ECG ppt for nurses.

1. Electrocardiography
Prepared By:
Barsha Silwal

2. The Heart
• All heart muscle is capable of
conducting an electrical impulse
and initiating a spontaneous
electrical discharge. .
• Calcium is major cation
responsible for cardiac
contraction.

3. ECG
ECG reflects the electrical activity of cardiac cells & useful to
detect arrythmia, MI & other abnormality.

4. Cont’d
ECG — A galvanometer & electrodes with four limb leads and
six chest leads which record electrical activity of heart on graph
paper with divisions.
• ECG recorders & monitors are standardized at a speed of
25mm/sec.

5. Cont’d
• Electrocardiographic paper: A
graph paper with each small
square measuring 1mm X 1mm.
• Time is measured on horizontal
(X) axis & voltage on Y axis.
• Each small square represents
0.04seconds.
• Five small squares make up one
large square representing 0.20
seconds.

6. Cont’d
In 12 lead ECG
Chest leads-6 (V1,V2,V3,V4,V5&V6 ) Electrode positioned in
the
• V1-4th intercostal space (ICS) in the right sternal border.
• V2-4th ICS in the left sternal border.
• V3- Midway between V2&V4.
• V4-5th ICS in the left midclavicular line.
• V5- Same level as V4, anterior axillary line.
• V6-Same level as V4 & V5, midaxillary line.

7. Cont’d

8. Cont’d
P wave Represents atrial contraction(depolarization).
QRS complex Represents ventricular contraction (depolarization) and is
composed of 3 waves, the Q, R & S. Q wave is the first negative
deflection. R wave is the first positive deflection after the P wave. S wave
is the negative deflection following R wave. It is about 0.08 to 0.12 sec,
represented by 3 small squares.

9. Cont’d
• ST segment representing early ventricular relaxation
(repolarization). Elevated ST segment in MI & depress ST
segment in myocardial ischemia.
• T wave Represents ventricular repolarization. Usually
positive, rounded, & slightly Asymmetric.
• U wave Results from slow repolarization of ventricular
Purkinje fibers. More common in lead V3. Due to
Hypokalemia.

10. Cont’d
PR interval :Measured from the
beginning of P wave to the beginning
of QRS complex. The normal PR
interval is 0.12 - 0.2 sec. The time it
takes for the impulse to spread from
atria to ventricles.
QT interval :Represents total time
required for ventricular depolarization
& repolarization. Normal QT interval
is 0.32 to 0.4sec.

11. Indications
• Myocardial Infarction& other types of CAD such as angina
• Cardiac dysrhythmias
• Cardiac enlargement
• Electrolyte disturbances
• Inflammatory diseases of the heart (RHD & myocarditis)
• Effects on the heart by drugs, such as antiarrhythmics.

12. Cont’d

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14. Cont’d

15. Cont’d

16. Cont’d