10
Index
Subject
Introduction
Principles of ECG
ECG graph
Comment on ECG










Rhythm
Rate
Axis
P wave
P-R interval
QRS complex
S-T segment
T wave
Q-T interval
U wave
Abnormal ECG





Chamber enlargement
Bundle branch block
Coronary Ischemia
Heart block
Others
How to interpret an ECG
How to diagnose an ECG
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Simple ECG
Innovation
Introduction
The electrocardiogram (ECG or EKG) is a special graph that represents the electrical
activity of the heart from one instant to the next. Thus, the ECG provides a time-voltage chart
of the heartbeat. For many patients, this test is a key component of clinical diagnosis and
management in both inpatient and outpatient settings. The device used to obtain and display
the conventional ECG is called the electrocardiograph, or ECG machine. It records cardiac
electrical currents (voltages or potentials) by means of conductive electrodes selectively
positioned on the surface of the body.
This book is devoted to explaining the basis of the normal ECG and then examining the
major conditions that cause abnormal depolarization (P and QRS) and repolarization (ST-T and
U) patterns.
Why is the ECG so clinically useful ?
The ECG is one of the most versatile and inexpensive of clinical tests. Its utility derives
from careful clinical and experimental studies over more than a century showing the following:
 It is the essential initial clinical test for diagnosing dangerous cardiac electrical
disturbances related to conduction abnormalities in the AV junction and bundle branch
system and to brady- and tachyarrhythmias.
 It often provides immediately available information about clinically important
mechanical and metabolic problems, not just about primary abnormalities of electrical
function. Examples include myocardial ischemia/infarction, electrolyte disorders, and
drug toxicity, as well as hypertrophy and other types of chamber overload.
 It may provide clues that allow you to forecast preventable catastrophies. A good
example is a very long QT(U) pattern preceding sudden cardiac arrest due to torsades de
pointes.
Physiological anatomy of the heart :
The heart is a hollow muscular pump situated in the left side of the thoracic cavity partly
behind the sternum, consisting of 4 chambers : 2 atria and 2 ventricles.
The heart is covered externally by epicardium ( which is the visceral layer of the
pericardial sac). The inside cavity of the heart lined by endothelial layer called the
endocardium. An intermediate muscular layer lying in between the epicardium & endocardium
known as the myocardium.
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Simple ECG
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Physiology of Cardiac Muscle :
The heart is composed of three major types of cardiac muscle:
atrial muscle, ventricular muscle, and specialized excitatory and conductive muscle fibers.
The atrial and ventricular types of muscle contract in much the same way as skeletal
muscle, except that the duration of contraction is much longer. Conversely, the specialized
excitatory and conductive fibers contract only feebly because they contain few contractile
fibrils; instead, they exhibit either automatic rhythmical electrical discharge in the form of
action potentials or conduction of the action potentials through the heart, providing an
excitatory system that controls the rhythmical beating of the heart.
The cardiac muscle has certain special properties which are :
1. Rhythmicity: ability of the heart to beat regularly at constant rate.
2. Contractility: ability of the heart to contract and push blood into circulation.
3. Excitability: ability of the cardiac muscle to respond to an adequate stimulus
contraction.
4. Conductivity: ability of the cardiac muscle to conduct excitation wave from one part of
the heart to another.
In EKG study we are concerned with study of Rhythmicity and conductivity of the cardiac
muscle.
we will review a few simple principles of the heart’s electrical properties. The central
function of the heart is to contract rhythmically and pump blood to the lungs for oxygenation
and then to pump this oxygen-enriched blood into the general (systemic) circulation. The signal
for cardiac contraction is the spread of electrical currents through the heart muscle. These
currents are produced both by pacemaker cells and specialized conduction tissue within the
heart and by the working heart muscle itself.
Pacemaker cells are like tiny clocks (technically called oscillators) that repetitively
generate electrical stimuli. The other heart cells, both specialized conduction tissue and
working heart muscle, are like cables that transmit these electrical signals.
Electrical Activation of the Heart :
In simplest terms, therefore, the heart can
be thought of as an electrically timed pump. The
electrical “wiring” is outlined in Figure.
Normally, the signal for heartbeat initiation
starts in the sinus or sinoatrial (SA) node. This
node
is located in the right atrium near the opening of
the superior vena cava.
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Simple ECG
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The SA node is a small collection of specialized cells capable of automatically generating
an electrical stimulus (spark-like signal) and functions as the normal pacemaker of the heart.
From the sinus node, this stimulus spreads first through the right atrium and then into the left
atrium. Electrical stimulation of the right and left atria signals the atria to contract and pump
blood simultaneously through the tricuspid and mitral valves into the right and left ventricles.
The electrical stimulus then reaches specialized conduction tissues in the
atrioventricular (AV) junction. The AV junction, which acts as an electrical “relay” connecting
the atria and ventricles, is located at the base of the interatrial septum and
extends into the interventricular septum. The upper (proximal) part of the AV junction is
the AV node. (In some texts, the terms AV node and AV junction are used synonymously.) The
lower (distal) part of the AV junction is called the bundle of His. The bundle of His then divides
into two main branches: the right bundle branch, which distributes the stimulus to the right
ventricle, and the left bundle branch, which distributes the stimulus to the left ventricle.
The electrical signal then spreads simultaneously down the left and right bundle
branches into the ventricular myocardium (ventricular muscle) by way of specialized
conducting cells called Purkinje fibers located in the subendocardial layer (inside rim) of the
ventricles. From the final branches of the Purkinje fibers, the electrical signal spreads through
myocardial muscle toward the epicardium (outer rim).
The His bundle, its branches, and their subdivisions are referred to collectively as HisPurkinje system. Normally, the AV node and His-Purkinje system form the only electrical
connection between the atria and the ventricles (unless a bypass tract is present). Disruption of
conduction over these structures will produce AV heart block.
Just as the spread of electrical stimuli through the atria leads to atrial contraction, so the
spread of stimuli through the ventricles leads to ventricular contraction, with pumping of blood
to the lungs and into the general circulation. The initiation of cardiac contraction by electrical
stimulation is referred to as electromechanical coupling. A key part of this contractile
mechanism is the release of calcium ions inside the atrial and ventricular heart muscle cells,
which is triggered by the spread of electrical activation. This process links electrical and
mechanical function.
The ECG is capable of recording only relatively large currents produced by the mass of
working (pumping) heart muscle. The much smaller amplitude signals generated by the sinus
node and AV node are invisible with clinical recordings.
Depolarization of the His bundle area can only be recorded from inside the heart during
specialized cardiac electrophysiologic (EP) studies.
Heart has two types of action
 Mechanical: Contraction &relaxation
 Electrical: Depolarization & repolarization
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Simple ECG
Innovation
Blood supply of the heart through the coronary arteries
Anatomy of the coronary arteries
The left Coronary artery:
It arises from the left sinus of Valsalva and
passes forwards & to the left in the
atrioventricular groove for a short distance and
then divides into two branches:
1. The left anterior descending artery: it
passes downwards in the anterior
interventricular groove to the apex of the
heart & then turns backwards to
anastomse with the posterior descending
artery.
2. The circumflex artery: it continues its
course in the left atrioventricular groove
to anastomse with the right coronary. It
gives several obtuse marginal branches.
The right Coronary artery:
It arises from the (right sinus) of Valsalva and runs in the right atrioventricular groove to
the posterior surface of the heart to anastomse with circumflex artery.
In the back of the heart it gives the (posterior descending artery which runs downwards,
in the posterior interventricular groove, to anastomose with the anterior descending artery.
Pattern of coronary supply
 Balanced circulation:
The left coronary artery supplies left atrium, left ventricle & anterior part of the
interventricular septum.
While the right coronary artery supplies right atrium, right ventricle & posterior part of
the interventricular septum.
 Right dominance:
The right coronary supplies also the posterior part of the left ventricle.
 Left dominance:
The left coronary supplies also the posterior part of the septum & the posterior wall of the
right ventricle.
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Simple ECG
Innovation
Principles of ECG
ECG
Electrocardiogram
Electro 
Cardio 
graph Gram 


ECG
relaxed
waves
<<
ECG
<<
ECG
ECG
<<
Lead
positive wave
Lead
negative wave
Lead
biphasic wave
negative
right ventricle
thickness of the muscle
wave
left ventricle
right ventricle
left ventricle
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
<<

<< ECG
ECG

<< ECG
Positive
ECG
Wave
wave
thickness of muscle
Simple ECG
Innovation
lead
wave
left ventricular hypertrophy
ECG
heart
Atria 
Ventricles 
septum
left ventricle
left ventricle
ventricle
right ventricle
ventricle
right ventricle
ventricle
septum
septum
right
left
septum
left bundle branch
right bundle
septum
septum
ECG
ECG
waves
positive wave
<< ECG
negative wave
<< ECG


Lead
Lead
right
V1
left
septum
chest lead
positive wave
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septum
thickness of muscle
wave
r wave
V6
chest lead
negative wave
Simple ECG
Innovation
septum
right ventricle
right ventricles
V1
bundle branch
thickness of muscle
wave
q wave
septum
waves
septum
chest lead
cavity
endocardium
positive wave
right ventricle
thickness of muscle
wave
r wave
V6
chest lead
negative wave
right ventricle
thickness of muscle
wave
q wave
waves
right
right
right ventricle
septum
wave
ECG
septum
small r wave in V1
wave
septum
q wave
ventricle
V6 ventricle
right ventricle
septum
left ventricle
waves
left ventricle
right ventricle
V1
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septum
chest lead
Simple ECG
Innovation
endocardium
bundle branch
cavity
negative wave
left ventricle
thickness of muscle
wave
S wave
V6
chest lead
positive wave
left ventricle
thickness of muscle
wave
R wave
chest leads
r wave
right ventricle
V1
V1
right ventricular pattern
S
left ventricle
V6
V6
s wave
left ventricular pattern
Five waves
complex
QRS P
T wave
Atrial depolarization
P wave
ventricular
QRS complex
depolarization
ventricular
T wave
repolarization
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


Simple ECG
Innovation
Multiple P waves before QRS
ventricle
absent P wave
Atrial depolarization
P wave
atrium
P wave
P wave
atrium
P wave
Atrium

contraction
atrium

contraction
atrium

Atrium
P wave
ventricular depolarization
QRS complex
ventricle
QRS
ventricle

ventricular tachycardia
ventricle

deformed
QRS
<< ventricle
arrhythmia
QRS
ventricle
T wave
Ventricular repolarization
atrial depolarization Atrial contraction
ventricular contraction ventricular depolarization
ventricular relaxation ventricular repolarization
Atrial repolarization
which is small and masked by QRS complex
QRS
QRS
A.V. node
ECG
PR interval
PR interval
A.V. nodal conduction
A.V. node
PR interval
A.V. nodal conduction
PR interval
A.V. nodal block
heart block
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Simple ECG
Innovation
ECG
12 leads ECG
Limb leads 
Chest leads 
Limb leads
Bipolar 
Unipolar 
:
both upper limbs
right upper limb and left lower limb
left upper limb and left lower limb
right arm
left arm
left foot
Bipolar limb leads
L1 
L2 
L3 
unipolar limb leads
augmented voltage
aVR 
augmented voltage
aVL 
augmented voltage
aVF 
Chest leads
precordial leads
chest wall
6 chest leads
V1, V2, V3, V4, V5, and V6
ECG
ECG
ECG
6 leads
chest leads
Right 4 space adjacent to the sternum : V1 
Left 4th space adjacent to the sternum : V2 
th
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Simple ECG
Innovation
Between V2 and V4
Left 5 space mid clavicular line :
at same horizontal level of V4 but at anterior axillary line
at the same horizontal level of V4 but at mid axillary line :
th
Dextrocardia
V1 and V2
V3
V4
V5
V6




chest leads
as V3 but on right side V3R 
as V4 but on right side : V4R 
as V5 but on right side : V5R 
as V6 but on right side : V6R 
heart
section
V1 and V2
Right ventricle

V5 and V6
left ventricle

V3 and V4
Septum

<< ischemia
right ventricle
ischemia
left ventricle
ischemia
V5 and V6
leads of ECG
topographism
Wall of the heart
Leads
Wall
II - III - aVF
Inferior
I - aVL
High lateral wall
V1 - V2
Septal ( antro-septal)
V3 - V4
Strict anterior
V5 - V6
Low lateral
V1 - V3R V6R
RV free wall
Louis Leads
Atrial Activity
N.B. posterior wall potentials are recorded in the anterior leads as a mirror image for
waves provided to be drawn in the posterior leads because posterior leads are
technically difficult to be made.
wall
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artery
11
topographism
Leads
Simple ECG
Innovation
ECG Graph paper
ECG
5X5


voltage
duration
duration
ECG
25 mm
0.04
0.20 0.04 X 5
1/5
300
60 X
1500
Standard
5
60 X
2 big squares
1 mV signal
10mm
1mV
Caliberation
25
Voltage
ECG
half caliberation
one big square
waves
double caliberation
4 big squares
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Simple ECG
Innovation
Comment on ECG
ECG
1. Rhythm
2. Rate
3. Axis
4. P wave
5. P-R interval
6. QRS complex
7. S-T segment
8. T wave
9. Q-T interval
10. U wave
1. Rhythm
ECG
Rhythm
Sinus or not 
Regular or irregular 
complex
S
R
sinus
P wave is followed by QRS complex
QRS complex
Q
R
S
Q
ventricular complex
P wave
regular
Numbers of big squares between each R-R interval are equal
<< R-R interval
R-R interval
rhythm is irregular
Atrial fibrillation
extra systole
irregular rhythm
marked irregularity

occasional irregularity

long strip
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rhythm
Simple ECG
Innovation
3
lead
long strip
R-R interval
2. Rate
rate
normal
beat per minute << 90 60


tachyarrhythmia << 100
bradycardia << 60
R-R interval
rate
rhythm
<< regular rhythm
1500
300 = heart rate
R-R interval
Irregular << rhythm
rate
R-R interval
300
average
mean
300
15
30
15 5 10
10
30/3
10
RR interval
9
3
100 beats per min.
300/3 <<
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300
3 9/3
rate
Simple ECG
Innovation
2
3
Lead 2

6
30
30
10
rate
heart rate
50 10 X 5
30
15

rhythm
rate
ECG
3. Axis
aVF
lead
lead
aVF
QRS
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Simple ECG
Innovation
QRS
Positive << QRS
Lead
lead
positive
QRS
normal
lead
positive << QRS
aVF
lead
Positive << QRS
Axis is normal
Axis is normal
Lead
negative << QRS
aVF
lead
positive << QRS
QRS
QRS
right axis deviation
QRS
positive
lead
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Simple ECG
Innovation
negative
lead
left axis deviation
lead
Normal
positive
Negative aVF
left axis
lead
aVF
Positive
Lead
lead
deviation
negative
positive aVF
right axis deviation
Lead
lead

axis deviation
Left axis deviation
right axis deviation
Normal axis deviation
normal axis deviation
Normal axis is not deviated
right and left axis deviation
Causes of right axis deviation
 Children
 Tall thin adults
 Right ventricular hypertrophy
 Chronic lung disease
 Anterolateral myocardial infarction
 Pulmonary embolus
 Atrial septal defect
 Ventricular septal defect
Causes of left axis deviation
 Q waves of inferior MI
 Artificial cardiac pacing
 Left ventricular hypertrophy
 Hyperkalemia
 Ostium primum ASD
 Injection of contrast into left coronary
artery
Note : pt. of left ventricular hypertrophy not
usually has LAD
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Simple ECG
Innovation
4. P wave
Atrial depolarization
1st positive wave before complex
Lead II and V1
Less than (2.5 X 2.5 ) small squares
Width (duration ) : = ˂ 2.5 small square ( ˂ 0.12 sec. ).
Height (amplitude) : = ˂ 2.5 small square ( ˂ 2.5 mm).
P wave
Present 
Absent 
Lead II and V1
less than 2.5 X 2.5 small squares
left atrial enlargement
P wave
Normal 
Abnormal 
<< abnormal << P wave
P mitral M shaped
2.5
P wave
left atrial strain
1
P pulmonale Peaked and high voltage P 2
2.5
P wave
right atrial strain
Pulmonale Mitral 3
P wave
2.5
Biphasic 4
P wave
negative
positive

Mitral
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Normal
Simple ECG
Innovation
V1
biphasic
V1
P wave
right atrium
left atrium
activate
SA node
right atrium
Left atrium activate
right
SA node
wave
right atrium
wave
Left atrium
P wave
biphasic
Positive

negative

negative
Positive
right atrial strain (enlargement)
left atrial strain ( enlargement)
Lead
absent << P wave
irregular << rhythm
AF
regular << rhythm
P wave
QRS
QRS
wide << QRS
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Simple ECG
Innovation
wide
3
QRS
3
3
Wide QRS
Ventricular tachycardia
Ventricular fibrillation


narrow << QRS
supra ventricular tachycardia
Nodal rhythm


rate
<< supra ventricular tachycardia
Nodal rhythm
Sawtooth appearance
atrial flutter
5. P-R interval
AV conduction (physiological delay)
Lead II
3-5 small squares (0.12 - 0.20 sec. )
PR
QRS complex
P
P-R interval
3 - 5 small squares
Normal 
5 small squares
Prolonged 
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Simple ECG
Innovation
3 small squares
Shortened 
prolonged << P-R interval
<< P-R interval
1
just prolongation of P-R interval
First degree heart block
<< P-R interval
2
beat
progressive prolongation of P-R interval until dropped beat
Wenckebach phenomena
peace maker <<
<<
peace maker
not fixed << P-R interval
3
ventricles atria
atrio-ventricular dissociation
ventricle
S.A. node
atrium
variable P-R
P-R interval
QRS complex
P wave
complete heart block
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Simple ECG
Innovation
shortened << P-R interval
Wolff-Parkinson-White
ventricle
A.V. node
impulse delay
atria
impulses accessory pathway
P-R interval
normal pathway
3 small squares
wide
QRS complex
<<
Wolff-Parkinson-White
type B
type A

QRS complex waves
complex
Criteria
Short P-R interval 1
Wide QRS complex 2
Delta wave 3
Wolff-Parkinson-White
V1
right ventricular pattern
left ventricular pattern


6. QRS complex
Ventricular depolarization
T
P
complex
Right ventricle (V1,2) 
Left ventricle (V5,6) 
first negative wave in the complex << Q wave
first positive wave in the complex << R wave
following R
the negative wave following R << S wave
Q wave
first negative wave in the complex
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Simple ECG
Innovation
one small square
R wave
pathological Q
Deep and wide
ECG
myocardial infarction
Q wave infraction
Non Q wave infarction
Q wave ( deep and wide )
anterior infarction << V1,2
septal infarction << V3,4
Lateral infarction << V5,6
antro-septal infarction << V1,2,3,4
Extensive anterior infarction << V1,2,3,4,5
Normal ECG
aVL
pathological Q
pathological Q





pathological Q

the cavity of the heart
<< lead of aVR
Q wave
<< Normally aVR
dextrocardia
<< pathological Q
S wave
V1
r wave
pathological Q ( deep and wide )
V1
Lead aVR and V1
pathological Q
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Simple ECG
Innovation
anterior V2 V1
<< infarction
V1
r wave is too small to be detected
pathological Q
R wave
first positive wave in complex
voltage criteria
only positive in the complex
big squares
3 small squares
Vent. Tachycardia
RBBB or LBBB
small squares
wide complex
S wave
first negative wave following R
Chest leads
V6
S and R wave
V1
S
R wave
principles
V1 right ventricle
r
V6 left ventricle
V5
V1


R
S in V2 is ˃ S in V1 
S progress from V2 to V5 
S usually absent in V6 
5 mm
small
5 mm
capital
s r <<
Waves
capital and small
wave
amplitude

<<
wave
amplitude

<<
Small
R, S <<
capital
Not every “QRS” contain “Q”,”R” & “S”, but it may be :
Monophasic (R or QS) 
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Simple ECG
Innovation
Biphasic (RS or QR) 
Triphasic (QRS or RSR’) 

high voltage low voltage
R wave
˃ 5 big squares (high voltage )
 Ventricular hypertrophy
˂ 1 big square (low voltage)
 Terminal heart failure
 Cardiomyopathy
 IHD
 Obesity
 Emphysema
 Pericardial effusion
7. S-T segment
Ventricular repolarization
leads
T
S
S-T segment
Iso-electric line 
Elevated 
Depressed 
iso-electric line
depression
elevation
J point
J point
 Point where QRS complex returns to isoelectric line.
 Beginning of S-T segment.
 Critical in measuring S-T elevation.
iso-electric line
T-P line
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P-R
Simple ECG
Innovation
S-T elevation
ST segment elevation
Pericarditis 
Myocardial infarction 
Prinzmetal’s angina 
PR
Pericarditis
ST segement elevation
Leads
Myocardial infarction Angina
some leads
myocardial infarction angina
Cardiac enzymes
infarction
timing
elevated
clinical diagnosis << angina
S-T
ECG
myocardial infarction
angina
S-T depression
ST segment depression
Digitalis

Hypokalemia

ischemia
angina

Myocardial infarction

Pericarditis

cardiac hypertrophy

bundle branch block

Digitalis
hypokalemia
pericarditis
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


Simple ECG
Innovation
diffuse ST segment depression
Leads
iso-electric line
digitalis
ST segment depression
sagging
J point
hypokalemia
serum potassium
stitchy << pain
Pericarditis
clinically
some leads
ischemia
angina

myocardial infarction

hypertrophy

bundle branch block

clinical diagnosis << angina
V3 V2 V1
right ventricle
Leads
ST segment depression
V3 V2 V1
right ventricular hypertrophy
strain pattern
right ventricular hypertrophy With strain pattern
secondary changes
V5 V4
left ventricular enlargement
ST segment depression
V3 V2 V1
right bundle branch block
ST segment depression
V6
left bundle branch block
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Simple ECG
Innovation
V6 V5 V4 ST segment depression
rSR’
V1
Right bundle branch block
ST segment
depressed
right bundle
right ventricular hypertrophy
left ventricular enlargement
V6
left ventricular enlargement
V6 V5 V4
ST segment depression
left ventricular hypertrophy secondary
clinical diagnosis << angina
ventricular hypertrophy
bundle branch block
ischemia
 angina
ST segment depression
ischemia
hypertrophy
leads
iso-electric line
J point
iso-electric line
J point << digitalis toxicity
ECG changes
cardiac muscle
Pericarditis
ECG
pericarditis
very superficial myocarditis
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Simple ECG
Innovation
8. T wave (Never absent )
Ventricular repolarization
Less than 6 small squares
R wave
1/3
positive
Upright 
negative wave Inverted 
T wave ( positive )
T
Normal 
Hyperacute 
hyperkalemia
ECG
T wave inverted
normal
T wave inversion
dynamic T
Upright
9. Q-T interval
T wave
QRS complex
11 small square
0.44 sec
Long Q-T interval
Drugs ( many antiarrhythmics, tricyclics & phenothiazines) 
Electrolyte abnormalities (K+, Ca++, Mg++) 
CNS disease (especially subarachnoid hemorrhage, stroke, trauma) 
Hereditary LQT 
10.
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U wave
29
Simple ECG
Innovation
These waves, usually most apparent in chest leads V2-V4,
may be a sign of hypokalemia or drug effect or toxicity (e.g.,
amiodarone, dofetilide, quinidine, or sotalol).
Abnormal ECG
Chamber enlargement
Bundle branch block (BBB)
Coronary ischemia (MI & ischemia)
Heart block
Others
1
2
3
4
5
1. Chamber enlargement
Atrial enlargement 
Ventricular enlargement 
atrial enlargement
Right atrial enlargement 
Left atrial enlargement 
ventricular enlargement
Right ventricular enlargement 
Left ventricular enlargement 
atrial enlargement
atrium
P wave
P wave
atrium
Lead II and V1 P wave
peaked << P wave
<<
P pulmonal
right atrial enlargement
broad << P wave
P mitral <<
Left atrial enlargement
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30
Simple ECG
Innovation

Mitral
Normal
biphasic
right atrium
left atrium
V1
P wave
activate
SA node
right atrium
Left atrium activate
right
SA node
wave
right atrium
wave
Left atrium
P wave
biphasic
Positive

negative

negative
Positive
right atrial strain (enlargement)
left atrial strain ( enlargement)
Lead
Ventricular enlargement
ventricular depolarization
QRS
QRS complex abnormalities
ventricle
V1,2,5,6 QRS
V1,2
r wave
S wave
V5,6
s wave
R wave
r wave
S wave
Normal
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31
V1,2
deep << S wave
Simple ECG
Innovation
s wave
R wave
normal
V5,6
<< R wave
exaggeration of normal
exaggeration of normal
voltage criteria
V2 V1 5 big squares
S
V6 V5 5 big squares
R
7 big squares
S+R
left ventricle
left ventricular enlargement
left ventricle
hypertrophy
Strain ischemia
ventricle
strain ischemia
strain ischemia
depressed ST segment
inverted T wave



Left ventricle
V5 and V6
V5 and V6
Strain ischemia
Left ventricle
right ventricle
V1,2 s wave
R wave
Normal
V5,6
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32
r wave
S wave
Simple ECG
Innovation
Normal

I can diagnose right ventricle from V1
V6
V5
V2
Right ventricle
right ventricle
Strain ischemia
strain ischemia
Inverted T wave
depressed ST segment
V1 and V2
right ventricle
V5 and V6
V2 V1
Strain ischemia
left ventricle
Bi ventricular hypertrophy
V5 and V6
V1 and V2
strain ischemia
ECG
bi ventricular hypertrophy
R S
exaggeration of normal

reversal of normal

exaggeration of normal
V1
reversal of normal
V2
2. Bundle Branch Block (BBB)
Right bundle branch block 
Left bundle branch block 
bundle branch block
M
QRS
RSR'
right bundle branch block
left bundle branch block
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33
V2
V6
V1
V5
Simple ECG
Innovation
right and left bundle branch block
Right
V2 V1 RSR' pattern
left
V6 V5 RSR'
QRS
QRS



shape
direction
voltage
QRS
voltage
direction
shape
shape
M shaped
bundle branch block
direction
direction
V1 and V2
R
S
V6 V5
S
R
reversal of normal
direction
right ventricular hypertrophy
Normal
<< shape
Normal
<< direction
voltage
voltage
exaggeration of normal
Left ventricular hypertrophy
QRS
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34
Simple ECG
Innovation
shape
direction
voltage



shape
abnormality
bundle branch block
voltage
direction
ventricle
direction
Normal shape
Normal shape
direction
direction
reversal of normal
voltage
3. Coronary Ischemia ( MI & ischemia )
myocardial infarction
central area of necrosis
surrounded by an area of tissue damage surrounded by an ischemic pattern
pathological Q
<< area of necrosis

elevated ST segment
<< tissue damage

inverted T
<< ischemia

wave or peaked T
infarction
necrosis
pathological Q
Once
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35
Simple ECG
Innovation
pathological Q
Old myocardial infarction
pathological Q
Myocardial infarction
finger print of MI is the pathological Q
Infarction
elevated ST segment
recent MI << Elevated ST segment
recent MI old MI
topographism
anterior wall
recent MI
Lateral wall
Inferior wall
old MI
topographism
topographism
Elevated ST segment
MI
pathological Q
Recent Old
Infarction
artery
Infarction
necrosis
elevated ST segment
recent
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36
Simple ECG
Innovation
ECG
pathological Q
ST
pathological Q
elevated ST segment
Once elevated ST segment
Q
Q
recent MI
recent anterior MI Old inferior MI
<<
Old inferior
leads

recent anterior
leads

Lead
artery
Ischemia
Depressed ST segment
topographism
Depressed
lateral ischemia anterior Inferior
topographism
4. Heart Block
ECG
Mainly
hear block
A.V. nodal block
A.V. node
first degree heart block
second degree heart block
ventricle
Atrium
third degree heart block
heart block
first degree heart block
second degree heart block
third degree heart block
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37
Simple ECG
Innovation
first degree heart block
A.V. node
Just prolonged PR interval
Just prolonged PR interval
first degree heart block
sinus brady cardia
S.A. node
sinus bradycardia
first degree heart block
P QRS T
sinus brady cardia
:
definition of first degree heart block
just prolonged PR interval
second degree heart block
A.V. node
A.V. node


Mobitz one
progressive prolongation of PR interval until dropped QRS
Mobitz one
Mobitz two
A.V. node
Long strip
RR interval
Mobitz one
irregular
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38
Simple ECG
Innovation
dropped beat
Long strip
Mobitz Two
A.V. node
atrium
system
Mobitz Two
regular drop of QRS
P P QRS T P P QRS T
QRS
P P
A.V. node
second degree heart block
Mobitz one
Mobitz Two
Irregular 
Regular 
third degree heart block
A.V. node
Atrium
ventricle
S.A. node
idioventricular rhythm
ectopic focus
atrium
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39
Simple ECG
Innovation
P wave
QRS
ventricle
bizarre shaped
ventricle
QRS
deformed
A.V. node
narrow normal
P wave
P
QRS
third degree heart block
A.V. dissociation
atrio ventricular dissociation
ventricle atrium
QRS P
QRS
deformed
Bizarre shaped
.Mobitz one << All type of heart block are regular except 
. third degree heart block << All types of heart block with normal QRS complex except 
Mobitz one
regular
complete heart block
Third degree
normal QRS
5. Others
ECG as a Clue to Acute Life-Threatening Conditions without primary Heart or Lung
Disease
 Cerebrovascular accident (especially intracranial bleed)
 Drug toxicity
 Tricyclic antidepressant overdose, digitalis excess, etc.
 Electrolyte disorders
 Hypokalemia
 Hyperkalemia
 Hypocalcemia
 Hypercalcemia
 Endocrine disorders
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40
Simple ECG
Innovation
 Hypothyroidism
 Hyperthyroidism
 Hypothermia
How to interpret an ECG
ECG
Relax and take a deep breath
Rhythm
1
Sinus or not 
Regular or not 
Rate 2
R-R interval
10
300
30 R waves
<< regular << rhythm
<< Irregular << rhythm
Axis 3
Normal axis << positive aVF
left axis deviation
<< negative aVF
right axis deviation
<< positive aVF
lead Positive
lead positive
lead negative
Lead
lead
lead



P wave 4
2.5
right atrial strain << peaked
left atrial strain << m shaped
2.5


2.5
2.5
P-R interval 5
complex
P wave
5
3
QRS complex 6
first negative wave in the complex << Q wave
first positive wave in the complex << R wave
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41


Simple ECG
Innovation
following R

the negative wave following R << S wave
R wave
Q wave
R wave
S wave
R wave
T wave
ST segment
7
T wave
8
S
MI
absent
6
R wave
diagnosis
diagnosis
How to diagnose an ECG
rhythm
regular
irregular


irregular
irregular
Atrial fibrillation 
Extra systole 
Mobitz one 
atrial fibrillation
absent P
tachy
irregular
Normal
QRS
Absent P
P wave
atrial fibrillation
absent P wave
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42
Simple ECG
Innovation
fibrillation
some time
Absent P
AF
slow AF
rapid
Slow AF
digitalis

Beta blocker

Heart block
associated

lone AF

slow AF
AF
irregular ECG
With absent P wave
AF
Extra systole
refractory period
stimlus
compensatory pause
irregular
irregular
ventricular extra systole
Mobitz one
Progressive prolongation of PR
interval until dropped QRS
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43
Simple ECG
Innovation
tachy cardia
rhythm
rate
<< regular
regular
Tachycardia 
bradycarida 
normo cardia
Regular tachycardia
Sinus tachycardia
Ventricular tachycardia
Supra ventricular tachycardia
Atrial flutter




Sinus Tachycardia
Sinus tachy cardia
S.A. node
Peace maker of the heart
ECG
P followed by QRS T
P QRS T
Ventricular tachycardia
Ventricular tachycardia
ventricle
Arrhythmia
ventricle
QRS
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44
Simple ECG
Innovation
T
deformed
QRS
P
wide
QRS
Supra ventricular tachycardia
supra ventricular
tachycardia
supra ventricualr
atrium

A.V. node

P
P
(
atrium
deformed
A.V. node
P ) Inverted
P
Inverted
P wave
A.V. node
absent
P
Masked by QRS
supra ventricular tachy cardia
absent
Inverted P
deformed P
P
P
Supra ventricular tachycardia
Atrial flutter
Atrial flutter
atrium
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45
Simple ECG
Innovation
A.V. node
reduction
Atrial beat in mathematical fashion
atrium
Atrial flutter
specific
atrial fibrillation Atrial flutter
regular atrial flutter
regular
atrial fibrillation


regular long strip
tachycardia
rate
QRS
deformed
Narrow normal


deformed
ventricular tachycardia
Narrow normal
P
P wave
single
multiple
sinus tachycardia
QRS T
single
P wave
multiple P
Atrial flutter
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46
Simple ECG
Innovation
Supra ventricular tachycardia
Regular bradycardia
Sinus bradycardia
first degree heart block
Mobitz two
third degree heart block
Nodal rhythm





Sinus bradycardia
regular bradycardia
sinus bradycardia
First degree heart block
first degree heart block
Just prolonged PR interval
Page |
47
Simple ECG
Innovation
Mobitz two
Mobitz two
regular drop of QRS complex
Third degree heart block
third degree heart block
deformed QRS
AV dissociation
peace maker
peace maker
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48
Nodal rhythm
nodal rhythm
A.V. node
A.V. node
P
inverted
Simple ECG
Innovation
absent
QRS
regular bradycardia
QRS
deformed

Narrow normal

third degree heart block
deformed
Narrow normal
P wave
single
Multiple
first degree heart block
sinus bradycardia
P wave
single
first degree heart block
just prolonged PR interval
multiple
Atrial flutter
bradycardia
tachycardia
P wave
Mobitz two
Mobitz two
Mobitz two
atrial flutter
Noda rhythm
long strip
QRS
diagnostic approach
rate
rhythm
P
segmented
P
QRS
Page |
49


Simple ECG
Innovation
ST segment
Long strip
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50