Question

Explain the diagram of ECG and write its uses.

Answer 1

Salient Features of ECG:

• The ECG is recorded on special graph paper which is divided into 1 mm² gride like boxes.
• The normal ECG includes P wave, QRS complex and ST – T – U complex.
• The P wave is a small upward deflection and it represents atrial depolarization.
• The QRS Complex represents rapid ventricular depolarisation (systole). It includes a small downward deflection, a rapid upright stroke and a small downward deflection.
• The ST – T – U complex includes ST regiment, T wave & U wave. It represents the ventricular repolarisation (diastole).
• The J point is the junction between the end of the QRS complex and the beginning of ST-segment.
• Trial repolarization is too low in amplitude to be detected.
• There are four major ECG Intervals –
  1. R – R interval: It is used to compute the heartbeats per minute.
  2. P – R Interval: It is used to measure the time between atrial & ventricular depolarisation.
  3. QRS interval: It reflects the duration of ventricular depolarisation & atrial repolarisation.
  4. QT interval: It includes both ventricular depolarisation and repolarisation times.
• The QRS Complex is subdivided into specific deflections or waves.
• The initial negative deflection is termed as Q – wave.
• The first positive deflection is termed as R – wave A negative deflection after the R – wave is termed as S – wave.
• An entirely negative QRS complex is termed as QS wave.
• Normal T wave is a dome-shaped upward deflection.
• Normal U wave is a small round upward deflection that follows the T – wave.