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Electrical Activity in the
Heart
ELECTROCARDIOGRAM Electrocardiogram (EKG) is a test of
heart that shows the pattern of heart beat.
It’s performed by putting electrodes on the chest to detect the activity .
The voltage pulse can be recorded by an instrument called Electrocardiograph (ECG).
To understand what does EKG tell as , we should know the basics of Heart Electrical Activity .
•The heart is consisted of four champers (two atria and two ventricles) .
•The right atrium contains specialized cells called Sinoatrial node or ‘pace maker’ which initiates the heart beat .
• The first beat – generated by SA node – spreads through right and left atria and causes them to contract .
The pulse that passes through muscle cells is called Depolarization Wave .
Depolarization removes the normal electrical distribution of each cell .
When this wave passes the cell it recovers the resting-state ‘ + out , - in ’ .
After the wave passes away from atria , it’ll reach the ‘Atrioventricular node’ (AV) .
AV node directs the pulse towards the ventricles through Purkingi fibers .
After the wave passes , the ventricles relax and SA node triggers the pulse again .
Elecrocardiograph
The adjacent figure shows the ECG for a normal heart .
P : just before the atria contracts . QRS : just before the ventricle contract . T : the ventricles begin to relax .
The device detects the depolarization wave not the contraction of muscles .
Abnormalities of Heart rhythm
Heart enlargement : one or more champers are enlarged , or Hypertrophy leading to muscle enlargement .
QRS is wider than normal
Abnormalities of Heart rhythm
Tachycardia and bradycardia
Bradycardia 50 BPM Tachycardia 100 BPM
Hope You Enjoyed this Presentation …By Muhammad Husain & Abdullah Badran