ECG

Question 1

What are the basic steps of interpreting an ECG? [5]

Answer 1

1. Before you get to the traces
   
   • always ask for clinical context
   • check the date, time & patient
   • assess technical quality (artefact/speed/gain)
2. Look at the rhythm strip
   
   • check the QRS (heart) rate/ECG intervals
   • identify P/QRS/T waves and determine the rhythm
3. Look at the limb leads
   
   • determine the QRS axis
4. Look across all leads
   
   • P/QRS/T morphology

Question 2

How do you calculate heart rate on ECG? [2]

Answer 2

• heart rate = 300
  
  • no. of large squares between each QRS complex

OR

• heart rate = no. of QRS complexes in rhythm strip x6

Question 3

What are the normal lengths of the ECG intervals (how many squares)? [3]

1. PR interval
2. QRS complex
3. QT interval

Answer 3

1. PR Interval
   
   • < 1 large square
   • < 200ms
2. QRS
   
   • < 3 small squares
   • < 120ms
3. QT interval
   
   • < 11 small squares
   • < 440ms