United Arab Emirates University

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United Arab Emirates University Faculty of
Engineering Electrical Engineering Department
Electrocardiogram (ECG) System
Asma Nassar 980224973 Muna Ali Anber
980724425 Muna Abdullah 980724558
Graduation Project 1
Dr.Idress S. AL-Kofahi
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• Overview
• Introduction
• Objectives
• Gantt Chart
• Anatomy and physiology of
• the heart
• ECG System
• ECG Block Diagram
• Filters
• Conclusion

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Introduction

• Heart is a muscle that works like a pump for
  blood.
• The heart contraction creates action potential
  which initiates electrical current.
• The different electrical potentials between
  different parts of the body can caused cardiogram
  .

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• Objective

• To design and construct an
• Electrocardiogram (ECG) System
• The detecte signal will be fed to a computer for
  immediate monitoring and interpretation.

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Gantt Chart for 1st semester

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Anatomy and physiology of the heart

• Sino-atrial (SA) node
• (also called the sinus node) is the heart's
  master pacemaker. The SA node sends electrical
  signals in a steady, rhythmic pattern to pace the
  heart's beat. Signals from the SA node travel to

• Atrio-ventricular (AV) node
• which transmits the signal from the upper
  chambers, or atria, to the lower chambers
  (ventricles). The ventricles are the major
  pumping chambers of the heart. The transmitted
  electrical signal triggers the powerful muscle
  contraction needed to pump blood into the lungs
  and throughout the body.

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ECG System

• The recorded signal of the hearts muscular
  potential, over a period of the time is called
  electrocardiogram.
• ECG is the graphic record of the hearts
  electrical activity which used in the
  investigation of heart disease.

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ECG waveform

• P wave is the result of action potential that
  cause depolarization of the atrial myocardium.
• QRS complex is composed of three individual
  waves, is result from ventricular depolarization
  and signals the onset of ventricular contraction.
• T wave represent repolarization of the
  ventricles and precedes ventricular relaxation.

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ECG leads

• Lead 1 is connected to the right arm and the
  positive terminal to the left arm.
• Lead 2 is connected negative terminal of the
  electrocardiograph which connected to the right
  arm and the positive terminal to the left leg and
  lead.
• Lead 3 is connected to the left arm and the
  positive terminal to the left leg.

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ECG Bloke Diagram
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Input Stage

• Protection Circuit

it protects the system from high level voltages
or DC shock (defibrillator) used to resuscitate
heart attack patients .
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• Lead Selector Design

Switches

• Connect the patient leads to either
• noninverting amplifier terminal ()
• inverting terminal (-)
• CM

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Processing Stage

• Calibration Circuit

It is a circuit consisting of resistive network
connected to a voltage source that gives at its
output 1mV. it is used to check the amplifying
factor of the system before using ECG machine.
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• Fault detector

it can be detected manually or automatically,
depending on operating modes and how quickly the
system needs to be restored. For a system that
requires human interfaces, system failures can be
detected quickly by human visual and/or auditory
sensors
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• Instrumentation Amplifier

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Circuit Design of instrumentation amplifier
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Simulation Result
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• Filters

-Low Pass Filter
There are many types of low pass filter like
Butterworth and Chebyshev filters (in the project
the Butterworth filter was used). Low pass filter
used to filter out signals at frequencies higher
than the filters cut off frequency which is
required in the project (to reject frequencies
higher than 100 Hz).
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Circuit design
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Simulation Result
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-High Pass Filter
A High Pass filter is a filter that passes high
frequencies and attenuates low frequencies. Also,
high pass filters are useful to filter out the
undesired low frequency components from the main
high frequency signals, they are usually used in
applications requiring the rejection of low
frequency signals.
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Circuit design
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Simulation Result
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-Notch Filter
A notch filter is required to eliminate the 50Hz
interference, this interference comes from the
power lines carrying this frequency in close
proximity to patient and equipment.
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Circuit design
fc 1/(2 p RnCn) Choose Cn 0.47 µF fc 50Hz

• 1/(2 p Rn 0.47 µF )
• Rn 6.773kO

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Simulation Result
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Output Stage

• Oscilloscope

The oscilloscope is basically a graph-displaying
device - it draws a graph of an electrical
signal.
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Conclusion