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