Introduction to ECG

1. ELECTROCARDIOGRAM
Dr Manjiri Honap
Ist M.D.S.
Department of Conservative Dentistry and
Endodontics 1

2. Learning objectives
Definition of Electrocardiogram
What is the purpose of recording it?
Terminologies used during ECG recording
(Leads, waves, segments, interval, ECG paper)
Calculate Heart rate and evaluate rhythm
Case studies and Quiz
Demonstration video
summary
Abbreviations used- Electrocardiogram - ECG
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3. What is ECG?
Graphic record of electrical activity of heart which is obtained by
placing electrode on body surface that records voltage differences
generated by heart
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4. Electrocardiography and
Electrocardiograph
Electrocardiography is a method of recording ECG
Wile electrocardiograph is a machine that records ECG which
amplifies and gives a plot of voltage as a function of time
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5. How does the surface electrode
record the activity of heart?
Human body is a volume conductor
ECG recorded at body surface is an algebraic sum of action
potential of individual cardiac muscle fiber
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6. What Is the purpose of recording
ECG?
Anatomical orientation of heart
Relative size of chambers
Disturbances of rhythm and conduction
Ischemia of myocardium if present
Location and extent of myocardial infarct
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7. Which all patients you will advise
ECG in your Dental office?
• The patients undergoing any major surgical procedure
• Previous history of any cardiac disease
• The patients which you are going to treat under General
Anesthesia
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8. Terminologies used during ECG
recording
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9. Electrode and Leads
• Electrode is a metal plate used to detect electrical currents of
heart in any location
• ECG lead shows different voltages recorded by electrodes
• A standard ECG is recorded with 12 leads
• Where does the 12 lead come from?
• Leads are placed in 2 different planes perpendicular to each
other
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10. 10
12 leads
Frontal plane
or limb leads
(6)
Bipolar Unipolar
Transverse plane
or chest leads
(6)
Unipolar

11. Frontal or limb leads or hex axial leads
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Lead I, II, III
Bipolar
Avr, Avf, Avl
Unipolar

12. Einthoven's
triangle
Bipolar limb leads
Lead I
Between right arm and left
arm
Lead II
Between left foot and right
arm
LEAD III
Between left foot and left
arm
Right foot is a grounded
electrode
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13. Unipolarlimbleads
• AVR, AVL, AVF
• Here A stands for augmented V stands for unipolar
• These are exploring electrodes while
• The reference point or an indifferent electrode is
connected to right arm, left arm and left leg through the
high resistance which is called as Wilson’s terminal which
is maintained at zero potential
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