ECG Quiz Answers

Question 1

Which leads show anterior view of the heart?

Answer 1

V3, V4

Question 2

ECG features of complete heart block?

Answer 2

P waves and QRS complexes are completely unrelated

- indicates no co-ordinated electrical communication between the atria and ventricles

Question 3

Lead I, II, III deflections in right axis deviation?

Answer 3

Lead III most positive

Lead I negative

Question 4

Lead I, II, III deflections in normal cardiac axis?

Answer 4

Lead II most positive

Question 5

Lead I, II, III deflections in left axis deviation?

Answer 5

Lead I most positive

Leads II, III negative

Question 6

Heart rate calculation on ECG?

Answer 6

• count number of large squares within one R-R interval
• divide 300 by this number to calculate heart rate

e.g. 4 large squares between R waves. HR = 300/4 = 75bpm

Question 7

Normal length of PR interval?

Answer 7

0.12-0.20 seconds (120-200 milliseconds or 3-5 small squares on ECG paper)

Question 8

What are short PR intervals associated with?

Answer 8

Pre-excitation syndromes e.g. Wolff-Parkinson-White syndrome

Question 9

What are prolonged PR intervals associated with?

Answer 9

AV blocks e.g. 1st-degree AV block/heart block

Question 10

How is first-degree heart block represented on ECG?

Answer 10

Fixed prolonged PR interval (>200ms)

Question 11

Common causes of first-degree heart block?

Answer 11

AV nodal disease
Enhanced vagal tone (e.g. athletes)
Myocarditis
Acute MI (esp acute inferior MI)
Electrolyte disturbances
Medications

Question 12

Drugs that commonly cause first-degree heart block?

Answer 12

CCBs
B-blockers
Cardiac glycosides (digoxin)
Cholinesterase inhibitors
Digitalis

Question 13

Features of Mobitz Type 1 second-degree heart block on ECG?

Answer 13

Slowly increasing PR interval with a regularly dropped QRS complex

Question 14

Inferior MI ECG features + corresponding coronary artery?

Answer 14

ST elevation in II, III, aVF

- most commonly right coronary artery

Question 15

Anterior/Septal MI ECG features + corresponding coronary artery?

Answer 15

ST elevation in V3, V4 (anterior) or V1, V2 (septal)

- left anterior descending artery

Question 16

High lateral MI ECG findings + corresponding coronary artery?

Answer 16

ST elevation in I, aVL

- left anterior descending artery branch

Question 17

Low lateral MI ECG findings + corresponding coronary artery?

Answer 17

ST elevation in V5, V6

- circumflex artery branch

Question 18

Occlusion of right ventricular branch of right coronary artery can give rise to?

Answer 18

Isolated ST elevation in V1, V2

Question 19

Occlusion of circumflex artery can also present with?

Answer 19

Posterior ST elevation (V7-V9) and anterior ST depression in V2-V4

Question 20

Earliest sign of MI?

Answer 20

Tall T-waves (rarely seen as is during the hyperacute period)
- ST elevation more commonly noted

Question 21

Tall tented T waves = ?

Answer 21

Hyperkalaemia

Question 22

Mobitz Type 2 second-degree heart block ECG findings?

Answer 22

PR interval but there are dropped beats (will be clarified by frequency of dropped beats)
- type 1 has prolonging PR interval

Question 23

Atrial fibrillation ECG features?

Answer 23

Irregularly irregular + absence of clear P waves

Question 24

Normal QRS complex duration?

Answer 24

~0.12 seconds or slightly less (3 small squares)

Question 25

What is a QRS complex described as if it lasts longer than 0.12 seconds and what is it a sign of?

Answer 25

"Wide QRS" | - sign of inefficient conduction of the ventricles, such as in bundle branch block

Question 26

Method of calculating HR from ECG when pulse is irregular?

Answer 26

Count number of complexes on the rhythm strip (10 seconds long) Multiply the number of complexes by 6 (average no. of complexes in 1 minute)

Question 27

What condition is a Delta wave associated with?

Answer 27

Wolff-Parkinson-White syndrome

Question 28

What does diagnosis of WPW syndrome require?

Answer 28

Evidence of tachyarrhythmias AND a delta wave

Question 29

What does a delta wave mean about the myocardial conduction?

Answer 29

Early activation of the ventricles from a point distant to the AV node - the early activation then spreads slowly across the myocardium causing a slurred upstroke to the QRS complex