The Electrocardiogram (ECG)

Question 1

What does the ECG record?

Answer 1

electrical activity of the heart (depolarisation and repolarisation)

Question 2

What information does ECG provide?

Answer 2

timing and direction of cardiac events
rate/rhythm disturbances
conduction abnormalities
mass of active myocardium

Question 3

Do the last ventricular cells to depolarise get repolarised first?

Answer 3

yes

Question 4

What are the 6 rules when labelling an ECG

Answer 4

1) first wave always P wave regardless of polarity
2) final wave is T wave
3) first positive wave after P is R wave
4) any negative wave after P wave but before R is Q wave
5) any negative wave after R is S wave
6) any positive wave after S is R’ wave