The 12-lead ECG

Question 1

What are the two distinct planes in which an ECG is viewed?

Answer 1

Frontal
• Limb leads; I, II, III, aVR, aVL, aVF
Horizontal
• Chest leads; V1-V6

Question 2

Describe Eindhoven’s Triangle

Answer 2

Three electrical axes, which form a triangle, representing the electrical fluctuations between Lead I-III;
Lead 1: R) arm (-) to L) arm (+)
Lead 2: R) arm (-) to L) leg (+)
Lead III: L) arm (-) to L) leg (+)
* (-) negative electrode, (+) positive electrode

Question 3

Which aspect of the heart do the traditional leads view?

Answer 3

I - Left lateral
II - Inferior
III - Inferior

Question 4

What are the 3 augmented leads?

Answer 4

aVR (augmented voltage right)
aVL (augmented voltage left)
aVF (augmented voltage foot)

Question 5

What is the central terminal?

Answer 5

A point of negative electrical reference which combines the electrical signals from certain electrodes

Question 6

What area of the heart dose aVF look at?

Answer 6

Inferior, between lead II & III due to using the central terminol

Question 7

Which lead mimics lead II and why?

Answer 7

aVR. It measures the electrical activity across the R) atrium which is almost opposite lead II. It provides predominantly negative deflections in P, QRS & T waves

Question 8

What view does aVR look at?

Answer 8

R) lateral

Question 9

What are of the heart does aVL view?

Answer 9

Later aspect, the L) ventricle

Question 10

Which limb lead & augemented lead are useful for viewing the left lateral aspect of the heart?

Answer 10

Lead I & aVL as they run adjacent

Question 11

Why is there an electrode placed on the R) leg?

Answer 11

To provide an earth in order to determine lead views

Question 12

Name the 6 chest leads, their view’ & position of placement

Answer 12

V1 - Septum - 4th intercostal space, R) of sternum
V2 - Septum - 4th intercostal space, L) of sternum
V3 - Anterior - Midway V2-V4
V4 - Anterior - 5th intercostal space, mid-clavicular line
V5 - Left lateral - Midway V4-V6
V6 - Left lateral - Mid-axillary line with V4

Question 13

In which direction does V1 deflect & why?

Answer 13

Predominantly negative as the electrical current is moving away from the V1 electrode with normal depolarisation.

Question 14

In which direction does V6 deflect & why?

Answer 14

Predominantly positive as most of the current from normal depolaristion is moving towards the V6 electrode