Electrocardiogram is the graphical registration of electrical activities of heart. Uses- 1. Heart rate 2. Heart rhythm 3. Abnormal electrical conduction 4. Poor blood flow to cardiac muscle 5. Coronary artery disease 6. Hypertrophy of heart chambers ECG leads- bipolar limb leads Unipolar limb leads Unipolar chest leads

1. ELECTROCARDIOGRAM
Syeda Nusrath Fatima (MPT)

2. ELECTROCARDIOGRAM
Electrocardiogram is a record or graphical registration of electrical activities of heart.

3. USES
ECG is useful in determining and diagnosing:
1. Heart rate
2. Heart rhythm
3. Abnormal electrical conduction
4. Poor blood flow to cardiac muscle
5. Coronary artery disease
6. Hypertrophy of heart chambers

4. ELECTROCARDIOGRAPHIC GRID
• The paper that is used for recording ECG is called ECG paper.
• ECG machine amplifies the electrical signals produced from heart and records these
signals on a moving ECG paper.
• Electrocardiographic grid refers to the markings on ECG paper. ECG paper has horizontal
and vertical lines
• Movement of paper through machine can be adjusted by 2 speeds, 25mm/sec and
50mm/sec.

5. ECG LEADS
• ECG is recorded by placing series of electrodes on the surface of the body.
• These electrodes are called ECG leads and are connected to the ECG machine.
• Electrodes are fixed on limbs
• Usually right arm, left arm and left leg are chosen.
• Heart is said to be in the centre of equilateral triangle drawn by connecting roots of these
3 limbs.
• This triangle is called Einthoven triangle.

7. ECG is recorded in 12 leads which are classified into 2 categories:
1. Bipolar leads
2. Unipolar leads
 Bipolar leads
Bipolar limb leads are also known as standard limb leads.
Standard limb leads are of 3 types:
a. Limb lead 1
b. Limb lead 2
c. Limb lead 3

9.  Unipolar leads
1 electrode is an active electrode , other one is an indifferent electrode.
Unipolar leads are of 2 types-
a. Unipolar limb leads/ Augmented limb leads
b. Unipolar chest leads/ V leads/ precordial chest leads
Unipolar limb leads-
Active electrode is connected to one of the limbs
Indifferent electrode is obtained by connecting the other 2 limbs through a resistance.

10. Unipolar limb leads are of 3 types:
• aVr lead
Active electode- right arm
Indifferent electrode- left arm and left leg
• aVL lead
Active electrode – left arm
Indifferent electrode- right arm and left leg
• aVF lead
Active electrode- left leg
Indifferent electrode- 2 UL

11. Unipolar chest leads-
Active electrode is placed on 6 points over chest.
Indifferent electrode is obtained by connecting 3 limbs through a resistance of 5000 ohms.
V indicates vector. It shows direction of current flow.

13. Duration- (in seconds)
P wave- 0.1 sec
QRS complex- 0.08-0.10
T wave- 0.2
P-R interval- 0.18
Q-T interval- 0.4 – 0.42
S-T segment- 0.08
Causes-
P wave- Atrial depolarization
QRS complex- Ventricular depolarization
T wave- Ventricular repolarization

14. THANK YOU