Electrocardiogram
Chapter 7
Electrocardiogram
7.1. Introduction in ECG:
7.1.1. What is an ECG?
It is a graphic produced by an electrocardiogram record the body surface potentials
generated by the electrical activity of the heart, this electrical activity can be measured by
an array of electrodes placed on the body surface, and it is an important aspect of the
clinical evaluation of an individual’s cardiac status and overall health. Its name is made
of different parts: electro, because it is related to electronics, cardio, Greek for heart,
gram, a Greek roots meaning "to write"
.
It is used to detect and locate the source of heart problem.
An ECG gives two kinds of information:
First: Time intervals of the ECG.
Second: The amount of electrical activity passing through the heart.
7.1.2 ECG graph paper:
Figure 7.1 ECG graph paper.
A typical electrocardiograph runs at a paper speed of 25 mm/s, although faster paper
speeds are occasionally used. Each small block of ECG paper is 1 mm².
At a paper speed of 25 mm/s, one small block of ECG paper translates into 40 ms). Five
small blocks make up 1 large block, which translates into 0.20 s (or 200 ms). Hence,
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Electrocardiogram
there are 5 large blocks per second. A diagnostic quality 12 lead ECG is calibrated at 10
mm/mV, so 1 mm translates into 0.1 mV. A "Calibration" signal should be included with
every record. A standard signal of 1mV must move the stylus vertically 1 cm, which are
two large squares on ECG paper.
7.1.3 What does the ECG record?
Three major waves of electric signals appear on the ECG
Figure 7.2 ECG Signal
1) The P wave:
The P wave is the electrical signature of the current that causes atrial contractions. Both
the left and right atrial contract simultaneously. Its relationship to QRS complexes
determines the presence of a heart block.
Figure 7.3 The formation of P wave
2) The QRS wave:
The QRS complex corresponds to the current that causes contraction of the ventricles,
which is much more forceful than of the atria. It involves more muscle mass, which
results in greater ECG deflection. The duration of the QRS complex is normally less than
or equal to 0.1 second.
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Electrocardiogram
Figure 7.4 The formation of QRS wave
3) The T wave:
The T wave represents the repolarization of the ventricles. It records the heart's return to
the resting state.
Figure 7.5 The formation of T wave
Doctors study the shape and size of the waves, the time between waves and the rate and
regularity of beating. This tells a lot about the heart and its rhythm.
The letters "Q", "R" and "S" are used to describe the QRS complex:
Q: the first negative deflection after the p-wave. If the first deflection is not negative, the
Q is absent.
R: the positive deflection
S: the negative deflection after the R-wave
small print letters (q, r, s) are used to describe deflections of small amplitude. For
example: qRS = small q, tall R, deep S.
R`: is used to describe a second R-wave (as in a right bundle branch block)
Parameter
P-R interval
Q-T interval
P wave
QRS wave
Duration
0.12-0.20ms
0.30-0.40ms
0.08-0.10ms
0.06-0.10ms
Table 7.1 Duration of Waves and intervals in a normal human heart
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Electrocardiogram
7.1.4. What can you expect during an ECG?
An electrocardiogram is obtained by measuring electrical potential between various
points of the body.
 Leads:
*The word lead has two meanings in electrocardiography: it refers to either the wire that
connects an electrode to the electrocardiograph, or (more commonly) to a combination of
electrodes that form an imaginary line in the body along which the electrical signals are
measured. Thus, the term loose lead artifact uses the former meaning, while the term 12
lead ECG uses the latter. In fact, a 12 lead electrocardiograph usually only uses 10
wires/electrodes. The latter definition of lead is the one used here.
*An electrocardiogram is obtained by measuring electrical potential between various
points of the body using a biomedical instrumentation amplifier. A lead records the
electrical signals of the heart from a particular combination of recording electrodes which
are placed at specific points on the patient's body.
*When a depolarization wave front (or mean electrical vector) moves toward a positive
electrode, it creates a positive deflection on the ECG in the corresponding lead.
* When a depolarization wave front (or mean electrical vector) moves away from a
positive electrode, it creates a negative deflection on the ECG in the corresponding lead.
* When a depolarization wave front (or mean electrical vector) moves perpendicular to a
positive electrode, it creates an equiphasic (or isoelectric) complex on the ECG. It will be
positive as the depolarization wave front (or mean electrical vector) approaches (A), and
then become negative as it passes by (B).
Figure 7.6 Effect of electrode movement in the ECG signal.
 Limb:
Leads I, II and III are the so-called limb leads because at one time, the subjects of
electrocardiography had to literally place their arms and legs in buckets of salt water in
order to obtain signals for Einthoven’s string galvanometer. They form the basis of what
is known as Einthoven's triangle. Eventually, electrodes were invented that could be
placed directly on the patient's skin. Even though the buckets of salt water are no longer
necessary, the electrodes are still placed on the patient's arms and legs to approximate the
signals obtained with the buckets of salt water. They remain the first three leads of the
modern 12 lead ECG.
* Lead I is a dipole with the negative (white) electrode on the right arm and the positive
(black) electrode on the left arm.
* Lead II is a dipole with the negative (white) electrode on the right arm and the positive
(red) electrode on the left leg.
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Electrocardiogram
* Lead III is a dipole with the negative (black) electrode on the left arm and the positive
(red) electrode on the left leg.
Figure 7.7 Proper placement of the limb leads.
 Augmented limb:
Leads AVR, AVL, and AVF are augmented limb leads. They are derived from the same
three electrodes as leads I, II, and III. However, they view the heart from different angles
(or vectors) because the negative electrode for these leads is a modification of Wilson's
central terminal, which is derived by adding leads I, II, and III together and plugging
them into the negative terminal of the EKG machine. This zeroes out the negative
electrode and allows the positive electrode to become the "exploring electrode" or a
unipolar lead. This is possible because Einthoven's Law states that I + (-II) + III = 0. The
equation can also be written I + III = II. It is written this way (instead of I +II + III = 0)
because Einthoven reversed the polarity of lead II in Einthoven's triangle, possibly
because he liked to view upright QRS complexes. Wilson's central terminal paved the
way for the development of the augmented limb leads AVR, AVL, AVF and the
pericardial leads V1, V2, V3, V4, V5, and V6.
* Lead AVR or "augmented vector right" has the positive electrode (white) on the right
arm. The negative electrode is a combination of the left arm (black) electrode and the left
leg (red) electrode, which "augments" the signal strength of the positive electrode on the
right arm.
* Lead AVL or "augmented vector left" has the positive (black) electrode on the left arm.
The negative electrode is a combination of the right arm (white) electrode and the left leg
(red) electrode, which "augments" the signal strength of the positive electrode on the left
arm.
* Lead AVF or "augmented vector foot" has the positive (red) electrode on the left leg.
The negative electrode is a combination of the right arm (white) electrode and the left
arm (black) electrode, which "augments" the signal of the positive electrode on the left
leg.
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Electrocardiogram
The augmented limb leads AVR, AVL, and AVF are amplified in this way because the
signal is too small to be useful when the negative electrode is Wilson's central terminal.
Together with leads I, II, and III, augmented limb leads AVR, AVL, and AVF form the
basis of the hex axial reference system, which is used to calculate the heart's electrical
axis in the frontal plane.
Figure 7.8 Proper placement of the augmented limb.
 Pericardial:
The precordial leads V1, V2, V3, V4, V5, and V6 are placed directly on the chest.
Because of their close proximity to the heart, they do not require augmentation. Wilson's
central terminal is used for the negative electrode, and these leads are considered to be
unipolar. The precordial leads view the heart's electrical activity in the so-called
horizontal plane. The heart's electrical axis in the horizontal plane is referred to as the Z
axis.Leads V1, V2, and V3 are referred to as the right precordial leads and V4, V5, and
V6 are referred to as the left precordial leads.
The QRS complex should be negative in lead V1 and positive in lead V6.
The QRS complex should show a gradual transition from negative to positive between
leads V2 and V4. The equiphasic lead is referred to as the transition lead. When the
transition occurs earlier than lead V3, it is referred to as an early transition. When it
occurs later than lead V3, it is referred to as a late transition. There should also be a
gradual increase in the amplitude of the R wave between leads V1 and V4. This is known
as R wave progression. Poor R wave progression is a nonspecific finding. It can be
caused by conduction abnormalities, myocardial infarction, cardiomyopathy, and other
pathological conditions.
Lead V1 is placed in the fourth intercostals space to the right of the sternum.
Lead V2 is placed in the fourth intercostals space to the left of the sternum.
Lead V3 is placed directly between leads V2 and V4.
Lead V4 is placed in the fifth intercostals space in the midclavicular line (even if the
apex beat is displaced).
Lead V5 is placed horizontally with V4 in the anterior axillary line
Lead V6 is placed horizontally with V4 and V5 in the mid axillaries Line
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Electrocardiogram
Figure 7.9 proper placements of the pericardial leads
 Ground:
An additional electrode (usually green) is present in modern four-lead and twelve-lead
ECGs. This is the ground lead and is placed on the right leg by convention, although in
theory it can be placed anywhere on the body. With a three-lead ECG, when one dipole is
viewed, the remaining lead becomes the ground lead by default.
Standard
Leads
Bipolar
Lead
Lead I
Lead II
Lead III
LimbLeads
Unipolar Leads
AVR
AVL
AVF
Table 7.2 ECG leads system
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Chest Leads
Unipolar Leads
V1
V2
V3
V4
V5
V6
Electrocardiogram
7.2. Noise in ECG Signal
In recent years the trend towards automated analysis of electrocardiograms has gained
momentum. Many systems have been implemented in order to perform such tasks as 12lead offline electrocardiogram analysis, Holter tape analysis in real-time patient
monitoring. This requires accurate detection of various parameters of interest even in the
presence of noise. For accurate detection however steps have to be taken to filter out or
discard the noise. Filtering can alter the signal and may require substantial computational
overhead.
The goal of denoising is to remove the noise while retaining as much as possible the
important signal features. Traditionally, this is achieved by linear processing. Most of
these methods are very useful and efficient in denoising of narrowband noise where
spectral of signal and noise is not conflicting.
Electrocardiographic signals (ECG) may be corrupted by various kinds of noise. Typical
examples are:
1. Power line interference
2. Electrode contact noise.
3. Motion artifacts.
4. Muscle contraction.
5. Base line drift.
6. Instrumentation noise generated by electronic devices.
7. Electrosurgical noise.
7.2.1. Power line interference:
It consists of 50-60Hz pickup and harmonics, which can be modeled as sinusoids.
Characteristics, which might need to be varied in a model of power line noise, of 60Hz
component (as most of the signals of study were digitized in USA) include the amplitude
and frequency content of the signal. The amplitude varies up to 50 percent of the peak to
peak ECG amplitude. It is shown in the figure where power signal is effecting the signal
between 1000 to 3000 units of time.2
Figure 7.10 Power line interference
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Electrocardiogram
7.2.2 Electrode contact noise
It is a transient interference caused by loss of contact between the electrode and the skin
that effectively disconnects the measurement system from the subject. The loss of contact
can be permanent, or can be intermittent as would be the case when a loose electrode is
brought in and out of contact with the skin as a result of movements and vibration. This
switching action at the measurement system input can result in large artifacts since the
ECG signal is usually capacitive couple to the system. It can be modeled as randomly
occurring rapid base line transition, which decays exponentially to the base line value and
has a superimposed 60Hz component. Typically the values of amplitude may vary to the
maximum recorder output.
7.2.3 Motion Artifacts:
Motion artifacts are transient base line changes caused by changes in the electrode skin
impedance with electrode motion. As this impedance changes, the ECG amplifier sees a
different source impedance which forms a voltage divider with the amplifier input
impedance therefore the amplifier input voltage depends upon the source impedance
which changes as the electrode position changes.
The usual cause of motion artifacts will be assumed to be vibrations or movements of the
subjects. The peak amplitude and duration of the artifact are variable, as illustrated in the
figure this type of interference represents an abrupt shift in base line due to movement of
the patient while the ECG is being recorded. It is simulated by adding a dc bias for a
given segment of ECG.
Figure 7.11 Motion Artifacts
7.2.4 Muscle contraction:
Muscle contractions cause artifactual millivolt level potentials to be generated. The base
line electromyogram is usually in the microvolt range and therefore is usually
insignificant. It is simulated by adding random noise to the ECG signal. The maximum
noise level is formed by adding random single precision numbers of 50% of the ECG
maximum amplitude to the uncorrupted ECG. A plot of the ECG corrupted by
electromyographic noise is given in the Figure.
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Electrocardiogram
Figure 7.12 Muscle contraction
7.2.5 Base Line Drift with Respiration:
The drift of the base line with respiration can be represented by a sinusoidal component
at the frequency of respiration added to the ECG signal. The amplitude and the frequency
of the sinusoidal component should be variables. The variations could be reproduced by
amplitude modulation of the ECG by the sinusoidal component added to the base line.
Shown the Figure
Figure 7.13 Base Line Drift with Respiration
7.2.6 Noise generated by electronic devices:
The parameter detection algorithms cannot correct artifacts generated by electronic
devices. The input amplifier saturates and no information about the ECG reaches the
detector. In this case manual preventive and corrective action needs to be undertaken.
7.2.7 Electrosurgical noise:
It completely destroys the ECG and can be represented by a large amplitude sinusoid
with frequencies approximately between 100kHz to 1MHz. Since the sampling rate of an
ECG signals 250 to 1000Hz an aliased version of the signal.
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Electrocardiogram
7.3. Filtering in ECG:
Signal processing, in general, has a rich history, and its importance is evident in
such a diverse fields as biomedical engineering, acoustics, Sonar, radar, Seismology,
speech communication, data communication, nuclear science, and many others. In many
applications, as, for example, in EEG and ECG analysis or in systems foe speech
transmission and speech recognition it can be used to extract some characteristic
parameters.
Alternatively, for to remove interference, such as noise, from the signal or to modify the
signal to present it in a form which is more easily interpreted by an expert.
Recent trends in the processing of the biomedical signals have been towards quantitative
or the objective analysis of physiological systems and phenomena via signal analysis.
The field of biomedical signal analysis or processing has advanced to the stage of
practical application of signal
processing and pattern analysis techniques foe efficient and improved noninvasive
diagnosis, online monitoring of critical ill patients, and rehabilitation and sensory aids for
the handicapped. Techniques developed by engineers are gaining wider acceptance by
practicing clinicians, and the role of engineering in diagnosis and treatment is gaining
much–observed respect.
The filters have a very important function in ECG which removes unwanted parts of the
signal extract useful parts of the signal
Figure 7.14 Function of the filters
7.3.1 How select type of filter?
To know type of filter must be use must be know the characteristics of signal that we
want filtered it, Characteristics like frequency & amplitude and another characteristic.
Example
If we want filter noise at 0.1 HZ
This noise low freq and cut off freq at 0.1 so we use low freq filter (HPF)
If we want filter noise at 50 /60HZ
This noise high freq filter and cut off freq at 50 so we use high freq filter (LPF)
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Electrocardiogram
7.3.2 Types of filters.
In signal processing, the function of a filter is to remove unwanted parts of the signal,
such as random noise, or to extract useful parts of the signal, such as the components
lying within a certain frequency range. there are two main kinds of filter, analog and
digital. they are quite different in their physical makeup and in how they work.
 Analog filter :
An analog filter uses analog electronic circuits made up from components such as
resistors, capacitors and opamps to produce the required filtering effect. Such filter
circuits are widely used in such applications as noise reduction, video signal
enhancement, graphic equalizers in hi-fi systems, and many other areas.
There are well-established standard techniques for designing an analog filter circuit for a
given requirement.
At all stages, the signal being filtered is an electrical voltage or current which is the direct
analogue of the physical quantity (e.g. a sound or video signal or transducer output)
involved.
Advantages:
 Simple and consolidated methodologies of plan.
 Fast and simple realization.
Disadvantages:
 Little stable and sensitive to temperature variations.
 Expensive to realize in large amounts.
 Digital filter
A digital filter uses a digital processor to perform numerical calculations on sampled
values of the signal. the processor may be a general-purpose computer such as a PC, or a
specialized DSP (Digital Signal Processor)chip.
The analog input signal must first be sampled and digitized using an ADC (analog to
digital converter). The resulting binary numbers, representing successive sampled values
of the input signal, are transferred to the processor, which carries out numerical
calculations on them. These calculations typically involve multiplying the input values by
constants and adding the products together. If necessary, the results of these
calculations,which now represent sampled values of the filtered signal, are output through
a DAC (digital to analog converter) to convert the signal back to analog form.
Note that in a digital filter, the signal is represented by a sequence of numbers, rather than
a voltage or current.
Figure 7.15 Basic setup of System
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Electrocardiogram
Operation of digital filters:
In this section, we will develop the basic theory of the operation of digital filters. This is
essential to an understanding of how digital filters are designed and used.
Suppose the "raw" signal which is to be digitally filtered is in the form of a voltage
waveform described by the function V = x(t) where t is time. This signal is sampled at
time intervals h (the sampling interval).
The sampled value at time
t = i h is xi= x( ih)
Thus the digital values transferred from the ADC to the processor can be represented by
the sequence x , x , x , x , ... 0 1 2 3 corresponding to the values of the signal waveform
at t = 0, h, 2h, 3h, ... and t = 0 is the instant at which sampling begins.
At time t = nh (where n is some positive integer), the values available to the processor,
stored in memory, are x , x , x , x , ... x 0 1 2 3 n
Note that the sampled values xn+1, xn+2 etc. are not available, as they haven't happened
yet!
The digital output from the processor to the DAC consists of the sequence of values y , y
, y , y , ... y 0 1 2 3 n
In general, the value of yn is calculated from the values x0, x1, x2, x3, ... , xn. The way in
which the y's are calculated from the x's determines the filtering action of the digital filter
The following list gives some of the main advantages of digital over analog filters:
 A digital filter is programmable, i.e. its operation is determined by a program
stored in the processor's memory .This means the digital filter can easily be
changed without affecting the circuitry (hardware).An analog filter can only be
changed by redesigning the filter circuit.
 Digital filters are easily designed, tested and implemented on a general-purpose
computer or workstation.
 The characteristics of analog filter circuits (particularly those containing active
components) are subject to drift and are dependent on temperature. Digital filters
do not suffer from these problems,and so are extremely stable with respect both to
time and temperature.
 Unlike their analog counterparts, digital filters can handle low frequency signals
accurately. As the speed of DSP technology continues to increase, digital filters
are being applied to high frequency signals in the RF (radio frequency) domain,
which in the past was the exclusive preserve of analog technology.
 Digital filters are very much more versatile in their ability to process signals in a
variety of ways; this includes the ability of some types of digital filter to adapt to
changes in the characteristics of the signal.
 Fast DSP processors can handle complex combinations of filters in parallel or
cascade (series), making the hardware requirements relatively simple and compact
in comparison with the equivalent analog circuitry
Due to advantages of digital filter so will use it to remove noises and there are many
types of digital filters will be know which any one proper in our case :
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Electrocardiogram
 Finite impulsive response (FIR):
FIR filters usually require no feedback (non-recursive).
Advantages
(1) may be realised by non-recursive structures which are simpler and more convenient
for programming especially on devices specifically designed for DSP.
(2) FIR structures are always stable.
(3) Because there is no recursion, round-off and overflow errors are easily controlled.
(4) An FIR filter can be exactly linear phase.
Disadvantage
(1) Large number of filter
(2) Expensive
(3) There are delay.
 Infinite impulsive response (IIR):
The Infinite Impulse Response (IIR) filter has the impulse response of infinite duration.
The general difference equation for an IIR digital:
Where ak is the k-th feedback tap depending on previous outputs. If ak=0 then the filter is
a FIR.
N is the number of feedback taps in the IIR filter & M is the number of feed forward taps.
Note that, unlike the FIR filter, the output of an IIR filter depends on both the previous M
inputs and the previous N outputs. This feedback mechanism is inherent in any IIR
structure. It is responsible for the infinite duration of the impulse response.
There are many standard for IIR filter as shown in the following figure
Low pass filter
high pass filter
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Electrocardiogram
band pass filter
stop band filter
Figure 7.16 Standards of IIR
Transfer function of digital IIR filter
p  p1 z 1  p2 z 2    pM z  M
H ( z)  0
d 0  d1 z 1  d 2 z  2    d N z  N
H(z) must be a stable function, N must be of lowest order.
To design IIR filter must be this approach
Design analog
lowpass filter
Apply Freq. band
transformation
s-->s
Apply filter
transformation
s-->z
Desired
IIR filter
Figure 7.17 Desired IIR filter
Convert the digital filter specifications into analog low pass prototype filter specifications
Determine the analog low pass filter transfer function to meet these specifications Then
transform it into the desired digital filter transfer function and we used this approach for
the following reasons:
 Analog approximation techniques are highly advanced
 Usually yield closed-form solutions
 Extensive tables are available for analog filter design.
Many applications require the digital simulation of analog filters.
Figure 7.18 The magnitude response
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Electrocardiogram
Equations:
In pass band
1   p  G ( e j )  1   p ,
G ( e j )   s ,
In stop band
for    p
for  s    
Where δp and δs are peak ripple values, ωp are pass band edge frequency and ωs are stop
band edge frequency
The pass band and stop band edge frequencies, in most applications are specified in Hz
p 
s 
p
FT

2Fp
FT
 2FpT
 s 2Fs

 2FsT
FT
FT
Where FT denote the sampling frequency in Hz, Fp and Fs denote, respectively, the pass
band and stop band edge frequencies in Hz
Discrimination parameter:
d
1   
2
p
2
 s 
1
1

or
A2  1
Number of filter:
1
1
 p [(1   p ) 2  1] 2 N   c   s [( s ) 2  1] 2 N
Types of IIR filter
Chebyshev
Butterworth
Elliptic
 Butterworth filter:
This filter is characterized by the property that its magnitude response is flat in both
passband and stop band.
Magnitude response
The order of filter
H a ( j ) 
2
N
1


1  
 c 
2N

 p 

with   

 c
16
 
1 log10 A2  1  2 log10 d

2 log10  s  p 
log10 k
N
Electrocardiogram
1.2
1
N=100
N=2
0.8
N=1
N=200
0.6
0.4
0.2
0
0
10
20
30
40
50
60
70
80
90
100
Figure 7.19 Effect the # of order on magnitude response
Advantages for IIR filter:
 Economical in use of delays, multipliers and adders So IIR filters are useful for
high-speed designs because they typically require a lower number of multiplies
compared to FIR filters.
 IIR filters can be designed to have a frequency response that isdiscrete version of
the frequency response of an analog filter
7.3.3 Application
The application on IIR(BUTTERWORTH FILTER)
Use to remove Power line interference from ECG signal By using lowpass butterworth
filter and Baseline wander from ECG signal By using highpass butterworth filter
Figure 7.19 Power line interference
Figure7.20 Baseline drift
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Electrocardiogram
In lab
Figure 7.21 Measurment of three channel
Measure three channel
channel_1(lead I)
the amp = .95mv
channel_2(lead II)
the amp =1.09mv
channel _3(lead III)
the amp =1mv
Choose the greatest channel and apply filtering on it (lead II)
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Electrocardiogram
Figure 7.22 The flow chart of first code
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Electrocardiogram
Figure 7.23 Flow chart of second code
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Results

Step 1:
Load data of three channel and display
F
i
g
Figure 7.24 Channel 2 has the largest amplitude
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Electrocardiogram

Step 2:
Calculate the average of three channel and calculate the noisy
signal
Figure 7.25
Noisy signal and its FFT
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Electrocardiogram

Step 3:
Zoom to discover the noisy.
Figure 7.26 Zooming of Noisy signal and its FFT
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Electrocardiogram

Step 4 :
Remove the noise at 50 HZ
Figure 7.27
ECG signal without 50 HZ component and its FFT
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Electrocardiogram

Step 5:
Zoom version to see ECG without 50 HZ.
Figure 7.28
FFT of zooming ECG signal without 50HZ component
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 Step 6:
Remove 0.5HZ using Butterworth highpass filter cut off .5 hz
Figure 7.29
ECG signal without 0.5HZ component and it’s FFT
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Electrocardiogram
7.4. ECG diagnosis:
Usually, doctors can tell whether a person has a heart or blood vessel disorder on
the basis of the medical history and the physical examination. Diagnostic procedures are
used to confirm the diagnosis, determine the extent and severity of the disease, and help
in planning treatment.
Medical History and Physical Examination.
A doctor first asks about symptoms. Chest pain, shortness of breath, palpitations, and
swelling in the legs, ankles, and feet or abdomen suggest a heart disorder. Other, more
general symptoms, such as fever, weakness, fatigue, lack of appetite, and a general
feeling of illness or discomfort (malaise), may suggest a heart disorder. Pain, numbness,
or muscle cramps in a leg may suggest peripheral arterial disease, which affects the
arteries of the arms, legs, and trunk (except those supplying the heart).
Next, the doctor asks about past infections; previous exposure to chemicals; use of drugs,
alcohol, and tobacco; home and work environments; and recreational activity. The doctor
also asks whether family members have had a heart disorder or any other disorders that
may affect the heart or blood vessels.
During the physical examination, the doctor notes the person's weight and overall
appearance and looks for paleness (pallor), sweating, or drowsiness, which may be subtle
indicators of heart disorders. The person's general mood and feeling of well-being, which
also may be affected by heart disorders, are noted. Assessing skin color is important
because pallor or a bluish or purplish coloration (cyanosis) may indicate anemia or
inadequate blood flow. These findings may indicate that the skin is not receiving enough
oxygen from the blood because of a lung disorder, heart failure, or various circulatory
problems.
The doctor feels the pulse in arteries in the neck, beneath the arms, at the elbows and
wrists, in the abdomen, in the groin, at the knees, and in the ankles and feet to assess
whether blood flow is adequate and equal on both sides of the body. The blood pressure
and body temperature are also checked. An abnormality may suggest a heart or blood
vessel disorder.
The doctor inspects the veins in the neck while the person is lying down with the upper
part of the body elevated at a 45° angle. These veins are inspected because they are
directly connected to the right atrium (the upper chamber of the heart that receives
oxygen-depleted blood from the body) and thus give an indication of the volume and
pressure of blood entering the right side of the heart.
The doctor presses the skin over the ankles and legs and sometimes over the lower back
to check for fluid accumulation (edema) in the tissues beneath the skin.
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Electrocardiogram
7.4.1 The 10 rules of normal heart beat:
Rule 1
PR interval should be 120 to 200 milliseconds or 3 to 5 little squares.
Figure 7. 30 (a)
Rule 2
The width of the QRS complex should not exceed 110 ms,
less than 3 little squares.
Figure 7. 30 (b)
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Electrocardiogram
Rule 3
The QRS complex should be dominantly upright in leads I
and II.
Figure 7. 30 (c)
Rule 4
QRS and T waves tend to have the same general direction
in the limb leads.
Figure 7. 30 (d)
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Electrocardiogram
Rule 5
All waves are negative in lead aVR .
Figure 7. 30 (e)
Rule 6
The R wave in the precordial leads must grow from V1 to
at least.
Figure 7. 30 (f)
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Electrocardiogram
Rule 7
The ST segment should start isoelectric except in V1 and V2
where it may be elevated.
Figure 7. 30 (g)
Rule 8
The P waves should be upright in I, II, and V2 to V6.
Figure 7. 30 (h)
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Electrocardiogram
Rule 9
There should be no Q wave or only a small q less than 0.04 seconds
in width in I, II, V2 to V6.
Figure 7. 30 (i)
Rule 10
The T wave must be upright in I, II, V2 to V6.
Figure 7. 30 (j)
Figure 7. 30 (a)-(j) Rules of normal heart
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Electrocardiogram
7.4.2 The abnormal cases heart beats:
 Myocardial Infarction (Heart Attack):
Myocardial infarction (MI) means that part of the heart
muscle suddenly loses its blood supply. Without prompt
treatment, this can lead to damage to the affected part of the
heart. An MI is sometimes called a heart attack or a coronary
thrombosis. An MI is part of a range or disorders called 'acute
coronary syndromes'. There is a brief explanation of the term
'acute coronary syndrome' at the end of this leaflet.
Characteristic changes in AMI
 ST segment elevation over area of damage.
 ST depression in leads opposite infarction.
 Pathological Q waves.
 Reduced R waves.
 Inverted T waves.
Figure 7. 31 Sequence of changes in AM







Accelerated Junctional Rhyth
Atrial Fibrillation With Moderate Ventricular Response
Atrial Flutter With Variable AV Block
Atrial Flutter With Variable AV Block
Electronic Atrial Pacing
Sinus Bradycardia with 2:1 AV Block
Electronic Ventricular Pacemaker Rhythm
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Electrocardiogram












Normal Sinus Rhythm
Pacemaker Failure to Pace
Pacemaker Failure To Sense
Pacemaker Fusion Beat
Rate-Dependant LBBB
right bundle branch block
First Degree block
Second degree block
Third degree block
Ventricular Pacing in Atrial Fibrillation
WPW and Pseudo-inferior MI
WPW Type Preexcitation.
------------------------------
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Electrocardiogram
Our Design
In our project we detect different heart diseases by using the following 20 abnormal
ECG
image.
Figure 6.32 Atrial Fibrillation With Moderate Ventricular Response
Figure 6.33 Atrial Flutter With Variable AV Block
Figure 34 Atrial Flutter With Variable AV Block
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Electrocardiogram
Figure 6.35 Sinus Bradycardia with 2:1 AV Block
Figure 6.36 Electronic Ventricular Pacemaker Rhythm
Figure 6.37 First Degree block copy
Figure 6.38 Electronic Atrial Pacing
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Electrocardiogram
Figure 6.39 Normal Sinus Rhythm
Figure 6.40 Pacemaker Failure to Pace
Figure 6.41 Pacemaker Failure To Sense
Figure 6.42 Pacemaker Fusion Beat
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Electrocardiogram
Figure 6.43 right bundle branch block
Figure 6.44 second degree block
Figure 6.45 third degree block
Figure 6.46 Ventricular Pacing in Atrial Fibrillation
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Electrocardiogram
Figure 6.47 WPW and Pseudo-inferior MI
Figure 6.48 WPW Type Preexcitation
Figure 6.49 Accelerated Junctional Rhythm
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Electrocardiogram
Using the following design of ANN
Figure 6.50 Our design ANN
The ANN is consist of 5 input layer , 5 hidden layer and only one output and
we will use 4 ANN to detect 20 different heart diseases as shown later.
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Electrocardiogram
Sequence of operations
Identification
Training
1-Training:
Figure 6.51 Flowchart of training program
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Electrocardiogram
1- Initiate and construct the Artificial Neural Networks which have many parameters:

Number of hidden layers.

Number of Neurons.

Acceptable sum squared error (error goal).

Activation functions.

Maximum number of epochs.

Weight.

Bias.

Output layer.
2- Starting training of ANN with the specified parameters to get the optimum values of
weight and bias of the network.
Illustration of some points in the program:
*The operation of neural networks is Non-linear, that is due to the activation functions
used.
*Histogram is a vector of gray scale levels, length=2n where n=intensity.
Figure 6.52 Histogram example
*Mean-variance is a vector of Mean-variance of each column of image matrix, the length
of the vector is the number of columns.
*Edge is the abrupt change of intensity.
*The hidden layer, the output layer, activation functions and number of neurons all are
constant.
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Electrocardiogram
*Only the input is variable.
*When the sum squared error decreases, the learning rate increases And here, the neural
network knows whether the direction of training network is the right direction or not.
Result
1st network:
2nd network
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Electrocardiogram
3rd network
4th network
*Target error is 0.0001.
*Learning cycle (Epoch) for reaching this target error:
1st network 154 Epoch.
2nd network 162 Epoch.
3rd network 178 Epoch.
4rd network 174 Epoch.
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Electrocardiogram
Recalling:
By entering the simulated case we get the image of heart disease and the name of disease
hence, we get the required objective of software.
Figure 6.53 Flowchart of Recalling program
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Electrocardiogram
Result
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Electrocardiogram
-------------------------------------------------
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