ECG Is a graphic representation of electrical activity produced by the heartbeat.

1. ECG / ELECTROCARDIOGRAM /
ELECTROCARDIOGRAPH/ EKG

2. DEFINITION
• ECG Is a graphic representation of
electrical activity produced by heart beat.
• The electrical activity spreads from heart
to the body surface from where it is
amplified by ECG machine and can be
graphically recorded.

3. Parts of an ECG
• 1) ECG Machine
• 2) Electrodes- The standard ECG has 12
leads.
– a) 6 leads are “limb leads”
– b) 6 leads are “precordial leads”

4. • A) 6 leads are “limb leads”
– The six limb leads are called lead I, II, III, aVL,
aVR and aVF.
– The letter “a” stands for “augmented".

5. • B) 6 leads are “precordial leads”
• The six precordial leads are called leads V1, V2, V3, V4,
V5 and V6

6. • V1- In the fourth intercostal space (between
ribs 4 and 5) just to the right of the sternum
(breastbone)
• V2- In the fourth intercostal space (between
ribs 4 and 5) just to the left of the sternum.
• V3- Between leads V2 and V4.
• V4- In the fifth intercostal space (between ribs
5 and 6) in the mid-clavicular line.
• V5- Horizontally even with V4, in the left
anterior axillary line.
• V6- Horizontally even with V4 and V5 in the
mid-axillary

8. • P-wave:
– It is a small upward wave that appears first.
– It indicates atrial depolarization (systole), during
which excitation spreads from SA node to all over
atrium.
• QRS wave:
– It represents the ventricular depolarization
(systole)Just after QRS wave begins, ventricles
starts to contracts.
– Hence QRS wave represents ventricular systole
• T- wave:
– It is third small wave in the form of a dome-shaped
upward deflection.
– It indicates ventricular repolarization (diastole)

10. • P-R interval:
–It represents the time required for an
impulse to travel through the atria, AV
node and Bundle of His to reach
ventricles.
• S-T segment:
–It is measured from the end of S to the
beginning of T- wave
–It represents the time when ventricular
fibers are fully depolarized

11. USES OF ECG
• 1) Diagnosis of heart disease like Ischemic
heart disease, Myocardial infarction
• 2) Hypertrophy of atria and ventricles
• 3) Electrolyte imbalance like potassium
cause T wave depression