ECG Interpretation

Question 1

Limb leads

Answer 1

I, II, III, aVL, aVR, aVF

Question 2

Precordial leads

Answer 2

V1, V2, V3, V4, V5, V6

Question 3

Lateral leads

Answer 3

I, aVL, V5, V6

Question 4

Inferior leads

Answer 4

II, III, aVF

Question 5

Septal leads

Answer 5

V1, V2

Question 6

Anterior leads

Answer 6

V1, V2, V3, V4

Question 7

How long is a typical ECG strip

Answer 7

20 seconds

Question 8

P Wave (Patria) represents:

Answer 8

Depolarisation (firing) of the atria

Question 9

Conduction pathway in 6 steps

Answer 9

1. SA Node initiates atrial depolarisation causing Pwave.
2. Impulse is delayed at the AV Node (PR segment)
3. Ventricular depolarisation begins at the apex (QRS) + atrial repolarisation occurs.
4. Vent depolarisation occurs (ST segment)
5. Ventricular repolarisation begins at the apex (Twave).
6. Ventricular repolarisation complete

Question 10

Normal length of P Wave:

Answer 10

Less than 3 squares or 0.12 seconds

Measurement starts from the start of the P wave and goes to the end of the P wave.

Question 11

Normal amplitude of a P wave:

Answer 11

Less than 1.5 squares in precordial leads (V1-V6).

Less than 2.5 squares in limb leads (I-III, aVL, aVR, aVF).

Question 12

A a abnormally large P wave indicates:

Answer 12

A problem with the atria.

E.g. left atrial/right atrial hypertrophy)

Question 13

Describe the QRS complex waveform:

Answer 13

Q -Initial deflection below the equatorial isoelectric baseline

R - Entire wave above the baseline

S - The entire wave below the baseline

Question 14

Length of a normal (narrow) QRS:

Answer 14

Less than 3 squares.

The QRS begins from the start of the Q wave and ends after the S wave.

Question 15

Wide QRS complex indicates:

Answer 15

Blockages along the conduction system (bundle branch blocks)

or

electrolyte abnormalities

Question 16

When you see the T wave, the ventricles are:

Answer 16

Recharging to fire again (repolarising)

Question 17

Normal T wave is:

Answer 17

Less than 1 box in precordial leads

Less than 2 boxes in the limbs leads`

Question 18

PR interval measures from:

Answer 18

Start of the P wave (atrial depolarisation)

to the

Start of the QRS complex (ventricular repolarisation)

Question 19

Describe the PR interval in simple terms:

Answer 19

Electrical impulse is sent from the Sinoatrial node (SA) to the atrioventricular node (AV)

AV node chills for a bit, and then activates the septum down the Bundle of His to the ventricles

If the AV node is chillin’ too much, then there is some form of ‘heart block’

Question 20

Normal PR interval:

Answer 20

Less than 1 box/ 5 small squares

Question 21

PRT segment is useful to look for:

Answer 21

Pericarditis

Question 22

PR segment is measured from:

Answer 22

The end of the P to the start of the QRS segment

Question 23

ST segment is measured from:

Answer 23

End of the QRS to the start of the T wave.

Question 24

Where is the J Point?

Answer 24

The point where the QRS changes slope and becomes the ST segment.

Question 25

U waves are:

Answer 25

Repolarisation waves.

Not well understood. Show up in a few clinicial scenarios including hypothermia.

Question 26

The R-R interval is:

Answer 26

The time between each ventricular depolarisation (beats).

Question 27

QT interval is measured from:

Answer 27

The start of ventricular repolarisation (QRS)

to the

End of ventricular repolarisation (T wave)

Question 28

A long QT interval indicates:

Answer 28

Ventricular depolarisation while