Basics

Question 1

What are the names of the three augmented leads?

Answer 1

aVF, aVL and aVR.

Question 2

Describe the Wilson Central Terminal.

Answer 2

A virtual reference point from which the average voltage of the left arms, right arms and left legs voltage can be calculated on and ECG.

Question 3

Which electrode should be placed on the anterior axillary line?

Answer 3

V5.

Question 4

Which electrode should be placed on the fourth intercostal space on the left border of the sternum?

Answer 4

V2.

Question 5

Which electrode should be placed on the mid-axillary line horizontal to V5?

Answer 5

V6.

Question 6

Explain the difference between positive and negative deflection.

Answer 6

Positive deflection is when the electrical vector is directed from the reference electrode to the exploring electrode, while a negative deflection is when that vector is directed from the exploring electrode to the reference electrode.

Question 7

How many seconds does a one millimetre size square (small square) represent?

Answer 7

0.04 seconds.

Question 8

Explain how the process of a normal sinus rhythm beat shows on an ECG (both waves and intervals).

Answer 8

Begins at the P-wave, which is the beginning of the P-R interval (the rest of the P-R interval is the P-R segment). The impulse continues into the QRS complex, which is followed by the ST segment. The process is finished with the T-wave. Everything between the beginning of the QRS complex and the end of the T-wave is called the Q-T interval.

Question 9

Explain what the waves in an ECG represent.

Answer 9

P-wave represents atrial depolarisation, QRS complex represents ventricular depolarisation, T-wave represents ventricular repolarisation.

Question 10

How long is the duration of each interval in a normal beat?

Answer 10

P-R: 0.12 - 0.20 seconds
QRS: less than 0.12 seconds
Q-T: 0.44 seconds in men, 0.46 seconds in women