ECG

ECG: 

The electric impulse that passes through the conduction system of heart during cardiac cycle can be recorded as electrocardiogram and the machine which record is known as 

Electrocardiograph

In clinical practise electrodes are positioned on arm and leg and at six position on chest to record the ECG. By ECG it is possible to determine 

1-If the heart is enlarge

2-Functioning of artificial pacemaker

3-Cause of chest pain

4-If certain region of heart is damaged

Fist wave in ECG is p-wave. When SA node discharge electrical impulses P-wave is form . The P-wave represent the atrial depolarization which spread from contractile fibre to both atria

  The second wave called QRS COMPLEX  begins as a downward deflection,

and continues as a large upright,triangular wave and end as a downward wave. The QRS complex represent ventricular depolarization

      The third wave is a dome shaped upward deflection called T-wave. 

It indicates ventricular repolarization. T-wave is smaller and wider then QRS complex because repolarization occur more slowly then depolarization 

        In reading ECG the size of wave provide clues to abnormalities

1-larger p- wave indicate enlargment of atrium 

2-Enlaged Q-wave indicate mycordial infarction

3-Enlarged R-wave indicate enlarged ventricles

4-T-wave is flatter then normal when the heart muscel is recieiving insufficient oxygen 

P-R interval is the period of time from the start of P-wave to the begining of Q-R complex