Download CVS-12-ECG

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CARDIOVASCULAR SYSTEM
ELECTROCARDIOGRAM (E.C.G.)
LECTURE - 5
DR. ZAHOOR ALI SHAIKH
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It is recording of Electrical
activity of the Heart by putting
Electrodes on the surface of the
body.
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ECG
What is Lead?
• ECG recorded on the paper after putting the
electrode.
What is Electrode?
• It is a metallic plate which conducts
electricity.
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ECG
Machine
Electrode
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Bipolar
Limb leads
Unipolar
Limb Leads
Unipolar
chest leads
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ECG
In bipolar lead, we record potential
difference between two active
electrodes.
In Unipolar lead, we record potential
difference between active electrode
and other electrode at zero potential.
If current is flowing towards the
recording electrode, we get upward
deflection.
If current is flowing away from the
recording electrode, we get downward
deflection.
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Heart Rate Calculation
= 1500 ÷ No. of small squares between R-R waves
Or
= 300 ÷ No. of big squares between R-R waves
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The Waves & Intervals
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P wave  Atrial Depolarization
During  0.12 sec
Voltage (Height) 1-3mm
QRS Complex  Ventricular
Depolarization
Time  0.08 – 0.1 sec
Voltage  10mm (1mV)
T wave  Ventricular
Repolarization
Height 2-3mm
U wave  Repolarization of
Papillary Muscles
PR interval  Conduction time from SA node to
Ventricular muscle through AV node. It measures
the time from beginning of P wave to beginning of
Q wave.
Time 0.12 – 0.2 sec.
QT Interval  Ventricular Depolarization or
Repolarization
Time 0.35 – 0.43 sec
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REMEMBER IMPORTANT NORMAL VALUES
P wave
- 0.12 sec
QRS
- 0.1 sec
PR Interval - 0.2 sec
QT Interval - 0.4 sec
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ELECTRICAL
AXIS
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1st Degree
Heart Block
ST Elevation – Myocardial Infarction
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WHAT YOU SHOULD KNOW
FROM THIS LECTURE?
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P wave ---- Atrial depolarization.
QRS complex ---- Ventricular depolarization..
T wave ---- Ventricular Repolarization.
P – R interval ---- conduction time from S-A node
to ventricular muscle through A-V node
time =0.12 – 0.2sec.
5. ↑PR interval more than 0.2 sec.---- Ist degree heart
block.
6. Q – T interval ---- Ventricular depolarization +
ventricular repolarization time =0.35 – 0.43sec.
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↑QT interval ---- hypocalcemia.
U wave ---- repolarization of papillary muscle.
Prominent U wave ---- hypokalemia.
Prominent T wave ---- hyperkalemia.
Heart rate calculation
Sinus tachycardia
Sinus bradycardia
Sinus arrhythmia (↑ heart rate during
inspiration)
15. Cardiac axis
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by looking at ECG lead I & III
By plotting
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16. Normal cardiac axis 0o to + 90o
(-30o to + 110o )
17. You should know about Left axis
deviation & right axis deviation.
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THANK YOU
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