ECG(ELECTROCARDIOGRAM) [Autosaved] new1.ppt

7/28/2019 ECG(ELECTROCARDIOGRAM) [Autosaved] new1.ppt

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ECG(ELECTROCARDIOGRAM)

Electrocardiogram was introduced by

Willem Einthoven in 1893

An electrocardiograph machine is a device

that measures and records electrical

activity in the heart by the use ofECG padsplaced on the chest and connected to

wires, call leads.

ECG pads are placed on several parts of

the body

.


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standard 12-lead ECG that is used throughout the world

It is called a 12-lead ECG because it examines the electrical

activity of the heart from 12 points of view


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From the ECG tracing, the following informationcan be determined:

the heart rate

the heart rhythm

whether there are conduction abnormalities

(abnormalities in how the electrical impulsespreads across the heart)

whether there has been a prior heart attack

whether there may be coronary artery disease

whether the heart muscle has become abnormally

thickened


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CORONARY ARTERY DISEASE


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BASIC ANATOMY OF HEART

The heart is a 4-chambered muscle whose function is

to pump blood throughout the body.

The heart is really 2 "half hearts," the right heart and

the left heart, which beat simultaneously.

Each of these 2 sides has 2 chambers: a smaller upperchamber called the atrium (together, the 2 are called

atria), and a larger lower chamber called the ventricle.

Thus, the 4 chambers of the heart are called the rightatrium, right ventricle, left atrium, and left ventricle.
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Blood vessels (veins) carry blood to the heart from the rest of

the body

This blood carries carbon dioxide and cellular waste products

The blood goes into the right atrium and then to the right

ventricle, where it is then pumped to the lungs to dispose of

wastes and receive a fresh oxygen supply.

From the lungs, the blood returns to the heart.

It returns to the left atrium and then to the left ventricle.


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The blood is then pumped out of the heart by the left

ventricle into the aorta.

The left ventricle is the chamber of the heart that is

responsible for pumping blood to all parts of the body.

The aorta sends this blood to small arteries, which carry the

oxygen-rich blood to the rest of the body.


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Each action potential in the heart

originates at the sinoatrial

(SA)node which is situated in the

wall of the right atrium and near

the entry of the superior vena

cava.

It is also called cardiac pacemaker


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A cardiac pacemaker is a small electrical device inserted

under the skin to control the heart rate and prevent the

discomfort and symptoms caused by a very slow or fast heart

rate.

Generates impulse at the normal rate of the heart,about 70

beats per minute at rest.


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The rate is governed by theautonomic nervous system,being increased by thesympathetic nerves and

parasympathetic nerves.


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Sympathetic nervous system

allow body to function under stress .

fight or flight . Parasympathetic nervous system

controls vegetative functions.

feed or breed or rest and respose feedrespose.

constant opposition to sympathetic system

constant system.


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http://www.nhlbi.nih.gov/health/dci/Diseases/hh

w/hhw_electrical.html
http://localhost/var/www/apps/conversion/tmp/scratch_9/Heart%20electrical%20system%20and%20EKG1.htmhttp://localhost/var/www/apps/conversion/tmp/scratch_9/Heart%20electrical%20system%20and%20EKG1.htmhttp://localhost/var/www/apps/conversion/tmp/scratch_9/Heart%20electrical%20system%20and%20EKG1.htmhttp://localhost/var/www/apps/conversion/tmp/scratch_9/Heart%20electrical%20system%20and%20EKG1.htm


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intercostal space the space between two adjacent ribs

The sternum is a flat, dagger shaped bone located in the middle of thechest. Along with the ribs, the sternum forms the rib cage that protects

the heart, lungs, and major blood vessels from damage.
http://www.mnsu.edu/emuseum/biology/humananatomy/skeletal/ribs/ribs.htmlhttp://www.mnsu.edu/emuseum/biology/humananatomy/skeletal/ribs/ribs.html


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Feature Description Duration

P wave

During normal atrial depolarization, the main electrical vector is directedfrom the SA node towards the AV node, and spreads from the right atriumto the left atrium. This turns into the P wave on the ECG.

80ms

PRsegment

The PR segment connects the P wave and the QRS complex. 150 to 200ms

QRS

complex

The QRS complex is a recording of a single heartbeat on the ECG thatcorresponds to the depolarization of the right and left ventricles.

70 to 110ms

ST

segmentThe ST segment connects the QRS complex and the T wave. 80 to 120ms

T wave

The T wave represents the repolarization (or recovery) of the ventricles.The interval from the beginning of the QRS complex to the apex of the Twave is referred to as the absolute refractory period. The last half of the Twave is referred to as the relative refractory period(or vulnerable period).

160ms

PR

interval

The PR interval is measured from the beginning of the P wave to thebeginning of the QRS complex.

120 to 200ms

ST

intervalThe ST interval is measured from the J point to the end of the T wave. 320ms

QT

interval

The QT interval is measured from the beginning of the QRS complex to theend of the T wave.

300 to

430ms[citation needed]

U wave The U wave is not always seen. It is typically small, and, by definition,follows the T wave.
http://en.wikipedia.org/wiki/P_wave_(electrocardiography)http://en.wikipedia.org/wiki/Atrium_(anatomy)http://en.wikipedia.org/wiki/Atrium_(anatomy)http://en.wikipedia.org/w/index.php?title=PR_segment&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=PR_segment&action=edit&redlink=1http://en.wikipedia.org/wiki/QRS_complexhttp://en.wikipedia.org/wiki/QRS_complexhttp://en.wikipedia.org/wiki/ST_segmenthttp://en.wikipedia.org/wiki/ST_segmenthttp://en.wikipedia.org/wiki/T_wavehttp://en.wikipedia.org/wiki/PR_intervalhttp://en.wikipedia.org/wiki/PR_intervalhttp://en.wikipedia.org/w/index.php?title=ST_interval&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=ST_interval&action=edit&redlink=1http://en.wikipedia.org/wiki/QT_intervalhttp://en.wikipedia.org/wiki/QT_intervalhttp://en.wikipedia.org/wiki/QT_intervalhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/U_wavehttp://en.wikipedia.org/wiki/U_wavehttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/QT_intervalhttp://en.wikipedia.org/wiki/QT_intervalhttp://en.wikipedia.org/wiki/QT_intervalhttp://en.wikipedia.org/w/index.php?title=ST_interval&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=ST_interval&action=edit&redlink=1http://en.wikipedia.org/wiki/PR_intervalhttp://en.wikipedia.org/wiki/PR_intervalhttp://en.wikipedia.org/wiki/T_wavehttp://en.wikipedia.org/wiki/ST_segmenthttp://en.wikipedia.org/wiki/ST_segmenthttp://en.wikipedia.org/wiki/QRS_complexhttp://en.wikipedia.org/wiki/QRS_complexhttp://en.wikipedia.org/w/index.php?title=PR_segment&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=PR_segment&action=edit&redlink=1http://en.wikipedia.org/wiki/Atrium_(anatomy)http://en.wikipedia.org/wiki/Atrium_(anatomy)http://en.wikipedia.org/wiki/P_wave_(electrocardiography)


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Placement of electrodes


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Limb leads
http://en.wikipedia.org/wiki/File:Precordial_leads_in_ECG.png


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http://en.wikipedia.org/wiki/File:Precordial_leads_in_ECG.png


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http://en.wikipedia.org/wiki/File:Axillary_lines.png


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There are two types of leads: unipolarand bipolar.

Bipolar leads have one positive and one negative

pole.

The limb leads (I, II and III) are bipolar leads.

Unipolar leads also have two poles, as a voltage is

measured; however, the negative pole is a composite

pole made up of signals from lots of other electrodes.

In a 12-lead ECG, all leads besides the limb leads are

unipolar(aVR, aVL, aVF, V1, V2, V3, V4, V5, and V6).


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ECG LEADS

ECG Leads

Bipolar

Leads I, II, and II

Unipolar aVR(augmented voltage Right arm)

aVL(augmented voltage Left arm)

aVF (augmented voltage Foot)

Precordial V1, V2, V3, V4, V5, V6


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ECG LEADS


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ECG LEADS

Bipolar Limb Leads

Lead I

Lead II

Lead III

Einthovens Triangle

R wave amplitude of Lead II = sum of the R wave


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R wave amplitude of Lead II = sum of the R waveamplitude of leads I and III,

VII=V1+VIII

AUGMENTED UNIPOLAR LIMB LEADS:

Two equal and large resistors are connected to a pair oflimb electrodes

Centre of this resistive network acts as central terminal

Limb electrode acts as the exploratory electrode. Small increase in ECG voltage can be realized due to the

augmented lead connections

Augmented voltage in terms of standard leads voltage:

aVR= -V1VIII/2

aVL = V1-VII/2

aVF = VII-V1/2


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ECG RECORDING SET UP


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ECG ELECTRODES

Limb electrodes

Floating electrodes

Pregelled disposable electrodes

Pasteless electrodes


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EEG(ELECTROENCEPHALOGRAPHY)

Study ofelectrical activity of the brain

Electrodes attached to the skull of a patient, the brain waves

are picked up and recorded.

These signals are sent to a computer to record the results.

It also is used to evaluate people who are having problems

associated with brain function.

These problems might include confusion, coma, tumors, long-

term difficulties with thinking or memory, or weakening of

specific parts of the body (such as weakness associated with a

stroke).

A l t h l (EEG) b d t
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An electroencephalogram (EEG) may be done to:

Diagnose epilepsy and see what type of seizures are occurring.

EEG is the most useful and important test in confirming adiagnosis of epilepsy.

Epilepsyis a nervous system disorder that produces intense,

abnormal electrical activity in the brain

Seizures are sudden bursts of abnormal electrical activity in the

brain that may affect a person's muscle

Check for problems with loss of consciousness or dementia.

H l fi d t ' h f ft h i
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Help find out a person's chance of recovery after a change in

consciousness.

Find out if a person who is in a coma is brain-dead. Study sleep disorders

Watch brain activity while a person is receiving general

anesthesia during brain surgery.

Help find out if a person has a physical problem (problems in

the brain, spinal cord, or nervous system) or a mental health

problem.
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If the normal conduction system is disturbed ,then the beat rate

will be slower than the normal rate.this state is called heart block.

Phonocardiography:

The graphic record of the heart sound is called phonogram.

Heart sounds:

1.valve closure sounds

2.ventricular filling sounds

3.valve opening sounds 4.extra cardiac sounds

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