This document provides information about electrocardiography (ECG) including its history, components, interpretation, and procedure. It discusses that ECG was invented in 1901 by Enthovan to record electrical impulses of the heart. It describes the normal conduction system, waves (P, Q, R, S, T), segments, intervals of ECG and placement of 12 leads. The document outlines the procedure for performing an ECG including preparing the patient, connecting the leads, and interpreting the results. It emphasizes the importance of properly performing and interpreting ECG to assess cardiac function and diagnose cardiac conditions.

1. Rahul Kumar Jaga
B.Sc.Nursing 4th year
JINR, GWALIOR

2. INTRODUCTION
Electrocardiogram (ECG) is
invented by Enthovan in 1901.
He is also known as father of
ECG.

4. MODERN ECG INSTRUMENT

5. THE NORMAL CONDUCTION
SYSTEM

6. NORMAL ECG

7. DEFINITION
It is a tracing made of the various phase of
the heart’s action by means of an ECG.
To understand the ECG, recall the events
that takes place in the cardiac cycle.

8. IMPULSE CONDUCTION & THE ECG
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers

9. purpose
To assess the cardiac functions, e.g. rate ,
rhythm, and conduction.
To diagnose the cardiac rhythm disorder, e.g.
Arrhythmia.
To diagnose cardiac disease, e.g. myocardial
infarction.
Electrolyte disturbances, especially in calcium
and potassium levels.
To evaluate effects of treatment, e.g.
administration of cardiac drug.

10. Basic principles of ECG
An ECG is a permanent record of the
electrical impulses generated in the heart
by the depolarization and repolarization
(contraction and relaxation) of the
myocardium.
These impulses are transmitted to the
surface of body where they are detected
and picked up by the electrodes and
measured by a galvanometer
(electrocardiography).

11. Components of ECG
ECG consist of :-
Waves (P, Q, R, S, T, U)
complex (QRS)
segments (P-Q, S-T, T-P)
Intervals(P-R, Q-T, R-R)

12. WAVES OR COMPLEX
It is deflexion that can be positive,
negative, or both.

13. THE “PQRST”
 P wave - Atrial
depolarization
• T wave - Ventricular
repolarization
• QRS - Ventricular
depolarization

14. SEGMENTS
A segments is the period of time between
a wave or complex and another wave or
complex; normally, it is a straight line
(isotonic line).

15. INTERVALS
An intervals is the period of time between two
points on the ECG that includes a wave, a
complex or both.

16. ECG INTERPRETATION

17. GRAPHICAL REPRESENTATION OF
ECG
1.P WAVE :-
P wave is the first positive deflection (appearing above
the base line) seen on the ECG.
It is smoothly rounded.
It appears just before the QRS complex.
Presence of P wave indicates that the stimulus began in
the S.A.node (pacemaker) and subsequently spread
through both atria causing atrial contraction.
It represents the name taken by the atria to empty the
blood in to the ventricles through the open A.V.valves.
Normally, P wave has a duration of less than 0.11 second
and a height of less than 2.5mV.(3 small squares width and
3 small squares height)

18. NORMAL ECG

19. Cont…
ABNORMALITIES:-
P wave may be hidden, absent, invented, or
there may be more than one P wave. An
abnormal P wave indicates that the excitation
impulses is in a pacemaker other than S.A.node
(ectopic focus) or atrial depolarization is normal.
When there are more P waves then QRS
complexes, it indicates atrio-ventricular
conduction block.
P wave is considered enlarge, if it is more than
3 small squares tall and / or 3 small squares
wide, indicatives or atrial enlargement.

21. Cont…
2.P-R INTERVALS:-
P-R intervals is measured from the beginning
of P wave to the beginning of QRS complex.
It represent the time duration which the wave
of contraction passes through the entire
conduction system from the A,V,node to the
purkinje fibres in the myocardium.
During the P-R interval, the filling of the
ventricles is completed.
Normally it measured less than 0.20 second (5
small squares in width).

22. NORMAL INTERVALS

23. THE PR INTERVAL
Atrial depolarization
+
delay in AV junction
(AV node/Bundle of His)
(delay allows time for the atria
to contract before the
ventricles contract)

24. NORMAL PR INTERVAL
0.12 to 0.20 s (3 - 5 small squares).
Short PR – Wolff-Parkinson-White syndrome.
Long PR – 1st Degree AV block

25. Cont…
ABNORMALITIES:-
P-R intervals more than 0.20 second and less
than 0.12 second are considered abnormal.
If prolonged beyond 0.20 second, it indicates
first degree atrio-ventricular block; P-R interval
less than 0.12 second indicates a pacemaker in
the atria than S.A.node or in the A.V.node.

27. Cont…
3.QRS COMPLEX :-
 The QRS complex consist of :
A. Q wave – initial downward deflection.
B. R wave – a large upward deflection.
C. S wave – a second downward deflection.
 It represent the depolarization of ventricles.
 It represent the time required for the impulses to
spread through the ventricles to complete the
ventricular contraction.
 Normal QRS complex is narrow with a sharply
pointed wave.
 It measures 0.08 to 0.11 second or less than 3
small squares in width.

28. Cont…
ABNORMALITIES:-
QRS complex more than 0.11 second in width
and often with a bizarre appearance unusual
indicate that depolarization is proceeding in
abnormal sequence and direction.
Widened QRS complex indicates of bundle
branch block.

30. Cont…
4.S-T SEGMENTS:-
S-T segments began at the end of the S wave
of terminates at the beginning of the T wave.
It correlates with the period between the
ventricles depolarization and repolarization
(reflactory period); the cardiac muscle cannot
respond to stimuli during this period.
Normally S-T segments remains on the
isoelectric line.

31. Cont…
ABNORMALITIES:-
If the S-T segments is more than 1mm above
or below the base line, it indicates possible
myocardial ischaemia, or infarction.
This may be associate with reciprocal
depression or elevation in leads uninjured open.

33. Cont…
5.T WAVE:-
T wave represent the electrical recovery of
ventricles (repolarization).
This is the most vulnerable period of the
cardiac cycle.
Normally it appears upright and measures less
than 0.20 second in width and not more than
5mm in height.

34. Cont…
ABNORMALITIES:-
Flat T wave indicates myocardial ischaemia;
inverted T wave indicates myocardial infarction,
usually tall T wave indicate elevated serum
potassium.

36. Cont…
6.U WAVE:-
U wave is a small upright of low voltage,
sometimes seen following T wave.
Its significant is not known.

38. 12 LEADS OF ECG
ECG consist of records from 12 leads.
3 Standard bipolar Leads (I, II, III)
3 unipolar Limb Leads(aVR, aVL, aVF)
6 Precordial/unipolar chest Leads (V1-V6)

39. LEAD PLACEMENT
3 STANDARD BIPOLAR LEADS
LEAD I:- RIGHT ARM – LEFT ARM
(recorded the difference of
electrical potential between the right arm and left arm.)
LEAD II:- RIGHT ARM – LEFT LEG
(recorded the difference of
electrical potential between the right arm and left leg.)
LEAD III:- LEFT ARM TO LEFT LEG
(recorded the difference of
electrical potential between the left arm and left leg.)

41. 3 UNIPOLAR LIMB LEAD
aVR (AUGMENTED VOLTAGE RIGHT):-
Recorded the difference
of electrical potential between the right limb and the central
terminal. The latter is also called the indifferent electrode and is
constructed within the ECG machine by connecting all three
extremities. It has practically zero potential.
aVL (AUGMENTED VOLTAGE LEFT):-
Recorded the difference of
electrical potential between left arm and central terminal.
aVF ( AUGMENTED VOLTAGE FOOT):-
Recorded the difference of
electrical potential between the left leg and central terminal.
NOTE :- one electrode is placed on the right leg and it serve as
the grounded electrode.

43. 6 Precordial/unipolar chest Lead
V1:
Lead V1 is to be placed 4th RICS of the sternum.
V2 :
Lead V2 is to placed directly across from V1 in the
4th LICS, on the left side of the sternum.
V4 :
Lead V4 is placed in the 5th LICS, midclavicular.
V3 :
Lead V3 is placed directly horizontally & equidistant
in between leads V2 and V4.
V6 :
Lead V6 is placed in the 5th LICS, midaxillary
horizontally level with V4 .
V5 :
Lead V5 is placed horizontally & equidistant in
between leads V4 and V6 (anterior axillary line )

46. Standard Chest Lead Electrode Placement
The Right-Sided 12-Lead ECG The 15-Lead ECG

47. LEAD “VIEWS”

48. PROCEDURE
1.PREPRATION OF PATIENT:-
There is no specific preparation for the investigation.
Explain the procedure to the patient and relatives that the seemingly
complex apparatus will do no harm but gill give information on the
action of heart.
There should not be any ornaments during ECG on the body or the
leads should not come in contact with the ornaments.
Apply jelly to the skin where electrode is to be attached to have a
good contact between the skin and the electrode.
Give flat and relaxed position to the patient because any movements
or twitching recorded by the machine may alter the tracings.
Clean the jelly off the electrodes site before leaving the patient.
There are specific position for the placement of the chest. The
improper placement of the chest leads can discomfort the tracing and
alter the diagnosis.

49. CONT…
2.PREPROCEDUAL CARE:-
Hand wash
Check and arrange the ECG machine, cables
and electrodes and needed articles ready in
advance.
Explain the procedure clearly to the patient and
family.
Check the doctor’s order for the ECG.
Identify the patient name, age, Id No. and
diagnosis.
Inform the patient not to move during
procedure time.

51. Cont…

52. Cont…

53. Cont…

54. CONT…
3.PROCEDURE:-
Position the patient relaxed and flat.
Inform the bystanders to keep away to prevent
them touching the patient during procedure.
Enter the identification data of the patient.
Expose the needed area for connecting
electrode.
Stay with the patient till it get over.

55. CONT…
4.AFTER CARE:-
Clean the patient electrodes site with gauze or
tissue paper.
Ambulate and transfer the patient send the
ECG record to the doctor for interpretation.
Replace the ECG machine and articles to
proper place.
Record and report in nurse’s sheet.

56. ANY QUESTIONS

57. Thank you
for your continuous efforts
to participate, be part of the team and be ready
to do an ECG when needed.
Perform an ECG,
Make a difference,
Save a life.