Tuesday, 25 February 2014

How To Read An ECG

The ECG paper is mostly standardised

  • Each large square on the paper represents 0.2 seconds
  • Each small square represents 0.04 seconds
  • 5 large squares therefore = 1 second
  • 300 large squares = 1 minute
  • To calculate heart rate – count large squares within an R-R interval & divide 300 by this number

  • P-waves represent atrial depolarisation
  • There should be a P-wave preceding each QRS complex
QRS complex
  • The QRS-complex represents depolarisation of the ventricles
  • It is seen as 3 closely related waves on the ECG (Q,R & S wave);
  • The first downward deflection is the Q-wave
  • Any upward deflection is an R-wave
  • Downward deflections after an R-wave is called an S-wave
  • It should be between 0.06-0.10 seconds
  • The T-wave represents ventricular re-polarisation
  • It is seen as a small wave after the QRS complex
Source: facmedicine

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