digital electrocardiographical data
    Joint project between St George’s University of London, Consiglio Nacionale delle Ricerche, and Bulgarian Academy of Sciences, 2010-2015.
  5. Methods and algorithms for registration, processing, analysis and classification of biomedical data, signals and images and their implementation in e-clinical and life-saving equipment
    Joint project between Schiller AG, Baar, Switzerland and Bulgarian Academy of Sciences, since 2006.

Past projects

International collaboration

  • Institute of Biomedical Technology, Patras, Greece
  • Schiller-Medical SA, Wissembourg, France
  • Schiller AG, Baar, Switzerland
  • Tampere international center for signal processing, Tampere, Finland
  • Institute of Biomedical Engineering, Consiglio Nazionale delle Ricerche, Padova, Italy
  • Cancer Institute “Regina Elena”, Rome, Italy
  • St George’s University of London, UK

Patents

  • Cansell A., Daskalov I. (2003) Modulated defibrillation elementary pulse train. European patent 20010934083, Assignee: Schiller Medical (Fr)
  • Cansell A., Daskalov I. (2003) Impulses or a series of impulses for defibrillation and device to generate them. United States Patent 20030078622, Assignee: Schiller Medical (Fr)
  • Mudrov N., Daskalov I., Peicheva E., (2002) Method and instrumentation for electrochemotherapy, № 63712.

Awards

  • 2008 – Mikhail Matveev – Diploma and Prize for High Scientific Achievements from the Union of Scientists in Bulgaria
  • 2008 – Mikhail Matveev – Prize for Best Presentation at the 2008 Annual Conference of Computers in Cardiology
  • 2008 – Ivaylo Christov – 1st prize winner in the Physionet/Computers in Cardiology Challenge “Detecting and Quantifying T-Wave Alternans”
  • 2007 – Vessela Krasteva – “Outstanding Scientific Achievements of Young Scientist” Award of the Union of Scientists in Bulgaria
  • 2007 – Irena Jekova – “Outstanding Scientific Achievements of Young Scientist” Award of the Union of Scientists in Bulgaria
  • 2006 – Ivaylo Christov – 2nd Award in the Physionet/Computers in Cardiology Challenge “QT interval measurement” in: Division 1: “Manual and semi-automated methods” and Division 3: “Fully automated methods with source code submitted”
  • 2006 – Vessela Krasteva – Diploma “Marin Drinov” for Young Scientist of the Bulgarian Academy of Sciences
  • 2006 – Vessela Krasteva – Outstanding Scientific Contributions Award of the Ministry of Education and Science
  • 2005 – Diploma for the device “Easy port defibrillator” by the Association of the French Inventors and Fabricants
  • 2005 – Diploma for the device “Noninvasive Respiration Monitor” by the Bulgarian Industrial Association

Lecture courses

  • Information technologies in medicine – Technical University-Sofia
  • Data processing and analysis of biomedical signals – Technical University-Sofia
  • Image Processing in Medicine – Technical University-Sofia
  • Artificial Intelligence – Technical University-Sofia
  • Computer Periphery – Technical University-Varna
  • Digital Design – Technical University-Varna

Selected publications

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