Electrocardiograhy (A topic in National Book Foundation Text Book for the Federal Board's Pre-Medical Students, up to their level for their Concepts and Understandings as well as the proper NOTES to have marks in Board's Exams). In'sha'Allah, they as well as Professors will Appreciate this Hectic Task of mine. It took 10 days to arrange and synchronize the material up to their Level of Understanding.

1. ELECTROCARDIOGRAMs
(ECGs)
FAZAIA (PAF) COLLEGE LAHORE
Presented By
EJAZ KHICHI
M.Sc ; B.Ed : M.Sc (Env. Sc.) Micro-Biology
Former Visiting Faculty PGCES , CIMR (PU)
Ex Vice Principal Fazaia (PAF) College Lahore
Head of Biology Deptt. Fazaia (PAF) College Lahore
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

2. Electrocardiography
An Electrical Impulse that passes through the Conduction
System of the Heart during the Cardiac Cycle, is called
Electrocardiogram ECG, which is recorded by a device
Electrocardiograph and its study is called
Electrocardiography
Electrocardiograph
A device used to detect the electrical changes (Rhythms),
resulted from the Depolarization and Repolarization of the
Cardiac Muscles, on the skin, is called Electrocardiograph
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

3. GRAPH 4 WIKIPEDIA

4. Wave Deflection
The Detection of the Heart function, through the particular
waves, over the Electrocardiograph, is known as Wave
Deflection
P - Wave represents the Depolarization of the Atria
The Ventricles are in Diastolic condition, during the Expression of P - Waves
QRS Complex represents the Depolarization of the Ventricles
The Ventricles are in Systolic condition and the Blood is being ejected from
the Heart, during the Expression of QRS Complex
T - Wave represents the Repolarization of the Ventricles
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

5. CONDUCTION SYSTEM
The Conduction System is situated within the
Myocardium. There is a Skeleton of Fibrous Tissue
that surrounds this Conduction System, which can be
seen on ECG.
- The Dysfunction of this Conduction System
causes Irregular Fast or Slow Heart Rhythms.
The Electrical Conduction System of the Heart,
transmits the Signals, usually generated by its SA
Node to cause the contraction of the Heart Muscles.
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

6. CONDUCTION SYSTEM (Contd…)
The Pacemaking Signals, generated in SA Node
travel through the R. Atrium to the AV Node, along
the Bundle of His as well as through the Bundle
Branches of Purkinje Fiber to cause the Contraction
of the Heart Muscles
These Signals stimulate the Contraction of the R & L
Atria (Auricles) first and then of the R & L Ventricles
This process of Signal Conduction, allows the Blood
to be pumped through out the Individual’s Body
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

7. CONDUCTION SYSTEM (Contd…)
on ECG
There are THREE main Components of the
Conduction System to an ECG
P - Wave represents the Depolarization of the Atria
QRS Complex represents the Depolarization of the
Ventricles
T - Wave represents the Repolarization of the
Ventricles
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

8. CONDUCTION SYSTEM (Contd…)
on ECG
Polarization : The phenomenon in which the light waves /
radiations are restricted in the direction of vibration
Depolarization : The loss of the difference in charge B/W the
inside and outside of the plasma membrane of a muscle / nerve
cell due to a change in permeability and migration of the
Sodium Ions to the interior
For Example : -
Partial Depolarization of the Ventricular Tissue, resulting from the rapid
Conduction of the Electrical Impulse from the Atrium to the Ventricle
Repolarization : The phenomenon of the Restoration of the
difference in the charge B/W the inside and outside of the
plasma membrane of a muscle / nerve cell, following the
Depolarization

9. PROCESS (CONDUCTION )
SA Node - Heart Pacemaker; located in the RA;
initiates the next step

10. PROCESS (CONDUCTION )
P Wave - Atrial Depolarization and Contraction

11. PROCESS (CONDUCTION )
AV Node – Slows down the Depolarization of the Atria;
connects Atria and Ventricles, Electrically

12. PROCESS (CONDUCTION )
QRS Complex - Ventricular Depolarization begins in the
Bundle of His

13. PROCESS (CONDUCTION )

14. VENTRICULAR DEPOLARIZATION
His Bundle
Left Bundle Branch & Right Bundle Branch
Purkinje Fibers
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

15. VENTRICULAR DEPOLARIZATION
• Q Wave - 1st downward wave of the Complex
• R Wave - 1st upward wave of the complex
• S Wave - downward wave preceded by an
upward wave
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

16. PROCESS (CONDUCTION )
ST Segment - Initial plateau phase of
Ventricular Repolarization

17. PROCESS (CONDUCTION )
T wave - Rapid phase of Ventricular
Repolarization

18. P – R Interval :- The period of time from the start of P –
Wave to the beginning of Q – R Complex. Actually it is the time
which is used by SAD Polarization to reach the Ventricles
QRS Interval :- The Complex Time Interval with the
Downward Deflection Q which continues as sharp upward Spike
R and ends at the Downward Deflection of S
- This interval actually shows the Depolarization of the Ventricles
During this interval, the Ventricles are in Systolic Condition and
the Blood is ejected from the Heart
S - T Segment :- The duration in which the Heart remains
in the Systolic Condition, is represented as a period B/W the
completion of Ventricular Depolarization S and initial
Repolarization which is represented by the T – Waves
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

19. Standardized Methods & Devices
ECG Paper
Device Paper Speed
Device Calibration
Electrode Placement
Variations Do Exist !
ECG Graph Paper
Vertical axis- voltage
1 small box = 1 mm = 0.1 mV
Horizontal axis - time
1 small box = 1 mm = 0.04 sec
Every 5 lines (boxes) are bolded
Horizontal axis - 1 and 3 sec marks
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

20. Standardized Methods & Devices
Paper Speed & Calibration
Paper Speed - 25 mm/sec standard
Calibration of Voltage is Automatic
Both Speed and voltage Calibration can be changed on most Devices
Electrode Placement
Standardization improves accuracy of comparison ECGs
3 Lead and 12 Lead Placement are most common
Assure good conduction Gel
Prep area with alcohol prep
Avoid Bone
Large Muscles or Hairy Areas
Limb Vs. Chest placement
Poor Electrode Placement or Preparation
Often results in artifact
Stray energy from other sources can also lead to poor ECG Tracings (Noise)
60 Cycle Interference
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

21. Components of ECG Complex
ECG
Components
&
Their
Representation
P, Q , R, S, T
Waves
PR Interval
QRS Interval
ST Segment
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

22. Components of ECG Complex
P Wave
First upward
Deflection
Represents the
Atrial
Depolarization
usually of
0.10
seconds or less
usually
followed by the
QRS
Complex
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

23. Components of ECG Complex
QRS Complex
Composition of
3 Waves
Q, R & S
represents
Ventricular
Depolarization
much variability
usually < 0.12 sec
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

24. Components of ECG Complex
Q Wave
First negative
Deflection
After the P wave
Depolarization
of septum
not always seen
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

25. Components of ECG Complex
R Wave
First positive
Deflection
following the
P or Q
waves
subsequent
positive
Deflections
are
R1, R2 etc
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

26. Components of ECG Complex
S Wave
Negative
Deflection
following
R wave
The Subsequent
Negative
Deflections
are S1, S2, etc
may be the part
of QS complex
absent R wave in
aberrant
conduction
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

27. Components of ECG Complex
PR Interval
Time which an
impulse takes to
move through the
Atria and Av Node
from beginning of
P wave to the next
Deflection
on baseline
(Beginning of QRS
Complex)
normally
0.12 - 0.2 sec
may be shorter
with the faster
rates
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

28. Components of ECG Complex
QRS Interval
time which an
impulse takes to
Depolarize the
Ventricles
from the
beginning of Q
wave to the
beginning of
St Segment
usually < 0.12 sec
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

29. Components of ECG Complex
J Point
The point where
QRS Complex
returns to the
Isoelectric Line
Beginning of
ST Segment
is critical in
measuring
ST Segment
Elevation
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

30. Components of ECG Complex
ST Segment
early
Repolarization
of the Ventricles
measured from
J point
to onset of
T wave
Elevation
or
Depression
may indicate the
abnormality
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

31. Components of ECG Complex
T Wave
Repolarization
of Ventricles
concurrent
with end of the
Ventricular
Systole
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

32. NORMAL ECG
represents the normal Heart Functioning

33. ECG ANALYSIS
Monitoring Lead can tell us:-
How often the Myocardium is Depolarizing
How regular the Depolarization is
How long Conduction takes in various areas of the Heart
The origin of the Impulses that are Depolarizing the
Myocardium
Monitoring Lead Can Not tell us:-
The Presence or Absence of a Myocardial Infarction
The Axis of Deviation
The Chamber Enlargement
The Right vs. Left Bundle Branch Blocks
The Quality of the Pumping Action
Whether the Heart is Beating!!!
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)

34. Uses of ECG
- Used to detect the Cardiac Arrhythmias (Abnormal rate of
Myocardial Contraction) and Conduction (Transmission of
Lub Dub Sound)
- Used to detect Myocardial Hypertrophy (Abnormal
Enlargement Heart due to Steroids) , Ischemia (Local Anemia
resulting from Vasoconstriction / Thrombosis / Embolism –
Occlusion of a Blood vessel by an Embolus (A loose Clot or an
Air Bubble or of an other Particle)) and Infarction (Localized
Necrosis resulting from Obstruction of the Blood Supply)
- Used to provide information about Electrolyte Imbalance
in the body of an individual
- Used to know the Level of Toxicity of the Drugs in an
individual’s body

35. ECG ANALYSIS
An ECG is a Diagnostic Tool
NOT a Treatment
No one was ever cured by an ECG!!
Treat the PATIENT not the Monitor!!!
HSSC – I FBISE Chap. 12 Electro-Cardiogram (ECG)
Presented By
EJAZ KHICHI
M.Sc ; B.Ed : M.Sc (Env. Sc.) Micro-Biology
Former Visiting Faculty PGCES , CIMR (PU)
Ex Vice Principal Fazaia (PAF) College Lahore
Head of Biology Deptt. Fazaia (PAF) College Lahore