IRJET- Study of Hypocalcemic Cardiac Disorder by Analyzing the Features of ECG Signal using DWT Technique

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 328
Study of Hypocalcemic Cardiac Disorder by Analyzing the Features of
ECG Signal Using DWT Technique
Deeksha Bekal Gangadhar1, Dr. Ananth A. G.2
1Student, Dept. of Electronics and Communication Engineering, NMAMIT, Nitte, Karnataka, India
2Professor, Dept. of Electronics and Communication Engineering, NMAMIT, Nitte, Karnataka, India
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Abstract - Heart diseases are one of the most fatal diseases
leading to deaths if they are not diagnosed and treated
properly on time. The electrical signals (ECG signals)fromthe
heart are monitored for detecting the cardiac disorders and
heart diseases. The ECG signals are significantly affected by
the various noises produced by the electronic devices used for
monitoring the ECG signals. It is very essential to develop an
effective de-noising technique to generate accurate ECG
signals to monitor diseases in heart patients. Further the
strategies are development and designed for the detection of
hypocalcaemia from the QRS complex of the ECG signal using
wavelet transform technique. The paper presents the effective
de-noising technique and statistical parameters like Mean
Square Error (MSE), Root Mean SquareDeviation(RMSD) and
Percentage Deviation (PD) are estimated for the ECG signal
which gives the amount of error in the ECG signal. The
comparison between parameter is made to distinguish
between healthy person and the cardiac patients.
Key Words: AD, Hypocalcemia, DWT,ECG,Mean,MSE,PD,
RMSD.
1. INTRODUCTION
The electrical wave duration decides whether the electrical
activity is normal, slow or irregular. Range of the frequencies
of an ECG signal is 0.05–100 Hz. ECG signal has five peaks
that are named as P, Q, R, S and T. Another peak called U is
also seen in some cases[1].
P, QRS and T are the waves present in ECG signal. The wave
corresponds atria depolarization,ventriculardepolarization,
and ventricular re-polarization. ECG signal showing various
peak intervals is as shown in Figure 1. ECG signal has three
segments namely, PR segment, ST segment and TP segment.
Normally, P-R interval is in the range of 0.12 to 0.2 second.
Range of QRS interval is from 0.04 to 0.1 second and the Q-T
interval is less than 0.42 second[2]. Usually ECG signals are
contaminated by various kinds of noise. Hence proper de-
noising of the ECG signal is carried out.
Wavelet transform is applied to the de-noised ECG signal to
obtain various peaks in the ECG signal like Q, R and S-peak.
From the peaks the average rise time andaverage fall timeof
ECG signal is determined. From the detectedQ,RandS-peaks
the QRS complex is determined. With the help of detected
QRS complex, the interval between QRS complex of ECG
signal is calculated.
After the calculation of these interval, hypocalcemia is
determined[4]. From the resulting value of QRS complex it is
detected whether the patient is normal or not. Patient is
normal if he has a QRS complex within 0.1 second other than
this range it is seen that hypocalcaemia is present.
Fig -1: ECG signal showing various peak intervals[3].
Mean value is determined forthe occurrence of QRScomplex
of ECG signal obtained from the Q, R and S-peaks. From the
determined mean value and sum of squared difference of
occurrence of the interval the value of RMSD is calculated.
Deviation of the value from mean value is determined.
Average Deviation (AD) from mean is calculated. From the
values of mean and average deviation from mean the
Percentage Deviation (PD) is calculated.
2. LITERATURE SURVEY
Muhammad Arzaki et al. 2017 [5], describes about the Mean
Square Error (MSE). MSE is a method to evaluate the
difference between actual and predicted data.
Modjtaba Rouhani et al. 2009 [6], describes about the RMSD.
RMSD is the square root of average of squared errors. It is a
non negative value. Lower RMSD yields better results.. It is a
measure of accuracy to compare errors.
Nicolae Marius Roman et al. 2015 [7], describes about
hypocalcemia. The conditionin which there is lower levelsof
calcium in plasma. If the ECG signal has prolongation of QT

interval because of lengthening of ST segment which is
directly proportional to hypocalcaemia.
M. J Burke et al. 2009 [8], describes about the average rise
and fall time for the ECG signal. Average rise time is the
average timeit takes for the edge of the pulsetoraisefromits
minimum to maximum value(Q-peaktoR-peak).Averagefall
time is the average time it takes for the edge of the pulse to
move from its maximum to minimum value (R-peak to S-
peak).
Hudson et al. 2017 [9] presented, describes about the
Savitzky Golay filter. Peakshapepreservationpropertyofthe
Savitzky Golay filters are attractive in applications such as
ECG signal processing. The major advantageofthismethodis
the preservation of important features of the original time
series, like relative widths and heights. SG filter fits a
polynomial in a window of points around each sample point
using least squares fitting.
Lim Choo Min et al. 2007 [10], describes the steps in ECG
signals analysis.
3. PROPOSED METHODOLOGY
The proposed methodology is based on the technique to
detect hypocalcemia using DWT based on QRS complex
detection. RMSSD and Percentage deviation are determined
for normal and abnormal signal. Original input signals are
taken from MIT-BIH Database directory of ECG signals from
www.physionet.org. Flow chart isasshowninFigure2which
depicts the steps involved in the detection which are as
follows:
3.1 De-noising of ECG signal
The derivative based approach amplifies high frequency
noises, which leads to high difference signals due to noise.
Therefore, initially smoothing and filtering of ECG signal is
carried out to eliminate low frequency noises in ECG signal.
Smoothing of the signal is done using SG filtering.
Smoothened ECG signal isFIRfiltered,hencede-noisedsignal
is obtained.
3.2 Detection of Q, R and S-peaks
Physiologic signals are frequently non stationary which
means that their frequency content changes over time.
Signals are often localizedintimeandfrequency,analysisand
estimation are easier when working with reduced
representations. DWT is used to find the Q-peak, R-peak and
S-peak from the ECG signal. DWT transformation is as given
by the equation 1.
Where, is the signal to be analysed,
is the mother wavelet.
All the wavelet functions used in the transform are derived
from the mother waveletthroughwavelettranslation ( ) and
scaling ( ).
3.3 Calculation of Average Rise Time (ART) and
Average Fall Time (AFT)
ART and AFT are calculated from the detected Q, R and S
peaks of the de-noised ECG signal. ART and AFT are
calculated in seconds. ART is obtained by finding average of
the duration between Q and R-peaks. Average Fall Time is
obtained by findingaverage of the duration betweenRandS-
peaks. Average QRS complex is determined from Q, R and S-
peak.
3.4 Detection of hypocalcemia
From the obtained Q, R and S-peaks of ECG signal, QRS
complex of ECG signal is determined. From these complexes,
the time interval between their occurrences is determined.
Duration between the QRS complex is calculated in seconds.
If the QRS complex duration is below 0.1 second then it is a
normal condition. If the QRS complex duration is above 0.1
second then hypocalcemia is detected.
3.5 Calculation of MSE
MSE is definedas the averagesquareddifferencebetween
the estimated values and what is to be estimated. MSE is a
non negative value and values closer to zero are better.
Smaller value of Mean Square error gives better results. MSE
is given by equation 2.
Where, 𝑀𝑆𝐸 is the Mean Square Error.
𝑌 is the mean value.
𝑌′ is the obtained value.
n is the number of samples.
3.6 Calculation of RMSD
RMSD is defined astheaverageofsquarederrors.RMSDis
always a non negative and a value of zero indicates a perfect
fit to data which is an ideal condition. RMSD values closer to
zero indicates better results. Lower RMSD is better than
higher value of RMSD. Thus larger errors have a
disproportionately large effect on RMSD. RMSD is given by
the equation 3.

Where, MSE is the Mean Square Error.
RMSD is the Root Mean Square Deviation.
3.7 Calculation of Percentage Deviation (PD)
Percentage Deviation (PD) refers to how much the mean
of a set of data differs from a known or theoretical value.
Mean and Average Deviation (AD) is used to find percentage
deviation. Mean is defined as the ratio of sum of values of all
data points to the number of data points. Average deviation
gives the average variation of the data points from the mean
value. Percentage deviation is given by the equation 4.
Where, 𝑃𝐷 is the Percentage Deviation.
𝑌 is the mean value.
The value of MSE, RMSD and PD are the measures for
calculation of accuracy which gives the amount of error
present in the ECG signal.
Fig -2: Flow chart.
4. RESULTS AND DISCUSSION
Original ECG signals are taken from MIT-BIH database
directory of physionet. These signals are smoothened and
filtered to remove low frequency noises presentinthesignal
to obtain de-noised signal. SinceECGsignal isnonstationary,
wavelet transform is applied to the de-noised ECG signal to
obtain Q, R and S-peak which forms the QRS complex. From
the obtained peaks, average QRS complex duration is
determined. Depending onthevalueofaverageQRScomplex
duration, patients are classified as normal or hypocalcemic.
If the average QRS complex duration is below 0.1 second
then the condition is normal. If it is above 0.1 second then
the condition is hypocalcaemia.
Three ECG signals MIT-BIH 200, MIT-BIH 203 and MIT-
BIH 107 are used as test signals. The original and de-noised
MIT-BIH 200, MIT-BIH 203, MIT-BIH 107 ECG signals are as
shown in the Figure 3, Figure 6, Figure 9. The filtered noise
and the R-peaks of MIT-BIH 200, MIT-BIH 203, MIT-BIH 107
ECG signal are as shown in the Figure 4, Figure 7, Figure 10.
The S-peaksand Q-peaks of MIT-BIH 200,MIT-BIH203,MIT-
BIH 107 ECG signal is as shown in the Figure 5, Figure 8,
Figure 11.
Fig -3: Original and de-noised MIT-BIH 200 ECG signal.
Fig -4: Filtered noise and the R-peaks of MIT-BIH 200 ECG
signal.

Fig -5: S-peaks and Q-peaks of MIT-BIH 200 ECG signal.
signal.
Various statistical analysis of the parameters are carried out
for MIT-BIH 200, MIT-BIH 203 and MIT-BIH 107 ECG signals
are as shown in the Table 1. Average QRS complex duration
for MIT-BIH 200 ECG signal is 0.0702 second. Therefore the
heart condition is normal. Average QRS complexdurationfor
MIT-BIH 203 ECG signal is 0.1750 second. Therefore the
heart condition is hypocalcaemia. Average QRS complex
duration for MIT-BIH 107 ECG signal is 0.1775 second.
Therefore the heart condition is hypocalcaemia.

signal.
Table -1: Calculated values of various parameters of QRS
complex for MIT-BIH 200, MIT-BIH 203 and MIT-BIH 107.
5. CONCLUSION
ECG is a very useful bio-signal which isusedbyphysiciansfor
the purpose of diagnosing and monitoring heart disease and
cardiac disorder. Therefore it becomes essential to examine
ECG signal so as to detect chronic diseases in its early stages.
ECG signals are prone to variousnoises.Thereforede-noising
of the ECG signal is carried out where low frequency noises
are removed. A method has been proposed to detect heart
conditions. From the detected Q, RandS-peaksusingwavelet
transform the QRS complex and its duration is determined.
Depending on this duration hypocalcaemia is detected. In
MIT-BIH 200, normal condition is observed. Hypocalcemia
condition is detected in MIT-BIH 203 and MIT-BIH 107 ECG
signals. Statistical parameters are analyzed which are
effectively used for distinguishing between the normal
persons and cardiac patients. MSE, RMSD and Percentage
Deviation (PD) forMIT-BIH 200 are less thanthatofMIT-BIH
203 and MIT-BIH 107 as a result of variation inthesignaldue
to hypocalcemia.
ACKNOWLEDGEMENT
We extend our gratitude towards the institute for the
constant support. We would like to acknowledgeoursincere
thanks to the HOD of ECE Department for the
encouragement. Finally, we would also like to thank
principal and all the faculties of the department for their
support.
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[7] Ciupe AM, Roman NM. Study of ECG signal processing
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IRJET- Study of Hypocalcemic Cardiac Disorder by Analyzing the Features of ECG Signal using DWT Technique

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