Analysis and Processing of Biomedical Signals and Data

Head of Department

Prof. Vessela Krasteva, PhD

  • E-mail:
  • Phone: 02 979 3631
  • Address: “Acad. G. Bonchev” Str., Block 105, Room 201
    Sofia 1113, Bulgaria


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. Computer aided diagnosis of cardiac arrhythmias based on machine learning and deep neural networks
    КП-06-Н42-3/27.11.2020 (KP-06-N42-3/27.11.2020)
    Bulgarian National Science Fund in a competition for financial support of basic research projects – 2020, main research area: “Mathematical sciences and informatics”
    Coordinator of the research team: Prof. Vessela  Krasteva
  2. 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

  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. System for computer aid of the decisions for weaning critically ill ventilator dependent from mechanical ventilation
    Bulgarian National Science Fund, 2010-2013.
  6. Detection and analysis of microvolt QRS and T wave alternans in electrocardiographic signals
    Joint project between Institute of Biomedical Engineering, Consiglio Nazionale delle Ricerche and Bulgarian Academy of Sciences, 2010-2012.
  7. Role of physical growth and pubertal maturation on the cardiovascular autonomic innervation in healthy children and young people
    Medical University – Sofia, Council of Medical Science, 2010-2011.
  8. Assessing the parameters of shock sequence for a successful defibrillation with minimum delivered energy to the patient
    Ref. No. DO-02-170, Bulgarian National Science Fund, 2009-2011.
  9. Study and development of high voltage generators for external defibrillation
    Ref. No. DOCF-01/101, Bulgarian National Science Fund, 2009-2011.
  10. Standardised tester for examination of digital electrocardiographs
    Public commission, Bulgarian Institute of Metrology, 2008-2009.
  11. Repolarisation phase in computerized electrocardiography: Analysis of T-wave morphology and QT dispersion
    Joint project between Institute of Biomedical Engineering, Consiglio Nazionale delle Ricerche and Bulgarian Academy of Sciences, 2007-2009.
  12. Electrocardiogram arrhythmia analyses by automated heart beat classification
    Joint project between Tampere International Center for Signal Processing, Academy of Finland and Bulgarian Academy of Sciences, 2005-2007.
  13. Pattern recognition in computerized electrocardiography and characterization of the repolarization phase
    Joint project between Institute of Biomedical Engineering, Consiglio Nazionale delle Ricerche and Bulgarian Academy of Sciences, 2004-2006.
  14. Denoising of surface electrocardiogram signals for micropotential recovery
    Joint project between Tampere International Center for Signal Processing, Academy of Finland and Bulgarian Academy of Sciences, 2003-2005.

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


  • 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.


  • 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

  1. Bortolan G., I.I. Christov, W. Pedrycz.  Hyperellipsoids for beat classification in electrocardiogram, chapter 10, pp. 219-236. In: ECG Signal Processing, Classification and Interpretation: A Comprehensive Framework of Computational Intelligence, Eds: Gacek A, Pedrycz W, Springer, 279 pages, 2011. ISBN 978-0-85729-867-6
  2. Krasteva V., I. Jekova, J.P. Didon. An audiovisual feedback device for compression depth, rate and complete chest recoil can improve the CPR performance of lay persons during self-training on a manikin, Physiological Measurement, 32, (6), 687-699, 2011, ISSN: 0967-3334.
  3. Kostov J., T. Mudrov, I. Dotsinsky, N. Mudrov. Comparison between two defibrillation waveforms. Journal of Medical Engineering & Technology, 35, 429-436, 2010, ISSN 0309-1902.
  4. Krasteva V., I. Jekova, I. Dotsinsky, J.P. Didon. Shock advisory system for heart rhythm analysis during cardiopulmonary resuscitation using a single ECG input of automated external defibrillators. Annals of Biomedical Engineering, 38, 1326-1336, 2010, ISSN: 0090-6964.
  5. Matveev M. Non-parametric Criterion for Estimation of the Sensitivity of Object’s Features to Influences of a Factor and its Application in Clinical Practice. pp. 569-572. In: V. Luzar-Stiffter, I. Jarec, Z. Bekic (Eds.), Information Technology Interfaces 2010, ISBN 978-953-7138-18-9.
  6. Didon J.P., I. Dotsinsky, I. Jekova, V. Krasteva. Detection of Shockable and Non-Shockable Rhythms in Presence of CPR Artifacts by Time-Frequency ECG Analysis., Comp. in Card., 36, 817-820, 2009, ISSN 0276-6547.
  7. Jekova I., V. Krasteva, S. Ménétré, T. Stoyanov, I. Christov, R. Fleischhackl, J-J. Schmid, J-P. Didon. Bench study of the accuracy of a commercial AED arrhythmia analysis algorithm in the presence of electromagnetic interference. Phys. Meas., 30, 695-705, 2009, ISSN 0967-3334.
  8. Didon J-P., G. Fontaine, R. White, I. Jekova, J.J. Schmid, A. Cansell. Clinical Experience with a Low Energy Pulsed Biphasic Waveform in Out-of-Hospital Cardiac Arrest. Resuscitation, 76, 350-353, 2008, ISSN 0300-9572.
  9. Dobrev D., T. Neycheva, N. Mudrov. Digital lock-in techniques for adaptive power-line interference extraction. Physiological Measurement, 29, 803-816, 2008, ISSN 0967-3334
  10. Dobrev D., T. Neycheva, N. Mudrov.  Bootstrapped two-electrode biosignal amplifier. Medical and Biological Engineering and Computing, 46, (6), 613-619, 2008, ISSN 0140-0118.
  11. Dotsinsky I, G. Mihov. Tremor suppression in ECG. BioMedical Engineering OnLine 7, 29, 2008, ISSN: 1475-925X.
  12. Jekova I., G. Bortolan, I. Christov. Assessment and comparison of different methods for heartbeat classification. Medical Engineering & Physics, 30, 248-257, 2008, ISSN 1350-4533.
  13. Mihov G., I. Dotsinsky. Power-line interference elimination from ECG in case of non-multiplicity between the sampling rate and the power-line frequency. Biomed. Sign. Proc. Control 3, No 3, 334-340, 2008, ISSN: 1746-8094.
  14. Simova I., S. Denchev, I. Christov, M. Matveev, S. Dimitrov, L. Vladimirova, S. Kurtev. Flow mediated dilatation and QT interval dispersion in stable coronary artery disease patients according to the presence or absence of myocardial infarction. The Internet Journal of Cardiology, 5, (2), 2008, ISSN 1528-834X.
  15. Tabakov S., I. Iliev, V. Krasteva. Online digital filter and QRS detector applicable in low resource ECG monitoring systems. Annals of Biomedical Engineering, 36, 1805-1815, 2008, ISSN 0090-6964.
  16. Christov I., I. Simova. Q-onset and T-end delineation: Assessment of the performance of an automated method with the use of a reference database. Physiol. Meas., 28, 213-221, 2007, ISSN: 0967-3334.
  17. Denchev S., I. Simova, M. Matveev. Evaluation of the SCHILLER BR-102 plus noninvasive ambulatory blood pressure monitor according to the International Protocol introduced by the Working Group on Blood Pressure Monitoring of the European Society of Hypertension. Blood Pressure Monitoring, 12:5, 329-333, 2007, ISSN 1359-5237.
  18. Dotsinsky I. Atrial wave detection algorithm for discovery of some rhythm abnormalities. Physiol. Meas., 28, 595-610, 2007, ISSN: 0967-3334.
  19. Iliev I., V. Krasteva, S. Tabakov. Real-time detection of pathological cardiac events in the electrocardiogram, Physiol. Meas., 28, (3), 259-276, 2007, ISSN: 0967-3334.
  20. Jekova I. Shock advisory tool: Detection of life-threatening cardiac arrhythmias and shock success prediction by means of a common parameter set. Biomedical Signal Processing & Control, 2, 25-33, 2007, ISSN 1746-8094.
  21. Krasteva V., I. Jekova. QRS Template Matching for Recognition of Ventricular Ectopic Beats. Ann. Biomed. Eng., 35, (12), 2065-2076, 2007, ISSN 0090-6964.
  22. Christov, I., G. Gómez-Herrero, V. Krasteva, I. Jekova, A. Gotchev, K. Egiazarian. Comparative study of morphological and time-frequency ECG descriptors for heartbeat classification. Medical Engineering & Physics, 28, (9), 876-887, 2006, ISSN 1350-4533.
  23. Christov, I., I. Dotsinsky, I. Simova, R. Prokopova, E. Trendafilova, S. Naydenov. Dataset of manually measured QT intervals in the electrocardiogram. Biomedical Engineering Online, 5, 2006, ISSN 1475-925X.
  24. Krasteva, V., M. Matveev, N. Mudrov, R. Prokopova. Transthoracic impedance study with large self-adhesive electrodes in two conventional positions for defibrillation. Physiological Measurement, 10, (27), 1009-1022, 2006, ISSN: 0967-3334.
  25. Matveev, M., R. Prokopova, Ch. Nachev. Normal and Abnormal Circadian Characteristics in Heart Autonomic Control New Opportunities for Cardiac Risk Prevention. Nova Science Publishers, Inc., New York, USA, 2006, ISBN 1594549087:9781594549083.
  26. Krasteva, V., P-L. Kerkhof. On the optimal defibrillation waveform – how to reconcile theory and experiment. IEEE Transactions on Biomedical Engineering, 8, (53), 1725-1726, 2006, ISSN: 0018-9294.
  27. Christov I.I., G.L. Iliev. Public access defibrillation: Suppression of 16.7 Hz interference generated by the power supply of the railway systems. Biomedical Engineering Online, 4, 2005, ISSN 1475-925X.
  28. Christov I., I. Jekova, G. Bortolan. Premature ventricular contraction classification by the K-th nearest neighbours rule, Physiological measurements, 26, 123-130, 2005, ISSN: 0967-3334.
  29. Dotsinsky I. Suppression of AC railway power-line interference in ECG signals recorded by public access defibtillators. BioMed. Eng. OnLine, 4, 2005, ISSN 1475-925X.
  30. Dotsinsky I., T. Stoyanov. Power-line interference cancellation in ECG signals. Biomedical Instrumentation & Technology, 39, (2), 155-162, 2005, ISSN 0899-8205.
  31. Jekova I., V. Krasteva. Subtraction of 16.67 Hz railroad net interference from the electrocardiogram: Application for automatic external defibrillators, Physiol. Measurement, 26, pp. 987-1003, 2005, ISSN: 0967-3334.
  32. Krasteva V., I. Jekova. Assessment of ECG frequency and morphology parameters for automatic classification of life-threatening cardiac arrhythmias. Physiol. Measurement, 26, 707-723, 2005, ISSN: 0967-3334.
  33. Levkov Ch, G. Mihov, R. Ivanov, I. Daskalov, I. Christov, I. Dotsinsky. Removal of power-line interference from the ECG: a review of the subtraction procedure. Biomedical Engineering Online, 4, 2005, ISSN 1475-925X.

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