Basics of ECG

Question 1

Which part of the conduction cycle does the P wave represent on an ECG?

Answer 1

Atrial depolarisation

Question 2

Which part of the conduction cycle does the QRS complex represent on an ECG?

Answer 2

Ventricular depolarisation

Question 3

Which part of the conduction cycle does the PR interval represent on an ECG?

Answer 3

Delay through the AV node

Question 4

Which part of the conduction cycle does the T wave represent on an ECG?

Answer 4

Ventricular depolarisation

Question 5

A positive deflection on ECG indicates that electricity in travel in which direction with respect to that lead?

Answer 5

Towards the lead

Question 6

A negative deflection on ECG indicates that electricity in travel in which direction with respect to that lead?

Answer 6

Away from the lead

Question 7

What is the normal duration of the QRS complex on ECG?

Answer 7

<120ms

Question 8

What is the normal duration of the PR interval on ECG?

Answer 8

120-200ms

Question 9

Which interval on ECG requires correction for heart rate in order to interpret it properly?

Answer 9

QT interval

Question 10

How long would a QT interval have to be on ECG for it to be considered prolonged?

Answer 10

> 450ms

Question 11

Why is a prolonged QT interval on ECG significant?

Answer 11

It can predispose the cardiac rhythm to change into a ventricular tachycardia which may result in cardiac arrest

Question 12

Which interval on ECG is used to determine heart rate?

Answer 12

RR interval

Question 13

How can heart rate be calculated on ECG when there is a normal rhythm?

Answer 13

300 / number of large squares between R waves

Question 14

How can heart rate be calculated on ECG when there is an abnormal rhythm?

Answer 14

Number of R waves present in rhythm strip x 6

Question 15

What are the names of the three chest leads on ECG?

Answer 15

V1
V2
V3
V4
V5
V6

Question 16

What are the names of the three limb leads on ECG?

Answer 16

I
II
III

Question 17

What are the names of the three augmented leads on ECG?

Answer 17

aVL
aVF
aVR

Question 18

Which ECG leads form a coronal view of the heart?

Answer 18

aVL
aVF
aVR
I
II
III

Question 19

Which ECG leads form a transverse view of the heart?

Answer 19

V1-6

Question 20

Which ECG lead points towards 0 degrees on the cardiac axis?

Answer 20

I

Question 21

Which ECG lead points towards +60 degrees on the cardiac axis?

Answer 21

II

Question 22

Which ECG lead points towards +90 degrees on the cardiac axis?

Answer 22

aVF

Question 23

Which ECG lead points towards +120 degrees on the cardiac axis?

Answer 23

III

Question 24

Which ECG lead points towards -150 degrees on the cardiac axis?

Answer 24

aVR

Question 25

Which ECG lead points towards -30 degrees on the cardiac axis?

Answer 25

aVL

Question 26

Which ECG leads show an inferior view of the heart?

Answer 26

II, III, aVF

Question 27

Which ECG leads show an anteroseptal view of the heart?

Answer 27

V1-4

Question 28

Which ECG leads show an lateral view of the heart?

Answer 28

I aVL V5 V6

Question 29

Where should the normal transition zone for R wave progression on ECG be?

Answer 29

leads. V3/4

Question 30

Between which degrees should the normal cardiac axis lie?

Answer 30

-30 and +90 degrees

Question 31

What are the signs of right axis deviation on ECG?

Answer 31

QRS complex is negative in lead I and positive in lead II

Question 32

What pathology can cause right axis deviation?

Answer 32

Right ventricular hypertrophy | Left sided dysfunction

Question 33

When might right axis deviation be normal?

Answer 33

In tall, thin individuals

Question 34

What pathology can cause left axis deviation?

Answer 34

Left ventricular hypertrophy | Right sided dysfunction

Question 35

What are the signs of left axis deviation on ECG?

Answer 35

QRS complex is positive in lead I and negative in lead II

Question 36

In which ECG leads can it be normal to see a Q wave?

Answer 36

``` V5 V6 I aVL i.e. the lateral leads ```