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Click below to check out all of the ECG questions in our BRAND NEW Geeky Quiz system! 🎉🎉🎉

Check out our new ECG quiz

Once on the ward, you’ll be asked to comment on ECGs regularly, therefore it’s really important to understand how to read an ECG quickly and effectively.

So make sure to check out the ECG articles here and then take the ECG quiz to test your knowledge!

ECG quiz

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Question 1
A patient is noted to have an abnormally shortened PR-interval on their ECG. Which of the following is the most likely cause?
A
Right bundle branch block
B
Wolf Parkinson White Syndrome
C
AV nodal fibrosis
D
Left bundle branch block
Question 1 Explanation: 
A short PR-interval indicates abnormally short conduction time between the atria and ventricles. This is caused by the presence of an accessory pathway between the atria and ventricles. Wolf parkinson white syndrome is an example of this kind of disorder. In WPW the an accessory pathway known as "the bundle of kent" is present. Most individuals are asymptomatic however there is a risk of sudden death without treatment.
Question 2
What is the duration of a normal PR-interval?
A
0.12 - 0.2 seconds (3-5 small squares)
B
0.04 - 0.12 seconds (1-3 small squares)
C
0.04 - 0.08 seconds (1-2 small squares)
D
0.08 -0.12 seconds (2-3 small squares)
Question 2 Explanation: 
n normal individuals the PR-interval is between 0.12-0.2 seconds. A PR interval longer than this can suggest the presence of heart block and a short PR-interval can suggest an accessory pathway between the atria & ventricles e.g. WPW syndrome
Question 3
What is the normal duration of a QRS complex?
A
0.16 seconds (4 small squares)
B
0.12 seconds (3 small squares)
C
0.04 seconds (1 small square)
D
0.08 seconds (2 small squares)
Question 3 Explanation: 
In most healthy individuals you would expect QRS complexes to be around 0.12 seconds or slightly less. If a QRS complex lasts longer it is described as a "wide QRS" and can be a sign of inefficient conduction of the ventricles such as bundle branch block.
Question 4
The absence of P-waves and an irregular rhythm would suggest a diagnosis of...
A
2nd degree heart block
B
Atrial fibrillation
C
1st degree heart block
D
Ventricular tachycardia
Question 4 Explanation: 
In atrial fibrillation the atria no longer conduct electricity from the SA in an orderly fashion. Therefore P-waves are lost. As a result of disordered atrial activity only occasional waves of depolarisation pass through to the AV node and cause ventricular activation. This causes the typical irregular rhythm.
Question 5
Which artery is most likely to be affected if ST elevation in present in leads V3 and V4?
A
All of the above
B
Left anterior descending coronary artery
C
Right coronary artery
D
Left circumflex coronary artery
Question 5 Explanation: 
Leads V3 and V4 related to the anterior portion of the heart. Therefore ST elevation in these leads suggests an anterior infarct. The anterior portion of the heart is supplied mainly by the left anterior descending artery therefore this is most likely to have been affected.
Question 6
What is the most common cause of left axis deviation?
A
Left ventricular hypertrophy
B
Right ventricular hypertrophy
C
Atrial septal defects
D
Defects of the conduction system
Question 6 Explanation: 
Left axis deviation is rarely the result of left ventricular hypertrophy and more often due to defects in the conduction system of the heart.
Question 7
What view of the heart do leads V3 & V4 represent?
A
Inferior
B
Lateral
C
Septal
D
Anterior
Question 8
What does ST-elevation suggest?
A
Heart block - Mobitz type II
B
Bundle Branch Block
C
Myocardial infarction
D
Heart murmur
Question 9
What view of the heart do leads V1 & V2 represent?
A
Lateral
B
Anterior
C
Septal
D
Inferior
Question 10
If there were 3 large squares in an R-R interval what would the heart rate be?
A
70 bpm
B
80 bpm
C
90 bpm
D
100 bpm
Question 10 Explanation: 
To calculate heart rate from an ECG you count the number of large squares in an R-R interval then divide 300 by this number. Therefore 300/3 = 100 bpm.
Question 11
What would it suggest if lead I became more positive than lead II and lead III became negative?
A
Left axis deviation
B
Right axis deviation
Question 12
If ST-elevation was noted in leads II, III and aVF what would it suggest?
A
A posterior myocardial infarction
B
An inferior myocardial infarction
C
A septal myocardial infarction
D
An anterior myocardial infarction
Question 12 Explanation: 
Leads II, III and aVF all look at the heart in the inferior plane. Therefore ST-elevation in only these leads suggests an inferior myocardial infarction.
Question 13
If a rhythm is described as sinus, what does this indicate?
A
A QRS-complex precedes each T-wave
B
A P-wave precedes each QRS-complex
C
QRS-complexes are present
D
P-waves are present
Question 13 Explanation: 
If a rhythm is described as sinus it indicates that a P-wave precedes each QRS-complex. However a rhythm can still be irregular even if it's sinus.
Question 14
What is often the earliest ECG change seen during myocardial infarction?
A
ST-elevation
B
ST-depression
C
Tall P-waves
D
Tall peaked T-waves
Question 14 Explanation: 
Tall peaked T-waves can suggest a number of abnormalities. If seen in all leads then they usually suggest the individual has hyperkalaemia. However if tall T waves are seen in a particular group of leads it suggests early MI. The tall T waves are due to potassium leaking through the damaged membrane over the infarcted area.
Question 15
What view of the heart do leads I, aVL, V5 and V6 represent?
A
Septal
B
Inferior
C
Lateral
D
Anterior
Question 16
What view of the heart do leads II, III and aVF represent?
A
Anterior
B
Inferior
C
Septal
D
Lateral
Question 17
The duration of the PR interval is noted to be increasingly prolonged. In addition QRS complexes appear to be dropped at regular intervals. What diagnosis would this suggest.
A
Second degree - Mobitz Type 2 - Heart Block
B
Second degree - Mobitz Type 1 - Heart Block
C
Hyperkalaemia
D
First degree Heart Block
Question 17 Explanation: 
Second degree - Mobitz Type 1 - Heart Block is a disease of the AV node. It is seen as progressive prolongation of the PR-interval with associated regular dropping of the QRS complex.
Question 18
What is a common cause of right axis deviation?
A
Right ventricular hypertrophy
B
Atrial septal defect
C
Ventricular septal defect
D
Left ventricular hypertrophy
Question 18 Explanation: 
In right ventricular hypertrophy the increased muscle mass of the right ventricle causes increased signal on the ECG. As a result the axis of the heart is shifted to the right with lead III becoming more positive and lead I and II becoming less positive.
Question 19
What would it suggest if lead I became negative and lead III became more positive than lead II?
A
Right axis deviation
B
Left axis deviation
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