Aamir ShariF BEMS University of Poonch Rawalakot

2. Presented By:
Aamir Sharif
BEMS Final Professional
Dept. Of EMS The University Of Poonch Rawalakot AJ&K
ELECTROCARDIOGRAPHY

3. Objectives
• The Basics
• Interpretation
• Clinical Pearls
• Practice Recognition

4. Introduction
• The electrocardiogram (ECG) is one of
the simplest and oldest cardiac
investigations available, yet it can
provide a wealth of useful information
and remains an essential part of the
assessment of cardiac patients.

5. The ECG
“An ECG is simply a representation of the electrical
activity of the heart muscle as it changes with
time, usually printed on paper for easier analysis”
Like other muscles, cardiac muscle contracts in
response to electrical depolarization of the muscle
cells. It is the sum of this electrical activity, when
amplified and recorded for just a few seconds that we
know as an ECG.

6. Cont.....
• The ECG device detects and amplifies the tiny
electrical changes on the skin that are caused
when the heart muscle depolarizes during
each heartbeat. At rest, each heart muscle cell
has a negative charge, called the membrane
potential, across its cell membrane. Decreasing
this negative charge towards zero, via the influx
of the positive cations, Na+ and Ca++, is called
depolarization, which activates the mechanisms
in the cell that cause it to contract.

7. 7
THE CONDUCTINGY SYSTEM
• During each heartbeat, a healthy
heart will have an orderly
progression of a wave of
depolarisation that is triggered by
the cells in the sinoatrial node,
spreads out through the atrium,
passes through the atrioventricular
node and then spreads all over the
ventricles. This is detected as tiny
rises and falls in the voltage between
two electrodes placed either side of
the heart which is displayed as a
wavy line either on a screen or on
paper. This display indicates the
overall rhythm of the heart and
weaknesses in different parts of the
heart muscle.

8. Lead Placement
• By convention, we record the standard
surface ECG using 12 different recording
lead ‘directions,’ though rather confusingly
only 10 recording electrodes on the skin
are required to achieve this.
• Six of these are recorded from the chest
overlying the heart – the chest or
precordial leads also called V1, V2, V3,
V4, V5 and V6.
• Four are recorded from the limbs – the
limb leads The limb leads are called leads
I, II, III, AVR, AVL and AVF.
• It is essential that each of the 10 recording
electrodes is placed in its correct position,
otherwise the appearance of the ECG will
be changed significantly, preventing
correct interpretation.

9. Normal E.C.G
• A typical ECG (Limb Lead II) tracing of the cardiac
cycle (heartbeat) consists of a
• P wave
• QRS complex
• T wave
• & U wave
(which is normally invisible
in 50 to 75% of ECGs bcoz
it is hidden by the T wave and upcoming new P wave)

10. Lets look at how the conduction system
related to what we record on the ECG.
• P wave: the sequential activation
(depolarization) of the right and left
atria .(Atrial Repolarization merge
with QRS complex)
• QRS complex: right and left
ventricular depolarization (normally
the ventricles are activated
simultaneously)
• T wave ventricular repolarization
• U wave: origin for this wave is not
clear - but probably represents
"after depolarization" in the
ventricles

11. Feature Description
Duratio
n
RR
interval
The interval between an R wave and
the next R wave: Normal resting heart
rate is between 60 and 100 bpm
0.6 to
1.2s
PR
interval
The PR interval is measured from the
beginning of the P wave to the
beginning of the QRS complex. The
PR interval reflects the time the
electrical impulse takes to travel from
the sinus node through the AV node
and entering the ventricles. The PR
interval is, therefore, a good estimate
of AV node function
120 to
200ms
VAT
(Ventricu
lar
activatio
n time)
It is time required for ventricular
depolarization This is from onset of QRS
complex to the peak of R wave
0.03 to
0.05 sec
for left
ventricle
s
QT
interval
The QT interval is measured from the
beginning of the QRS complex to the end
of the T wave. A prolonged QT interval is
a risk factor for ventricular
tachyarrhythmias and sudden death.
Up to
0.42 sec
in heart
rate of
60 bpm

12. Interpretation
• Develop a systematic approach to reading ECGs and use it every
time.The system we will practice is:
– Rate
– Rhythm (including intervals and blocks)
– Axis Deviation
– Hypertrophy
– Ischemia
– P wave
– PR Interval
– Q wave
– QRS complex
– ST Segment
– T wave

13. Rate
• Before discussing how to calculate
heart Rate we Should have
knowledge about ECG paper.
• Paper
• ECG paper is traditionally divided
into 1mm squares. Vertically, ten
blocks usually correspond to 1
mV, and on the horizontal axis, the
paper speed is usually 25mm/s, so
one block is 0.04s (or 40ms). Note
that we also have "big blocks" which
are 5mm on their side

14. Cont..
• EKG paper is a grid where time is
measured along the horizontal
axis.
• Each small square is 1 mm in
length and represents 0.04
seconds.
• Each larger square is 5 mm in
length and represents 0.2
seconds.
• Voltage is measured along the
vertical axis.
• 10 mm is equal to 1mV in
voltage.

15. Cont..
• Knowing the paper speed, it's easy to work
out heart rate. It's also very convenient to
have a quick way of eyeballing the rate, and
one method is as follows:
• Remember the sequence:
300, 150, 100, 75, 60, 50
• Identify an R wave that falls on the marker of
a `big block'
• Count the number of big blocks to the next R
wave.
• If the number of big blocks is 1, the rate is
300, if it's two, then the rate is 150, and so
on. Rates in between these numbers are
easy to `interpolate'.
Number of
big boxes
Rate
1 300
2 150
3 100
4 75
5 60
6 50

16. Rhythm
• This is checked by the intervals b/w two R peaks or
two S waves is equal in all leads, the rhythm is said
to regular & if it is not. The rhythm is said to be
irregular.
• If rhythm is not, the rhythm is said to be irregular
or irregularly irregular.
• If the regularity is after regular intervals the
rhythm is regularly irregular,Otherwise irregular
irregular.
• Irregular rhythm is called Arrhythmias

17. Heart rate can be easily calculated from the
ECG strip
• When the rhythm is regular, the heart rate is 300
divided by the number of large squares between
the QRS complexes. For example, if there are 4
large squares between regular QRS complexes, the
heart rate is 75 (300/4=75). OR
• Each second of time is represented by 250 mm (5
large squares) along the horizontal axis. So if the
number of large squares between each QRS
complex is:
• 5 - the HR is 60 beats per minute.
• 3 - the HR is 100 per minute.
• 2 - the HR is 150 per minute.
• The second method can be used with an irregular
rhythm to estimate the rate. Count the number of
R waves in a 6 second strip and multiply by 10.
– For example, if there are 7 R waves in a 6
second strip, the heart rate is 70 (7x10=70).

18. Arrhythmias
• These are groups of disorders.
In which there is disturbance of cardiac
rhythm.
These are classified into following groups
• 1. sinus arrhythmia
• 2. Atrial arrhythmia
• 3.AV junctional (nodal)arrhythmia
• 4.Ventricular arrhythmia
• 5.Miscellaneous
(a) Accelerated conduction
(b) Heart block
(c) Conduction defect

19. Sinus Arrhythmia
• Sinus arrhythmia: The normal increase in heart rate that occurs during
inspiration (when you breathe in). This is a natural response and is more
accentuated in children than adults.
• The "sinus" refers to the natural pacemaker of the heart which is called the
sinoatrial (or sinus) node. It is located in the wall of the right atrium (the right
upper chamber of the heart). Normal cardiac impulses start there and are
transmitted to the atria and down to the ventricles (the lower chambers of the
heart).
• Sinus tachycardia refers to a fast heartbeat (tachycardia) because of rapid firing
of the sinoatrial (sinus) node. This occurs in response to exercise, exertion,
excitement, pain, fever, excessive thyroid hormone, low blood oxygen (hypoxia),
stimulant drugs (such as caffeine), etc.
• The lack of normal sinus rhythm is an arrhythmia, an abnormal heart rhythm

20. Bradycardia-Tachycardia Syndrome
• Also known as Sick sinus syndrome

21. Atrial Arrhythmia
• Types of Atrial Arrhythmias
• Atrial Ectopic Beats
• Supraventricular tachycardia (SVT).
• Atrial fibrillation.
• Atrial flutter.

22. Atrial Ectopic Beats
• Atrial ectopic beats (AEB) refers to a contraction of the upper heart
chamber which occurs before it would be expected.
• Also known as premature atrial beats, premature atrial complex
(PAC), or atrial extrasystole.
• As people age, extra beats tend to happen more frequently even in
perfectly healthy individuals. AEB may be triggered
bystress, caffeine, smoking, and some medicines,i.e ephedrine or
pseudoephedrine .
• AEB may also be the result of an enlarged atria, lung disease, or the
result of reduced blood supply to that area of the heart.

23. Atrial tachycardia or
Supraventricular tachycardia (SVT).
• Supraventricular tachycardia (SVT)
means that from time to time
our heart beats very fast for a
reason other than exercise, high
fever, or stress.
Types of SVT include:
• Atrioventricular nodal reentrant
tachycardia (AVNRT).
• Atrioventricular reciprocating
tachycardia
(AVRT), including Wolff-Parkinson-
White syndrome.

24. Atrial flutter.
• When the heart rate is sufficiently elevated so that the isoelectric
interval between the end of T and beginning of P disappears, the
arrhythmia is called atrial flutter.
• The origin is also believed to involve a reentrant atrial pathway. The
frequency of these fluctuations is between 220 and 300/min. The
AV-node and, thereafter, the ventricles are generally activated by
every second or every third atrial impulse

25. Atrial fibrillation.
• Atrial fibrillation (AF or A-fib) is where the signal doesn't originate
only from the SA node, and so the atrium doesn't contract
simultaneously, causing an incredibly high heart rate, as well as lack
of atrial systole. It is the most common cardiac arrhythmia (irregular
heart beat). It may cause no symptoms, but it is often associated
with palpitations, fainting, chest pain, or congestive heart failure.

26. AV Junctional (Nodal) Arrhythmia
• In junctional rhythm, the sinoatrial node does not control the heart's rhythm - this
can happen in the case of a block in conduction somewhere along the pathway
described above. When this happens, the heart's atrioventricular node takes over
as the pacemaker.
• In the case of a junctional rhythm, the atria will actually still contract before the
ventricles; however, this does not happen by the normal pathway and instead is
due to retrograde conduction (conduction comes from the ventricles or from the
AV node into and through the atria).[3]
• Junctional rhythm can be diagnosed by looking at an EKG: it usually presents
without a P wave or with an inverted P wave. Retrograde P waves refers to the
depolarization from the AV node back towards the SA node

27. Ventricular Arrhythmia
• Ventricular ectopic beats
• Ventricular Tachycardia
• Ventricular Fibrillation

28. Ventricular Ectopic beats
• A ventricular ectopic beat (VEB) is an extra heart-beat originating in
the lower chamber of the heart. This beat, also called a premature
ventricular contraction (PVC), occurs before the beat triggered by the
heart's normal function.
• Ventricular ectopic beats are common and do not indicate a problem
in people without heart disease. However, if a person has aortic
stenosis, heart failure, or a previous heart attack, VEBs may be
followed by ventricular tachycardia and fibrillation, which can lead to
suddendeath.

29. Ventricular Tachycardia
• Ventricular tachycardia (VT) is a fast heart rhythm that
occurs in one of the ventricles of your heart. It is like
one electrical short circuit that races in a circle. In a
VT, the heart beats with each race around the circuit at
rates from 150 to 250 bpm.

30. Ventricular Fibrillation
• VF originates from many different locations in the ventricles, each
one trying to signal the heart to beat. In this case, the heart beats
much faster than normal, sometimes over 300 beats a minute. The
lower chambers quiver instead of contract, and very little, if
any, blood is pumped from the heart to the rest of the body. If your
heart is in VF, you can become unconscious very quickly.

31. HEART Block
• AV blocks
– First degree block
• PR interval fixed and > 0.2 sec
– Second degree block, Mobitz type 1
• PR gradually lengthened, then drop QRS
– Second degree block, Mobitz type 2
• PR fixed, but drop QRS randomly
– Type 3 block
• PR and QRS dissociated

32. First-degree AV block
• First-degree AV block, or PR prolongation, is a disease of
the electrical conduction system of the heart in which the PR
interval is lengthened beyond 0.20 seconds.[1]
• In first-degree AV block, the impulse conducting from atria to
ventricles through the AV node is delayed and travels slower than
normal.

33. 2nd degree HB
• Type 1 (Mobitz I/Wenckebach)
• Type 2 (Mobitz II/Hay)

34. Type 1 (Mobitz I/Wenckebach)
• progressive prolongation of the PR interval on (ECG)
• consecutive beats followed by a blocked P wave (i.e., a 'dropped' QRS
complex). After the dropped QRS complex, the PR interval resets and
the cycle repeats.
• One of the baseline assumptions when determining if an individual
has Mobitz I heart block is that the atrial rhythm has to be regular. If
the atrial rhythm is not regular, there could be alternative
explanations as to why certain P waves do not conduct to the
ventricles

35. Type 2 (Mobitz II/Hay)
• Type 2 Second-degree AV block, also
known as "Mobitz II," is almost
always a disease of the distal
conduction system (His-Purkinje
System).
• Mobitz II heart block is characterized
on a surface ECG by intermittently
nonconducted P waves not preceded
by PR prolongation and not followed
by PR shortening. The medical
significance of this type of AV block is
that it may progress rapidly
to complete heart block, in which
no escape rhythm may emerge.

36. Third-degree AV block
• Also known as complete heart block, is a medical condition in which the impulse
generated in the SA node in the atrium does not propagate to the ventricles.[1]
• an accessory pacemaker in the lower chambers will typically activate the
ventricles. This is known as an escape rhythm. Since this accessory pacemaker
also activates independently of the impulse generated at the SA node, two
independent rhythms can be noted on the electrocardiogram (ECG).
• The P waves with a regular P to P interval represents the first rhythm.
• The QRS complexes with a regular R to R interval represent the second rhythm.
The PR interval will be variable, as the hallmark of complete heart block is no
apparent relationship between P waves and QRS complexes

37. Ischemia

38. Remaining................
– Rate
– Rhythm (including intervals and blocks)
– Axis Deviation
– Hypertrophy
– Ischemia
– P waves
– PR Interval
– Q wave
– QRS complex
– ST Segment
– T wave