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Jekova I.,Bulgarian Academy of Science | Krasteva V.,Bulgarian Academy of Science | Dotsinsky I.,Bulgarian Academy of Science | Christov I.,Bulgarian Academy of Science | Abacherli R.,Schiller AG
Computing in Cardiology | Year: 2011

The upgrade of mobile phones with applications for acquisition, pre-processing and transmitting the patient's ECG to a hospital unit would be of great benefit for prevention against the most frequent mortality caused by heart failure. This idea is promoted by the Computing in Cardiology Challenge 2011, which encourages the development of algorithms for analysis of the ECG quality within few seconds, aiming to warn about diagnostically unacceptable recordings. This paper presents an algorithm for scoring the noise corruption level by evaluation of ECG amplitude dynamics, baseline wander, powerline interference, EMG and peak artifacts. The score achieved for participation in Event 1 is 0.908. Additionally unacceptable ECGs with interchanged leads are detected with sensitivity of 96.8% (30/31 files) for peripheral leads and 87% (40/46 files) for chest leads. © 2011 CCAL. Source


Christov I.,Bulgarian Academy of Science | Simova I.,National Diagnostics | Abacherli R.,Schiller AG
Computing in Cardiology | Year: 2013

No signal processing technique has been able to reliably deliver an undistorted fetal electrocardiographic (fECG) signal from electrodes placed on the maternal abdomen because of the low signal-to-noise ratio of the fECG recorded from the maternal body surface, resulting in increased rates of Caesarean deliveries of healthy infants. In an attempt to solve the problem a Physionet/Computing in Cardiology announced the 2013 Challenge: Noninvasive fetal ECG. © 2013 CCAL. Source


Christov I.,Bulgarian Academy of Science | Simova I.,National Diagnostics | Abacherli R.,Schiller AG | Abacherli R.,Cardiovascular Research Institute
Physiological Measurement | Year: 2014

No signal processing technique has been able to reliably deliver an undistorted fetal electrocardiographic (fECG) signal from electrodes placed on the maternal abdomen because of the low signal-to-noise ratio of the fECG recorded from the maternal body surface. As a result, this led to increased rates of Caesarean deliveries of healthy infants. In an attempt to solve the problem, Physionet/Computing in Cardiology announced the 2013 Challenge: noninvasive fetal ECG. We are suggesting a method for cancellation of the maternal ECG consisting of: maternal QRS detection, heart rate dependant P-QRS-T interval selection, location of the fiducial points inside this interval for best matching by cross correlation, superimposition of the intervals, calculation of the mean signal of the P-QRS-T interval, and sequential subtraction of the mean signal from the whole fECG recording. Three signal decomposition methods were further applied in order to enhance the fetal QRSs (fQRS): principal component analysis, root-mean-square and Hotelling's T-squared. A combined lead of all decompositions was synthesized and fQRS detection was performed on it. The current research differs from the Challenge in that it uses three signal decomposition methods to enhance the fECG. The new results for 97 recordings of test set B are: 305.657 for Event 4: Fetal heart rate (FHR) and 23.062 for Event 5: Fetal RR interval (FRR). © 2014 Institute of Physics and Engineering in Medicine. Source


Jekova I.,Bulgarian Academy of Science | Krasteva V.,Bulgarian Academy of Science | Abacherli R.,Schiller AG
Computing in Cardiology | Year: 2013

This study presents methods for automated detection of interchanged precordial and orthogonal ECG leads that may prevent from incorrect diagnosis and treatment. For precordial leads V1-V6, correlation coefficients of QRS-T patterns and time-alignment of R and S-peaks are assessed. For orthogonal leads (X,Y,Z), analysis of QRS loops in the frontal plane, a set of correlation coefficients and a time-alignment of leads are implemented. The methods are elaborated using 15-lead ECG databases - 77 healthy control recordings from PTB database (training), and the total set of 1220 ECGs in CSE database with various arrhythmias (test). The specificity (Sp) for detection of the correct precordial leads configuration (V1 to V6) is 93.5% (training) and 91% (test) and the mean sensitivity (Se) for 23 simulated most common chest electrode swaps is 95.7% (training) and 95% (test). Sp for detection of the correct orthogonal leads X,Y,Z is 98.7% (training) and 93.3% (test), while mean Se for 47 reversals of electrode couples A/I, F/H, M/E is 98.5%, equal for both training and test databases. © 2013 CCAL. Source


Simova I.,National Diagnostics | Christov I.,Bulgarian Academy of Science | Bortolan G.,CNR Institute of Neuroscience | Abacherli R.,Schiller AG | And 2 more authors.
Computing in Cardiology | Year: 2016

ECGs of 59 patients undergoing hemodialysis (HD): 52% males, age 59±13 years, renal disease duration 9.7±6.7 years, hemodialysis duration 5.2±4.4 years were recorded. Serum electrolytes (potassium-K, sodium-Na, phosphorus-Ph and calcium-Ca), urea and creatinine levels were evaluated before and after HD. ECG analysis on an average P-QRS-T interval in order to avoid accidental events or noise was performed. © 2015 CCAL. Source

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