ECG

Question 1

What does the P-wave represent

Answer 1

Atrial depolarisation

Question 2

What does the QRS wave represent

Answer 2

Ventricular depolarisation

Question 3

What does the T wave represent?

Answer 3

Ventricular repolarisation

Question 4

How to calculate the heart rate?

Answer 4

R wave to R wave (peaks). 1 small box = 0.04 seconds, 1 big box = 0.2 seconds. 1500/ number of small boxes, or 300/number of large boxes.

Question 5

How to measure the PR interval and what are the norms?

Answer 5

Beginning of P-wave to beginning of Q-wave. Should be 3-5 small boxes (120-300ms). >3-5 boxes is indicative of heart block.

Question 6

What does an elevated ST segment indicate?

Answer 6

Transmural myocardial ischemia (STEMI); Must be 1 mm (1 small box) in 2 or more contiguous limb leads or >2mm (2 small boxes) in 2 or more chest leads

Question 7

What does a ST depression indicate?

Answer 7

Myocardial ischemia - must be ≥ 0.5 mm (~1 small box) in ≥ 2 contiguous leads

Question 8

What is absence of P-waves indicative of?

Answer 8

Atrial fibrillation