Electrocardiogram_20240614_173859_0000.pdf

Basics of Electrocardiogram
CONTENTS
●Conduction System of the Heart
●What is ECG or EKG?
●ECG Leads
●Normal waves of ECG.
●Dimensions of ECG.
● Abnormalities of ECG
CONDUCTION SYSTEM OF THE HEART
ECG:
●ECG is a graphic record of the electrical activity of the heart.
●Electrical activity precedes the mechanical activity of the heart.
●Electrical activity has two phases:
Depolarization- contraction of muscle
Repolarization- relaxation of muscle
ECG Leads:
●6 Chest leads
●6 Limb leads
1. Bipolar Limb Leads:
Lead 1- Between right arm(-ve) and left arm(+ve)
Lead 2- Between right arm(-ve) and left leg(+ve)
Lead 3- Between left arm(-ve)
and left leg(+ve)
2. Augmented unipolar Limb Leads:
AvR- Right arm
AvL- Left arm
AvF- Left leg

3.Chest Leads:
V1 : Over 4th intercostal
space near right sternal margin
V2: Over 4th intercostal space near left sternal margin
V3:In between V2 and V4
V4:Over left 5th intercostal space on the mid
clavicular line
V5:Over left 5th intercostal space on the anterior
axillary line
V6:Over left 5th intercostal space on the mid
axillary line.
Normal ECG:
Waves of ECG:
P Wave
•P Wave is a positive wave and the first wave in ECG.
•It is also called as atrial complex.
Cause: Atrial depolarisation
Duration: 0.1 sec
QRS Complex:
•QRS’ complex is also called the initial ventricular complex.
•‘Q’ wave is a small negative wave. It is continued as the tall ‘R’ wave, which is a positive wave.
‘R’ wave is followed by a small negative wave, the ‘S’ wave.
Cause:Ventricular depolarization and atrial repolarization
Duration: 0.08- 0.10 sec
T Wave:
•‘T’ wave is the final ventricular complex and is a positive wave.
Cause:Ventricular repolarization Duration: 0.2 sec

Intervals and Segments of ECG:
P-R Interval:
•‘P-R’ interval is the interval
between the onset of ‘P’wave and onset of ‘Q’ wave.
•‘P-R’ interval cause atrial depolarization and conduction of impulses through AV node.
Duration:0.18 (0.12 to 0.2) sec
Q-T Interval:
•‘Q-T’ interval is the interval between the onset of ‘Q’
wave and the end of ‘T’ wave.
•‘Q-T’ interval indicates the ventricular depolarization
and ventricular repolarization,
i.e. it signifies the
electrical activity in ventricles.
Duration:0.4-0.42sec
S-T Segment:
•‘S-T’ segment is the time interval between the end of ‘S’ wave and the onset of ‘T’ wave.
Duration: 0.08 sec

R-R Interval:
•‘R-R’ interval is the time interval between two consecutive ‘R’ waves.
•It signifies the duration of one cardiac cycle.
Duration: 0.8 sec
Dimension of ECG:
How to find heart rhytm of the heart?
Regular rhytm:
Irregular rhytm:
More than or less than 4
How to find heart rate using ECG?
If heart Rhytm is Regular :
Heart rate =
300/No.of large b/w 2 QRS complex
= 300/4
=75 beats/mins
How to find heart rate using ECG?
If heart Rhytm is irregular:
Heart rate = 10×No.of QRS complex in 6 sec 5large box = 1sec
5×6=30
10×7 = 70 Beats/min
Abnormalities of ECG:
Cardiac Arrythmias:
1.Tachycardia
Heart Rate more than 100 beats/min

1. BASICS OF
ELECTROCARDIOGRAM
Elackkiya B
BPT 4th Year

2. Conduction System of the
Heart
1.
What is ECG or EKG?2.
ECG Leads3.
Normal waves of ECG.4.
Dimensions of ECG.5.
Abnormalities of ECG6.
CONTENTS

3. CONDUCTION SYSTEM OF THE HEART

4. ECG is a graphic record of the electrical
activity of the heart.
Electrical activity precedes the mechanical
activity of the heart.
Electrical activity has two phases:
Depolarization- contraction of muscle
Repolarization- relaxation of muscle
ECG

5. ECG Leads:
6 Chest leads
6 Limb leads
1. Bipolar Limb Leads:
Lead 1- Between right arm(-ve)
and left arm(+ve)
Lead 11- Between right arm(-ve)
and left leg(+ve)
Lead 111- Between left arm(-ve)
and left leg(+ve)

6. 2. Augmented unipolar Limb Leads:
AvR- Right arm
AvL- Left arm
AvF- Left leg
3. Chest Leads:
V1 : Over 4th intercostal
space near right sternal
margin
V2: Over 4th intercostal
space near left sternal
margin
AvR AvL
AvF
Ground lead

7. V3:In between V2
and V4
V4:Over left 5th intercostal
space on the mid
clavicular line
V5:Over left 5th intercostal
space on the anterior
axillary line
V6:Over left 5th intercostal
space on the mid
axillary line.

8. Normal ECG:

9. Waves of ECG:
P Wave
•P Wave is a positive wave and the first wave in
ECG.
• It is also called as atrial complex.
Cause: Atrial depolarisation
Duration: 0.1 sec

10. QRS Complex:
•QRS’ complex is also called the initial
ventricular complex.
•‘Q’ wave is a small negative wave.
It is continued as the tall ‘R’ wave,
which is a positive wave.
‘R’ wave is followed by a small
negative wave, the ‘S’ wave.
Cause:Ventricular depolarization and
atrial repolarization
Duration: 0.08- 0.10 sec

11. T Wave:
•‘T’ wave is the final ventricular complex and is
a positive wave.
Cause:Ventricular
repolarization
Duration: 0.2 sec

12. •‘P-R’ interval is the interval
between the onset of ‘P’wave
and onset of ‘Q’ wave.
•‘P-R’ interval cause atrial
depolarization and
conduction of impulses
through AV node.
Intervals and Segments of ECG:
P-R Interval:
Duration:0.18 (0.12 to 0.2) sec

13. Q-T Interval:
•‘Q-T’ interval is the interval
between the onset of ‘Q’
wave and the end of ‘T’ wave.
•‘Q-T’ interval indicates the
ventricular depolarization
and ventricular repolarization,
i.e. it signifies the
electrical activity in ventricles.
Duration:0.4-0.42sec

14. •‘S-T’ segment is the time
interval between the end of ‘S’
wave and the onset of ‘T’ wave.
S-T Segment:
Duration: 0.08 sec

15. R-R Interval:
•‘R-R’ interval is the time interval between two
consecutive ‘R’ waves.
•It signifies the duration of one cardiac cycle.
Duration: 0.8 sec

16. Dimension of ECG:

17. How to find heart rhytm of the heart?
Regular rhytm:
Irregular rhytm:
More than or less than 4

18. How to find heart rate using ECG?
If heart Rhytm is Regular :
Heart rate =
300
No.of large b/w 2 QRS complex
___________________________
300 ________
4
= = 75 Beats/min

19. How to find heart rate using ECG?
If heart Rhytm is irregular :
Heart rate = 10×No.of QRS complex in 6 sec
5large box = 1sec
= 70 Beats/min
5×6=30
10×7

20. Abnormalities of ECG:
Cardiac Arrythmias:
1.Tachycardia:
Heart Rate more than 100 beats/min
•P-R interval shortened

21. Abnormalities of ECG:
Cardiac Arrythmias:
2.Bradycardia:
Heart Rate less than 60 beats/min
•P-R interval prolong

22. Abnormalities of ECG:
Cardiac Arrythmias:
3.Atrial flutter
Heart Rate more than 200 beats/min
• Saw tooth pattern at P wave

23. Abnormalities of ECG:
4. Myocardial infraction:
• S-T segment elevation

24. Abnormalities of ECG:
5. Ischemia:
• T wave inversion

25. ACTIVITY TIME

26. PREVIOUSLY ASKED
QUESTIONS
1.Normal ECG?
2.Abmormal ECG
Arrhythmias
Mycardial infarction