ECGs

Question 1

Antero-Septal Leads

Answer 1

V1-V4

Question 2

Inferior Leads

Answer 2

II, III and aVF

Question 3

Lateral Leads

Answer 3

V5-V6, I, aVL

Question 4

ST elevation in antero-septal leads, with ST depression in inferior and lateral leads

Answer 4

Acute antero-septal MI

Left anterior descending coronary artery

Question 5

Broad Complex Tachycardia

Answer 5

Ventricular Tachycardia

Question 6

What may be seen on ECG in a digoxin overdose (with no toxicity)?

Answer 6

Reversed-tick-ST segment depression

First degree heart block

Question 7

What may be seen on ECG in digoxin toxicity?

Answer 7

Complete atrioventricular block

Ventricular tachycardia

Question 8

Causes of prolonged QT interval?

Answer 8

Drugs
Hypokalaemia
Bradycardia
Congenital

Question 9

Normal QRS axis on ECG?

Answer 9

-30 to +90

Question 10

Right axis deviation values?

Answer 10

+90 to +180

Question 11

Causes of right axis deviation?

Answer 11

Right ventricular hypertrophy 
Acute right ventricular strain (e.g. PE)
Anterolateral MI 
Some types of WPW syndrome
Right bundle branch block
Left posterior hemiblock (rare)

Question 12

What would you see on ECG of Wolff-Parkinson-White Syndrome?

Answer 12

Delta wave

Question 13

What does the delta wave on ECG of Wolff-Parkinson-White Syndrome represent?

Answer 13

Premature activation of the ventricles via an accessory electrical conductance pathway between the atria and ventricles

Question 14

What does the P wave represent on an ECG?

Answer 14

Atrial depolarisation

Question 15

What does the QRS complex represent on an ECG?

Answer 15

Ventricular depolarisation

Question 16

What does the T wave represent on an ECG?

Answer 16

Ventricular repolarisation

Question 17

Why is no atrial repolarisation visible on ECG?

Answer 17

It is masked by the QRS complex (ventricular depolarisation)

Question 18

Which point on the ECG coincides with the first heart sound?

Answer 18

QRS complex

Question 19

Which point in the ECG coincides with the second heart sound?

Answer 19

T wave

Question 20

What does the QT interval represent?

Answer 20

Ventricular systole

Question 21

How do you calculate ECG heart rate?

Answer 21

Divide 300 by the number of big squares per R-R interval

Question 22

Sinus rhythm characterisation?

Answer 22

P wave followed by QRS complex

Question 23

Atrial fibrillation characterisation?

Answer 23

No discernable P wave

Irregularly irregular QRS complex

Question 24

Atrial flutter characterisation?

Answer 24

Saw tooth baseline of atrial depolarisation

Regular QRS complexes

Question 25

Nodal rhythm characterisation?

Answer 25

Normal QRS complexes | Absent P waves (or P waves which occur just before/within QRS)

Question 26

Ventricular rhythm characterisation?

Answer 26

Broad QRS complexes with P waves following

Question 27

Left axis deviation values?

Answer 27

-30 to -90

Question 28

Causes of left axis deviation?

Answer 28

``` Left anterior hemiblock Inferior MI VT from LV focus Some types of WPW syndrome Left ventricular hypertrophy ```

Question 29

What could cause absent P waves?

Answer 29

Atrial fibrillation Sinoatrial block Junctional (AV nodal) rhythm

Question 30

What is the normal duration of the PR interval?

Answer 30

0.12-0.2s

Question 31

What is the normal duration of the QRS complex?

Answer 31

Less than 0.12s

Question 32

What might cause prolonged QRS complex?

Answer 32

Ventricular conduction defects

Question 33

What might cause a large QRS complex?

Answer 33

Ventricular hypertrophy

Question 34

When might you see pathological Q waves?

Answer 34

Hours after an MI

Question 35

What does ST elevation imply?

Answer 35

Infarction

Question 36

What does ST depression imply?

Answer 36

Ischaemia (e.g. NSTEMI)

Question 37

When would T waves be peaked?

Answer 37

Hyperkalaemia

Question 38

When might T waves be flattened?

Answer 38

Hypokalaemia

Question 39

How do you calculate ECG heart rate if it is irregular?

Answer 39

Count the number of QRS complexes in 30 large squares and multiply by 10

Question 40

How would First Degree AV Block present on an ECG?

Answer 40

Prolongation of PR interval | Every P wave is still followed by a QRS

Question 41

How would Mobitz Type I present on an ECG?

Answer 41

Progressive prolongation of PR interval until QRS is dropped

Question 42

How would Mobitz Type II present on an ECG?

Answer 42

Regular PR interval, with every nth QRS complex missing

Question 43

How would Third Degree AV Block present on an ECG?

Answer 43

No relationship between P waves and QRS complex | May see bradycardia and low cardiac output due to ventricular pacing by Purkinje fibres

Question 44

ST elevation in leads I, II and aVF is likely to be caused by stenosis in which artery?

Answer 44

Right coronary artery

Question 45

ST elevation in leads V1-6, I and aVL is likely to be caused by stenosis in which artery?

Answer 45

Left main stem

Question 46

ST elevation in leads I, aVL and V5-6 is likely to be caused by stenosis in which artery?

Answer 46

Circumflex

Question 47

ST elevation in leads V1-V4 is likely to be caused by stenosis in which artery?

Answer 47

Left anterior descending

Question 48

How would right bundle branch block appear on ECG?

Answer 48

Deep S waves in leads I and V6 | Tall later R waves in lead V1

Question 49

How would left bundle branch block appear on ECG?

Answer 49

Deep S waves in lead V1 Tall late R waves in leads I and V6 Abnormal Q waves

Question 50

How would a posterior STEMI appear on ECG?

Answer 50

Tall R waves | ST depression in V1-V2