ECG

Question 1

How can electrical activity through heart be recorded?

Answer 1

• Currents generated by cardiac muscle are conducted through body fluids.
• small part of electrical activity reaches body surface where electrodes detect it.

Question 2

What are the six limb leads?

Answer 2

I, II, III, aVR, aVL, aVF

• Leads I, II, III are bipolar leads as two recording electrodes are used. The tracing records the difference in potential between to electrodes.
• Other three leads are unipolar leads. Only two electrodes are used: one is at 0 potential, the other is the exploring electrode.

Question 3

What are the six chest leads?

Answer 3

V1 to V6 - unipolar leads.

Question 4

What are the three waveforms of the ECG?

Answer 4

P wave = atrial depolarisation
QRS complex = represents ventricular depolarisation
T wave = represents ventricular repolarisation