ECG interpretation

Question 1

Which way does an ECG spike when a signal is moving towards a recording electrode?

Answer 1

Upwards

Question 2

What should the patient’s position be when undergoing an ECG?

Answer 2

Lying down 30-40˚

Question 3

Where should V1 be placed?

Answer 3

4th right intercostal space, sternal angle

Question 4

Where should V2 be placed?

Answer 4

4 left intercostal space, sternal angle

Question 5

Where should V4 be placed?

Answer 5

5th left intercostal space

Question 6

Where should V6 be placed?

Answer 6

Mid-axillary line, same level as V4

Question 7

What is the order in which an ECG should be interpreted?

Answer 7

1. Name, DOB, date and time of ECG
2. Calibration
3. Rate
4. Rhythm
5. Axis
6. P wave
7. PR interval
8. QRS complex
9. ST segment
10. T waves

Question 8

What’s the usual calibration of an ECG?

Answer 8

25 mm/sec

Question 9

How is heart rate calculated?

Answer 9

300/number of large squares between beats

Question 10

What does the PR interval represent?

Answer 10

The delay created by the AV node

Question 11

What is a normal PR interval?

Answer 11

120-200 ms

2-5 small squares

Question 12

What does the QRS complex represent?

Answer 12

Ventricular depolarisation

Question 13

What is a normal QRS complex length?

Answer 13

<120 ms

3 small squares

Question 14

What is QRS complex elongation caused by?

Answer 14

Aberrant conduction or ventricular origin

Question 15

What does a P wave represent?

Answer 15

Atrial depolarisation

Question 16

What is a normal P wave?

Answer 16

<2.5mm in height

<3mm in width

Question 17

What does a T wave represent?

Answer 17

Ventricular repolarisation

Question 18

What is a normal T wave?

Answer 18

Normally same directions QRS and no more than 1/2 QRS height

Question 19

What is sinus rhythm?

Answer 19

Normal rhythm where heart is controlled by SA node

Question 20

What is sinus arrhythmia?

Answer 20

Sinus rhythm but heart rate is irregular

Question 21

What is the origin of supraventricular arrhythmias?

Answer 21

Within or above the ACnode

Question 22

What is happening in atrial fibrillation?

Answer 22

Atria are in fibrillation, only some of the SA impulses arrive in the AVN

Question 23

What are features of AF on an ECG?

Answer 23

Absent P waves
Irregularly irregular
Ragged baseline
Ventricular rate 30-200bpm

Question 24

What is there a risk of in AF?

Answer 24

Embolic stroke

Question 25

What are features of atrial flutter on an ECG?

Answer 25

Narrow complex tachycardia Atrial rate of approx. 300bpm Sawtooth baseline

Question 26

What is Wolf-Parkinson-White syndrome?

Answer 26

Arrhythmia with an accessory AV pathway which does not have AVN delay. This causes pre-excitation and upscoping of the QRS (delta wave)

Question 27

What are features of supraventricular ectopic arrhythmia on ECG?

Answer 27

Varying PR and RR interval

Question 28

Why do ventricular arrhythmias have broad QRS complexes?

Answer 28

Excitation spreads slower moving through normal myocardium than through the regular conduction system

Question 29

What arrest rhythms are shockable?

Answer 29

Ventricular tachycardia or fibrillation

Question 30

For which arrest rhythms would you do CPR?

Answer 30

Pulseless electrical activity, asystole

Question 31

What causes ventricular tachycardia?

Answer 31

Damaged heart muscle formed scar tissue, creating abnormal (re-entrant) electrical pathways

Question 32

What is the difference between monomorphic and polymorphic ventricular tachycardia?

Answer 32

Monomorphic - tachycardia coming from a single focus | Polymorphic - tachycardia coming from multiple foci

Question 33

What are the features of monomorphic ventricular tachycardia on an ECG?

Answer 33

Regular broad complex tachycardia

Question 34

What are the features of polymorphic ventricular tachycardia on an ECG?

Answer 34

Long QT | Torsade de Pointes (arctic monkeys cover type pattern)

Question 35

What is happening in ventricular fibrillation?

Answer 35

Ventricles fibrillate (contract at rates of up to 500bpm), renders heart incapable of synchronised beat

Question 36

What are features of ventricular fibrillation on ECG?

Answer 36

Irregular random baseline with no discernible waveform

Question 37

Which leads most detect a lateral MI?

Answer 37

1, aVL, V5, V6

Question 38

Which leads most detect an anterior MI?

Answer 38

V1-4

Question 39

Which leads most detect an inferior MI?

Answer 39

II, III, aVF

Question 40

What are features of ischaemia on ECG?

Answer 40

T waves: tall, biphasic, inverted, flattened | ST depression

Question 41

What is classed as ST elevation?

Answer 41

ST elevation in 2 contiguous limb (>1mm) or chest (>2mm) leads

Question 42

What are features of NSTEMI on ECG?

Answer 42

Transient ST elevation ST depression New T-wave inversion

Question 43

What is heart block?

Answer 43

Block in conduction between atria and ventricles due to AV node dysfunction

Question 44

What is first degree heart block?

Answer 44

PR interval >2s, no progressive lengthening, stable rhythm

Question 45

What is second degree heart block Mobitz I?

Answer 45

Progressive PR elongation with eventual missed beat

Question 46

What is second degree heart block Mobitz II?

Answer 46

Constant PR interval, every 2nd p-wave (approximately) missing QRS

Question 47

What is third degree/complete heart block?

Answer 47

No p-wave and QRS relationship, broad QRS

Question 48

What is bundle branch block?

Answer 48

Block in one of the 2 main branches coming off the Bundle of His

Question 49

What does bundle branch block look like?

Answer 49

WILLIAM MARROW - LBBB: V1 = W, V6 = M  - RBBB: V1 = M, V6 = W